Northern Goshawk Fieldwork Expedition 2: The South Hills

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Just as Rob and I turned off the paved road onto a mountain pass, we were greeted by three yearling moose who inched towards us with curiosity.  Eventually they decided to cross the road and make their way up into the trees, but not before posing in front of the camera.

Throughout another delightful ten days, I saw an incredible amount of wildlife, searched for and located occupied Northern Goshawk nests, climbed into these nests to band the nestlings, assisted with trapping adult goshawks, and collected data on the habitat characteristics at nest sites.  Not to mention all the hiking and exploring in between!  In total, we found 13 occupied nests in the South Hills, which makes up the bulk of our known nests this season.

My first encounter with a goshawk in the South Hills was different from any I have yet experienced.  I was checking occupancy of known nests in a territory that had hosted breeding goshawks for (at least) the past five years.  After searching each known historic nest and finding none occupied, I began surveying by playing a goshawk alarm call at a call point near an old nest cluster.  A bird echoed my call back to me, and I immediately set out in the direction of the response.  I caught a glimpse of a goshawk flying silently towards me and off through the trees.  It landed on the forest floor, and as I followed the path it took, the bird disappeared.

I searched the stand, crossed the road into another historic nest stand, and wandered around, hoping to come across the bird again.  Just beyond the nest used in the previous year, I found a new unoccupied nest.  As I approached, the goshawk let out a rapid, high-pitched alarm call and flew out of the nest.  I checked the nest for signs of occupancy–whitewash around the base of the tree, green leaves or needles on the top of the nest as a sign of nest improvement…the nest was not occupied.

I spent hours trying to interpret the actions of this bird in the hopes of finding an occupied nest.  The bird was vocal but otherwise not very defensive.  Several times I watched as it flew up above the canopy, circled, and took a sudden dive down into the trees.  After several hours of making circles around the territory, retracing my steps, and attempting to call in the bird, I retreated from the territory with no answers.  When I relayed the experience to Rob, he told me that it was likely an unpaired male.  The strange flight patterns were probably flight displays to attract a mate.  Male goshawks will advertise nests when attracting a female, which explains why I flushed him out of an unoccupied nest.  Finally, I showed Rob a picture I took of the bird, and he noted that the smaller-looking legs and narrow shoulders were indicative of a male bird as well.

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This is the unpaired male who fooled me for about four hours.  He was also displaying for me.  At this stage in the breeding season, most nestlings are at least a couple weeks old, so he missed his chance this year.

This year, a territory located just down the road from our camp was occupied for the first time since 2011.  Pictured below are the two nestlings at 32-34 days old.  The nest was only about 25 meters from the road, subjecting them to routine disturbance.  In addition, their close proximity to the road made them more visible and easily located by humans.  Just two days after I took this picture, we revisited the nest in an attempt to see if the female was banded.  As we approached the tree, Rob and I could only see one nestling, and we noticed marks on the tree indicating someone had climbed it to access the nest.  Legal and illegal falconry take often affect this population of Northern Goshawks.  It is completely legal to take these birds from the wild as long as it is registered with the Idaho Department of Fish and Game within 30 days after the it is taken.  However, Northern Goshawks and other accipiters do not make good falconry birds since they are high-stress, high-maintenance, and do not do well in captivity.  I must admit that I was upset by the abduction of this nestling.

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Two nestlings in a nest located very close to the road, before one was taken.

The first new nest I found by myself was being defended by two very vocal and aggressive parents.  I was greeted by a screaming female whose anxiety intensified as I walked towards a stand across the dirt road from the old nest stand.  Eventually, the male joined her in defending the nest.  As I walked through a particularly good-looking lodgepole pine stand, both birds alternated diving through the trees in my direction.  I knew I was near the nest.  I made my way through the stand, hiding behind each tree to avoid being hit by the angry birds.  Finally, I came upon a nest in a large aspen.  I could see a large nestling, likely 28-30 days old, sitting in the nest.

A few days later, I set out for my first tree climb into a real goshawk nest.

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Me ascending the tree using single-rope technique, with Rob below holding the rope for stability.  Yes, I am wearing a lacrosse helmet to protect myself from the goshawk parents’ talons just in case they were to hit me in the tree.
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In order to access the nest and handle the nestlings safely, I had to balance between two tree limbs.

Once I secured myself in the tree, I looked across into the nest.  I was shocked to see not one but three healthy, beautiful nestlings.  They all stared at me with confusion and alarm.  While balanced in the tree, I carefully picked up each nestling, placed them in a cloth bag, and lowered them safely to the ground to be banded by the crew below.  Once they were finished processing the bird, it was placed back into the bag and sent up the tree, and I would release it back into the nest.

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This nestling was the largest and most active of the three.  She attempted to look even bigger by spreading her wings as I carefully secured her legs between my fingers and placed her in the cloth bag.

Once all three nestlings were free and safe in the nest, I set up my repel and lowered myself down the tree.  On my way down, I looked back up at the three nestlings, which looked even more confused and disheveled than before.  I hope we will be able to resight them in territories of their own one day.

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Repelling from the tree.

Much of my time in the field is spent searching for goshawks.  Of course, wildlife encounters always take place when I am trekking through the forest surveying or checking known nests.  On one quiet morning, I was making my way through a rather thick aspen and mixed conifer stand when I sensed I was not alone. I noticed fresh scat on the ground and heard a stick break and a series of thumping sounds. I stepped on a large dead branch, causing a loud cracking noise. Suddenly, an entire herd of elk cows and calves stood up at once and galloped away through the dense forest. A small calf was the last to follow the stampeding herd through the trees. After that day, I could recognize a nearby elk herd by their heavy, wild scent.

In another territory, I was making my way across a stretch of sagebrush when I heard a strange, almost metallic rattling sound.  A large sandhill crane was making its way across the landscape about 100 meters away from me.  The large crane stretched its wings and lifted itself from the ground, pumping its limbs in slow motion and gliding out of sight.

Undoubtedly, the hunt that ensues after a goshawk detection can be one of the most exciting parts of this job.  Sometimes, finding the nest requires some detective work.  In one particularly puzzling case, I was searching a regularly occupied territory.  I played an alarm call from a hillside a received a response from below.  I ran downslope rather clumsily through the brush until I reached an incredible aspen stand and sighted a nest located over 80 feet up a dead aspen.  Initially, I thought she was defending this nest, until I examined the tree more closely.  There were no signs of occupancy–no nest improvement, no whitewash or small heads visible.  Confused, I walked further into the stand and found another large nest in a healthy-looking aspen.  The bird seemed to respond strongly to my advances toward this second tree, but once I reached the tree, she disappeared.  Again, no blatant signs of occupancy.  I did, however, catch this majestic picture which allowed me to claim my first resight:

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I was able to read the two-digit code on this goshawk’s purple color band, P4, and confirm that she was resighted in the territory she had previously occupied.
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She also provided some impressive photo opportunities.  I love the silhouette of a goshawk in flight.

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Though I didn’t find the nest, I did happen upon another one of nature’s treasures as I exited the territory: a mother fox and her young pup were enjoying the midday sun on the porch of a small cabin.  At first, I thought it was someone’s small dog, until the adult stood up and her tail fluffed out behind her.  The small orange bundle followed her behind the cabin and into the woods out of sight.

A few days later, Rob entered her territory to attempt to locate the nest site.  After some searching, he found this extremely well-disguised nest:

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Nestled on a platform of mistletoe just slightly over halfway up the small lodgepole, this is the strangest nest location we have seen this year.  
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The nestling does look rather handsome, however.
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The P4 female had a gloriously ferocious personality.  During both of my visits to her territory, she fearlessly defended her nest, diving with great agility through the forest and screaming loudly. 
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I had the opportunity to band the nestlings from the tree that Rob climbed.  This nestling was very docile.

My second climb was much different than my first.  Rather than an aspen, this nest was in a lodgepole pine with no feasible branches on which to throw a line.  Instead of using single-rope technique, I used spurs to climb this tree.  I was quite nervous to climb using this technique, since I felt less secure in the tree.

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Ascending using a spurring technique with a steel-core flipline around the tree
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Once I reached the nest, I put another anchor rope around the tree for support and pulled the cloth bag up on the green rope.

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After the two banded nestlings were placed safely back in the nest, I set up my repel.
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Repelling from the tree.
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Beautiful young female who mothered the nestlings in the tree I climbed.
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Goshawks hatch from the egg with black irises which rather quickly turn blue.  A fledgling will have yellow eyes, and as the bird ages, its eyes will turn from yellow to orange to crimson.  This female has red-orange eyes, suggesting she is a younger bird.
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Rob holding the female while I climb the tree.

Over the weekend, the other students participating in the Raptor Research internship program at Boise State came up to my field site to check out my work.  They watched me climb into nests and assisted with banding.  On their second day, we went to revisit a territory where I had experienced a defensive female bird but had not found the nest.  We all split up and walked in the direction of my initial detection.  The female began responding soon after we began the search, and finally we happened upon the nest.  At least three fully fledged birds were in the area, in addition to the adult female.  Once Northern Goshawk nestlings fledge, they continue to rely on their parents for food and inhabit an area around the nest site known as the post-fledging area.

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Northern Goshawk fledgling
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Kristin Hasselblad, friend and previous Northern Goshawk researcher, and her family witnessed the trapping of this female in a newly occupied territory.

Sometimes when playing broadcast calls, I receive responses from other avian inhabitants.  One day, I surprised a Cooper’s Hawk when I played a goshawk alarm call.  The Cooper’s called back to me with a very similar alarm call, though lower-pitched and faster than a goshawk’s.

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Cooper’s Hawk in flight.

I have come to know Red-tailed Hawks pretty well, as they often respond to my goshawk calls.

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A beautiful adult Red-tailed Hawk circling above the trees and screaming angrily.  Its mate joined in, and I stared in awe as they circled above me.
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A juvenile Red-tailed Hawk, actually molting some tail feathers.

I will conclude this post the way it began–with moose pictures.  Below is a mother and her calf enjoying a beaver pond on a swelteringly hot day.

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This young moose was taking its evening stroll through another string of beaver ponds about 300 meters from our campsite.  We stopped on the road, and she didn’t seem to mind the camera.

During my next trip into goshawk country, we will be revisiting the areas we have been to determine nest success by attempting to locate fledglings in nest areas.  We will hopefully be doing some additional trapping and banding, and maybe even find a new nest or two!  Stay tuned!

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