Thursday, June 23, 2011

Black Flies, Bachelors, and Technology Woes

Here's the latest update on the progress I have made during my first field season of my master's thesis project in Raptor Biology studying the Northern Goshawk. This post covers weeks five and six. Previous posts:

The project has been progressing very well. We have accomplished more during the past two weeks than during the first four weeks. The melting snow, day by day makes our jobs easier, but also opens up new territories where work needs to get done. The learning continues to progress at a rapid rate and I am more and more optimistic about the project. Both Lauren and I continue to improve our skills as well. I am more and more comfortable in the tree climbing arena, with four climbs under my belt. On a personal convenience front, we now have water in the cabin! It arrived just in time for the hot sweaty weather. Unfortunately, 1,000 of our friends on ATVs have also arrived, but I guess we can't claim the entire place to ourselves any longer.

Working in the field

One of the most important things I like about field work is being in the field exploring and working to interpret what the surroundings have to say. There are some researchers who can simply take data from field assistants and synthesize it into research manuscripts without ever getting their feet dirty. I am not one of those. I believe the data is critically important, but I often get the interpretation from my experiences and observations which were not designed into the protocol. For my undergraduate research, which has just hit the presses in the Journal the Condor, it was instrumental that I participate in the bird banding and raptor counting to get a sense for what answers I should be looking for in the data. It is when the data agrees and disagrees with personal observations that can drive to the next set of questions.

One of the questions we are looking into in the South Hills is whether this population of Northern Goshawks are doing well. Additionally, I am looking into what influences within the environment, most notably prey availability, may be influencing that success. Whether prey is the primary influence, will have to wait for my thesis, but there are other theories out there. One theory is that this population is not doing well. In a ten year study documented by Kaltenecker et al. 2004, there was no evidence that goshawks raised in the South Hills returned to breed there. General raptor life history would predict that male offspring would return to their natal area to breed. A potential cause of no returning nestlings could be high mortality to a black fly blood parasite which attacks the nestlings and the female while on the nest. I am not studying blood parasites, but I can attest to the black fly as a potential vector. On the third nest I entered, the nestlings were covered in black flies. A few other nests I have observed have had similar issues. Maybe next year I will recruit an undergraduate researcher to look into the parasite issue.

17 day old goshawk nestlings from nest #3 w/ Black Flies

We have also observed adult male goshawks in three territories where our protocol has yet to find an occupied nest. Of course, it is possible that we have just not found the nest; we will continue to monitor those areas. In another territory a sub-adult female was on a nest, usually a sign of a shortage of females. Is there a shortage of females in the area? A sub-adult female breeding and possibly three bachelor males? Is the blood parasite killing offspring? Is this a healthy population? So many questions... For now mine are focused on the population structure and the prey influences on this equation.

Nest Cameras

One of our main tasks are the installation of nest cameras. These cameras will enable a quantification of the prey consumed. They will also provide insight into other interesting behavioral aspects of a nestling's life. But first the cameras have to get up the tree.

Climbing nest tree #3 to install camera.

One of the most unsettling things for me about tree climbing is working over the branches. The harness is set up with two slings around the tree. When you reach a branch you put the second sling over the top and release the first sling. That release step, removing the only protection you have been using to hold on the tree, takes very careful consideration. The new sling must be attached and locked correctly. With eight to ten sling swaps per climb, there is ample opportunity for mistakes. I remain as focused as I can, take my time, and double check every move.

The first look into the nest.

Holding cable in my teeth while aligning camera. Note black flies on nestlings.

I align the camera in the tree while Lauren looks at the monitor below and provides instructions on how to adjust the alignment. The camera units are set up so that batteries and memory cards/tapes can be exchanged 200 feet away so that subsequent disturbance to the nest is minimized.

Double checking the configuration and video feed when back on the ground.

The focus, effort, and adrenaline take its toll. I am on a high for about an hour, then I want to nap away the afternoon...

It will take months to sort through the video I am capturing, but it doesn't take long to find interesting behavior. At age 4 days the nestlings begin to defecate over the rim of the nest. This 15 second video of a 10 to 13 day old nestling provides a great example.

But as I mentioned earlier,my focus is on prey. Here is a 25 day old goshawk walking around the nest then eating a chipmunk (meal starts about 40 seconds in).

Nature does know how to deliver surprises. Once I put my head over the rim of nest #2, this is what I saw.

Dead Nestling in nest #2.

The cause of death is not determinable. Sometimes nestlings are killed by their nest mates to decrease competition for food, but there was no sign of that here. Maybe starvation? The clutches are smaller this year than in previous studies, so resources could be more scarce. Unfortunately the dead nestling was gone before the camera was fully operational (12 hours later). We therefore do not know if the female removed it or if it was eaten. Few resources are wasted in nature.

The cameras are complicated technology for the outdoors. While they provide tremendous insight, they have been the source of frustration and have not worked out as well as planned. I had originally planned six cameras. Due to the battery recharge challenges, I scaled that back to 5 cameras. Two of these are analog units that only record for a day and a half at a time. I replace these batteries every two days. I have three digital units which can last a week on a battery charge. Unfortunately, one of these recorders died while operating in nest number one. I replaced it with my last available unit the day before I discovered a new candidate nest. I still have one analog unit, but this new territory is 2 hours each way by motorcycle. It would take far too much time to replace the battery every other day. So here I am with three cameras installed, each providing about 75% of the daylight hours. The TV monitors used to align the camera and configure the recorder has only worked on one of our three installs, requiring more followup to get the system fully functioning. I will defintiely be re-evaluating choices at the end of the season. For now, I hope the three units keep working for a few more weeks.  


Before heading into the field I have heard many stories of individuals getting attacked by goshawks. This usually occurs when 50 meters or closer to the nest tree. After my first encounters I was beginning to believe that these stories were overly exaggerated. While climbing my first tree, the two adults protested and flew toward us, but only brushed me with a wing twice. During the second camera installation, the female perched nearby, never even bothered to leave her perch. She didn't issue the first alarm call until I was three steps up the tree! On climb number 3, while the female made many flying approaches, no contact was ever made. What was all of the excitement about? Well, I would find out the hard way.

I was completing a prey survey in a new territory which had not yet been searched. Searching would be my task for the afternoon. I was 600m from where my information had told me the historic nest location would be. Just as I finish the survey a male goshawk issued the alarm call to my right. The female shot up out of the forest! I got the nest! I move in to find the tree and check on nestling status. The adults flew toward me while screaming their call. I ducked to the side, stayed close to trees, etc. I could see the nest and could see the evidence of nestlings (fecal marks on the ground). I quickly turned to retreat. Within moments the alarm calls ceased then wham!! my head gets knocked forward. I picked up the pace and got out of there. I touched my head... OUCH! Hmmm... Blood...

I like the full foot print of talons on the right.

The adults do get more aggressive as the nestlings get older. On Wednesday I reclimbed nest #1 to band the nestling. While I was only brushed twice during the first climb, the second climb produced a dozen direct hits from the female. She was able to hit me once just below the helmet to scratch the back of my neck! I will definitely turn up my collar for the next climb. The warnings from the ground crew are very important, "incoming!", so I am not in a critical climbing move when she's coming in.

Helmet ringer!

The Beginning of the End

The project is now six weeks complete, with only 2-3 weeks remaining. The end of the field season is no longer an abstract concept, but a huge boulder rolling down the hill. We constantly rearrange tasks to make them more efficient. We make decisions based largely on minimizing time. We hike double time through the sage to fit one more prey survey in before the 11:30am cutoff the protocol specifies. Right now, it looks like we will make it. Barely...

Other Observations

The other wildlife observations have taken a back seat to goshawks in recent weeks. Notable are many observations of moose including a few new moose calves. The bull elk are herded up and in full velvet. The mule deer are prevalent and the bucks are spectacular. More coyotes, badgers, beavers, and cougar tracks. Red-tailed Hawks, Turkey Vultures, Short-eared Owls, Golden Eagles, Northern Harriers, Cooper's Hawks, Sharp-shinned Hawks, etc.  The South Hills are definitely a special place to have as a study area.


This session we had a number of volunteers join us in the field. Uri, Nicole, Kerry, Jeri, Cristen, Dave, Carol, Cathy, and Karyn all spent time hiking through the woods with Lauren and I, taking notes, and carrying gear. Uri had the honor of finding a nest which we had spent days looking for. Dave, Carol, Cathy, and Karyn all fixed us dinner on different evenings to try and keep us from withing away (I am down 6 pounds in 6 weeks!). It is great to have such excellent family, friends, and volunteers.

Lauren, field assistant Superstar! The next climb is hers!
Dave and Carol, excellent Idaho Bird Observatory volunteers. Thanks for Dinner!
Cathy, excellent volunteer, photographer, and cook!

Saturday, June 11, 2011

Mmmm, Warbler for Lunch

Local Cooper's Hawk preparing Yellow Warbler for lunch.

Cooper's Hawk plucking Yellow Warbler.
Cooper's Hawks in nest eating Yellow Warbler

The Tale of the Stolen Jacket!

In my previous post I told the story of a Northern Goshawk stealing my jacket. Here is a slow motion helmet cam video of the incident. The green fleece jacket was placed over the nestling while I was installing a nest camera in the tree. This helps to protect the nestling from the elements and to reduce its stress. While I was setting up my rappel to come out of the tree, one of the adult goshawks flew by and took the jacket from the nest. A field volunteer ran through the forest and retrieved the jacket after it was dropped by the raptor.

In this slow motion video you can see the jacket as I am working with the climbing rope. Suddenly its gone! Look low and to the left in the frame and you will see the adult flying into the trees with the jacket. It makes total sense to attack the jacket as it was on top of their only nestling. It was a very cool experience.

Friday, June 10, 2011

The project is rolling now!

Here's the latest update on the progress I have made during my first field season of my master's thesis project in Raptor Biology studying the Northern Goshawk. This post covers weeks three and four. I have previously posted an introduction, a summary of the first week, and a summary of the second week.

As expected, we have become more and more busy as the new protocols come online and as access to new territories occur. Although at the end of week 4 we can still only access 13 of the original 23 historic territories I plan to work in. I am eagerly hoping that next week opens up new opportunities.

Lauren and I were joined for three days by another volunteer Michelle, a former student of mine. She provided excellent field support and likely learned a great deal. Dusty and Mike joined us in the field for the camera installation as well. I have a couple of other volunteers joining during the next few weeks and possibly for the session after that. Some are former students and others are friends considering a career in biology. It's great to have the extra help.

New Nests

The new week enabled access into five previously unvisited territories (due to snow and mud), bringing my total accessible territories to 13. This quickly delivered two new occupied nests, for a total of four. Lauren and Michelle discovered the first, and I discovered the second. On the nest that I discovered it looked as if the female was sitting very high on the nest. This can often mean that nestlings have hatched. As I watched a small white head popped out from under the female. Nestlings! The first observed of the season. Very cool! This would lead to this nest being the first to be installed with a nest camera (story below).

Newly discovered occupied goshawk nest.

Call Stations

One of the new techniques for this week is the use of broadcast call stations. This procedure consists of playing the goshawk alarm call and then listening for a response. This procedure is not used until the first of June as the goshawks don't generally respond until after the chicks have hatched. June 1st is the average hatching date in my area. Our first day using the new technique was productive as both Lauren and I had aggressive responses to the call backs. I had a female aggressive vocal response as she flew toward me calling. Lauren had an aggressive male response in another territory. Unfortunately, neither response has yet lead us to a new nest. We have yet to give up on these territories though. As we have the areas localized, if there is a nest, it could be close. Another aggressive female response later in the week did lead to new nest discovery (fifth of season).

Volunteer Michelle broadcasting goshawk alarm call.
Fifth nest of season, this one located in Lodgepole Pine.

Prey Surveys

A core premise of my thesis is the relationship between prey abundance and goshawk nest success. One of the mechanisms I hope to use in a series of prey surveys in each nesting territory. These prey surveys will be used to generate a general prey abundance measure of the territory which can be used for comparison between successful and unsuccessful nests. The method I chose to use is called distance sampling along line transects. Each historic goshawk territory has four 750m lines randomly placed within its bounds. For each round of surveys we will walk one of the 750m transects, noting any potential prey observed - Ground Squirrels, Chipmunks, Robins, Grouse, etc, and measuring the perpendicular distance from the transect with a laser rangefinder. These measures will be used to generate detection probabilities and ultimately estimate prey abundance for the each territory. I had hoped that I could do each round across all 23 territories within a period of three to four days. As mentioned earlier, I do not yet have access to many territories. Regardless, I chose to complete the first round on the 13 territories I did have access. New procedures often bring many new learnings. The first challenge was the two inches of new snow on the ground the morning that we began. I walked 500 meters before seeing my first potential prey item. This was in an occupied territory as well! Learning number two is that 30 minutes after sunrise, does not mean the sun has risen on the territory. As a result, I have shifted the surveys later in the morning - 30 minutes after sunrise in the territory, not what the calendar says. It is way too early to look at the data, but I can say there was no initial obvious correlation. We will initiate the second round of surveys next week on the 13 territories and hopefully the first round in some new areas.

Nest Cameras

The story of the week is definitely the installation of the first nest camera. This was scheduled for Wednesday as the nestlings were estimated to be 8-10 days old. A lot of coordination was required to get the gear in place, invite my climbing coach down to the area, and to align our schedule around the weather so as to minimize exposure to the nestlings during the camera installation. It looked like it could all come together.

The proposed climb! - Not a very big tree!

We staged the gear about 100m from the nest. We completed the last bit of training on the spot, then it was time to make a decision. We needed 2 hours of clear weather, at least no rain, to proceed. The fog was rolling in, but there was no immediate threat of precipitation. We made the decision to go. The four of us (myself, Lauren, Dusty [climbing coach], and Mike [Dusty's student]) all had our roles. I would climb, Dusty would coach, Lauren would belay if needed and coordinate the camera once I reached the nest. The camera is installed in the nest, but the recorder and battery are at the end of a 200 foot cable. This allows for remote battery and tape exchange without disturbing the nest again. Mike would take pictures, assist on demand, and yell a warning when a goshawk was about to take my head off! A very important task! We gathered the gear and moved toward the tree.

About 80m from the nest the male goshawk issued the alarm call! Dang! I had hoped he was miles away hunting. I would have to deal with two angry parents from the start. I approached the tree, rapped the sling around and left the ground. The female left the nest and the clock was started. We hoped to be out of the territory within an hour.

Dusty coaching me up the tree.

It was hard not to just watch in admiration as the parents flew through the forest heading to attack me, but I had a job to do. Up I went.

Approaching the nest bowl.

This tree proved much more difficult than the training tree. I guess the training isn't over yet. The hardest move is getting around the nest. I planted an anchor at the base and attempted to move up and over the side. I worked up over the lip and FALL #1! Yikes! A dead limb broke... Nothing gets your attention like taking a fall 30+ feet above the ground. I hugged the tree and tried to recover my senses and my wind. This is hard work! The clock was ticking, but I forced myself to relax and take my time. I worked the move again... FALL #2! Wow, getting tired. Focus... I rapped the limb again and wrenched myself up over the rim and into another anchor. I was there and ready to work. What?!? Only one nestling. I had expected three or four. Five was not out of the question. Only one. It was big, not 8-10 days old, but 14-17 days old. I guess measuring age by the amount of fecal material on the nest rim doesn't work when there is only one nestling. I placed my fleece jacket over the nestling to protect it from exposure and help it to relax. Not that it would relax with the parents' alarm calls flying by my head.

I hoisted the camera up and began the installation. On the ground the monitor failed. Dang, I would have to align the camera on sight alone. It was done.

As I was setting up my rappel, one of the adults flew over the nest and snatched my fleece coat covering the nestling! Off through the woods it went! Unbelievable! Mike went running after and eventually returned with the jacket. I set up my rappel and got out of the tree. We quickly grabbed the gear and retreated as far as possible. Without the monitor, I cannot ensure the camera settings are correct. I hit record and we left. High def, low def, motion activated or always on. Who knows... We get what we get... I will find out Monday...

I was cooked. Exhausted from the stress and the effort to climb the tree, I needed a break, but there was still work to do. We existed the territory in 55 minutes - ahead of my time allotment. It seemed like a blur of confusion and chaos, but even with the falls and equipment malfunction, we got our job done and mostly right. The camera monitor was the only real problem. It's a great team I work with! It is an honor to work with them.

Other Challenges

Field work is always presenting new challenges. The setback of the week was the broken motorcycle. After finding the nest with nestlings, Lauren volunteered to perform prey surveys in that area in the hopes of stopping by the nest and seeing the nestlings. Little did she know when she volunteered, that it would be a balmy 26 degrees in the morning and the motorcycle was the only vehicle to get there! She was undeterred. Adding to the challenges was a couple of new inches of snow on the ground. She headed off for the slippery cold ride as Michelle and I climbed into the heated truck. Six hours later when our work was done, we would learn of Lauren's fate. The roads were very snowy and slippery which quickly turned into wet and slippery after the sun came up. Not the ideal conditions for a motorcycle. The bike unavoidably slipped into a rut and the chain came off. Six miles from camp on a dead end road. What a beautiful morning for a walk! While Michelle and I were performing prey surveys and call stations, Lauren was hiking the muddy road back to camp. Just before arriving back at camp, the first person she saw was the man, Rick, from the neighboring camp who Lauren had made friends with the night before. He offered to help, took her to the bike and got it back on the road. When we returned later in the day, Lauren was sleeping on the ground next to the bike in camp. Next on the agenda was a bike repair in Twin Falls! On Saturday I took it to the shop. Standard answer - sometime next week. I tried to politely reemphasize my urgency - it was a work bike and the only way I could get my study complete. Well, maybe they would get to it later in the day. Ok, I will wait.  This was not the answer he was expecting. They decided to put it on the rack right then. About an hour and a half later, I was headed back into the hills! Thank you to Kevin at Adventure Motorsports!

The Week ahead

The week ahead brings much of the same, but on a larger scale. More nests to find, more prey surveys to do, and more cameras to install! Hopefully with access to new territories. It will be a busy, but wonderful time. For the next ten days we will have a second field assistant and possibly one or two other volunteers spending time in the field.

Other experiences

One of the things I love about field work, is you come across many different surprises and discoveries. Such as spooking up a deer or an elk while walking through the woods. I actually logged an elk at 60m during a prey transect! Ok, maybe a goshawk can't take an elk, but I wrote it down anyway. Lauren saw a Moose, and I had a Badger. Coyotes, Beavers, White-tailed Jackrabbits, you name it.

One of three Beavers working this pond.

Since we spend a lot of time looking for nests, we have a high probability of find them. To add to our five Northern Goshawk nests, we have found an occupied Red-tailed Hawk nest (with nestling), an occupied Cooper's Hawk nest, and an occupied Common Raven nest (with nestlings). The most surprising was the American Robin nest that I discovered when my face was about 2 feet away and the female Robin flushed from the nest! Scared the crap out of me!

American Robin Nest.

Another surprise was having a Northern Saw-whet Owl fly right by me mid-day and perch in a tree.

Northern Saw-whet Owl.

Unfortunately, one thing we are likely to see a lot more of is dead raptors. Once raptors fledge, their chance of survival greatly diminishes. Over 50% will likely die during the next 3 or 4 months. While not a raptor, this fledgling Raven didn't do so well.

Dead Common Raven Fledgling.

You can tell it is a fledgling as its feathers were still growing. An adult will only replace a few feathers at a time, whereas a fledgling will still be growing all of their feathers. This fledgling Long-eared Owl also met its fate. I found this right after watching an adult Long-eared Owl fly by.

Very dead Long-eared Owl Fledgling.

Yes, only a geeky biologist photographs the dead things he finds...

With that, I have a few days off an then its back to work. Prey surveys, nest cameras, new territories, it feels like a whole new project. I can't wait to get back out there!