I am seeing voles all over the place right now. And Boris and Natasha, the two farm cats that have adopted me, keep bringing in big, fat voles to my residence (against my express wishes). We appear to be in the beginning of a high in the vole multi-year cycle. This is very good for all rodentivore raptors and I expect to see a ton of hawks this winter on the wintering grounds. I expect to see more rough-legs than usual and short eared owls should make an appearance in their typical habitat. White-tailed kites may show up in colonies this winter. Survivorship of juveniles should be high and probably reproduction next year will be exceptional. Voles drive raptor populations and voles are very abundant right now. Be on the watch all through the summer and winter and I predict a lot of hawks and owls will be around.
Stan Moore
Sunday, May 24, 2009
Monday, May 11, 2009
An interesting opportunity (hawk habitat photography)
Very recently I heard from Brian Wheeler of the Wheeler Raptor Guides. He is working on a new book, to be published in a couple of years. He said it would include photos of habitat used by various raptors and he needed photos of habitat used by California red-shouldered hawks, and he had modest funding to pay for one or two such photos. He preferred slides, and so I bought a roll of professional grade slide film (Fujichrome 50) and went out Sunday (yesterday) and shot the entire roll.
I visited somewhere between twelve and fifteen red-shoulder territories and took photos of nests, nest trees, nest tree groves, foraging habitats, creekbeds and bottoms, vineyards adjacent to nest groves, oak habitat with grass below, fields with wildflowers and nest trees in the background, etc. It was a glorious day with powder blue skies and bright sun. The hawks were out and bringing food back to their nests. I was watching one nest when a group of three local ladies came walking by just as an adult red-shoulder carried in a small snake to the nest. The ladies were totally unaware that they had such a nest in their neighborhood and they got to see nestling stretching its wings above their heads.
There were a few fledglings flying around of both red-shoulders and redtailed hawks. You could hear the baby redtails food begging in some cases before you saw them away from their nests, but I was not photographing redtails yesterday.
I had shot the entire roll of film by 1:00 and I hope Brian finds one or two of the photos suitable for his book. He contacted me at the perfect time because the weather was great and the birds were out and it offered an opportunity for nest habitat photos to actually show birds present on the nest or perched nearby or foraging nearby while still showing a broader view of what the habitat is like.
I must say, though, that northern California habitat is somewhat different from red-shoulder habitat I have seen in southern California. In Orange County, the habitat is typically canyon habitat that is too precipitous to be developed and the hawks are packed into linear space up and down those canyons. They live in canyon bottoms and hunt much like Coopers hawks in the understory of the canopy. In San Diego County, there is a lot of riparian habitat, but the birds again stay in the riparian corridors except for places where they reside on ranchette lands and amongst rural homes as they do in small towns in northern California. Also in San Diego County, the red-shoulders like among the huge avocado orchards, where they proliferate due to the abundance of prey amongst the orchards. But the avocado orchards I saw are somewhat different than our vineyards up north because the avocado orchards hold few grassy fringes and are solid agriculture as far as the eye can see. In my area, red-shoulders can be found adjacent to vineyards in the grassy fringes and hunting the grass-bottomed ditches, but in southern California the birds are right in the orchards themselves.
So, if I had been assigned to photograph red-shouldered hawk habitat in Southern California, I would have different scenery than I photographed in the Bay Area. Both areas hold large numbers of red-shouldered hawks.
It was a fun assignment to photograph them yesterday.
I visited somewhere between twelve and fifteen red-shoulder territories and took photos of nests, nest trees, nest tree groves, foraging habitats, creekbeds and bottoms, vineyards adjacent to nest groves, oak habitat with grass below, fields with wildflowers and nest trees in the background, etc. It was a glorious day with powder blue skies and bright sun. The hawks were out and bringing food back to their nests. I was watching one nest when a group of three local ladies came walking by just as an adult red-shoulder carried in a small snake to the nest. The ladies were totally unaware that they had such a nest in their neighborhood and they got to see nestling stretching its wings above their heads.
There were a few fledglings flying around of both red-shoulders and redtailed hawks. You could hear the baby redtails food begging in some cases before you saw them away from their nests, but I was not photographing redtails yesterday.
I had shot the entire roll of film by 1:00 and I hope Brian finds one or two of the photos suitable for his book. He contacted me at the perfect time because the weather was great and the birds were out and it offered an opportunity for nest habitat photos to actually show birds present on the nest or perched nearby or foraging nearby while still showing a broader view of what the habitat is like.
I must say, though, that northern California habitat is somewhat different from red-shoulder habitat I have seen in southern California. In Orange County, the habitat is typically canyon habitat that is too precipitous to be developed and the hawks are packed into linear space up and down those canyons. They live in canyon bottoms and hunt much like Coopers hawks in the understory of the canopy. In San Diego County, there is a lot of riparian habitat, but the birds again stay in the riparian corridors except for places where they reside on ranchette lands and amongst rural homes as they do in small towns in northern California. Also in San Diego County, the red-shoulders like among the huge avocado orchards, where they proliferate due to the abundance of prey amongst the orchards. But the avocado orchards I saw are somewhat different than our vineyards up north because the avocado orchards hold few grassy fringes and are solid agriculture as far as the eye can see. In my area, red-shoulders can be found adjacent to vineyards in the grassy fringes and hunting the grass-bottomed ditches, but in southern California the birds are right in the orchards themselves.
So, if I had been assigned to photograph red-shouldered hawk habitat in Southern California, I would have different scenery than I photographed in the Bay Area. Both areas hold large numbers of red-shouldered hawks.
It was a fun assignment to photograph them yesterday.
Saturday, May 2, 2009
Is peer review a problem in today's science?
I saw an article in the popular press recently about problems in universities in general. The author is not a scientist, but a university scholar in a non-scientific field, but one of his points was that pressure to publish and peer review are perceived to be obstacles to excellence in his own field. I find similar problems in science, including ornithological sciences, including in university-based science programs.
I have noticed on a personal level a disturbing number of published papers in mainstream journals that I feel are shockingly weak, full of biases and unreliable. These include products of ornithological science (raptor and raptor migration and raptor genetics research originating with UC Davis' genetics lab in collaboration with the Golden Gate Raptor Observatory) . I wonder if part of the problem is that such papers are reviewed by peers who are too close to the authors in the sense that the reviewers and editors are largely uncritical of important aspects of the science involved.
As an example, I recently read three different papers published in three different journals that were components of a recent PhD dissertation in the general field of conservation genetics as related to birds. All three papers contained what appeared to be excellent lab work in terms of genetic sequencing and analysis, which may have been the expertise of the peer reviewers. But all three papers suffered from eggregious sampling areas regarding the field work that led to the lab processing. Sampling was variously nonrandom, nonrepresentative of the populations being assessed for gene flow, inadequately distributed amongst regions under comparison, and strongly biased among geographic regions being assessed. As an example, one object of the study was to assess regional genetic traits of subpopulations of multiple widespread subspecies, but instead of random sampling of subjects known to reside in those separate regions, the vast majority of the samples were conveniently gathered from birds of unknown origin as they happened to be in transit (migration) at migration study sites. There was documented reason to believe that such transient birds were known to regularly travel between the regions under analysis during the sampling period and so there was no likelihood whatsoever that the sampling could accurately represent local regions to be compared with each other. This was a terrible case of "convenience sampling" or biased sampling at its worst. A careful analysis of the results of the study clearly showed this bias to be evident in the study itself, yet the study presented the results as "accurate" and even made management and conservation suggestions on the basis of the flawed analysis!
A major concern of mine is that peer reviewed publications provide precedents for research to follow. An author of weak research often uses one of his/her publications to build on for future work, that may also be similarly flawed. Other researchers may read the research line by line, sentence by sentence, and cite in their work or utilize in their own work poor methodology or accept weak findings on the ground that they were published resources . Many authors will pick and choose portions of published literature to support their own studies, methods, research premises, etc without reading the entire papers and discovering for themselves the weaknesses and flaws that are duplicating. Scientists are so busy nowadays that publications are often read, but rarely studied in depth in any sort of critical or questioning manner.
My fear is that peer reviewers may have the same mindset as authors in focusing on technical aspects of science, such as statistical methods, laboratory methods, etc. and not look closely enough at research concepts, study design, field methodologies prior to data analysis, and so forth. At minimum, peer review ought to be more of an adversarial process than it seems to be. I often get the impression that many editors and peer reviewers are more interested in spell checking that in in-depth analysis of the quality of science. Many peer reviewers may not understand the technical aspects of publications in this age of growing reliance on technology and statistics as well. Because publication of science invites replication of that science, one bad publication invites more of the same.
Somehow these problems in peer review need desperately to be minimized and corrected. An additional problem that I can mention only briefly is the reluctance of journal editors to address published error. Not long ago, a colleague and myself became concerned about poor science in a mainstream journal and we contacted the editor of the journal for opportunity for a rebuttal. The editor reluctantly offered us a tiny allotment of space in comparison with the original publication to make a rebuttal case, but then refused altogether to publish the rebuttal because the original authors would not agree that our rebuttal was justified! In this case, I know that worldwide experts on the species involved agreed with myself and my colleague on the problematic quality of the science, the the journal editors sided with the authors, who have never published before or since on the species involved. Peer review and editing need to be of high quality in our system of sharing of scientific knowledge.
This is a matter that deserves serious attention, in my opinion.
Stan MooreSan Geronimo, CA
I have noticed on a personal level a disturbing number of published papers in mainstream journals that I feel are shockingly weak, full of biases and unreliable. These include products of ornithological science (raptor and raptor migration and raptor genetics research originating with UC Davis' genetics lab in collaboration with the Golden Gate Raptor Observatory) . I wonder if part of the problem is that such papers are reviewed by peers who are too close to the authors in the sense that the reviewers and editors are largely uncritical of important aspects of the science involved.
As an example, I recently read three different papers published in three different journals that were components of a recent PhD dissertation in the general field of conservation genetics as related to birds. All three papers contained what appeared to be excellent lab work in terms of genetic sequencing and analysis, which may have been the expertise of the peer reviewers. But all three papers suffered from eggregious sampling areas regarding the field work that led to the lab processing. Sampling was variously nonrandom, nonrepresentative of the populations being assessed for gene flow, inadequately distributed amongst regions under comparison, and strongly biased among geographic regions being assessed. As an example, one object of the study was to assess regional genetic traits of subpopulations of multiple widespread subspecies, but instead of random sampling of subjects known to reside in those separate regions, the vast majority of the samples were conveniently gathered from birds of unknown origin as they happened to be in transit (migration) at migration study sites. There was documented reason to believe that such transient birds were known to regularly travel between the regions under analysis during the sampling period and so there was no likelihood whatsoever that the sampling could accurately represent local regions to be compared with each other. This was a terrible case of "convenience sampling" or biased sampling at its worst. A careful analysis of the results of the study clearly showed this bias to be evident in the study itself, yet the study presented the results as "accurate" and even made management and conservation suggestions on the basis of the flawed analysis!
A major concern of mine is that peer reviewed publications provide precedents for research to follow. An author of weak research often uses one of his/her publications to build on for future work, that may also be similarly flawed. Other researchers may read the research line by line, sentence by sentence, and cite in their work or utilize in their own work poor methodology or accept weak findings on the ground that they were published resources . Many authors will pick and choose portions of published literature to support their own studies, methods, research premises, etc without reading the entire papers and discovering for themselves the weaknesses and flaws that are duplicating. Scientists are so busy nowadays that publications are often read, but rarely studied in depth in any sort of critical or questioning manner.
My fear is that peer reviewers may have the same mindset as authors in focusing on technical aspects of science, such as statistical methods, laboratory methods, etc. and not look closely enough at research concepts, study design, field methodologies prior to data analysis, and so forth. At minimum, peer review ought to be more of an adversarial process than it seems to be. I often get the impression that many editors and peer reviewers are more interested in spell checking that in in-depth analysis of the quality of science. Many peer reviewers may not understand the technical aspects of publications in this age of growing reliance on technology and statistics as well. Because publication of science invites replication of that science, one bad publication invites more of the same.
Somehow these problems in peer review need desperately to be minimized and corrected. An additional problem that I can mention only briefly is the reluctance of journal editors to address published error. Not long ago, a colleague and myself became concerned about poor science in a mainstream journal and we contacted the editor of the journal for opportunity for a rebuttal. The editor reluctantly offered us a tiny allotment of space in comparison with the original publication to make a rebuttal case, but then refused altogether to publish the rebuttal because the original authors would not agree that our rebuttal was justified! In this case, I know that worldwide experts on the species involved agreed with myself and my colleague on the problematic quality of the science, the the journal editors sided with the authors, who have never published before or since on the species involved. Peer review and editing need to be of high quality in our system of sharing of scientific knowledge.
This is a matter that deserves serious attention, in my opinion.
Stan MooreSan Geronimo, CA
Thursday, April 30, 2009
a letter to the UC Davis wildlife genetics lab
Below is a letter I sent yesterday to Drs. Ernest and Hull of the UC Davis wildlife genetics lab at the veterinary school. These two have collaborated with the Golden Gate Raptor Observatory to publish some of the weakest science I have ever read. The worst science is not false science, but science with small remnants of intriguing elements of value intermingled with a lot of chaff. That is how I would characterize three recent publications from this lab, two on redtail hawks and one on redshoulders. I will be commenting in more detail soon...
Stan Moore
To Drs. Ernest and Hull --
Hello -- I have been reading recent publications from your lab, all of them with Joshua Hull as lead author. I have been more than disappointed with several that I have read, but I have not read all of them. I find at least three of them to be appalling in the sense that they grossly exaggerate their own scientific and conservation value and generally rely on poor field methodologies with a profound lack of appropriate rigor in sampling. The conclusions and the assertions in the text are usually hollow and sometimes unrelated to any level of demonstrated data gathering or analysis. I had to literally laugh out loud at the profound revelation that California red-shouldered hawks are genetically different than eastern red-shouldered hawks and that "management as separate conservation units may be warranted". Really! Is someone going to start managing these birds anywhere? Some of the papers present interesting data that could be shared as brief research notes, but the papers I am reading are full of meaningless prose and exceedingly self-serving to the authors and not to science or to conservation of the raptors that I love and which I personally study intensely in northern California, not just in migration, but in the totality of their local lives. I see a waste of public funding in a time of economic crisis. I see misleading characterizations of real-world conservation relevance of your published work. I would not necessarily call it scientific fraud, but it approaches a nexxus between incompetence and fraud and the fact that this work is being published is a horrible indictment of peer review in today's scientific world. I understand why several prominent ecologists have stated publicly and privately that peer review is broken in a profound way. It is especially sad to see labs like yours cranking out bad work and training new scientists to replicate the bad work using poorly reviewed and edited publications to demonstrate precedents. I will be commenting on this publicly and privately within the raptor and conservation communities. Stan Moore San Geronimo, CA
Stan Moore
To Drs. Ernest and Hull --
Hello -- I have been reading recent publications from your lab, all of them with Joshua Hull as lead author. I have been more than disappointed with several that I have read, but I have not read all of them. I find at least three of them to be appalling in the sense that they grossly exaggerate their own scientific and conservation value and generally rely on poor field methodologies with a profound lack of appropriate rigor in sampling. The conclusions and the assertions in the text are usually hollow and sometimes unrelated to any level of demonstrated data gathering or analysis. I had to literally laugh out loud at the profound revelation that California red-shouldered hawks are genetically different than eastern red-shouldered hawks and that "management as separate conservation units may be warranted". Really! Is someone going to start managing these birds anywhere? Some of the papers present interesting data that could be shared as brief research notes, but the papers I am reading are full of meaningless prose and exceedingly self-serving to the authors and not to science or to conservation of the raptors that I love and which I personally study intensely in northern California, not just in migration, but in the totality of their local lives. I see a waste of public funding in a time of economic crisis. I see misleading characterizations of real-world conservation relevance of your published work. I would not necessarily call it scientific fraud, but it approaches a nexxus between incompetence and fraud and the fact that this work is being published is a horrible indictment of peer review in today's scientific world. I understand why several prominent ecologists have stated publicly and privately that peer review is broken in a profound way. It is especially sad to see labs like yours cranking out bad work and training new scientists to replicate the bad work using poorly reviewed and edited publications to demonstrate precedents. I will be commenting on this publicly and privately within the raptor and conservation communities. Stan Moore San Geronimo, CA
Sunday, April 12, 2009
This Blog Facilitates Identification of Origin of Wing-tagged Bald Eagle
Dear all --
Yesterday I received a telephone call from a lady I did not know. She reported the sighting of a bald eagle on the Russian River near Forestville, CA by a friend of hers the same day. The eagle was wearing a blue wing tag with the number 19 inscribed. The caller said that her friend did not know how or to whom to report the sighting, so she helped her friend by going to her computer and doing a Google search using terms like "Sonoma County, Bald Eagle". That search led to my blog because I had posted a message on the recolonization of bald eagles to the North Bay earlier.
I instructed the lady to have her friend call the Bird Banding Lab to report the sighting. Meanwhile, I put a posting on the ornithology listserver asking if anyone there had knowledge of wing tagging of bald eagles that might end up on the Russian River in California. I heard from Dr. Peter Sharpe of the Institute for Wildlife Studies and learned that the bird seen on the Russian River had been removed as a chick from a nest in Alaska in 2003 and hacked on Santa Cruz Island off the coast of California. Dr. Sharpe said that the radio transmitter originally attached to this bird was no longer functioning, but similar birds had been tracked to southern Oregon and Northern California.
Several years ago, another female bald eagle from Dr. Sharpe's release program, also taken as a nestling from an Alaska nest, paired up with a male bald eagle at Del Valle Reservoir in Alameda County and producing young. That bird may still be there, as far as I know.
Blue A-19 was hatched in 2003 and so should be about old enough to pair up and breed. It may be too late for this year, but if the bird stays in the area, it would be fun to contemplate nesting bald eagles in the Russian River area in 2010.
It is a reminder that bald eagles are increasing in the area. And a tagged bird, including a color marked bird can be reported to the Bird Banding Lab. I will provide the contact on a separate posting in the near future.
Stan Moore
Fairfax Raptor Research
P.O. Box 341
San Geronimo, CA 94963
hawkman11@hotmail.com
707.479.9863
Yesterday I received a telephone call from a lady I did not know. She reported the sighting of a bald eagle on the Russian River near Forestville, CA by a friend of hers the same day. The eagle was wearing a blue wing tag with the number 19 inscribed. The caller said that her friend did not know how or to whom to report the sighting, so she helped her friend by going to her computer and doing a Google search using terms like "Sonoma County, Bald Eagle". That search led to my blog because I had posted a message on the recolonization of bald eagles to the North Bay earlier.
I instructed the lady to have her friend call the Bird Banding Lab to report the sighting. Meanwhile, I put a posting on the ornithology listserver asking if anyone there had knowledge of wing tagging of bald eagles that might end up on the Russian River in California. I heard from Dr. Peter Sharpe of the Institute for Wildlife Studies and learned that the bird seen on the Russian River had been removed as a chick from a nest in Alaska in 2003 and hacked on Santa Cruz Island off the coast of California. Dr. Sharpe said that the radio transmitter originally attached to this bird was no longer functioning, but similar birds had been tracked to southern Oregon and Northern California.
Several years ago, another female bald eagle from Dr. Sharpe's release program, also taken as a nestling from an Alaska nest, paired up with a male bald eagle at Del Valle Reservoir in Alameda County and producing young. That bird may still be there, as far as I know.
Blue A-19 was hatched in 2003 and so should be about old enough to pair up and breed. It may be too late for this year, but if the bird stays in the area, it would be fun to contemplate nesting bald eagles in the Russian River area in 2010.
It is a reminder that bald eagles are increasing in the area. And a tagged bird, including a color marked bird can be reported to the Bird Banding Lab. I will provide the contact on a separate posting in the near future.
Stan Moore
Fairfax Raptor Research
P.O. Box 341
San Geronimo, CA 94963
hawkman11@hotmail.com
707.479.9863
Wednesday, April 8, 2009
thoughts on albinism in birds; particularly redtail hawks
The photo attached to this posting shows a white gyrfalcon on the left and a white redtail hawk on the right.
Note the talons of the hawk. The photo was sent to me by Henry Kendall of Chesterfield, Missouri who was caring for the birds at the time the photo was taken, in the 1960's if I recall correctly. I believe the falcon was the mascot at the time for the U.S. Air Force Academy and the hawk (named "Whitey") was part of Henry Kendall's breeding project in which he hoped to produce white redtail hawks for falconers. Kendall is the first falconer to breed a prairie falcon in captivity in the early 1960's, which was before the first successful breeding of peregrine falcons in captivity in the U.S. and helped demonstrate that medium to large falcons could be produced in a captive breeding program.
I know of at least one person who would look at the photo of "Whitey", the redtail hawk on the right and say Whitey was not an albino hawk or albinistic, because the bird had normal, dark eyes and thus was not missing the normal pigment in the eyes. Thus, such a bird was just a hawk with some extra white in it, but not albino nor albinistic, any more than a woman can be partially pregnant.
Of course, such a thought process depends on a particular, simplistic definition of albinism that limits albinism to birds with no pigment at all, including feathers, skin or eyes and does not account for birds with lesser degrees of albinism. I consider such self-limiting definitions to be scientifically flawed and unnecessarily confusing because they do not describe the fullness of relevant reality, but impose artificial limitations not present in reality.
A better definition of albinism is used by Paul Johnsgard in "Hawks, Eagles and Falcons of North America". His succinct definition is as follows: "Albinism: Absence (locally or overall) of melanins or other pigments in individuals that normally are more highly pigmented."
Terres, in "The Audubon Society's Encyclopedia of North American Birds" describes albinism as:
"an albino has white feathers instead of the usual colors of its species and the white feathers may cover the bird wholly or in part, as there are various degrees of albinism. Some birds such as swans, geese, herons, egrets, gulls and others that are normally white are not albinos." (I would add that the same is true of horses and other animals with all or partial white in their normal coloration).
Terres goes on to describe the four degrees of albinism as follows:
"Total Albinism: the rarest form, in which the bird has a complete absence of melanin from the eyes, skin and feathers.
Incomplete Albinism: Pigment is completely absent from either eyes, skin or feathers, but not all three.
Imperfect Albinism: Pigment formation is partially inhibited (reduced) in eyes, skin or feathers, but pigment is not totally inhibited in any
Partial Albinism: The commonest form: ... within local parts of the body may involve certain feathers only; it is often symmetrical and each side of the bird may show white feathers in the same pattern.
Clearly, "Whitey" was an incomplete albino redtail hawk. That is the best available precise scientific terminology for that bird. The eyes were normal but the feathers and the talons were white. I have photos of similar redtails white normal talons and normal eyes, but all white feathers. I have photos of partially white redtail hawks with normal talons and eyes, and these would be scientifically called "partial albino" redtail hawks, not "hawks with some white feathers".
Interestinly, I happened to look in Ron Austing's very important book "The World of the Redtailed Hawk and found photos of a hawk he and his friends captured in Ohio in 1960 which is shown on page 27 of that book. The photo is black and white. It shows an adult redtail white white feathers and white talons and a white eye with yellowish tinge. The text describes the color of the feathers as white, though the photo appears to me to show some degree of pigmentation. In the absence of better information, I would tend to describe that bird as an "imperfect albino" hawk, or with dilute plumage. The eyes were not pink, but whitish and the bird was described as having excellent vision, which should not be typical of a total or pure albino redtail hawk.
I personally trapped and banded an imperfect albino (or leucistic) redtail hawk in my study area and its eyes were paler than normal, but not pink and the bird showed diluted pigmentation throughout its plumage.
In summary, to limit the definition of albinism to its purest and rarest form is to limit understanding of what albinism is and how it is expressed in birds. This information on the four degrees of albinism has been published in ornithological textbooks for five or more decades and has always been readily available. Why some authors continue to provide only a superficial and abbreviated definition of albinism, making it synonymous only with pure or total albinism is beyond me. Clearly, partial albinism is the most common form of albinism in birds and the other forms are well-documented. I have seen photos and descriptions of pure or total albino owls in the literature, but hardly so of hawks. Ron Austing mentions an albinistic red-shouldered hawk discovered by Dr. Heinz Meng in New York that had pale blue irises and which lived less than three years in captivity. Such a bird may not have survived to adulthood in the wild. Several sources reveal that albinism in hawks is not expressed in the plumage until adulthood.
Henry Kendall told me and others that he had documented over 550 case histories of albinism in redtail hawks. I am unaware that he ever documented any case of pure or total albinism, including pink eyes. Clearly, those hundreds of birds were either incomplete, imperfect, or partial albinos, according to the most precise definitions available. The most common form of albinism in birds, including redtail hawks is partial albinism, which is a term that has been used in ornithology for decades and is highly appropriate, accurate, specific and scientific.
Stan Moore
Tuesday, April 7, 2009
California raptors and palm trees
While palm trees may be "exotic" for California raptors, the birds seem to find utilitarian uses for them, including roosts, hunting perches and nesting substrates. Note: You may click on the images to enlarge them.
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