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Archive for December, 2017

By Zoey Greenberg, Hawk Mountain Conservation Science Trainee

21 Dec 2017

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Female black vulture named Donald over a quarry during September of 2016 near Palmyra, PA.

The tires crunched on gravel, and I shut the engine off. We had entered vulture country. With scope, data sheets, and binoculars in hand my project partner, trainee Adehl Shwaderer and I walked carefully up the gravel road as we scanned the tree tops for hunched silhouettes or soaring shadows. This was our first foray into the Kempton Valley, east of Hawk Mountain, in search of black vultures (Coragyps atratus). Our expectations were not high. However, we had innovation on our side: we were testing a method called “groundtruthing” to better understand the movement ecology of several vultures that had been tagged with satellite transmitters by Hawk Mountain scientists. After investigating their movements in Google Earth, we had discovered interesting patterns including an individual who spent time near quarries, and another that seemed to prefer cities. The problem was, we didn’t know why.

 

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Some tools used for groundtruthing method: laptop, smartphone with hotspot, and a vehicle.

Groundtruthing works like this: we, the field researchers, embark into the field with an internet hotspot and laptop in tow. We look up the locations of tagged vultures on an online database called MoveBank.org and then drive to meet individual birds and watch their behavior. By combining technology with old-school methods, we are able to gain visual access to black vultures and unveil mysteries about their movements that remain when we rely exclusively on satellite tracking data to explore patterns. As I became more comfortable with groundtruthing, I realized that the beauty of the method exists in its simplicity, utility, and the truism that even in this day-and-age there is no substitute for in-person observation.

 

A wonderful realm of study exists when we move beyond discovering where birds are, and incorporate studies that investigate why. Black vultures provide irreplaceable ecosystem services for us through their removal of carcasses that can carry harmful diseases. However, due to their curious nature and adaptability, they are often involved in conflict with humans that can result in noise-hazing, shooting, and other forms of human persecution. Therefore, investigating their movement patterns is necessary.

 

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Versace’s movements within the Kempton Valley, November, 2017.

At the beginning of our project, we relied on the signals of three birds, Gifford, Hillary, and Versace. (Donald, who turned out to be an adult female, flew to Washington DC after being tagged. We have not heard from her since.) By following these individuals, we discovered three night-time roosts within the first week and I feel confident that any bystander watching our first roost discovery would have been convinced we’d won the lottery. A silent performance of spastic jumping, “air-fives”, and the spontaneous creation of a vulture dance quickly occurred before we got back to business and counted the birds.

 

In the weeks that followed, we experimented with various observation techniques and read multiple papers on roosting ecology, black vulture foraging strategies, and behavioral study methods. We talked vultures at breakfast, lunch and dinner. We bored our housemates at the trainee residence with discussions on the most pungent types of road kill and the antics of our favorite birds. We filled our brains with vultures, and above all, became true detectives through a process of trial and error that taught us the value of being innovative in the field. Those first weeks were memorable, solidifying in me a hunger for scientific questioning.

 

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Zoey with a tagged turkey vulture.

There was an additional aspect to this project that I found consistently rewarding: the opportunity to speak with landowners in the Kempton Valley. Many of the roost trees preferred by “our” vultures were on private property, and in addition to observing the birds, we were looking for optimal trapping sites near already-established roosts in hopes of catching wing-tagged birds. This would provide us with information on associations among individuals. However, our trapping method entailed staking road kill to the ground and waiting for vultures to arrive while we waited nearby. In general, people aren’t thrilled about the prospect of hosting dead possums in their backyard. Nonetheless, we were rarely told no. Even landowners who professed a hatred of vultures were open and willing to hear our reasons for loving the birds, and eventually developed a tolerance of their own.

 

Vultures are hard to sell, and they do have some less-than appreciated habits, such as defecating on cars and toying with the rubber on windshield wipers. However, every “bad” habit has an explanation. For example, vultures are scavengers, meaning they rely heavily on maintaining strong neck muscles for tearing and pulling apart carcasses. To a vulture, rubber is an irresistible training opportunity to both strengthen their neck and satisfy their characteristically curious nature. It became clear that explaining to people why the birds were choosing their property provided them with a new dimension of understanding. This makes groundtruthing not only important for answering scientific questions, but also for enhancing a culture of appreciation around birds that struggle to gain respect. After all, our home ranges overlap with other species, and as such, perhaps we have a duty to critically evaluate our collective perception towards all of our neighbors, including vultures. After spending this season in the field, I am convinced that the Kempton Valley is a perfect place to start.

 

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Conservation science trainees Adehl (left) and Zoey (right) embark on an early morning search.

So what’s next for the vulture detectives you ask? Our field tested method of groundtruthing will be used to fill in more gaps in places with tagged vultures, contributing to our knowledge of why the birds go where they go. Ideally, this information can then be directly applied to informing locals, politicians, conservationists, biologists, and other groups affected by or connected with vultures in their region. As for Adehl and me, early morning roost searches and tactfully placed road kill may remain in both of our futures. There are few sights that compare to a group of dew-covered vultures eyeballing you from above as they slowly swivel their body to absorb the sun’s first rays. With a sight like that there’s only one outcome: once a vulture detective, always a vulture detective.

 

To learn more about our interesting findings, stay tuned for Vulture Detectives: Part 2 written by Adehl Shwaderer.

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