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Posts Tagged ‘vulture restaurants’

By Adehl Schwaderer, Hawk Mountain Conservation Science Trainee

03 Jan 2018

 

As a Hawk Mountain Conservation Science Trainee, you have the opportunity to be a part of many influential experiences, including counting migrants as they pass North Lookout and educating visitors about the importance of raptor conservation. But the experience that I have learned the most from this autumn was working with my fellow trainee Zoey Greenberg on our black vulture movement ecology project. This blog is part two of our vulture series so be sure to check out part one to gain a complete understanding of our project.

 

The plan was to locate three black vultures, Versace, Gifford, and Hillary, based on their recent GPS locations and observe what the birds were doing at these locations. To be honest, I wasn’t sure what to expect. I was excited to get started and gain new field experience, but no one had ever attempted groundtruthing with this species before, and it is still a new concept. We accepted this challenge with enthusiasm but were anxious about getting results. In the end we knew that no data would still be valuable information, however who doesn’t want groundbreaking results from their first ever field study?

 

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Versace perched on a barn in the Kempton Valley, notice her wing tag and antennae of the telemetry unit.

Thankfully, our first day in the field was a success! Zoey and I followed Versace’s movements from the previous month, which led us to a large roost of black and turkey vultures in the Kempton Valley. We were ecstatic, and from that point on, we were on a roll! Throughout the next three months we kept up our tracking efforts and found many more roosts (some permanent and some temporary), observed interesting behaviors, and made an effort to trap and tag these birds. By doing all of this, we were able to confirm some of our suspicions. However, we also discovered things we did not expect.

 

One of the suspicions we were able to confirm was that black and turkey vultures more often than not share the same roost sites. These two species have very different tendencies when searching for food, feeding, and perching, but that did not stop them from co-existing at the same roosting sites and air space. We also suspected that the vultures would use some roosts more consistently than others depending air temperature, trees available, and proximity to their next meal. We determined what each roost site was being used for, as well as observed a shift in preferred roost locations and species composition as winter set in and turkey vultures began migrating south.

 

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Turkey vulture trapped and tagged in Kempton Valley by Adehl, Zoey, and David Barber. 

We found the most unexpected results attempting to trap “our” black vultures. We enlisted the help of Hawk Mountain biologists, David Barber and Jean-François Therrien, who both have extensive trapping and tagging experience with vultures and other raptors. The goal was to capture and wing tag a substantial number of the black vultures we followed around in the Kempton Valley.

 

 

To do so, we staked down road kill (a vulture delicacy) at several roost sights we had determined were used mainly for feeding. Once the bait was staked, we placed noose traps made of fishing line and parachute cord in a diamond around the carcass. Once everything was in place, we would wait for the vultures to descend on the meal and consequently get their feet stuck in our traps—a process that does not harm the birds).

 

That is exactly what we did. We waited… and waited… and waited to no avail. The first site we chose to bait was seemingly perfect. There was already an area on the property where the landowners frequently discarded rotting vegetables and meat scraps. In addition, dead trees and conifers, which provided many roosting options for the birds, surrounded the dump.

 

However, shortly after we began baiting, two unwelcome visitors decided to join the flock: an adult and immature bald eagle. Now you may be thinking, “Wow! How amazing you get to observe vultures and the majestic bald eagle in one place!” Well, you would be wrong. We learned immediately that vultures and eagles do not enjoy sharing the same air space, or the same dining room table for that matter.

 

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Adehl holds the trapped and newly tagged turkey vulture.

We are confident that this interaction caused us to be unsuccessful in trapping vultures at this trap site, and the second area we chose to bait and trap. As soon as the eagles were seen at the roosting areas, black and turkey vultures were not seen roosting in those locations again during our observations. We did not expect this to occur because in other locations, like the Conowingo Dam in Maryland, eagles and vultures co-exist in the same feeding sites with no apparent issue. We believe the higher tolerance in these areas could be due to a larger food source with enough to go around for everyone, meaning that there is no need to initiate a food fight. The availability of only one carcass at our bait sites and providing large carcasses that were more easily discovered could have been the reason that the vultures and eagles in our study did not get along at our sites. However, all was not lost! In the end we did manage to trap and tag one turkey vulture, which was a very valuable learning experience for Zoey and myself.

 

 

Ultimately, I was able to witness unique behavioral patterns through this opportunity that will stick with me the most. I will never forget the breezy autumn morning when over twenty turkey vultures performed aerial acrobatics on a freshly plowed hill between bouts of picking through the soil with their bills and talons. Nor will I forget standing in the pouring rain, watching more than forty black vultures run across the bars of an information tower with their bills clapping and wings spread wide.

 

Zoey and I learned so much by only taking the time to stop and observe, and we are excited to see what else others that take the time to do the same will discover.

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By Keith L. Bildstein, Ph.D., Sarkis Acopian Director of Conservation Science
Hawk Mountain Sanctuary

12 December 2016

We typically characterize vultures as gluttonous creatures, obligate scavenging birds of prey that engage in rough-and tumble feeding frenzies at large ungulate and pachyderm carcasses in the company of dozens of other “all consuming” vultures, scarfing up enough meat to last for several days.  And indeed, vultures sometimes eat so much food that they remain grounded for an hour or more after feeding for partial digestion to take place, before they are light enough to take off.  Having watched these birds feed for many years, I can tell you that all of this is true.  But watching vultures at so-called “vulture restaurants,” where humans routinely provide food, sheds light on an aspect of vulture feeding that goes largely unrecognized by the general public.

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The vulture restaurant at the Hoedspruit Endangered Species Centre in northeastern South Africa after dinner is served. Note the Marabou Storks in the foreground and the ling-necked African White-backed Vultures in the background. Hoodies are nowhere to be seen in the initial scrum.

In fact, some vultures are “finicky” as well as “voracious,” feeders; especially at vulture restaurants where daily meals are typical.  The world’s first vulture restaurant, in the Drakensburg Mountains of South Africa opened in the 1960s to help supplement the diets of local Bearded Vultures.  Today, vultures restaurants (bird feeders for vultures, if you will) are used to provide “clean,” lead-free meat to recently released California Condors in the American West.  Many of the restaurants are associated with ecotourism, serving a useful purpose in bringing vultures and people together.  One such restaurant at the Hoedspruit Endangered Species Centre near Kruger National Park in northeastern South Africa has been feeding wild vultures and other scavenging birds for more than 30 years.  The restaurant works well at attracting handfuls of Pied Crows and Black Kites, dozens of Marabou Storks and Hooded Vultures, and hundreds of African White-backed Vultures, the latter two of which are now Critically Endangered.

Earlier this month, University of KwaZulu-Natal post-doctoral student and Hawk Mountain research associate, Dr. Lindy Thompson, and I spent four days at the Centre near Hoedspruit trying to catch Hooded Vultures.  During that time we learned a lot about the finicky feeding behavior of the birds.  Our goal was simple enough: catch as many as three of the Hooded Vultures visiting the restaurant, and fit them with satellite-tracking devices that would allow us to monitor the movement ecology of the species, including information on how dependent individuals were on vulture restaurants in the region versus how much time they spent in the nearby Kruger National Park feeding on native wildlife, and how they interacted with other species in the region.

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Dr. Lindy Thompson, releasing “Don King” after his capture in February. Note his downy top-knot and relatively thin bill.

We already had caught and fitted 10 Hooded Vultures with tracking devices in South Africa, and two of our previously tagged birds actually showed up at the restaurant during our four days of observation, even though neither has been tagged there.  One of the two, Don King, had been caught at a private nature reserve 45 miles north of the Hoedspruit restaurant in February of 2016.  Don looked healthy enough, although he had lost his downy top-knot that led to its name.  The second tagged bird, Mopane, had been caught in Kruger National Park about 60 miles northeast of the restaurant in August of 2014.   It, too, looked quite healthy.

The two marked birds were joined by about 30 unmarked individuals that visited the restaurant daily.  Unfortunately we were unable to capture any of them.  We did snare several of the far larger African White-backed Vultures that clearly dominated the smaller “hoodies” at the restaurant’s offerings.   Hooded Vultures, it turns out, are finicky feeders when feeding in the company of White-backed Vultures, pecking at and gleaning only tiny scraps of meat with their small, thin bills, after the meat had been torn apart by the larger white backs during feeding frenzies.  By the time the hoodies got close enough to our traps, the snares we had set already had been pulled closed by the white-backs, making capturing the former all-but-impossible.

Lindy Thompson and Andre Botha of the South African Endangered Wildlife Trust will try to capture the hoodies at other feeding sites that attract fewer white backs.   Older elephant carcasses work well for this purpose, as they often continue to be visited by the more fastidious hoodies for several days after larger vultures, hyenas, and jackals have stripped most of the flesh from carcass.

The finicky feeding behavior of hoodies is well known among those of us that study the birds.  It appears that hoodies have instituted their own specialized feeding niche, one that involves “cleaning up” after the larger and less finicky species.  Although this makes hoodies a bit more difficult to capture, it is somewhat endearing as well.  As I see it, a vulture that cleans up after other vultures can’t help but be appreciated.

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