Sunday, November 06, 2016

Mi Regreso a España

I recently had the opportunity to return to Spain to work with partners and friends of the Intermountain Bird Observatory, Fundación Migres. This was my third time over there working with the team during the fall migration. It was great to spend time working with old friends and colleagues. I have previous summaries of my 2-week-long 2013 trip (HERE, with links to more stories) and Karyn and my two-month-long 2014 trip (HERE, with links to more stories).

This year’s trip was a little bit different in that the two previous trips were always during the first half of the fall migration season, whereas this trip was scheduled toward the end of the season. This gave me the opportunity to experience different birds and different projects. Another big difference was the fact that the Migres group has a new center, where I was allowed to stay!

Sunrise at the southern-most tip of Europe, Africa is visible in the distance on the right.

The beginning of the trip was a little rough. The plane was delayed out of Boise, leaving me just enough time to run to my flight to Europe at the Seattle airport. I boarded the plane just 5 minutes before the doors closed. This is never a good scenario from a checked baggage perspective! Landed in Paris and then in Malaga Spain. My bags did not. It would be another two days before my bags would join me at the Centro Internacional de Migración de Aves. Two days later, the airline attempted to deliver the baggage, but could not find the center. They asked around and someone sent them to closest count site (not the one I was at). They walked up and asked one of the Spanish employees of Migres (Andres) if he was “Rob Miller”. No, but he knew who I was and the airline handed him the bag.

Twenty hours of airports and flying, then a train, and a three hour bus connection, and I was closing in on Tarifa Spain, my home for two weeks. I texted my friend Alejandro asking for a ride from the bus station. He replied and asked if I was going to go band swallows that night in Laguna de La Janda. Ha ha, absolutely! Alejandro and I have a long standing joke about not getting any sleep upon arrival during my previous trips. This must surely be a joke. “Indeed” I reply. Lola, Wioleta, and Javi pick me up at the bus station. I am excited to arrive at the center, take a shower, get some food, and then sleep. Lola drives out of Tarifa toward the center, but then takes a left turn…what…wait… are we really going to La Janda? Yes. No food, no water, seven more hours before sleep… Welcome to Spain.! (Actually, it was a great evening and I was glad that I went). We banded 55 Barn Swallows and then stopped for a mid-night pizza on the way back to the center. I did great until I ate the pizza, then I was ready to sleep right there.

My home and office for two weeks in Spain.
It was great to be back, even without clean clothes! Migres has opened their new center which has dormitory rooms, shared kitchen, office space for employees and for visitors, a library, conference room, is a 5 minute walk from the Mediterranean, and is only a 20 minute walk to downtown Tarifa. But the biggest thrill was to be back to see one of the largest raptor migrations on earth – a place where most of the raptors in western Europe travel to for the 10 mile cross to Africa.

Cigueña blanca (White Storks) approaching the Strait of Gibraltar.
All things in Tarifa are dictated by the wind – recreation, energy, bird migration, etc. As one example, people don’t use weather apps to get the weather forecasts, they use wind apps – WindGuru – being the most reliable source. The birds approach the Strait of Gibraltar for the crossing to Africa, but if conditions are not perfect, may turn back to wait days and sometimes more than a week for conditions to improve. It can make conditions for counting very difficult – we have to discern which birds are crossing and which birds are not.

Flock of over 300 Cigueña blanca (White Storks) and 4 Espátulas (Spoonbills) with wind turbines in the background. These birds did not cross on this day due to the string Levante (east) winds.

I joined three previous Boise State University graduate students (Michelle, Erin, and Tempe) who were each spending three months working in Spain with our Migres partners. I was there for their final two weeks on the project to help wrap up the research plan and begin the work toward manuscript publication. Through IBO's partnership with Fundación Migres, we have published two research manuscripts. My previous paper from my work in Spain was published earlier this year - Local and regional weather patterns influencing post-breeding migration counts of soaring birds at the Strait of Gibraltar, Spain.

But, most of my time was out in the field counting, and in some cases identifying the age and sex of, the migratory raptors.

Rob (me) trying to identify birds at Observatorio del Estrecho. The Strait of Gibraltar is roughly 50 meters behind me.
Inmaduro Águila Culebrera (inmature [2 –4 years old] Short-toed Snake Eagle).

Milano Real (Red Kite).
One day at the Cazalla count site, we observed a very interesting bird. Carlos was very excitedly shouting in Spanish too fast for me to understand. I understood Águila (“Eagle”). It was an eagle. It was a rare eagle. It was an extremely rare eagle! Águila Esteparia – what is that?!? I am challenged enough with Spanish names for the birds I do know, but I was not prepared for a very rare sighting. Luckily the bird was flying toward us. Carlos had originally spotted it miles away. I grabbed the book and found what he was talking about – a Steppe Eagle from Africa. Woah! Spectacular. It was flying closer and closer.

It had a snake in its talons… no… it has falconry jesses on its legs… This bird is an escaped falconry bird. We don’t get to count it… We later received the owners name and was asked to call him if we encountered the bird again, which we did. I haven’t heard if he was able to recapture the bird or if it is still flying wild.

Águila Esteparia (Steppe Eagle), this one is an escaped falconry bird.
But I would get my rare bird after all. On my final half day of work before catching the bus to Malaga, a rare Águila pomarena (Lesser-spotted Eagle) would fly over the Cazalla count site, close enough for photos.

Águila pomarena (Lesser-spotted Eagle).
Another highlight of my final day at the Cazalla count site was the Griffon Vulture migration. Griffon Vultures are very large birds. Late in the season we would count hundreds of Griffon Vultures flying around the count site, but none were crossing to Africa. On my final morning there, that all changed. The wind was right and it was time to move. We could sense the change in behavior. They climbed up the ridgeline, soaring higher and higher and then streamed across the Strait. Ten, hundreds, thousands! In all, 5000 Griffon were counted migrating to Africa that day. What a great finish!

Buitre Leonado (Griffon Vulture) migrating to Africa.
But my trip was not all about raptors. The week that I arrived the team started counting the seabird migration at the very tip of Europe. I would spend two days out there counting Gannets, Cory Shearwaters, Balearic Shearwaters, Sandwich Terns, Lesser-crested Terns, Storm-petrals, etc. Being seabirds, these guys were not migrating from one continent to another, but instead from one ocean to one sea (or vice versa). The Gannets were migrating from the Atlantic Ocean into the Mediterranean Sea, as were the Balearic Shearwaters. The Cory Shearwaters were headed in the other direction. Presumably their food sources were also migrating. Tuna migrate through the Strait, which is why there are Orca at the Strait. We also observed dolphins migrating, one pod of more than 100!

The counts begin at sunrise on the Isle de Tarifa, the southern-most tip of Europe.

Michelle and Carlos counting for this round. We count for ten minutes and then rest your eyes for five minutes, with a longer break after three rounds, hence counting 30 minutes per hour. 
Adult Gannets migrating from Atlantic Ocean into the Mediterranean Sea. Their white feathers are more iridescent and reflective than most white birds. Spectacular.

We get to see other birds too, such as these Sanderlings and Mediterranean Gull.
And this Northern Wheatear perched on the very tip of Europe, possibly contemplating a crossing.
I also got to spend two nights banding swallows and one morning banding songbirds in Laguna de La Janda. Here are some of my favorites.

Male Blackcap.
Male Bluethroad, my favorite!

Pied Flycatcher. A new bird for me, but one I have read many papers on. This species is a model example of how climate change has negatively affected long-distant migrants when their food source changes its phenology (timing), but they do not.
We had a few days of spotty weather which closed some of the observatories. What do bird biologists do in these scenarios – they go birding. Alejandro took us on a birding trip up through and around Laguna de La Janda, where the weather was surprisingly good. We enjoyed three sightings of Spanish Imperial Eagles and the critically endangered Bald Ibis. Both species are benefiting from reintroduction efforts in the area.

Águia Imperial Ibérica (Spanish Imperial Eagle) in Laguna de La Janda.
The Bald Ibis was completely extirpated from Europe. Just a few years ago the estimated global population was around 500 birds! After numerous attempts at reintroduction in Europe, one colony just north of Tarifa has been successful. This colony has grown since my last visit, just two years ago.
Critically Endangered Bald Ibis.
Critically Endangered Bald Ibis allopreening.
Here is a short video I took of the Allopreening behavior. These are truly fantastic creatures.

As expected it was a fantastic trip that I got to spend with great friends from the past and new friends I made on this trip. I look forward to my next visit!

I will close with a fun video that the Migres team put together featuring some of the volunteers and collaborators including team America (myself and the three women from Boise State).

Sunday, July 03, 2016

Nature, Nurture, Environment, or All of the Above?

Wow, another Northern Goshawk field season is beginning to wrap up. How does it go so fast? The Intermountain Bird Observatory’s Team Goshawk 2016, led by me, has been busy with many expected and unexpected discoveries. As with the past two years, I am once again hosting a National Science Foundation funded intern. My 2016 intern is Lauren Whitenack. She has been a great team player, putting up with me for the past month in the field. Be sure to check out her blog for her personal view of these adventures: Wild Life.

2016 Team Goshawk intern Lauren releasing newly banded adult goshawk Female Z5

One of the reasons I like fieldwork, is that it presents many mental challenges to try and figure out. While walking through the woods, I like to think about the roles of various plants and animals, how they evolved to be who they are, and why they are so different from each other. In some cases, these mental challenges may lead to formal research questions. In other cases, it may just be an interesting thought exercise. For example, one that I have been bouncing around in my head for years, is why are Common Ravens, that sometimes nest in similar habitats as goshawks, able to be so loquacious or noisy in the nest, whereas, goshawks which seem better able to defend themselves, have evolved to generally remain silent. Is anyone interested in a behavioral evolution study?

Newly banded nestling goshawk Female AM (right) amidst jackrabbit prey remains in the nest. The first evidence I have of breeding season use of jackrabbits. The nestling on the left remained out of reach for banding.

Another one of my age-old questions rolling around in my noodle pertains to the intensity of defense behavior exhibited by different goshawks when an intruder, typically me, enters their domain. Some goshawks are prepared to give their life in defense of their young while I may still be 50m from the nest. Others simply sit silently, or even more passively, fly out of the area leaving the nest behind. What factors influence these decisions and why the different approaches?

A great deal of research, of which I am not an expert, has focused on aggressive behavior in various organisms, including humans. Is aggressive behavior dictated by nature (i.e., encoded in our genes), influenced by nurture (i.e., parental up-bringing), or by environment (i.e., events and conditions around the organism throughout its life). If only it were that simple... We biologists like to put things into simple little categories, but it rarely works out. Well, I say the answer is - all of the above!

Here I will tell the tale of three different goshawks or family of goshawks, with differing levels of aggression, that may support my hypothesis for all of the above. Furthermore, it is generally agreed that goshawks in North America are on average more aggressive than their European counterparts. This, in and of itself, is not well understood, although a number of hypotheses exist.

Part of my research involves color marking goshawks (with 2-digit purple color bands) to keep better track of breeding bird turnover and recruitment. However, like humans and other animals, these birds have unique personalities that in many cases allow me to be reasonably confident in the continued persistence of individual breeding birds, without having to read the bands. In my opinion, anyone who does not believe that birds have emotions and personalities has not spent much time getting to know them. Confirmation of identification via the color band definitely increases our confidence.

Photos of color bands I took while resighting previously banded birds during the 2016 field season.

Case #1: Female 9Z and her offspring Female Z3.

Female 9Z sitting on the nest in the campground (May 16, 2011).

Female 9Z occupied a nest within 50m of the busiest campsite within the busiest campground within my study area. She nested in the same tree for years. Clearly she was well adapted to disturbance as the summer brings non-stop ATV and motorcycle noise from dusk until dawn. We know from other studies that even birds that are well adapted to disturbance, still suffer lower productivity as a result (Strasser and Heath 2013), yet she returned year after year. I don’t know her productivity over time, but her final two years in the area did result in below-average success. There are many interesting questions that this raises? What was the advantage she saw in the area? In a world of increasing noise and disturbance, is there an evolved adaptation to be more tolerant? Was she tolerant of disturbance upon arrival, or did she grow accustomed over time?

Female Z3, daughter of Female 9Z, as a nestling in the campground (July 10, 2012).

Female 9Z was very calm. She never attacked and never flew out of the area when we visited. I twice climbed her nest tree to band her nestlings (in 2011 an 2012). On one occasion, she didn’t even issue an alarm call until I was 10 feet off the ground. She never left her perch. In 2012, I banded her single nestling Female Z3 within this nest. I have later found Z3 breeding (2014, 2015, and 2016) in a neighboring mountain range. She is just as calm and collected as her mother was, yet she is nesting in an area very isolated from human disturbance. Is her calm demeanor the result of nature (i.e., genetics - calm mother = calm daughter) or the result of nurturing (Z3 observed the calm demeanor of 9Z in the nest and learned or not over-react)? Their two environments could not have been more different, so probably not a string influence in this case. Very cool questions indeed!

Female Z3 as a breeding “Third-Year” bird in a nearby mountain range (June 23, 2014).
Also observed in the same territory in 2015 and 2016.

Case #2:  Unbanded Female.

I have an unbanded female in one of the territories I monitored that I am fairly certain was the same female for four years in a row. During 2011, I visited this nest once a week to check on the nest status. In each case the female carefully watched me enter the territory, do my status check, and then leave. She never protested, she never flew off, she never attacked.

Unbanded female in nest stand (June 18, 2012).

In 2012, I once again returned to the area on a weekly basis to the same general response. That was until I decided to climb her nest tree to install a video camera as part of my diet study on this species. This action apparently crossed a trust barrier that we had in place. A trust that I had broken. She would never forgive the intrusion. This female transformed from one of the most calm individuals to the most defensive goshawk I have ever met. My intrusion had changed her world view. This aggressive behavior lasted for the two additional years with which she was breeding in the area. She may have had a predisposition to aggressive behavior (via nature or nurture), but it took a trigger to engage (environment). This environmental trigger had a long-term affect on the individual. I think about this bird, and my impacts upon her, before I initiate any action within my goshawk studies. Knowing that we have a long-term impact on individuals is not something I am completely comfortable with. I also use the knowledge of this situation to better interpret other behaviors. For example, I now know that environmental conditions can change behaviors. When I find an aggressive bird, I often think about what kind of other triggers that the bird may have experienced.

Case #3: Female N4

In contrast to case #2, Female N4 is another bird I have grown to know well. I, or one of my field technicians, have climbed her nest tree on three occasions over the past six years to band her young. We have also captured her for banding in 2014. This is a very high amount of intrusive behavior. However, in contrast to case #2, this female has not grown more aggressive. If anything she has become more accepting. This year I found her perched on the rim of her nest. I spent ten minutes walking around within the stand gathering habitat data for a new study that Lauren is leading. She never took her eye off me, but also never flew, protested, or attacked me. I spoke to her with admiration and respect, apologized for the inconvenience, wished her well, and left the area as soon as possible. Clearly the same environmental factors applied to two different birds, produced different results. Nature? Nurture, Environment, or all of the above? Yes!

Female N4 on her nest in 2016 (June 21, 2016).

Yes, I talk to birds. I believe that birds are capable of reading our emotions, at least to some extent. When handling birds, if you are calm and confident, the bird will be more likely to be calm. Sure, they do want to get out of your grip. However, the same bird will be more calm with an experienced bander than with a nervous bander. I talk to most of the birds I handle in the off chance that speaking calmly and slowly somehow reduces their stress, if just a little.

We may never know what really goes on in the heads of these birds, but I will continue to admire them for their grace, calm beauty and for the ferocity. I will also continue to believe that they, like ourselves, are influenced by many factors including nature, nurture, and their environment.

#GoshawksRule #TeamGoshawk2016 #LongLiveN4

Sunday, March 06, 2016

Early Spring Visit to City of Rocks National Reserve

Karyn and I just returned from a few fabulous days exploring the City of Rocks National Reserve. It is a great time of year to visit as we were essentially the only people camping there. The first night there was one other campsite occupied, the second night – none.
The weather cooperated providing us with 60 degree, calm , sunny days.

The view from our campsite at sunrise
Our campsite was spectacular. Great views and great sounds. We watched the courtship flight displays of Northern Harriers (two males courting a female), listened to male solicitation calls of the nearby Northern Goshawks, and heard three owl species – Two Great Horned Owls courting all night, a Barn Owl, and on our last night there, a nearby Northern Saw-whet Owl calling for a mate. Love was definitely in the air!
The landscape is unique and spectacular.

The park superintendent, Wallace, is an avid birder and joined us for a morning hike as we explored the park.

Wallace and Rob (me) searching for Cassin’s Finches.

Male Spotted Towhee.

Western Scrub-jay
At one point Wallace, Karyn, and I were sitting on a rock when I spotted a Short-tailed Weasel (a.k.a, Ermine) still in winter fur passing under a rock. I was too slow to grab my camera. However, the animal turned and headed straight toward us providing excellent opportunities for photographs. It eventually passed under the rock we were sitting on.

Short-tailed Weasel (a.k.a., Ermine) in winter fur.

Don’t forget to visit nearby Castle Rocks State Park.

Yellow-bellied Marmots in Castle Rocks State Park.
We definitely plan to return!

Wednesday, December 30, 2015

2015 Idaho and Utah Short-eared Owl Survey Results

In 2015 I had the honor of leading, on behalf of the Idaho Bird Conservation Partnership and the Intermountain Bird Observatory, an Idaho and Utah State-wide initiative to survey for Short-eared Owls. We recruited 128 volunteer citizen scientists to spread out across the region and implement a consistent protocol. Here is an extended presentation of the results (~40 minutes) including rationale, objectives, methods, results, and next steps.  It was a fantastic project and I look forward to next year. View on PresentationTube HERE

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.