The Cactus Ferruginous Pygmy-Owl
The Pygmy-Owl Issue in Perspective
Dr. Lisa Harris
The Pygmy-Owl in Historical Context
Russell Duncan
The Natural History of the Ferruginous Pygmy-Owl in Texas
Glenn Proudfoot
The Pygmy-Owl in Arizona
Scott Richardson
THE PYGMY-OWL ISSUE IN PERSPECTIVE
Lisa K. Harris, Ph.D, President of Harris Environmental Group,
Inc.
The Arizona population of the cactus ferruginous pygmy-owl was listed as an endangered species under the Endangered Species Act a mere two years ago. I thought that was interesting because my life has been obsessed with it over the last two years and it seems like a lot longer than that. At the time of its listing we knew virtually nothing about the bird or we knew very little.
There were very basic questions that needed to be answered such as the following:
1.How many birds are out there?
2.What is the life history of the bird?
3.What is the natural history of the bird?
4.What are the habitat needs?
5.What components of the landscape does this species need to go about its daily business?
These are basic questions; questions that science and studies answer. At the time the pygmy-owl was listed we knew the whereabouts of about 12 individuals. In the two years, there have been a lot of studies initiated that aid in answering the questions, however, we still have a long way to go.
Now we have studies that are funded at the local level by Pima County, at the state level by Arizona Game and Fish; at the federal level by the U.S. Fish and Wildlife Service and at the academic level by Texas A &M University, and these studies have provided more information about this individual species in Arizona.
We now know the whereabouts of approximately 70 individuals. So in the two years, we have gotten a lot better about finding them. Last year was a very good year because of the increased rainfall. About one-half of the individuals out there are juveniles and one-half are adults. It is hoped that next year those juveniles will survive to be breeding individuals.
Three experts will discuss what is known about the species and what has been learned within the last two years.
Russell Duncan will be the first presenter. Mr. Duncan is the President of R.B. Duncan and Associates, a natural resource consulting firm located in Tucson, Arizona.
Mr. Duncan is one of the better field biologists in the country and Russell is going to discuss the historic distribution of the owl as well as the current distribution which is one of the basic questions needing an answer in order to help this bird get off the Endangered Species list.
THE PYGMY-OWL IN HISTORICAL CONTEXT
Russell Duncan, R.B. Duncan &Associates Biological Consultants
I plan to speak about the ferruginous pygmy-owl in Arizona, its historical context beginning in 1872 when the bird was first identified in the Tucson Basin, all the way up to 1997. That is the historical context brought to light this afternoon.
First of all, I started this project about four years ago when the cactus ferruginous pygmy- owl was beginning to become the focal species in Tucson. The last species that was as notorious in Tucson was the Tumamoc Globeberry, a rare plant that had a lot of affects on private lands and federal lands for development.
(Slide)
First I would like to acknowledge the Fish and Wildlife Service
for partially funding this study and I would also like to thank
my colleagues who assisted the most with this historical data
gathering and discussion: Roy Johnson, Gale Monson, Steve Russell,
Tim Tibbetts and a host of others. I would also like to thank
the museum curators who really do not get their due and recognition.
There is a wealth of information in museums throughout the United
States and Canada. I am also thankful to all the technicians who
helped us beat the bush for pygmy owls last year and those who
are assisting this year. Pamela Swantek Ecological Database Designs
now with Saguaro National Park assisted with the maps you will
see tonight.
I contacted all the museums and fortunately with the Internet today, you can simply do that with one E-Mail message by sending it simultaneously to all the museum curators throughout North America and then you wait. Sometimes you wait and wait and wait until they get back from Borneo or some other hinterlands where they may be collecting birds. I also spoke with professional biologists and competent lay persons regarding the pygmy-owls in Arizona.
There is a wealth of information available from many people in Tucson who are both professionals and lay persons, and who are familiar with this species for all the time they have been here. I met one person who is 80 plus years who witnessed Alan Phillips blast a bird from their drinking fountain back in 1948 which was one of the last birds to be seen at Campbell and River Road. I produced a series of maps and I used those maps to delineate the known range of the species to base our survey of last year. Lisa Harris and I, with a host of our employees, went about surveying the species throughout its range from north of Phoenix, west along the Gila River and south all the way to the International border with Mexico.
THE RESULTS: I identified approximately 165 pygmy-owl records from various sources between the years 1872 to 1997. The species was first identified in Tucson at Fort Lowell Road near Craycroft Road where the Fort Lowell Museum is currently located, but probably a little more upstream where there is still some springs in evidence. The species was found as far north as New River, the dates and parentheses are when they were first collected at these sites. Cave Creek, and this is the northernmost extent of their range and then south to the Mexican border. In the border region they have been found at Organ Pipe and on the Tohono O'odham Nation. The first year they were sited in Organ Pipe was in 1954, but I actually think the records were in the late 1940's. The Tohono O'odham Nation, had a collection from 1933, the Altar Valley in 1982, Patagonia in 1975, Ruby along Sycamore Canyon in 1979. The westernmost record of pygmy-owl presence was in Agua Caliente in 1896, this is in the extreme western Maricopa County along the Gila River near Yuma County. If you have ever been there, it is incredibly arid at this time and it was a former stagecoach stop and hot springs. It was a welcome respite for people on their way to Yuma and to the west coast from Tucson. The easternmost credible record was from Old Camp Goodwin near present day Geronimo along the Gila River in western Graham County. There are no verifiable records from either Cochise or Greenlee Counties. The two published records for Cochise were later recanted by the authors who submitted them for publication. The one record, unpublished for Greenlee County, has yet to be verified and it was probably misidentified.
Another record, unpublished again, was from eastern Graham County that has not been substantiated and was probably also misidentified. These were along the Gila River, or a confluence of them, near the San Francisco River area in eastern Arizona. To date, no one has ever identified the one-time records by one individual observing the birds. This is not to say that person was not a credible observer, but it has never been resubstantiated.
(Slide)
This is what the map looks like from all of the records from 1872
to 1997 and these two are the northernmost including New River
and Cave Creek in the Phoenix Area on the Salt River. This is
the blue point area at the confluence of the Verde River, the
Salt River and the Agua Caliente. It is an incredibly dry area.
An individual (?) in southeastern Yuma County was probably a transient
bird and has never been seen since 1955. The records for the Organ
Pipe area I have are more toward the middle of the Tohono O'odham
Nation.
When I had this map made, I received one record from Occidental College in Los Angeles and there is also a record now for Fresno Canyon on the Tohono O'odham Nation on the west side of the Baboquivari Mountains. These are all the Altar Valley records, the Patagonia area has two records that are credible. One record at Sycamore Canyon and all of these records have now been refuted or are questionable that include two in Cochise County, one in Greenlee and one in eastern Graham counties. This is Fort Goodwin; it is very difficult to locate the old fort and there are all of these records in the Tucson Basin. Some of the records represent present day while others are historical. The 1872 record along the Rillito Creek indicate it was once intimately flowing in that area. Pinal County is mostly associated with the Gila River watershed; at Superior, it was actually at the Boyce-Thompson Arboretum which is a combined map.
(Slide)
This is the first 50-year period where all the historical explorers
were spending their time and found pygmy-owls. The Tucson area
associated with Fort Lowell, the Sacaton area and Blackwater area
had a BIA agent working on the Pima Reservation. The New River
and Cave Creek area represent museum collections. These are birds
that were actually collected by collectors who were "hired
guns" by universities. Many of them were biologists, others
were amateurs and egg collectors and they were actually paid by
the egg set or by the bird. The more important the bird, the more
they would get paid for it. Again, the Agua Caliente was a stage
stop and we can thank those collectors for knowing where the pygmy-owl
was because it has lost ground as you will understand today
(Slide)
This is the second 50-year period where some of their research
was just beginning on birds in general in Arizona. There was a
researcher in the late 1940's who later published his studies
on birds in Organ Pipe. Gale Monson, one of the co-authors of
"The Birds of Arizona," with the Fish and Wildlife
Service out on the refuge identified an individual bird at the
Cabeza Prieta Tanks. If anybody has been out there, you would
just never think it would be pygmy-owl habitat since Bighorn Sheep
do fairly well out there. As a point of information, many records
are in a museum in Northern Arizona at Flagstaff in a little used
bird collection.
(Slide)
This map represents a 20-year period in the 60' and 70's. This
is where a lot of the records came from in that time period and
most of these records are from non researchers. They continue
to be found here, and you can see how the range has contracted
since they are no longer being found in this area around the Phoenix
Salt River and Gila River. This is where they are all known to
be from, from the Organ Pipe area on the Tohono O'odham Nation
and are also known in a fairly good sized population of six or
more territories in the Altar Valley and in the Tucson Basin.
Many of these are found in the Tortolita fan as you well know
that spreads out in the south flank and west flank to the mountain
ridge.
We identified four sites last year. Out of all that acreage that we surveyed, we only identified four sites. We concentrated on areas outside of the Tucson Basin Proper. Game and Fish was covering much of that area since we already knew where they were in the Tucson Basin area. We covered areas in the Altar Valley all the way up to New River and even went as far as Wickenburg along the Hassayampa Creek, which I thought was possibly potential (pygmy-owl habitat) even though no historical records came from there. We went all the way over to the Superior area, Florence, down to Santa Cruz County and all we found were four territories. Two are in southern Pima County in the Altar Valley and two in southern Pinal County.
The two sites identified in Pinal County were in Arizona Uplands Desertscrub and the two sites were found in backwoods. The two sites in Pinal County are interesting in that they are in the same general habitat that was described historically. That is, they are in mesquite/ cottonwood/ hackberry habitat along free flowing reaches of streams and their tributaries.
In addition, there are other territories found recently that is different than what is now being found in Pima County. Most of it is Sonoran Desertscrub with the Arizona Upland being palo verde and the characteristic saguaro being ever present. In that habitat it has been saguaros and down in the Altar Valley where we found them, they likely nest in woodpecker cavities that have been excavated in Arizona walnut and ash. Although they do make nests in the mesquite, the softer broadleaf trees are a preferred site since there are no saguaros there whatsoever. The results of our historical records search and all our surveys definitely validate the map that was produced by Phillips et al. in 1964. It differs with Monson's in that all of the records included by Monson in eastern Graham and western Greenlee counties are highly suspect because they have never been verified before. The maps are also likely extralimital and do not really reflect the normal range of the species. I am not saying they were not ferruginous pygmy-owls it is just that such records would not be accepted by the Arizona Bird Committee which is why I left them out of the credible record. The published Yuma County record that Gale Monson identified should still be considered hypothetical and extralimital because it is a single observer record, even though Gale Monson is one of the most competent, he is certainly probably the top, living ornithologist in Arizona but still, it should be considered suspect even though it was a credible record because there was no photographic voucher and no subsequent records. There have been no records west of Organ Pipe Cactus National Monument despite hundreds of hours of effort being funded by the military on Cabeza Prieta and on the Barry M. Goldwater Gunnery Range with no pygmy-owls being identified. Again, habitat at the Pima County sites and on the Buenos Aires are like the historical records of the 1800's and early 1900's. The Sonoran Riparian Deciduous Forest with surface or near surface water present differs from most of our Pima County observations. At these sites which are east of Red Rock and on the north side of the Tortolita's, we found just Sonoran Desertscrub. If you are familiar with the Park Links Roadway between Red Rock and the Tom Mix Highway, that too is pygmy-owl habitat.
(Slide)
This is the habitat on the Buenos Aires and if you look at it,
it is much different from pygmy-owl habitat in the Tucson area.
As you can see there is water on the Buenos Aires. The tallest
trees are walnuts and hackberry's, mesquite, gray thorn and several
other thorn scrub-like species.
(Slide)
This is a view of the interior where the pygmy-owls were in incredibly,
very lush habitat. This is probably what Bendire found them in
along the Rillito at Fort Lowell. I have a picture of that general
area back in 1988 that I will show you. If you are familiar with
that stand that is now waning at the Craycroft Road crossing at
River Road and that is directly due to down pumping.
(Slide)
This is another site in Buenos Aires where there are seeps along
the drainageway. This is an ash tree, there is more ash and a
lot of mesquite. The upland habitat is scrub grassland, it is
more of what is described as mesquite savannah and unlike where
they are mainly found in the Tucson area. I'm not saying the pygmy-owl
spent a whole lot of time out there, certainly they probably forage
but they likely nest in the ash and hardwood trees. They spend
a lot of time along the corridor.
(Slide)
Here's a site in Pima County east of Red Rock which is typical
Sonoran Desert Scrub. There is no ironwood present there, but
there is a lot of mesquite. It is very diverse structurally.
(Slide)
Here is a picture of that area near Fort Lowell. Most of the trees
are dying and there is very little recruitment going on and we
will probably lose that entire stand in the next 10 years...if
that.
(Slide)
To wrap things up, the historical record search and our recent
surveys definitely show a decline of species that is notably evident
in the northern part of the former range along the Gila and Salt
River Basins near Phoenix. Declines have also occurred elsewhere
in these watersheds. There has been a local decline in the Tucson
Basin but we are finding more and more birds everyday, much more
than (we knew were present) when the bird was listed. According
to Roy Johnson as a collaborator, we have a manuscript in preparation
that has incorporated the historical data. The range contraction
is likely the result of direct/indirect human related impacts,
primarily dam construction for diversion and flood control beginning
in the early 1900's in the Phoenix area, conversion of both riparian
and upland, non-riparian desertscrub habitats to croplands in
the Phoenix area, urban development, lowering of groundwater tables
for urban and agricultural uses and other causes.
There is a wealth of historical information out there and it still trickles in every day. I just uncovered some personal records by Florence Thornburg at the University of Arizona. She kept what is known as wetmore style cards; individual cards for individual species observations, detailed notes in a card file collecting dust at the U of A. If it were not for the curators such as Tom Huels, we biologists or the public would not have that information today. It is important that universities carry on that curatorial responsibility. There was (also a historical) record for the Immaculate Heart Catholic Nunnery on Sabino Canyon Road just before the Kolb Road bypass in 1949.
THE NATURAL HISTORY OF THE FERRUGINOUS
PYGMY-OWL IN TEXAS
Glenn Proudfoot, Texas A&M University
Thank you. I would like to begin by thanking Pima County for the opportunity to present some of my research on ferruginous pygmy-owls.
(Slide)
As mentioned, I will be presenting some of my research in Texas
on the natural history of the ferruginous pygmy-owl.
I would like to acknowledge all those who contributed to this project. It was a multifaceted study that could not have been conducted without the cooperation of federal and state agencies and private corporations. Eagle Optics should be added to this list.
The historical range of the ferruginous pygmy-owl included areas of Southern Arizona, Southern Texas extending south along both coasts in Mexico, through Central America into the southernmost population in Argentina. However, over the past 150 years urban and agricultural expansion within the United States has reduced its population to a few isolated pockets of uncertain stability. As you are all aware, in 1994 the U.S. Fish and Wildlife Service acting under petition, proposed listing the species as endangered in Arizona and threatened in Texas. In 1997, it was listed in Arizona as endangered, however, the listing in Texas was withheld until further research was conducted.
My primary study area is located on the Norias Division of the King Ranch. It is approximately 50 km south of Kingsville, Texas, about 100 miles south of Corpus Christi, Texas. The Norias Division is composed of three habitat types which include the coastal sand prairie, the live oak-mesquite forest which makes up about 100,000 acres, and the mesquite bosque or mesquite savannah areas. Norias overall is approximately 240,000 acres.
In 1992, Dr. Sam Beasom set the foundation for a ferruginous pygmy-owl nest box study by establishing 40 next boxes in areas of Norias known to be occupied by pygmy-owls. Now, the logic behind this was first off, to determine if pygmy-owls would use artificial nest structures and then if they would be a viable management tool if the species was listed. This was, as I say, started in 1992.
Secondly, it was to determine if they preferred a specific nest box configuration. They placed the boxes in eight sets of five and within each group, the configuration varied. The entrance diameter and the box depth varied. At this initial study, it was determined that pygmy-owls would use artificial nest structures. They had three of the sets being used in the first year and they did seem to prefer a specific configuration which was 14 inches deep from the center of the entrance and with a two-inch entrance diameter. Now this information allowed us to expand the project to what became my master's and the objectives were to determine if the availability of cavities controlled pygmy-owl habitat selection, determine nest box placement criteria, physical characteristics of habitat use, food habits and monitoring nesting biology.
Throughout this study, I have now established a little over 200 nest boxes for pygmy owls. I have placed them in various habitat types in areas that contain natural cavities with moderate to dense understory, areas that contain natural cavities with minimal to sparse understory, areas that lacked natural cavities with minimal to sparse understory and areas that lacked natural cavities with dense understory. Now with this study, the information suggests that the pygmy-owls were not selecting areas based alone on cavity availability but on habitat characteristics. They avoided all the areas with minimal to sparse understory and are only uses nest boxes in areas with moderate to dense understory. The age of the stand was not a significant variable since they would use them in young growth or old growth stands. They used them where they were cavities or without cavities.
On this initial study I kept with tradition and for the first six months or so of the study we inspected nest boxes with a ladder. However, in the second year of the study we were concerned that this type of inspection may cause a flushing of the individuals and abandonment of the nest. We incorporated the use of a miniature video camera placed on the end of a telescoping pole. Within that aluminum housing there is a camera that measures 1o" x 1o" x o" in and at the front of it we have a light source. This was then a fairly simple matter to extend the pole and insert the camera into the nest box and via video patch cable we ran the image to a monitor at the ground level. This system was beneficial not only in determining occupancy of nest boxes but it was also applied to natural cavities and in using this system I have as of yet, not had any birds abandon during inspection. I have now monitored 99 nests so far.
Although it worked well, it did have its limitations and that being the depth of field and the field of view of the camera limited the use to cavities that were only of a cylindrical configuration. When I came across natural cavities that had somewhat of a curvature to them I would use a flexible fiber optics stratoscope. With this system I could insert a lens that measures less than a quarter inch in diameter to a depth of eight feet inside the cavity to determine occupancy. Once occupancy was determined, they system was also used to monitor the nest sites to determine things such as incubation, hatching efficiency, nestling development and provide information that allowed me to determine when it was time to come out and band the young.
To obtain information on physical characteristics, of course, we first had to trap some of the birds and I used two capture techniques. The primary techniques used were mist nets. Mist nets were placed in areas known to be occupied by pygmy-owls and they are set up in various configuration, usually either a V-shape or a triangle. I would establish a net around either a mesquite or catclaw and then I would place a Johnny Stewart bird and animal caller at the center of the mist net configuration and broadcast specific calls.
The logic behind this was the territorial aggressive behavior of the pygmy-owl that would draw them into the mist nets responding to the call. In some instances, they will respond to the call and come in but they do not display enough aggressive behavior to get drawn into the nets so then I would establish baited bownets at the interior and exterior of the mist net configuration hoping that they would be drawn in and may not go into the net but that they may opt to try capturing the prey item. Once captured, whether it was in the bownet or mist net, they were removed and each individual was equipped with a U.S. Fish and Wildlife Service aluminum leg band for identification so we could obtain information on site fidelity, life expectancies, dispersal, movement patterns and physical measurements were taken which included the wing cord, the tail measurement, the (?) beak from the (?) down, tarsus and individuals were weighed.
Here, I have a 1.5" PVC for a restraining device to hold the birds. Initially, I started out -- to give you an idea of their size -- I started out using a 6 oz juice can for a restraining device, however, the first bird I put in it crawled out, there was so much room he just turned around and took off. So the very first pygmy-owl I caught, I lost. In addition to obtaining information on physical characteristics and after I trapped the birds during the first two years of the study, I would also collect blood samples to test the birds for hematozoa, blood parasites. This was done following veterinarian techniques. I would clip one toenail back until I obtained enough of the pulp to make blood flow and I made four smears.
They were separated into two sets. One set was sent to the International Reference Center for Etian Hematozoa at St. Johns University in Newfoundland and examined by Dr. Bennett who was the premier researcher on hematozoa at the time, he is now passed away. The other set was examined in-house at the Kleberg Institute. Throughout the study I have examined blood smears from 64 individuals and none of them have contained any blood parasites, hematozoa, plasmodium and luckocytazoan so this suggests that at least during the time of the study, blood parasites were not affecting the population.
In addition to making blood smears I also collected serum and this was to compare the mitochondrial DNA and in the initial study, we compared samples from birds in Texas as well as birds collected from northeastern Mexico and Argentina. This was done to determine if possible geographic variation has affected the genetic variability within the population. In Texas, there was also concern the population we were looking at was separated from the continuous population down in Mexico due to the urban and agricultural expansion along the Rio Grande River which between 1940 and 1970, over 90% of the habitat was removed. Now when we compared our samples, looking at the Cytochrome B in the MD loop, it showed that all of the birds within Texas had basically no variation at all, there was absolutely no difference in their genetic makeup and they could have all been clones of one another. This started throwing up red flags about inbreeding and we were concerned that this was actually showing some reduction in genetic variability. However, when we compared them to the population from northeastern Mexico which is also considered the cactus ferruginous pygmy-owl, there again, there was no variation in the genetic make up and in fact, there was no variation between the populations. The birds in Texas were similar to the birds in northeastern Mexico. This suggested that this might be a species specific physiology characteristic that the birds just do not have much variation within their genetic make up. However, when we looked at the birds from Cordova, Argentina, there was a 1.6% variation.
Now depending upon which geneticist you talk to this is enough of a variation to list a separate subspecies and when we compared it to the birds from (?) Argentina, we had a 2.1% variation which according to some geneticists, Dr. Kunig from the Stuttzgart Museum of Germany suggest that there is enough variation to list a separate species. Now we also were able to obtain one sample from Arizona during this analysis and we had a 1% variation so it suggests that there may be a difference between the Arizona population and the Texas population. However, more importantly, it suggests that additional research needs to be conducted when you are dealing with a sample of one.
Each individual was then affixed with a clotting agent and released.
(Slide)
This is a little indication of their size and this is not their
typical behavior. Usually if they have a chance to put their talons
on you, it is putting them in you and not just on you. Now while
I was obtaining information on the physical characteristics I
noticed a plumage difference between the males and the females.
Out of all the individuals that I have trapped so far in Texas
which now this year I approach #400 I believe I was running 387,
the females display more of a cinnamon rufous colortone than the
males in the wrinkle in the back in the upper wing and there is
less of a drastic variation in the tail vine, between the dark
and the cinnamon rufous colortones. The male is more of a chocolate
brown and has more of a variation in the tail vine. The males
is basically like comparing Hershey's Cocoa and Hershey's Nestle's
Quik, the female being Nestle's Quik of course. Now this information
was obtained from the birds in Texas and after looking at a few
of them, I suspect I have looked at approximately 18-20 pair that
first year. I decided that we should expand this study so I, like
Russell, contacted museums throughout the U.S. and I obtained
703 study skins to compare this characteristics to the identifications
made by museum preparator as far as sexual differences. When I
looked at the species throughout their range from Texas, Arizona
all the way down to Argentina there was a 68% correlation between
plumage characteristics and sex which really is not all that substantial.
When I separated out the northern population the cactus ferruginous
pygmy-owl, the correlation raised up to 82%, there was an 82%
correlation between plumage, colortones and sex. With the few
birds that we have been able to look at here in Arizona there
also seems to be these sexual dimorphic plumage characteristics.
(Slide)
Now here we have a test, how many females and how many males do
we have?
(Audience response) Six females.
Correct. This slide also shows a little variation in the plumage characteristics throughout their range. You will notice that some of the individuals like this one lacks the cinnamon rufous colortones that are actually used to distinguish the ferruginous pygmy-owl from the northern pygmy-owl or the eastern pygmy-owls. The characteristics we have here in the tail barring are similar to the Arizona population. The Arizona birds seem to be a little fainter than the Texas birds, the Texas birds as you saw before have more of the cinnamon rufous colortone in their tail.
(Slide)
To obtain information on habitat use, I established transmitters
on selected individuals captured. Now the first year, I only placed
transmitters on adults and I monitored them in the fall and during
the breeding season. However, during the second year I included
juveniles and this was done because I felt that tracking adults
would buy us more information, it would provide habitat and aerial
use from the adults, but it would not provide the information
needed to determine how much of an area you need to bring off
a successful brood.
What do you need for a nesting season for a nesting pair to be successful?
So far I have monitored 69 individuals of which 26 have been juveniles. They are tracked using portables receivers and yagyi antennas, using compass bearings and pace factors to estimate geographic location along with GPS units, satellite imagery. Satellite location, when you are working with it has its limitations because when you are in a heavy canopy, you cannot receive enough satellites to actually get a location so then I would use the compass bearing and pace factors.
To obtain information on habitat use, on each visual siting I would establish a tenth acre plot beneath the perch of each individual and collect information on habitat characteristics which included the number of trees, the species of the tree and the diameter at breast height of each tree. It also included understory values. There was a density board placed at the center of the tenth acre plot and each of the eight panels was read for the percentage of vegetation covering the panel. Now these readings were taken at the four cardinal directions; north, south, east and west. All of this information was logged for habitat characteristics of areas used.
Now for a comparative study then, I collected similar information throughout the study area. I ran a systematic random sample, I placed a grid over the study area, assigned numbers to each of the intersections and then I used the random numbers table to select the areas for sampling. I then went out and conducted similar tenth acre plots to determine the habitat use versus its availability on the study area. Some of the results indicate aerial use of the adult males in the fall of 1994, that initial year, they were using between 19.6 and 116 hectares. You multiply these numbers by 2.47 and you get the acreage. So they were using fairly large areas, especially the top two at approximately 250 acres. During the spring of 1995, their aerial use was drastically reduced to only 1.34 to 8.52 and just a little hypotheses, we think this may be due to variations in prey availability during the spring during nesting season, you have an influx of grasshoppers, lizards and everything coming out, birds are moving through during migration which may require less foraging and they like to maintain proximity to the nest site for territorial defense.
As you move through into the fall, even in south Texas and Arizona you have a reduction in the grasshopper numbers, the lizards during the cool periods go into a pseudo hibernation and what remains then will be the birds that are left in the area and small mammals so they have to increase their foraging to get food.
In 1996, we had a significant increase in aerial use by the adult males. Here they were using 6.7 to 110 hectares. Although we do not have enough to substantiate this, we feel this may be due to the drought we were experiencing over that time because there was less biomass out there, there wasn't any grass, less insects, etc. so it may have required increased foraging.
(Slide)
Here we have one bird during the nesting season using 110 hectares
during that time, almost double to what they were using the year
before. When I ran the statistical analysis comparing the habitat
use to its availability on the study area the results suggest
they were avoiding areas with small trees and using areas with
larger trees which seems logical. They were avoiding areas that
were not old enough to contain natural cavities. The understory
values, we have a range between 1 and 192 for zero to 100% coverage.
They were using areas that were almost twice as dense as the average
throughout the study area so they were selecting foraging areas
with the moderate to dense understory. This also proved out in
1996, they were using areas with fewer of the small trees in significantly
greater number of the large trees and again, much denser understory.
Here the understory value being low and again, we attribute that
to the drought that we were experiencing since there was not as
much vegetation in the area.
(Slide)
To obtain information on the food habits, I kept with tradition
and established a blind in proximity to a natural cavity and from
this vantage point I was able to view the adults as they brought
prey into the young and make identification. Here we have a ground
skink. There are three different species of ground skink they
are foraging on, however, when you are dealing with a small cavity
nesting species in many instances, they would enter the cavity
before identification could be made, especially when you are dealing
with small prey such as grasshoppers and beetles.
(Slide)
Here again, I incorporated the use of artificial nest structures
and miniature video cameras and established miniature video cameras
in the top of the nest boxes and recorded all the activity that
took place 24 hours a day from incubation through fledgling. It
was then a fairly simple matter to take the tapes into my studio
which is a reclining chair and the television and make identification
which included the adults bringing the prey into the young, you
could easily do your fast forward, stop and make identification.
(Slide)
In addition, I also collected prey remains. Here again, nest boxes
proved beneficial. Pygmy-owls are not clean. They let prey remains
accumulate in the bottom of the nest structure and by the time
these young are old enough to leave the nest, there will be prey
remains stacked up to here, about three inches of it. With nest
boxes then, it is a fairly simple matter to go out and once the
young are fledged, remove the prey remains and bring them into
the laboratory for analysis.
(Slide)
During the food habit study for the first two year period, we
cataloged 36 different prey species in the diet of the pygmy-owl
suggesting that they are a generalistic predator. They are also
an opportunistic predator, I think they basically take anything
that moves. In the class of mammals they were taking common evening
bats, Mexican free-tailed bats and I cannot imagine them taking
a bat on the wing, I believe they take them when the bats are
roosting inside natural cavities during the day. I viewed the
adults going around checking out cavities and removing young woodpeckers
so I feel that is probably how they get their bats also. They
are also taking kangaroo rats, northern pygmy mice and the largest
prey taken was a hispid cotton rat which on average, outweighs
the pygmy-owl by about twofold and when they take them they have
to sever them to get the load down so they can carry it up to
the nest.
(Slide)
In the class of birds, they were again taking bird species that
were much larger than themselves. Pygmy-owls were taking northern
mockingbirds, cardinals, paraloxias (sp?) and right here, we have
the remains of an eastern meadowlark, grosbeaks, finches, they
seem to really like sparrows.
(Slide)
In the reptile class, they are taking small and large prey, whatever
moved they would grab it. They are taking a Texas spiny lizards
with the largest one being about 8o" I guess but they were
taking a keel deerless lizard, three or four different species
of skinks, whiptail lizards, race runners, etc.
(Slide)
The insect class was the most diverse as far as numbers and as
far as prey deliveries, however, I do not believe it is the most
significant as far as nutritional contributions. It takes a lot
of grasshoppers to make up one kangaroo rat.
(Slide)
Here again, we have a little indication of size, that grasshopper
is probably about an inch and a half I would guess. The opportunistic
thing here again in the insect field, they were taking walking
stick and I do not know what you could get out of a walking stick
but they were bringing them into the nest. They were also taking
fireflies.
(Slide)
Just after they fledge, notice the young attempting to capture
insects but they really are not successful until they are about
a week out of the nest.
(Slide)
Using artificial nest structure again was a benefit in collecting
information such as laying sequence, the pygmy-owls areas asynchronous
since they put one egg down about every 30-39 hours. They are
also asynchronous in hatching, there are some nests that would
hatch the entire brood in one day while others span out their
hatching over a week's time and it will be 24 to 26 hours between
egg hatching.
(Slide)
Nestling development is about 28-31 days for nestling development
before they fledge. We were able to determine that the females
are the sole incubators, they have a very distinct brood patch
on the female. They are also basically the sole provider of piecemeals.
The female is the only one that I have seen tear a prey apart
to feed the young, the male will bring it in, drop it off and
take off. The male has also been recorded, after the female would
bring in a cardinal or something, on three occasions I observed
the male coming in and taking it away and going out and feeding
on it.
(Slide)
At four days the young are covered in white down, they are unable
to hold their heads erect, their eyes are closed and they still
have remnants of an egg tooth on their beak. At 12 days they now
respond well to movement. The primary and secondary feathers are
beginning to erupt from their feather sheath.
(Slide)
At 20 days, their primary and secondary wing feathers are about
half of their adult length and the tail feathers are just starting
to emerge. There are approximately three millimeters, they have
little remnants of the down left on their crown, however, on their
back in the scapular region most of the down is absent.
(Slide)
When they do fledge one of the distinguishing characteristics
between adults and juveniles is the streaking on the crown. This
adult female has very distinctive streaking, the juvenile is just
starting to develop some streaking in the crown.
(Slide)
Now post-fledgling, the young remain in proximity to one another
for about the first week. Usually if you find one you are going
to find all of them and very often, they will sit just like this,
just side by side with their mouths open, begging.
(Slide)
At about 3-4 weeks, they begin to separate a bit and it is closer
to four weeks and you will still find them in the same tree but
they have started to separate. These are both hatchlings of the
year at five weeks I believe is what they were and their tails
are now the adult length and they are displaying much of the adult
characteristics. In other words, Scott pointed out to me something
that I missed until he came across it. The juveniles also display
these white teardrops along the crease of the wing and they were
more distinctive in the juveniles than the adults. The adults
have them, however, they just are not as distinctive.
(Slide)
Since Scott pointed that out I have now for the last two years,
I have been trying to catch adults and young at the same time
just so I could have a photographic record of it but I am not
real successful. I am getting some photos but they just do not
satisfy me. That was basically what I did before my master's.
(Slide)
Now while I was conducting that research we had a high level of
nest predation. We have the nest cavity, this was the nest owl
of a pygmy-owl and it was opened up by a raccoon. The first year
I had 75% nest predation which is fairly high. Of course, that
was due in part to sample size. Over the past six years now it
has gone down to just a little over 40% which is still high.
After that first year in the high level of nest predation, we are very concerned with nest predation and we were wondering exactly who the culprits were. We had evidence here that definitely a raccoon, bobcat, ocelot or something was up there tearing the cavities open. We also had cavities where no disturbance was really observed, we could not find any eggshells so what we have done for a couple of years now is establish time lapse recording units at the nest cavities and record all the activity that takes place. This is somewhat of an ongoing project. I have now been able to establish recording units at nine nest cavities and with that, I have just under 9,000 hours of video footage that needs to be analyzed to determine the cause of predation and monitor activity patterns and so forth but with what I have been able to run, I have monitored a little over 3,000 hours and we have determined that raccoons are the number one predator basically in that initial analysis.
(Slide)
I started another little nestbox project that we are hoping would
deter and reduce predation by raccoons. I established nestboxes
in sets of three and the first box was just a fascial board. The
second box, I placed another box over the fascial board and this
was to increase the entrance the entrance depth. On the third
box I placed a 2 x 4 over the entrance so it would get it from
three quarter to an inch and a half to a 2o" entrance depth
before you get into the cavity. Now the logic behind this was
that raccoons, being the primary predators the ones we were able
to identify so far, the raccoon would stick his arm into the entrance
and because of the depth he would not be able to bend it to get
down and predate the cavity. I have established 120 nestboxes
in 40 sets of three like this to first off, determine if the pygmy-owl
would use one of these boxes with the deep entrance and then its
viability as a management tool. I have found that pygmy-owls will
use those nestboxes with a deep entrance so there is a possibility
that we could establish nestboxes with a deep entrance and reduce
predation by raccoons, which is a good thing.
(Slide)
It does not deter predation by snakes. This snake happens to be
a five foot, eight and a half inch bullsnake. He is inside that
box which is just six inches by six inches and this is just after
he had a six pygmy-owl lunch. There were six young in that nestbox
the day before and I was able to get a photographic record of
where they went.
(Slide)
To try and develop a management tool to reduce predation, the
last year I established nestboxes on metal poles to determine
if pygmy-owls will first off, use a nestbox on a metal pole and
if they will, then we can establish these metal poles with the
nestboxes out in the areas where pygmy-owls are and hopefully
reduce predation. Raccoons and snakes would hopefully not be able
to climb or slither up the metal poles. Establishing nestboxes
on metal poles would reduce the impact to trees and we would no
longer be putting nails or climbing trees. If this does not deter
predation and if a snake can still squiggle up it, it would be
a very simple matter to put a cone on it so this is what I am
looking at right now. It is just in its infancy. I established
six sites last year and I had one of them used by pygmy-owls so
with a small sample anyway, it is suggesting that pygmy-owls will
use artificial nest structures established on metal poles.
(Slide)
Just a little shot to show the cryptic coloration of juveniles.
Even if you have a transmitter on these little owls it is sometimes
hard to find them. A juvenile about five and a half weeks to post
fledgling and he is sporting a radio transmitter. At this age,
they are just starting to develop the eye patches on the back
of the neck in the nap. When they become adults they will be lined
with that white ring. Here again, we have this very distinctive
color pattern of the white teardrops along their upper wing.
(MR PROUDFOOT BEGINS SHOWING A FILM OF THE PYGMY OWL AT THIS POINT)
This is some of the typical habitat I find them in. Now here you can see the ants crawling up into the cavity, all of the prey remains attract a large number of ants and they are basically foraging on what the birds are leaving. I have not recorded any negative impact on the birds from the ants as of yet. Every nest that I have visited has ants going in and out of them eating the prey remains and I never have as yet noticed red ants taking any of the young.
This is recorded from the blind that you saw in the earlier blind in the slide. It's not quite time, he jumped the next day and he fledged. Some of the nests are situated on the underside of the upward/outward sloping limb and from this blind it was interesting to watch the adults as they would fly in there, they would go in there in almost an inverted flight to get into the cavity. This nest is approximately 20 feet off the ground I would say, it is in a live oak tree that measured almost five foot across.
Now here I tried to give you a little image of what I see when I look inside with a stratoscope. It is a lot different when you put your own eye up there, you get a much wider field of view.
This real-time footage, unlike the time lapse of which I have way too much of was recorded in a little over 200 hours so far.
One of these has a transmitter so beneficially you get the whole brood. This is a juvenile and it is about six weeks old doing his begging call which is what they do most of the time. They just sit there and chitter.
Now here we have an adult female in the fall in August, the adults go through a full tail molt, here is all the tail feathers and here is the transmitter on the bird. Now this molt of the tail feathers coincides with the dispersal of the young. Within a week after they lose their tails the young disperse. That was a juvenile that took off.
I'm not sure if you can pick this out but on the top of the crown of all the juveniles, the nestlings, I mark them so that I can do a little study on dominance that develops within the brood and there is definitely a dominance.
There is definitely aggression that develops, or a dominance that develops within the brood. In one instance we recorded siblicide where the older ones predated on the younger. When they hatch over the wide span, for example one every day and you have one week's difference between the hatching of the first egg and the last, there is definitely a size difference that develops. It can be up to say 12-14 grams which is a lot considering the birds only weigh 50 grams.
Even at this age they are beginning to show some of the plumage characteristics of the adults where there is a little more similar rufous colortones beginning to develop so when you have two of them together, you can confidently sex them.
Nest boxes are good for providing opportunities such as this to record behaviors, activities and getting the basic nesting ecology. I have placed cameras at nine nests now and I have yet to have any of them abandon when I am doing the recording. I am sure there is individual variation but so far it has not seemed to affect them.
Another fledgling, this about one week after dispersal when it left its natal site, it is another bird with a transmitter on it of course. It was doing well foraging on its own. Lizards, in Texas seem to make up a significant part of their diet. As far as nutritional value I think it is the most significant as far as the five classes that I have identified. One that I did not have a slide on was amphibians. I recorded them taking a narrow mouth toad.
They have over 150 windmills on the Norias Division so there is always a water source within two miles of the next. Before the King Ranch established itself and started drilling for water there was absolutely no riparian areas, there are no creeks, rivers or anything on this 240,000 acres. There are possibly five freestanding water pools but I have not as yet run an analysis to determine if there is a correlation between nest site location and proximity to water. It is something that can be done but time is needed to do that.
DR. LISA HARRIS INTRODUCTION OF SCOTT RICHARDSON:
Our next speaker is Scott Richardson. He is a habitat specialist here in Tucson and Region V of the Arizona Game and Fish. Mr. Richardson has been involved from the beginning with the species here in Arizona and is responsible for many of the results from our early survey efforts and nest monitoring and all the telemetry that has been done to date in the state. He has looked at dispersal patterns of the young just like we saw in Glenn's films. Habitat selection and the types of habitat components that are out there in order to get a better grip on the natural history of the species. Scott will be talking about the pygmy-owls here in Arizona.
THE PYGMY-OWL IN ARIZONA
Scott Richardson, Arizona Game and Fish Department
I am excited to be here tonight and hopefully with all this good information you are getting on pygmy-owls you will go away tonight and think you attended a meeting on everything you wanted to know about pygmy-owls but were afraid to ask, and given the current climate around pygmy-owls in Arizona that may really be the case. A lot of people are afraid to ask questions about pygmy-owls. I think tonight is good because I think it brings home to you, particularly with the things you have seen in Glenn's and Russell's work that despite what you hear around town, pygmy-owls actually do exist. They are an actual species of wildlife in Arizona that we are concerned about and trying to deal with a very complicated and controversial issues surrounding this species.
We are about three to five years behind Glenn with our research work on pygmy-owls. There are two reasons for that and one of the primary reasons is that we do not have nearly as many owls as Glenn has, and anytime you are trying to gather information on a species when you are working with one or two, or in a really good year, perhaps 30 owls, the ability to gather all this natural history and habitat and home range use, all the things we need to manage this species it is very difficult to gather that in any kind of a rapid way because you needs lots of birds to find out these things.
The second aspect hindering us and as you see slides and pictures of this owl it is difficult to get a perspective of what we are dealing with. It is a very small owl and because of its small size, there are limitations regarding what you can do with the owl without killing them. I wanted to show you what one of these transmitters look like that we are discussing which will give an idea of the size of the pygmy-owl. This is the transmitter that we are attaching to the pygmy-owls to find out all this information.
In reality, once the transmitter is attached to the bird about this much of it sticks out from the bird and is much is much longer than the bird itself. The transmitter covers a lot of the bird. One of the things we have to be very careful about when we are working with the birds to obtain information is that we do not hinder their natural cycles and ability to do what these allow you to do. The limitations faced by those studying the bird is that we cannot put very much on them because they are so small. These transmitters only weigh about a gram and a half and the restrictions that places on us as we try to find out this information is this battery is only good for about 12 weeks. In order to find long term breeding, dispersal and all the things we need to find out, we only have about 12 weeks and you cannot get all the information you need to know in that 12 week span of time. The birds are pretty smart and in order to extend this 2 week battery life we have to catch them again, and that is not a given.
It is a fascinating species, there is a lot to be learned and as a biologist it is exciting to be able to work on this species because there is not much known about it. Everything you learn is new and exciting. It is frustrating dealing with limitations.
What I would like to do quickly is run through some of the work that we are doing in Arizona. As you will see, it parallels a lot of what Glenn has done, but we are just a little further behind. There is still a lot we do not know about the owl as we begin using new technology like transmitters. We are finding out a lot more but we still have a long way to go so hopefully after I finish up you will know Tucson's status regarding what we are doing.
As part of an advisory role with what the County is doing, their conservation plan and what you folks are charged with as part of the steering committee on that conservation plan, hopefully you will understand what we are dealing with this species as it plugs into the plan, the limitations with date, where we need to go from here and any direction, that you folks as part of this committee, can give us it would greatly be appreciated. If I can have the slides turned on we will run through here real quick and show you some of the things that are occurring in Arizona.
I want to acknowledge the fact that the work and information I will share was done by Game and Fish but was only accomplished through funding from cooperating agencies such as the Forest Service and the U.S. Fish and Wildlife Service, and primarily the funding through the Arizona Game and Fish has been through our Heritage Program.
(Slide)
I would really be remiss if I did not acknowledge people who helped
with the work in Arizona because this is pretty typical of a lot
of our pygmy-owl work until recently in Arizona. To see us sitting
in somebody's front or backyard, climbing up their saguaro to
figure out what is occurring with pygmy-owls is a typical picture
in northwest Tucson because fortunately or unfortunately, depending
upon what your perspective is, most of the owls until just the
last couple of years have been found in residential areas in northwest
Tucson. Because of that, they are found on private property and
so I want to acknowledge all the private property holders and
residents who have allowed us to come in and access their property
and do the biological work that we need to do to find out the
information that we need to. That is not a small thing because
we can be there at three o'clock in the morning or 11:00 o'clock
at night or 24 hours a day so we try to be as non-invasive as
possible. It really takes a lot of cooperation on the parts of
private residents to help us get the work done that needs to be
done. Even though I am the one standing up here talking about
this, in reality the work was accomplished by some people who
do not get paid very much and work a lot of hours. Specifically
I would like to acknowledge Dennis Abbate who is a seasonal biologist
who is working with me and has been since 1996. More recently,
Renee Wilcox who has been working on some the habitat related
issues, the report of which you see in your materials. Over the
last four or five years I have had summer interns who have worked
with me on this project: Colby Henley, Sandy Diddee, Stacy (?)
and this year, Sarah Lance who have been working very hard and
these poor U of A students are excited to get out and get some
field experience and then when they find out they have to get
up at two o'clock in the morning and sit and watch some bird feed
its young dead lizards and such it can become somewhat of a challenge
to them but they do it and the reason we have the information
we have in Arizona is because these people are willing to find
it out. I just want to acknowledge them for their work. There
is a lot of cooperation and people's help that goes into this,
it is not just me.
You have heard Glenn talk a lot about the owl. It looks basically
the same in Arizona. We have noticed since Glenn has been helping
us this year and I would be remiss if I did not acknowledge Glenn
because he basically has guided us through our efforts locally.
We have drawn on his experiences and knowledge every step of the
way here in Arizona. Since he has seen birds in Texas and Arizona
so maybe there is some plumage differences between Arizona and
Texas birds and of course, he is looking at the genetics of the
situation.
These are incredible little birds and you might think, why do
we have to worry about this tiny little owl in Arizona? When you
think about it, it actually fills an interesting role in the environment,
it is more of a diurnal versus nocturnal like our screech owls
or elf owls so it feels like a unique niche in the whole Sonoran
southeast Arizona scheme of things. Here you can see the eye spots
on the back of the head which differentiate it from other small
owls in Arizona.
This is a picture of a juvenile fledgling bird. There are differences in coloration and plumage which allow us to differentiate juveniles from adults. In the resource material contained in your packet you will see that we have recently put out a preliminary report on some early work that we have done and habitat information is really a big unknown and a big mystery for us and so that is one of the things we are concentrating on. Historically, they are found along more of these western wet riparian areas, at least that is where a lot of the records are found. We are finding them now, not so much in those but more in upland, dry wash situations and even more so in the Sonoran Desertscrub types of habitats. As Russell alluded, recently we found some birds in some different kinds of areas, even though down south in the Altar Valley with a few sites in more typical riparian types of settings. In the Altar Valley we are finding them in this desertscrub type of habitat.
We have been finding the pygmy-owl frequently in low density residential areas that is becoming typical area to find the pygmy-owl.
(Slide show utilized in discussion)
Questions to consider:
a.What is it that defines pygmy-owl habitat?
b.What levels of human activities allow pygmy-owl habitat to remain
in the state it can be utilized?
c.Are we removing a component out of that landscape that is critical
for pygmy owls such as understory?
d.What actions can we take to reduce those impacts?
e.Is plant salvaging a possible answer?
f.Do we need to replace the whole vegetative structure and components?
g.Do roads act as barriers for pygmy-owls? We know owls fly very
low to the ground and crossing a road could present potentially
present a bit of a challenge.
Those are the kinds of questions we are looking at trying to answer with the habitat work we are undertaking.
What is pygmy-owl habitat?
What do we as humans do to impact that?
We go out and sample habitat and as you can see, we are using a lot of the same methodology, at least with regard to the cover board that Glenn had used and we are trying to characterize, what is pygmy-owl habitat? Through the first couple of years of our investigation, we found basically that in these areas where we are finding pygmy-owls that plant species diversity is very high. We measured non-vegetative variables in the habitat and that is somewhat variable. In the areas where owls are there is not a lot of actual on the ground cover but we need to do additional work to find out if that is simply characteristic of Sonoran Desertscrub or if that is something that characterizes these sites. The vertical structure you saw in Glenn's trees, even though they are much larger than ours, is that vertical structure seems to be important in that there is equally distributive vegetative cover at all layers within the area. More information is needed.
This is just to show you what we were looking at with regard to the non-vegetative characters; things like distances to roads, washes, water, and various structures. One of the real restrictions we have is that we are dealing with an extremely small sample size and it is very difficult to draw any statistically significant conclusions when you are working with such small numbers.
The prey habits, Glenn did a great job and we are finding basically the same kind of things here. This is a picture of a lizard that an owl cached in a tree. We find that oftentimes if they catch prey and they are not hungry or the young are not ready to take them, they will simply cache it in a tree and come back to it later. They have an incredible memory in remembering where those food stores are and in fact, I one time saw a Gila woodpecker take a lizard that a pygmy-owl had cached and the owl knowing that the lizard used to be there spent the next half hour looking for it; he knew it was there. They have great memory of where these things are.
The other incredible thing about pygmy-owls and their prey bases is they are so versatile and they are such great little predators. They will take things as small as hummingbirds and as Glenn talked about, they will also take very large prey up to the size of adult morning doves which outweigh them by two and half times. They are very versatile and very effective predators.
We, like Glenn, are looking at some other things to try to determine what their food habits are. Observation is not the best way to do it as Glenn explained so this happens to be the contents from a saguaro cavity that was being used by a pygmy owl that blew over during a windstorm and so we were able to go in there and extract the contents.
Also, owls like other raptors, particularly owls regurgitate pellets after they are done eating which contain the undigestible remains of their prey such as bones and feathers. We have a collection of those started which we will be looking at in more detail what is being preyed upon.
This is the only picture I have of a snake eating something so that is not a pygmy-owl.
We do not have a good idea of what is going on with predation in Arizona, we have not utilized the technology that Glenn has up to this point. Therefore, we do not have a good idea what is out there as far as predators. We do know there are other factors in the desert landscape which present hazards and this is my test for you: can you find the pygmy-owl in this picture? It is right here and this was a fledgling bird that was out of the nest a couple days and he thought he would try his wings out and he did not quite make it and instead landed in a Cholla and he was impaled on this Cholla and if we had not been there, I am positive that bird would have perished. Everything that we know about, the owl comes out of the nest and fledges. What we are seeing this year with a few more birds is we are seeing mortality after they fledge but these saguaros seem to be a pretty suitable nesting site. I think that helps in predator avoidance.
This is a picture of a fledgling and I just put this in to illustrate the unique behavioral adaptation the pygmy-owl have to avoid predators. This is a young bird just out of the nest and we are going up there to catch it and they elongate themselves and stretch themselves up just as tall as they possibly can and I am not kidding you, they are just like a stick. You have a transmitter on a bird, you know it is in the nest but it looks just like a stick. That is another behavioral adaptation they have to avoid predation.
They hide from you, they duck down in the crotch of a tree and it is a pretty interesting bird to study. We are looking at things like productivity and nesting success. This is a group of fledglings in an ironwood tree at one of the nest sites. Beginning last year, we have begun doing more hands on research trying to do transmitter work, banding work and we are using many of the same techniques as Glenn and in fact, he trained us and taught us how to do it.
You can see behind this, you can see the mist net that we use to catch birds and bow traps.
This is a fledgling that we have caught and banded. Because we have the luxury of working with only a handful of birds we are actually trying to individually identify each bird we capture. The Fish and Wildlife Service bands do not do that because it is hard to read the little number on these guys so what we are doing is using color bands to identify each individual and we are finding out interesting information just by utilizing the color bands and it is kind of like a soap opera, you know, Glenn was talking about siblicide. Well we found incest so it is just like a soap opera and that brings up a real interesting point in what we have seen is two generations of incest in the same line and that raises the question about inbreeding and what the affects of that are and hopefully we will ferret some of that out with some of the work that Glenn is doing.
This is a bird that we caught and placed a transmitter, I showed you the transmitter. These guys are very cryptic and to find the bird without a transmitter is almost impossible if they are not vocalizing. You can see the transmitter on the owl and size wise most of the antenna is hanging out below the bird so these birds are small.
With telemetry we are able to gather more on just a few birds than we were able to gather in years of only survey and monitoring so it is a very helpful technique.
Obviously we have gathered a lot of information, you saw we have our report from 1996, that is our most recent report we have out. We will be coming out hopefully within the next month or so with a 1997 and 1998 report which includes much of the telemetry, transmitter and habitat work. We will continue to increase our survey efforts. Obviously, we have to find the birds to work on them, we need to know where they are and how many there are. We need to find out more about habitat. We have done preliminary effort regarding where birds are, we need to sample size where they aren't and do some random comparative sampling on use versus availability and telemetry will help us do that as well. I will look at some additional use areas.
This year in the Altar Valley we are finding some birds down there in some different types of habitats. We need to look at these additional use areas and look at random areas for comparative purposes and then continue our monitoring through observation and telemetry. We are at an exciting point, we are learning a lot but it is frustrating because we have a lot more to learn. Our objective is to gather as much information as fast as possible to feed into the process to make this County plan based on the best available science that we have.
This is an owl at sunset which I thought was appropriate for my last slide.
That brings you up-to-date generally with what is going on in Arizona.
QUESTION AND ANSWER PERIOD:
Q.What kind of proximity do you find to dense human population of the birds in Mexico? Have we placed nestboxes in relatively dense human habitat?
A.No nestboxes have been established in dense residential areas.
Q.What about in Mexico?
A.I am not aware of any work that has been done in Mexico with the cactus ferruginous pygmy-owl.
Q.There has been some work in South America, is that correct?
A.I cannot recall the city but there has been some reports saying that there are pygmy-owls close to human habitation. I do not know, they did not list the density of the housing, they just said in a one line sentence that the pygmy-owl seem to be tolerant of human habitation. Other than that, there is very little know.
Q.With the concern about the two observations of incest occurring
for the last couple of years, is there concern about that? Since
we only have a 1% difference between the Texas owl and our owl,
can we bring some in to try to disperse that incest?
A.The pairs that we are seeing, the incest is only cause for concern if lethal genes happen to express themselves. There are some species that do very well with a high degree of inbreeding and is only a problem if some detrimental gene is emphasized because of that. So far, both of these incestuous pairs have raised normal, healthy offspring so it does not appear to be a problem so far.
Q.Do you know to what elevation they will thrive? Down to what
temperature they will thrive in and to what extent the research
is being done in Gila National Forest? In other areas in New Mexico
between Texas and Arizona?
A.They have never been located in New Mexico that I am aware of and there is about a 864 mile bird area where they have never been located. With regard to elevation, I believe it is about 4,000 feet is the highest they have been located. As far as I know, the temperature variations for the birds found north of Phoenix would be at the most northernmost part of the range and experiencing the most temperature variation.
Q.One of my colleague's in the Casas Adobes Town Council dismisses
this little controversy over the ferruginous pygmy-owl because
he says that their numbers may be very limited here in Arizona
but there is a lot of them in Texas and millions of them in Mexico.
What are the numbers of the cactus ferruginous pygmy-owl? Are
there really millions of them in Mexico and are they relatively
plentiful in Texas?
A.There is actually not a lot known about them in Mexico, although in our historical research I found twice as many historical records than was published in recent research north. I suspect there are much more populace in Mexico than there are here, simply by the fact that this is the northern area of their range and the further south you go the more increase in numbers there will be. We do not know how many there are and there needs to be research in Mexico which is just as important as research here. We need to know how they are doing, where they are most populace and where they are less common.
Q.Would fairly common or common be a good word to use in discussing
numbers of the pygmy-owl?
A.I hate using that type of relative term. What does uncommon mean? What does not uncommon? That is one of the historical descriptions. What does not uncommon mean?
Q.And in Texas, what is the number?
A.In Texas, I know that I have banded approximately 400 of them so far and based on the amount of habitat out there in my study area, based on habitat use versus availability, it could support between 350 to 400 nesting pairs. Over the 27th parallel, when you move outside the live oak mesquite forest, I am finding birds in the mesquite bosque, the area south of there but they are definitely in fewer numbers and that type of habitat is limited. I would hate to guesstimate how many there are in southern Texas but I would say there are at least 1,000.
Q.Would you guess there is some relationship to where you are
not finding them anymore because of the water table lowering?
Are you finding them in close proximity to low density residential
because of lawns or water sources? Do you have any guesses about
owls and water or owls and food because of water or no water?
A.I think Scott would agree that they are being found where there is no free water and yes, they were found historically along riparian corridors. That may or may not be a artifact of where the collectors were spending most of their time. If you were out here in 1872, you might spend most of your time when you are on horseback avoiding Apaches as Bendire did and also being accompanied by the military. He was a doctor attached to the Fort and Fort Lowell happened to be the best area because of the spring that was there so he spent most of time there and it may be an artifact that he was collecting. In my opinion, when I looked at a lot of historical records I see less time being spent in the Arizona deserts than in the bottom land riparian. Where could you get the biggest bang for your buck in sending birds back to Harvard? You could get them in the bottom land riparian habitat as opposed to going out to the Sonoran Desertscrub where some of the species diversity may be limited. You could get those same species at the edge of the riparian rather than going out to where there was no water.
Q.Do I understand correctly that your research is largely on a
historic cattle ranch in Texas with water developments put in
by the rancher on the Norias?
A.Yes.
Q.Did you say that currently that owls in Texas are on the threatened
list?
A.There is no listing for them at all in Texas, the listing was withheld in Texas.
The Cactus Ferruginous Pygmy-Owl
Species of Concern - A discussion paper for the Sonoran Desert Conservation Plan