Monday, September 28, 2015

Musings on Molt, Body Mass, and Migrating Cooper’s Hawks

Last week I was scheduled for only a single day in the raptor trapping blind at the Intermountain Bird Observatory’s Lucky Peak station (some weeks I get two or three days). Gusty southeast winds made for a slow day (as predicted by my previous research manuscript – Miller et al. 2011). We only trapped six raptors in eight hours. Not bad, but this is peak season and we should be getting at least 20 birds a day. But you can’t argue with the wind… Believe me, I’ve tried!

While it was a slow day and we didn’t trap any “sexy” birds (e.g., Northern Harriers, Peregrine Falcons, Golden Eagles, etc.), we did process two birds that presented some unique points of interest. The first was a hatch-year female Cooper’s Hawk that was banded back in August. A local! Cool! One of the main points of banding birds is to get reports from recaptures which help us to understand the movement patterns of the birds. What made this bird interesting, beyond the re-capture which we always celebrate, was that it was adventitiously molting two tail feathers – Right R1 and R2. This suggests that something, possibly a predator or mobbing bird trying to defend itself, got a hold of the tail and pulled out two tail feathers. When a full feather is pulled out (versus broken off), most birds will adventitiously grow a replacement without waiting until the annual molt cycle (which would be next summer for this bird). These adventitious feathers can be interesting, especially on birds, like this one, that are currently in juvenile plumage, but their next molt will be in adult plumage. The feather can come in as juvenile, adult, or even in between. The feathers of this bird appears to be fully in juvenile coloration (which I would expect just four months after hatching).

Hatch-year female Cooper’s Hawk adventitiously molting two new juvenile tail feathers.

The second interesting bird of the day, was an after-hatch-year female Cooper’s Hawk that weighed 500 grams (sorry, didn’t take a photo…).  At 500 grams, this bird is in the 94th percentile for weight among female Cooper’s Hawks that we have banded along the Boise Ridge.  Impressive! Furthermore, this bird was nearly complete with it’s full body molt, hence the after-hatch-year age instead of the more specific second-year or after-second-year age classification (we need two ages of feathers present to assign a more specific age).  We do catch many birds that fall in this age category, but most (~2/3) come later in the season. I suspect the bird was a second-year bird judging by the color of it’s eye, but we are not allowed to use eye color to age at this level of detail. The conclusion: this particular bird must be a very good hunter. Both the weight and the progression of molt indicate that this bird was much more successful than most.

Research has shown in raptors, and in Cooper’s Hawks specifically, that larger females have greater lifetime reproductive success and their offspring are recruited into the population at a higher rate (Curtis et al. 2006). This bird appears well prepared for the next breeding season and for the years after that. Poor body condition can take years to overcome and most are never able to recover. Great body condition, leads to less expensive migration, greater over-wintering success, less expensive return migration, and ultimately better eggs next breeding season. The chain continues.

Did she breeding this year? We have no way to determine that, but it is possible that she did not breed this year, thus enabling her to grow her personal resources for the future. Many second-year birds do not breed. This brings up a good research question – what is the better strategy – breed early resulting in more years of breeding, or build resources, thus increasing success in later years. To my knowledge this has not been studied in Cooper’s Hawks, but studies in other species have found the lifetime reproductive success to be similar between the two strategies. If there was a strong advantage one way or the other, evolution would likely instill that strategy within the population. Cool stuff to think about. I can’t wait to get back up there on Thursday (although another day of SE winds are predicted…)!

Literature Cited

Curtis, O.E., R.N. Rosenfield and J. Bielefeldt. 2006. Cooper's Hawk (Accipiter cooperii), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from:

Miller, R. A., J. D. Carlisle, and G. S. Kaltenecker. 2011. Effects of Regional Cold Fronts and Localized Weather Phenomena on Autumn Migration of Raptors and Landbirds in Southwest Idaho. Condor 113: 274–283.

Thursday, September 24, 2015

A Short Visit to Grand Teton National Park

After living in Idaho for 27 years, I finally made it over to visit Grand Teton National Park in neighboring Wyoming. Karyn and I visit Yellowstone National Park almost annually and I manage a woodpecker survey project which borders the park, yet this was my first time there! It was a short and rewarding trip.

Grand Teton and surrounding mountains.

Our trip consisted of a quick four day visit to the park. Our goal was for general sightseeing,  hiking the trails and watching the wildlife. The landscape was stunning, highlighted by the fantastic fall weather. We were also very successful in the hiking department, but a little disappointed in the abundance of wildlife. We had expected viewing opportunities more similar to Yellowstone, but our lack of observations may be related to lack of knowledge of where to go to have the best observations. Regardless, it was still a fantastic trip.

Mount Moran and Jackson Lake from Hermitage Trail.

Morning reflection, Leigh Lake.

Morning reflection, Leigh Lake.

The signature wildlife for Grand Teton National Park is the Shiras Moose. The only place we would see them was within our campground where there were near permanent fixtures. I was even trapped in the restroom by this bull that was standing a mere 10 meters away (facing me at the time…)!

Bull Shiras Moose, Gros Ventre Campground.

Shiras Moose, Gros Ventre Campground.

Bird watching was good. There were an unbelievable number of Mountain Chickadees. My favorite birds of the trip were the abundant and gregarious Gray Jays. They were mostly unafraid, approaching us closely, and putting on quite a show.

Gray Jay drinking water, Leigh Lake.

Gray Jay drinking water, Leigh Lake.

Gray Jay blocking our trail, String Lake.

Another wildlife viewing highlight was watching a pair of American Beaver along the Snake River just before sunset.

American Beaver adult and juvenile, Snake River.

American Beaver adult and juvenile, Snake River.

American Beaver adult and juvenile, Snake River.

And who doesn’t love American Pikas?

American Pika, Hidden Falls, near Jenny Lake.

Double-crested Cormorant, Oxbow Bend.

Ruffed Grouse, Moose Ponds Trail.

It was a great trip. Next time we will plan to spend more time, take our bikes (there is more than a 100 miles of bike paths) and our inflatable kayak to paddle the lakes and rivers.

Friday, August 14, 2015

The Ins and Outs of Northern Goshawk Research at the Intermountain Bird Observatory

My fifth year as part of the Intermountain Bird Observatory (IBO) leading the research on Northern Goshawks within the Sawtooth National Forest has come to a close. By all measures it was a very successful year, but unfortunately my time trouncing through the woods has finished for this season.

Two goshawk nestlings in a newly discovered nest in Piñon Pine, an uncommon nesting substrate.

I thought it might be helpful to dive a bit deeper into the objectives of this program. As with many programs, our efforts are balanced among a number of objectives. Some of our objectives are mostly nested within the other objectives, so we can be efficient in addressing multiple objectives with the same effort.

Core objectives for the Northern Goshawk research and monitoring efforts:

  • Evaluate the population trend for this species within the Minidoka Ranger District of the Sawtooth National Forest.
  • Evaluate the genetic health of this species within the northern Great Basin region of the western United States, which encompasses the Minidoka Ranger District of the Sawtooth National Forest.
  • Evaluate threats to this species, with an emphasis on blood parasites, within the northern Great Basin of the western United States.
  • Provide educational and training opportunities for undergraduate students preparing for a career in wildlife biology.

Here’s more detail on each of these objectives.

Objective 1. Evaluate the population trend for this species within the Minidoka Ranger District of the Sawtooth National Forest.

The USDA Forest Service has a set of guidelines requiring each forest to identify Management Indicator Species (MIS) that align with their forest structural objectives. The basic concept is that instead of monitoring all species within the forest, which is not generally feasible, each forest should monitor a few key species whose population status is generally dependent and aligned with the type of forest structure they desire. There are generally a wide range of criteria for choosing good management indicator species (Caro and Girling 2010). Seddon and Leech (2008) suggested a focus on seven criteria for choosing appropriate species: they should have a well-known biology; large home range size; high probability of population persistence; co-occurrence of species of conservation interest; management needs that are beneficial to co-occurring species; sensitivity to human disturbance; and ease of monitoring. The Northern Goshawk meets most of these criteria, at least to some degree. While this approach has its critics, Sergio et al. (2006) has demonstrated a high correlation between Northern Goshawk presence and species diversity including the number of avian species (richness), the number of vulnerable avian species, the number of tree species, and overall avian species diversity (richness and evenness). It is not surprising that many forests, including most in Idaho, have chosen the Northern Goshawk as one of their Management Indicator Species.

Nestlings ready to fledge in the City of Rocks National Reserve.
36 - 38 days old (usually fledge 34-42 days old).

The Sawtooth National Forest is one forest that has specified the Northern Goshawk as an MIS species. They partner with the Intermountain Bird Observatory to accomplish their monitoring objectives as we deliver core biological science to the key questions within the forest. The work within the Sawtooth National Forest has been implemented in steps. IBO worked with the Sawtooth National Forest on goshawks in the late 1990 and early 2000’s. This work was renewed in 2011. My first two years, my thesis years (2011 and 2012), were focused on how the the goshawks utilize the local forest from both a forest structural perspective (Miller et al. 2013) and a prey perspective (Miller et al. 2014). These results had both scientific and management implications. The goshawks within the Minidoka Ranger District of the Sawtooth National Forest have had to adapt to the highly fragmented, island-like structure of the forest, and the absence of the primary food source they consume in most other regions of the world where they exist – tree squirrels.

They don’t all make it. ~20-day old nestling. I discovered this failed nest on the day it failed. Apparently predated by an aerial predator, likely an owl.  The nest was covered in feathers.
South Hills, Idaho.

The next two years of the study have included utilizing the habitat models that I established with my thesis work and a lot of effort on the ground to locate previously unknown nesting territories. This activity has been very fruitful in doubling the number of known goshawk territories within the forest while also further refining our understanding of the habitat use.

While we have not located all of the nesting territories within the forest, we now have sufficient coverage to shift our primary attention toward population size, structure, and dynamics. Historical data within the northern Great Basin suggests that female turnover is much higher in the region than elsewhere (Bechard et al. 2006). It has been suggested that turnover rate may be a much more important measure of population health than population size as sink populations, those with a much higher immigration rate than emigration rate, can show stable population size even as the local population heads toward collapse. Turnover refers to the replacement of a breeding adult from one year to the next within a territory. Turnover can occur as the result of death or abandonment (one adult disperses to a new mate and territory). Turnover is primarily measured by mark-resight studies involving trapping and banding the adult birds with color bands which can be read from a distance without having to recapture the bird. In 2014 and 2015, we have deployed many color bands on adult birds in the area and our efforts have already been paying off. 

Female Purple Z3 nesting for at least her second year in the Albion Mountains, Idaho. Purple color band Z3 clearly visible on her right leg (photo from 2014, but observed again in 2015). Originally banded as a nestling in the South Hills in 2012. With this single band we have established a natal dispersal distance for this individual and have identified that she has bred for two years in a row in the same territory, all without recapturing her.

These banding activities will enable us to monitor occupancy, productivity, turnover rates, and responses to management actions. Our preliminary results from 2015 suggest that the high turnover observed a decade ago is still occurring at similar rates.

I have two leading hypotheses regarding why the turnover rate may be higher within this forest as compared with other nearby forests.

  • My post-fledging mortality hypothesis (leading hypothesis) 
    • Nest productivity is good by both common measures (young fledged per occupied nest and young fledged per successful nest). (CONFIRMED)
    • The breeding season diet within the area is predominantly ground squirrels.  (CONFIRMED - Miller et al. 2014)
    • Ground squirrels estivate mid-summer removing them from the available food supply for goshawks. (CONFIRMED)
    • Female goshawks generally abandon territory the year after a brood failure at a rate of 50% (CONFIRMED).
    • There is insufficient food to support the cohort of fledglings after ground squirrel estivation causing high fledgling mortality resulting in complete failure of some broods  (NOT confirmed)
    • Females abandon the territories in our study area due to these late season failures (NOT confirmed).
  • My disease hypothesis
    • Black flies within the family Simuliidae are pervasive in the area and carry/pass the Leucocytozoon blood parasite (CONFIRMED - Twin Falls County Pest Abatement District 2012)
    • Blood parasites are pervasive within the study area (CONFIRMED – Jeffries et al. 2015)
    • Females are more at risk than males due to the amount of time they spend immobile at the nest (Partially Confirmed).
    • Female survival is lower as a result of the parasite and the onslaught of black flies (blood loss; NOT confirmed).

We will be working through these research questions in the coming years, assuming we can get funding for the work.

Objective 2. Evaluate the genetic health of this species within the northern Great Basin region of the western United States, which encompasses the Minidoka Ranger District of the Sawtooth National Forest.

The northern Great Basin provides unique habitat for a wide variety of species. The area is home to unique genetic composition for a number of species - a sub-species of Red Crossbill, known as the South Hills Crossbill, that is endemic to the area; an endangered plant called Christ’s Paintbrush that is endemic to the area; a unique form of Lodgepole Pine tree; and a number of bird species that exist nowhere else in Idaho.

Bayard de Volo et al. (2013) investigated the inter-relationship of various North American goshawk populations. Among other things, they found that there were unique mitochondrial haplotypes located in the Rocky Mountains which appear not to have travelled back to the coastal mountain populations. Think of a haplotype as a genetic signature. Bayard de Volo and team believe that as the glaciers retreated in North America, the Rocky Mountains were populated with goshawks from the historical refuges within the coastal mountains and from Arizona. The birds developed new haplotypes in the Northern Rockies, but these haplotypes have not migrated back. Bayard de Volo and team did not investigate the northern Great Basin populations. That is where we at IBO come in.

Rob (me) climbing tree to access the nestlings for banding and genetic sampling.

Team Goshawk intern Kenny and forest biologist Scott banding and sampling the first goshawk nestling of the season. Sublett Mountains, Idaho.

The forest structure and prey composition within the northern Great Basin presents unique challenges for goshawks (Miller et al. 2013, 2014). It is conceivable that the goshawk populations in these areas have undergone evolutionary changes which enable them to better adapt to these environmental options. Therefore, we postulate that we may find unique genetic haplotypes in the area which have not migrated to the core of the Rocky Mountains or back to the coastal populations. Furthermore, if connectivity does exist to these larger contiguous populations to the east and west, to which are the northern Great Basin birds integrated?

Mitochondrial DNA sequences from Northern Goshawks within the South Hills
of the Sawtooth National Forest collected in 2012. Each row represents a different bird. In this case all samples shown represent the same haplotype.

A separate analysis process (microsatellites) allows us to look for signs of inbreeding depression. This process is a bit more complicated and takes more time. The mitochondrial haplotype process described earlier looks further back (i.e., thousands of year), whereas the microsatellite process allows us to look more into the past 100 years – post-modern human settlement.

We collect genetic samples by taking blood, removing a feather from a bird, or even collecting a molted feather from the ground beneath the nest.  The adult female often molts feathers while incubating eggs on the nest. Some of these molted feathers contain sufficient DNA for extraction. We prefer the least intrusive method (molted feather from ground), but if we need blood for the parasite study (discussed below), then we use it for the DNA as well as blood provides the highest quality sample.

For two years now I have had National Science Foundation funded undergraduate students, Steph in 2014 and Kenny in 2015, working on the genetic analysis. Each have worked with me in the field for a period of four weeks surveying for birds and collecting samples before reporting into the laboratory for the delicate work of genetic analysis.

We are still processing samples, but so far we have not discovered any unique haplotype signatures for the northern Great Basin. This is both good news and bad. Good as that decreases the chance of genetic bottlenecks in the population, bad because it would be really cool to discover that goshawks have evolved specifically to this dry forest island environment. Additionally, our early results indicate that at least the Minidoka Ranger District of the Sawtooth National Forest is well integrated with the Rocky Mountains to the east. We have processed fewer samples using the deeper analysis, but so far we have discovered no signs of inbreeding depress. That is great news from a conservation perspective.

We have collected samples from the Owyhee Mountains in southwestern Idaho (still in analysis)  and are partnering with forest biologists across Idaho and in Oregon to expand the geographic scope of our work.

Objective 3. Evaluate threats to this species, with an emphasis on blood parasites, within the northern Great Basin of the western United States.

When I began my work with the goshawks back in 2011, I was informed that most of the birds in the Minidoka Ranger District of the Sawtooth National Forest probably die of a blood parasite that was believed to be in the area. This occurred after I had already designed my thesis work focusing on prey and habitat or I probably would have just focused on the parasite. Regardless, I was able to recruit a volunteer undergraduate student, Michelle, to work on collecting and analyzing blood samples searching for a blood parasite related to Malaria known as Leucocytozoon.

The vector for the disease are flies of the family Simuliidae. These flies are pervasive in the area and pose a double threat. The first threat is from blood loss. At first I didn’t believe that a small fly could have such an impact, but even livestock are at risk of blood loss with these flies. The flies are relentless, targeting the neck and eyes of the nestlings and adult females. I have even donated my blood to one or two of them! The second threat of course is the blood parasite disease.

Goshawk nestlings covered in flies from the family Simuliidae, sucking blood and known vectors of the blood parasite Leucocytozoon. South Hills, Idaho, 2011.

Skin lesions around the neck of an adult female goshawk, likely caused by Black Flies. South Hills, Idaho, 2012.

The adult male birds we handle rarely show the effects of the Black Flies. We believe that these birds have the parasite (confirmed in some), but they are more mobile during the breeding season, better able to avoid the flies. In goshawks the female performs 100% of the incubation and brooding, putting her at constant risk at the nest.

Adult male goshawk with little sign of Black Fly lesions.

Leucocytozoon blood parasite (center) amongst goshawk red blood cells from a sample of blood from a South Hills nestling goshawk taken in 2012. Note: avian blood cells are nucleated, unlike mammalian blood cells.

Our results from 2012 have shown that 28 nestlings from 12 separate nests were all infected with the Leucocytozoon blood parasite. Since samples were taken at a nestling age of approximately 24-28 days old, and the disease takes two weeks to show up in the blood, they were all infected within the first 10 days of their life. This speaks to the pervasiveness of the disease. It is believed that the flies do not themselves have the disease intrinsically, but pick it up as the bite the adult female in the nest and then pass it along as they bite the nestlings. This is referred to as vertical transmission within the nest.

Michelle has submitted a research manuscript for publication in the Journal of Raptor Research, which is due out in the September issue! Woo Hoo!

Jeffries, M. I., R. A. Miller, M. D. Laskowski, and J. D. Carlisle. 2015. High prevalence of Leucocytozoon parasites in nestling Northern Goshawks (Accipiter gentilis) in the northern Great Basin USA. Journal of Raptor Research 49 (3): In Press.

Our next steps are to use genetic techniques to analyze the blood samples for other blood parasites such as avian malaria and Hemaproteus. These diseases are transmitted by mosquitos so we expect less pervasiveness as there are fewer mosquitos in the area. We are working to acquire funding and organize this effort at this time.

4. Provide educational and training opportunities for undergraduate students preparing for a career in wildlife biology.

In my five years of work on goshawks, I have directly employed six undergraduate students on these projects. Four are working as wildlife biologists or in related fields (Lauren, Emmy, Mike, and Steph), one is in graduate school leading her own research (Michelle), and one is still an undergraduate (Kenny). I hope that I have provided an excellent opportunity for them to learn and grow and have provided sufficient guidance to help them be more successful in their careers. Michelle’s publication due out next month is a tremendous accomplishment. I feel more honored to have mentored her in the process than to have my own publication. I expect this to be the first in a number of mentored publications in which I get to participate (I am still working on my own as well).

In addition to the direct engagement of students on the project, for the last two years I have hosted a two day goshawk workshop for the group of undergraduate raptor research students participating in the National Science Foundation funded Research Experience for Undergraduates (REU) program at Boise State University. This program hires eight or nine undergraduates each year from across the country. It is highly competitive with over 250 applicants each year. I have hosted one student each of the past two years – Steph in 2014 and Kenny in 2015, focusing on genetics. However, for one weekend each year, we bring all eight or nine students to the study area to focus on goshawks. For most students this is the first time they have seen a goshawk in the wild. They are trained on identification, surveying, tree climbing, genetic sampling, etc. What a great opportunity!

It is hard to boil down five years of work into a single blog post! Hopefully you found it worthwhile.

An old friend. Banded adult female goshawk nesting where I would expect her – Band: Purple N4.

Literature Cited:

Bayard De Volo, Shelley, Richard T. Reynolds, Sarah A. Sonsthagen, Sandra L. Talbot, and Michael F. Antolin. 2013. “Phylogeography, Postglacial Gene Flow, and Population History of North American Northern Goshawks (Accipiter Gentilis).” The Auk 130 (2): 342–354.

Bechard, M. J., G. D. Fairhurst, and G. S. Kaltenecker. 2006. “Occupancy, Productivity, Turnover and Dispersal of Northern Goshawks in Portions of the Northeastern Great Basin.” Studies in Avian Biology 31: 100–108.

Caro, Timothy M, and Sheila Girling. 2010. Conservation by Proxy Indicator, Umbrella, Keystone, Flagship, and Other Surrogate Species. Washington, D.C.: Island Press.

Jeffries, M. I., R. A. Miller, M. D. Laskowski, and J. D. Carlisle. 2015. High prevalence of Leucocytozoon parasites in nestling Northern Goshawks (Accipiter gentilis) in the northern Great Basin USA. Journal of Raptor Research. In Press.

Miller, R. A., J. D. Carlisle, M. J. Bechard, and D. Santini. 2013. “Predicting Nesting Habitat of Northern Goshawks in Mixed Aspen-Lodgepole Pine Forests in a High-Elevation Shrub-Steppe Dominated Landscape.” Open Journal of Ecology 3 (2): 109–115.

Miller, R. A., J. D. Carlisle, and M. J. Bechard. 2014. “Effects of Prey Abundance on Breeding Season Diet of Northern Goshawks (Accipiter Gentilis) within an Unusual Prey Landscape.” Journal of Raptor Research 48 (1): 1–12.

Seddon, Philip J., and Tara Leech. 2008. “Conservation Short Cut, or Long and Winding Road? A Critique of Umbrella Species Criteria.” Oryx 42 (02): 240–45.

Sergio, F., I. Newton, L. Marchesi, and P. Pedrini. 2006. “Ecologically Justified Charisma: Preservation of Top Predators Delivers Biodiversity Conservation.” Journal of Applied Ecology 43 (6): 1049–1055.

Twin Falls County Pest Abatement District. 2012. Why all the Black Flies. Twin Falls, Idaho.

Wiens, J. D., and F. T. Reynolds. 2005. “Is Fledging Success a Reliable Index of Fitness in Northern Goshawks?” Journal of Raptor Research 39 (3): 210–221.

Sunday, July 12, 2015

Public Outreach and Education

My job at the Intermountain Bird Observatory occasionally calls for me to participate in, and in some cases lead, public outreach and education. Most of my work days involve solo fieldwork or sitting behind the computer. However, these public outreach events provide an opportunity for me to share the results of much of that work.

Over the past couple of years, I have made a number of presentations to local birding groups. The first was a tour with the results of my thesis studying the breeding ecology of the Northern Goshawk. I presented those results to the volunteers at the Peregrine Fund, the Golden Eagle Audubon Society of Boise, the Prairie Falcon Audubon Society of Twin Falls, and the Southwestern Idaho Birders Association in Nampa. More recently, I presented an overview of the various research projects in which I participated while working in Tarifa, Spain in late 2014. I have delivered this presentation to the Golden Eagle Audubon Society and the Prairie Falcon Audubon Society.

Presenting at the Golden Eagle Audubon Society meeting in Boise, Idaho.

A good sized audience for the presentation in Boise.

The presention included an overview of the eight research projects in which I was involved – flamingos, raptor migration counts, osprey re-introduction, songbird banding, swallow banding, Black Kite banding, seabird migration, and songbird moon counts – an photos of our cultural experiences. A highlight of the presentation was the viewing of a video about the flamingo banding project that Karyn and I had the honor to participate in at Laguna de Fuente de Piedra.

Playing the Flamingo video.

The video was created by a Spanish friend of mine, Manuel, who was kind enough to allow me to use it in my presentation. He maintains a great blog at

The full flamingo video may be viewed on youtube at or here:

While I enjoyed all of the projects in Spain, the flamingos were clearly the most fascinating!

In May, I presented preliminary results from the Idaho Bird Conservation Partnership’s Short-eared Owl project to the Upper Snake chapter of the Idaho Master Naturalists. I expect to provide an updated version of this talk to other local groups this fall. In August, I will also lead a half day field trip with the New Roots organization to the Gregory fire near Idaho City to discuss the importance of fire ecology on forest dwelling birds, most notably woodpeckers. I am looking forward to engaging these students on this very important aspect of our natural world.

Wednesday, June 17, 2015

Team Goshawk 2015 – a new year, a new team, and we are off to a great start!

June has once again brought me into the Minidoka Ranger District of the Sawtooth National Forest to study the Northern Goshawk. This year I am joined by a new intern from University of Wyoming who will assist in all field activities and be leading his own research into the genetics of the birds.  Kenny is investigating the bio-geographic distribution of certain haplotypes within the mitochondrial DNA of the birds. This work builds upon work that my 2014 intern Steph performed last year and of other prominent goshawk researchers (Bayard De Volo et al. 2013). We will also be working alongside the Forest Service wildlife biologist and other volunteers.

We have just returned from the first week and a half in the field. We have had great success in finding new territories, new nests, and new birds. Most of the occupied nests we have discovered have had three nestlings, leading me to believe that productivity might be slightly higher this year than in years past (usually averages around 2.4 nestlings per nest). We will have to wait for all of the results to know for sure.

Sunrise on Team Goshawk, Albion Mountains, Idaho.

Our survey work operates in stages. The first stage consists of checking the status of all known historical nest structures. For many historical territories, we find the birds occupying one of these nests. If not, we survey the area within one mile of these structures by broadcasting the call of the goshawk in an attempt to solicit a response, what we call a detection. These call points are spaced 300 meters apart in suitable habitat. This can result in up to 40 call points per territory which can require days of effort to complete. With 45 historical territories, this can be a great deal of work. However, once we get a response, we stop the survey of the area and move to the next step.

Adult female Northern Goshawk, note white brood feathers around the waist.

Once we have a detection of a local bird, we begin searching for the nest. This too can take some time and requires properly interpreting the response of the bird to the call. Is the bird defensive of the area, indicating a nest may be nearby, or did we simply surprise the bird while it was out hunting, in which case it usually flies off. Did it approach silently, most often male, or did it call remotely, most often female. Does it get more aggressive when you move in a certain direction versus others.

Northern Goshawk nestlings in Piñon Pine tree, approximately 30-32 days old.

In the end, we hope to find an occupied nest. However, the bird could be a territorial bird without a mate, a territorial bird with a mate but did not breed, a territorial bird whose nesting attempt had failed before we got there. As you can see there many challenges and many opportunities for false interpretation. Five years of experience definitely helps, but does not completely eliminate false conclusions.

Northern Goshawk nestlings in Aspen tree, approximately 38-40 days old, ready to fledge!

Upon finding the nest, we approach quietly to minimize disturbance, try to ensure that it is occupied, identify the number and age of the nestlings, and to look for molted feathers on the ground for DNA analysis. We are often successful in collecting samples in this minimally intrusive way.

If we have not sampled the nest previously, if we fail to find a molted feather on the ground, or if banding of the nestlings is justified, then we must climb the tree. In some cases the tree is not safely climbable, but many are. Kenny and I have each climbed one tree so far this year.

Rob (me) in a Northern Goshawk nest n a Douglas Fir tree.

If we are only banding the young, that is often performed in the nest. However, for genetic sampling, we often lower the bird to the ground to be processed. It is safer for all involved. We fit a sleeve over the bird to protect the wings and lower one at a time to the ground in a bag.

Kenny (left; Team Goshawk intern) and Scott (right; Forest Service Biologist) banding male goshawk nestling.

Rob (me) rappelling out of the tree.

I should note that this process and level of disturbance requires proper training, a federal permit, a state permit, and an Institutional Animal Care and Use permit, all of which require justification that the research is worth the impact on the individual birds. The goshawk is considered a sensitive species by the USDA Forest Service and a local Management indicator Species (MIS) for the Sawtooth National Forest. This is why we study them and why we must be conservative with our level of impact. We work hard to minimize the disturbance. The goal is to limit total disturbance to less than a hour.

Interesting tree to climb.

Kenny ascending the rope to the nest.

Kenny approaching the nest to band and collect a feather sample for DNA.

Kenny rappelling out of the nest. Success.

Sometimes when we play the call of the goshawk, other species respond. For large birds, resident Red-tailed Hawks, Common Ravens, and Great Horned Owls often respond. Of the smaller birds, Mountain Chickadees, American Robins, and many woodpeckers can also respond. If there are tree squirrels in the area, they too join in.

Red-tailed Hawk unhappy about our presence.

While in the woods we get to observe many unexpected things, both positive and negative. From this recent trip, the most disturbing and outraging observation was to find more dead birds in a water storage tank that I reported last year. Last year we saved an adult male goshawk from death in this tank (story here). Apparently my report got passed around to the responsible party and they made a half-assed attempt to resolve this issue by placing a mesh picnic table vertically on the side of the tank. I can confidently say that their counter-measure was completely useless. I was once again shaking with rage upon making the discovery. I have alerted the authorities and pressed them for a more thorough resolution to the matter.

Dead Cassin’s Finch (I think) in “Dead Bird Spring”.

Other downers from the woods are the beer cans, balloons, and other garbage which is now pervasive across the landscape. It is difficult to walk a 1/2 mile through the woods without finding garbage. We as a society must do better.

Turning to the positive, wildlife! More time in the woods means more opportunities to view awesomeness. While not as awesome as a goshawk, a Short-tailed Weasel (a.k.a. Ermine) is pretty darn close. BTW, I have video evidence that goshawks do eat these guys…

Short-tailed Weasel, Sublett Mountains, Idaho.

Moose, Albion Mountains, Idaho.

We have seen numerous deer fawns, elk, and moose. Kenny even found a recent Mountain Lion killed deer fawn, half buried. He said that he chose not to stick around!

We have a few days off before we are back to the long, hard, and wonderful days in the woods. My friend and mentor from Spain, Alejandro, arrived last night and will be joining us for the next round of work (Tengo que practicar mi español!). I can’t wait to get back out there!

Wednesday, May 27, 2015

What About the Birds?

Karyn and I just returned from a week long vacation exploring the wilds of Yellowstone National Park. This is our second in a series of posts highlighting some of our observations (previous post - Three Dog, Two Bear Day). Our activities included lots of wildlife watching, meeting with our friends from visits past, and a daily hike.

Many people travel to Yellowstone in the hopes of seeing the large mammals, ourselves included. However, the birding there is also great. We had a great time enjoying the avifauna, some of which was up close and personal.

Many of our most interesting observations included the community of Common Ravens in the park. These intelligent birds are very cunning and quite entertaining. They are often found following bears and wolves. There is even a theory that ravens might actually lead predators to prey.

We had a mix of entertaining observations. In the Yellowstone picnic area a family turned away from the table and their bag of potato chips were gone in an instant. They didn’t even see the bag disappear! On another observation we watched a raven fend off the attacks of six Black-billed Magpies to eventually find their nest. After close to five minutes of attacks, it finally found the nest and flew off with at least one magpie nestling in it’s beak, maybe two.

Common Raven, Yellowstone Picnic Area, Yellowstone National Park.

Common Raven, Yellowstone Picnic Area, Yellowstone National Park.

Common Raven nest, near Gibbon Falls, Yellowstone National Park.

We have watched on previous trips as Common Ravens mobbed Bald Eagles. In my observations over time, it is a common occurrence. However, in the instance of this particular eagle, a group of six Common Ravens were perched behind the eagle. They appeared to be waiting for the eagle to make a kill, that they might then try to steal. When the eagle flew off, so did the ravens.

Bald Eagle and Common Raven, Floating Island Lake, Yellowstone National Park.

Bald Eagle, Floating Island Lake, Yellowstone National Park.

Sticking with Raptors, we once again observed the Peregrine Falcon nest that we found last year (near Tower Falls). We also observed them in Lamar Canyon which brings the total distinct locations we have observed Peregrine Falcons within the park to four. It is always great to observe these birds that just decades earlier were at the risk of going extinct.

Peregrine Falcon on a nest, Yellowstone River, Yellowstone National Park.

Of course, we observed lots of other birds as well. Here’s a collection of higher quality photos.

White-breasted Nuthatch, Slough Creek, Yellowstone National Park.

House Wren, Slough Creek, Yellowstone National Park.

Black-headed Grosbeak, Upper Mesa Falls, Idaho (just outside of park).

White-crowned Sparrow, Tower Junction, Yellowstone National Park.

Killdeer, Slough Creek, Yellowstone National Park.

Gray Jay, Slough Creek, Yellowstone National Park.

Yellow-rumped Warbler, Specimen Ridge, Yellowstone National Park.

Western Meadowlark, Slough Creek, Yellowstone National Park.

Brewer’s Blackbird, Lamar Valley, Yellowstone National Park.

Townsend’s Solitaire, Specimen Ridge, Yellowstone National Park.

Canada Goose family, Slough Creek, Yellowstone National Park.

Barrow’s Goldeneye, Slough Creek, Yellowstone National Park.

Cinnamon Teal, Slough Creek, Yellowstone National Park.

Mountain Bluebird, Lamar Valley, Yellowstone National Park.