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wingtagged vulture 70 by jeff dietschBy Keith L. Bildstein, Ph.D.
Sarkis Acopian Director of Conservation Science
Hawk Mountain Sanctuary

8 January 2016

Why are some species of birds of prey widespread and abundant whereas others are not?

It turns out that this critical ecological question, one that is fundamental to understanding biological diversity, along with many other aspects of ecology, is easy to ask, but not easy to answer.

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Article in The Auk

Earlier this month two former Hawk Mountain trainees, Dr. Todd Katzner (now the head of the U.S. Bureau of Land Management’s Boise State University Raptor Research Center) and Julie Mallon (now a Ph.D. student at the University of Maryland) and I published an article in the ornithological journal The Auk that helps to explain why turkey vultures are one of the world’s most abundant and widespread avian scavengers. The field work was conducted while Julie was a Master’s degree student at West Virginia University.

The short answer to the question is that turkey vultures have evolved two so-called “key innovations” that, together, make them decidedly “above average” as avian scavengers. The long answer, which follows, is a bit more intriguing.

The turkey vulture’s first key innovation is their acute sense of olfaction. This is something that is quite handy when the food you are searching for is decaying carcasses and smells.  Turkey vultures have the largest nostrils of all New World vultures, including the far more massive California condor and Andean condor, as well as the largest olfactory bulbs in their brain–the next largest being those of the king vulture, a species that does not appear to use olfaction in its search for carcasses. Two other Central and South American species of vultures, the lesser yellow-headed vulture and greater yellow-headed vulture, are both close relatives of the turkey vulture and also locate carcasses by both smell and sight.

turkey vulture 03 03 15 bill moses, at french creek .jpg

Turkey vulture at carcass by Bill Moses

Intriguingly, although there is no evidence that black vultures are able to locate carcasses by smell directly, the species indirectly locates carcasses by smell. Indeed, black vultures routinely seek out turkey vultures and then follow them to carcasses, capitalizing on the latter’s olfactory capacity. Old World vultures, on the other hand, show no evidence of locating carcasses via their sense of smell.

The turkey vulture’s ability to locate carcasses by smell is a key innovation because it allows individuals to search over forested as well as more open habitats for dead animals, thereby considerably expanding their feeding habitat. This key innovation explains–at least in part–why turkey vultures are the most wide-ranging of all vultures.

The turkey vulture’s second key innovation and the focus of our recent publication in The Auk provides the rest of the story. This innovation is the species dihedral wing posture, which allows it to engage in what my coauthors and I call “contorted soaring” while flying close to the ground in search of carcasses. What atmospheric scientists call “small-scale, shear-induced atmospheric turbulence” routinely occurs close to the ground. It happens anywhere the topographic features such as mountains and valleys, forest edges, and small-scale thermal mosaics, disrupt the flow of wind near the earth’s surface. This creates small pockets or eddies of swirling air that alternately push and pull on objects flying through them. Many of us have experienced this kind of turbulence during bumpy take-offs and landings at airports.

Turkey vultures are lightly-wing loaded (i.e., they have big wings for their body mass), making it easy for them to soar in large packets of warm, rising air called thermals. Other vultures, too, are able to do this. Close-to-the-ground, contorted soaring, however, is another matter entirely. It is close to the ground where the dihedral (“V” shaped) configuration of the species’ wing profile comes into play.

DSC_9244 turkey vulture 10 14 18 bill moses

In addition to a relatively long, rudder-like tail that allows them to turn in tight circles while soaring in small-scale turbulence, turkey vultures have long, narrow wings that they hold above their backs in a dihedral. The latter is a key innovation that serves as an “aerodynamic self-righting (or stabilizing) mechanism.” This allows the bird to continue to soar in turbulent air even when its two wings are exposed simultaneously to different up- and down-drafts.

The unusual wing profile functions whenever one wing (either the left or the right) experiences more lift than the other. When this happens the wing experiencing greater lift tilts upward making it less parallel to the ground and reducing its aerodynamic surface and, hence, lift while the opposite occurs to the other wing. The side-to-side rocking, which at first suggests instability, actually is an energy-efficient, soaring flight that allows the birds to stay aloft. It also allows them to continue soaring without having to flap its wings to right itself, which is usually what happens when “flat-profile-wing” soaring birds encounter small-scale turbulence.

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Other lightly wing-loaded soaring birds that regularly scavenge for food close to the ground, including greater and lesser yellow-head vultures, Egyptian vultures, black kites, bateleurs, and zone-tailed hawks, all have slight to strong dihedral wing configurations, as do more predatory harriers, which also forage close to the ground. Intriguingly, turkey vultures soaring at greater heights tend to do so in a less pronounced dihedral, whereas black vultures flying close to the ground frequently adopt a slight dihedral rather than their more typical flat-wing profile.

That they are able to extract useful updraft energy while soaring in small-scale turbulence near the ground means that turkey vultures can soar closer to the carcasses they are both looking and smelling for, which makes them easier to locate before turbulent winds jumble and disperse odors associated with them.

Low soaring flight has a second benefit as well. Contorted soaring allows low-flying turkey vultures to stay below the radar screen of potential competitors. This is important when a located carcass is squirrel-sized rather than deer-sized and there might not being enough food to share with others.

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Ornithologists speak in awe of just how high vultures can fly while searching for prey. The world record, for example, is held by a Rüppell’s vulture that was sucked into a jet engine while soaring 37,000 feet, an altitude high enough to require special hemoglobin to capture oxygen sufficient for metabolism. But the ability to soar close to the ground also has benefits, particularly if you are searching by smell and want to keep a carcass to yourself. A keen sense of smell, coupled with a wing dihedral help makes turkey vultures what they are today, one of the most abundant and widespread of all raptors.

But of course the question then becomes “why don’t other vultures do the same?” The short answer is because they have not evolved these two key innovations. The long answer requires another blog.

You can find our paper on turkey vultures, “In-flight turbulence benefits soaring birds” on the Sanctuary’s website under “Numbered Publications” on our Science tab. Look for contribution to conservation science number 258.

Finally, if this work interests you, or any of our other research projects that better conserve raptors, please consider making a gift now. Just click here to donate now, writing “research” in the comments.

By Keith L. Bildstein, Ph.D.
Sarkis Acopian Director of Conservation Science
Hawk Mountain Sanctuary
9 December 2015

Together with African colleagues and Hawk Mountain research associates, I have been studying the “Critically Endangered” hooded vulture for going on three years. The work is beginning to pay off. I have just returned from 10 days in the field in and around Kruger National Park in northeastern South Africa where temperatures soared to 108 °F, and I have much to report.

As of early December 2015 we have placed satellite tracking devices on four “hoodies” in The Gambia, four units on birds in Ethiopia, and nine units on birds in South Africa. We also have placed “camera traps” at a number of hoodie nests in South Africa, as well as at several “vulture restaurants” there. Initial results at the latter are fascinating. But first some background…

hooded vulture nestling with tag

Fitting a tracking unit on a young hoodie

This summer, a second round of roadside counts in The Gambia indicated that hoodie populations there continue to do well, with numbers in the western part of the tiny African nation hovering at an astounding 15 birds per square kilometer, a density that makes the region home to the highest population of hooded vultures anywhere. Unfortunately, things are not nearly so good in South Africa where roadside counts in Kruger National Park, a supposed stronghold, indicate a population of far less than a single bird per square kilometer. My field work in South Africa earlier this mont

olifants river, kruger national park

Olifants River in Kruger National Park, South Africa

h also produced close-up looks at more than 10 active nests in private game reserves immediately west of “The Kruger,” where nests along some sections of the Olifants River are sometimes as close as 100 meters or less.

 

As in any collaborative endeavor, working with the right people makes all the difference and the Sanctuary’s hooded vulture studies in South Africa are not exception. Kerri Wolter at VulPro (a vulture NGO outside of Pretoria), consistently offers up exciting results and insights regarding hoodies breeding in the Olifants River Private Game Reserve. And Andre Botha at the Endangered Wildlife Trust (an NGO in Johannesburg) is doing likewise for birds breeding and feeding in The Kruger, as well as several adjacent private reserves. Dr. Marc Bechard at Boise State University continues to help with trapping and harnessing hoodies with satellite tracking devices, as well as helping on road counts within The Kruger.

Lindy, Marc, and Andre at the Selati Vulture Restaurant

Lindy, Marc and Andre at the Selati “vulture restaurant”

The newest addition to the South African team, Dr. Lindy Thompson, a Post-Doc in the Department of Biology in at the University of Kwa-Zulu Natal, adds an additional level of excitement and expertise to the team. On the job for less than a year, Lindy is following the nesting successes and failures (baboons and a hail storm appear to be responsible for at least some of the latter) of a number of hoodie nesting pairs in private reserves west of The Kruger.

 

Lindy also has initiated studies at several “vulture restaurants” in the region, where human provisioning of hoodies and other vultures with offal and assorted body parts of domestic animals slaughtered at local abattoirs, is helping the birds meet their daily caloric needs. Although such provisioning can disrupt the normal behavior of avian scavengers, human “nutritional assistance” at vulture restaurants provides “clean” food to birds in areas where poachers have been known to purposely lace with poison the carcasses of rhinos and elephants they kill for their horns and tusks. Their intent is to kill the vultures, whose flocking behavior often alerts game rangers of poachers’ activities.

 

Having spent considerable time in the field at a vulture restaurant last week, I now have a much better understanding of how hoodies and other vultures use the restaurants, as well as of the benefits of such sites in providing close-up looks at several of our satellite- and wing-tagged individuals. The vulture restaurant at the Selati Game Reserve, for example, routinely attracts dozens of hoodies, with attendance on some feeding days reaching 25% or more the regional breeding population. And indeed, I managed to visually locate two of our satellite-tracked birds at the site–both of which appeared healthy. (Actually, our tracking records indicate that four of the nine birds we are tracking visited the site while I was there.) Later this month Lindy and Andre plan to trap and measure up to three additional hoodies at this important site and place satellite tracking units on them.

Lindy and Marc at the Selati trap sitre

Marc and Lindy at the Selati trapping site

Trapping birds at the Selati site and, possibly, at other restaurants will help speed our wing-tagging and satellite-tagging efforts and also will provide us with much needed information on the health of individuals captured and examined there. Given the precarious nature of the species in South Africa, the restaurant work may make all the difference in helping us offer solutions for better managing this declining population.

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Lindy will visit the Acopian Center this spring

Finally, Lindy plans to visit Hawk Mountain’s Acopian Center for Conservation Learning for several months this spring, at which time the two of us will begin to analyze tracking and nesting data already collected. Plans for 2016 also call for me to make two additional trips to Africa or field work in South Africa and The Gambia.

No one has assembled a better team of vulture specialists and is working as hard as we are to protect this globally endangered species and I very much look forward to keeping you up-to-date with our field efforts in the coming months.

Do not hesitate to contact me by phone (610-781-7358) or email (Bildstein@hawkmountain.org) if you are interested in supporting our work.

Until then, all the very, very best,  Keith

By Keith L. Bildstein, Ph.D.
6 August 2015

Vulture survey route along the California coast.

Vulture survey route along the California coast.

I have dreamed about surveying turkey vultures in California for a long, long time. The opportunity finally arrived this July when spring 2015 Hawk Mountain trainee Katie Harrington returned to her home base in San Francisco late last month. Katie and her fiancée James Fahlbusch volunteered to help and the three of us mapped out seven, day-long road surveys that would follow the coast north and south of San Francisco as well as inland from just north of Redding to south of Bakersfield. The plan was to travel the roads at 35 mph and record all of the turkey vultures we saw. Then, repeat the same route in mid-winter 2015-2016 to investigate seasonal changes in vulture distribution and abundance. We also planned to record the flight heights and group sizes of all of the birds we saw, as well as to look for and record the locations of California condors along the way.

Having conducted road surveys in 22 other regions stretching from Canada at the species’ northern limits to Tierra del Fuego, at its southern limits, I was excited to say the least. The fact that California was exceptionally hot and tinder-box dry this summer only added to my excitement.

A California condor with wingtag soars overhead.

A California condor with wingtag soars overhead.

Our surveys, which covered 1,280 miles, produced 1,306 sightings of turkey vultures, or more than one vulture per mile, a relatively surprising find given that several of the routes passed through “agro-industrial” and suburban areas. We also saw seven California condors, most of which flew close enough for us to read their wingtags. Intriguingly, all but one of the condors sighted were flying in close proximity to turkey vultures.

Remarkably enough, the ecological relationship between these two species has been little studied. Except for the not-surprising fact that turkey vultures are known to be behaviorally subordinate at carcasses to the more massive condors we know little of the ecological relationships between these two avian scavengers. What we do know is that while larger and more-agile avian scavengers typically dominate smaller and less-agile ones at food sources, numerical abundance at a carcass sometimes allows smaller scavengers to dominate larger scavengers. And this is exactly what happens when large gangs of black vultures overwhelm and dominate far larger, but less numerous, Andean condors at carcasses in South America.

A turkey vulture feeding on a racoon.

A turkey vulture feeding on a raccoon.

Although turkey vultures are far less social than black vultures and rarely group in large numbers at carcasses, they may out-compete the large California condor in other ways. First, their keen sense of olfaction should allow them to locate rotting carcasses faster than condors, and thereafter consume at least smaller ones before the condors find them. Second, their larger numbers might allow them to finish off larger carcasses partially fed upon by condors–and then left for later–more rapidly, thereby reducing the amount of food available to the larger birds.

Intriguingly, our miniscule one-week field effort suggests that the two species sometimes share the same airspace and, presumably, the same carcasses. Given the current status of condors as a globally-endangered species and the amount of field work and funding now focused on speeding their recovery, careful studies of interactions–both behavioral and ecological–between condors and turkey vultures would seem to be in order.

Keith and Katie examine the racoon.

Keith and Katie examine the raccoon.

Our next road surveys in California are scheduled for winter 2015-2016. Katie, James, and I look forward to exploring the distribution and abundance of vultures then, as well as to observing the behavior of vultures and condors as they search for food across the California landscape.

At long last, my “California dreamin’ is becoming a reality.”

By Keith L. Bildstein, Ph.D.
21 June 2015

Yesterday, Hawk Mountain Sanctuary Summer Field Experience Interns Kaitlin Schafer and Emile Luttman, and I drove more than an hour through pouring rain to try to find a special Turkey Vulture.

Named in honor of Irma Broun, the wife of the Sanctuary’s first ornithologist Maurice Broun, Irma the Turkey Vulture had been caught by then Hawk Mountain Graduate Student Jamie Mandel at a garbage dump in Penn Argyl, Pennsylvania, in August 2004. Shortly thereafter she was tagged with a solar-powered satellite tracking device. We also placed a data logger in her body cavity to record her core body temperate and heart rate. Placing the latter in Irma meant that we would need to recapture her the following year to extract the logger and download the data.

Former Hawk Mountain Graduate Student Jamie Mandell

Former Hawk Mountain Graduate Student Jamie Mandel at work in the field.

The bad news is we were never able to re-catch Irma in 2005 despite numerous attempts to do so. The good news is that both she and her tracking device are both still ticking more than a decade later. The tracking devices have a life expediency of three to five years, so Irma’s unit by far is our best overachiever.

This summer Kaitlin and Emilie have been spending time mapping Irma’s movements. Although she migrated to South Jersey during the winters of 2004-2005 and 2005-2006, since then she has been a year-round resident of an area near Easton, Pennsylvania, and Phillipsburg, New Jersey, shuttling between feeding and roosting sites on both sides of the Delaware River. Last week we decided to try and reconnect with her.

Using the movebank.org website that we use to store our tracking data, we located Irma’s roost site on the evening of Friday 19 June. She appeared to be resting for the night in the middle of a hilly old-growth forest outside of Riegelsville, New Jersey. Our plan, outrageous as it seemed, was to go to the forest, spot Irma, and photograph her.

We arrived at the forest a little after 8 a.m. on June 20. The rain had kept the vultures in their roosts later than normal so we thought that we might get lucky. As we approached Irma’s last location GPS location, we slowed the car to a crawl and began to search for basketball-sized black objects perched in trees.

Almost immediately Emile screamed from the back of our Subaru Forester, “Stop, stop!! Backup … I saw her.” Backup we did, and there she was, soaking wet, 30 feet up in a large sycamore, 30 yards from the side of the road. As soon as we put  binoculars on her we could see the antenna of the tracking device.

Irma then accommodated us by turning completely around to show us both the antenna and the device. Although feathers normally cover the device on perched birds, the rain had soaked her feathers permitting us to see the unit itself. After 15 minutes of snapping photos (and yes, we took dozens) and looking for other vultures in the forest (we saw none), we got back in the car just as the rain picked up and drove off… all three of our heads spinning. Fifteen minutes later we were having a hot breakfast in Riegelsville.

Irma and her tracking device, spotted more than a decade after this vulture was first tracked and tagged.

Irma and her tracking device, spotted more than a decade after this vulture was first tracked and tagged.

To successfully catch and satellite tag a wild bird is one thing. I still get chills when I do so. But to be able to track a wild bird and its movements for more than a decade is something else again.To be able to spot the same bird perched in a thick forest on a rainy morning more than 10 years after first releasing it is truly is an ornithological epiphany.

Emilie, Kaitlin, and I plan to finish our analysis of Irma’s movements this summer, and I plan to spend September writing up the results. All of the publications I have been involved with over the years have been unique, but this one not only will be unique, but remarkably unexpected as well.

And yes, pending funding, I plan to mount an effort to re-catch Irma later this summer, so that we can replace her current tracking device with a new one and keep the information rolling in.

More later.

Another view of Irma on the morning of June 20 in a wet forest outside Riegelsville, New Jersey.

Another view of Irma on the morning of June 20 in a wet forest outside Riegelsville, New Jersey.

By Keith L. Bildstein, Ph.D.
Santiago, Chile
31 May 2015

I have been studying Striated Caracaras, a.k.a. Johnny Rooks, on the Falkland Islands since December 2010. Until my most recent trip I have timed my visits to study the birds either in mid-summer or mid-winter. The plan had been to contrast rook ecology in those two seasons and to draw conclusions regarding seasonal differences in their behavior.

The trip I am now returning from has been a “temporal anomaly.” I spent two weeks on the islands in late May, which is “austral autumn’’ (think late November north of the Equator), to learn how the birds make the transition from the summer food largess to the cold and snowy winter lean times.

I have known for some time that the bulk of the 150 or so rooks that inhabit Saunders Island in the northwestern part of the archipelago spend most of their summers at and around Gentoo and Rockhopper penguin colonies at the wind-swept “Neck” in the northwestern part of the island (see first photo below) and then move from there to a farm settlement (second photo) at the eastern edge of the island in winter. Penguins and their young provide the rooks with food in summer and the island’s farmer-owner and his family provide most of the food in winter. Ten miles separate the Neck from the Settlement sites and I have seen individually-marked rooks at both locations on the same day, meaning they are able to make the journey between the two sites in a single flight or rapid series of flights.

A penguin colony at "The Neck," a summer hotspot for Johnny Rooks.

A penguin colony at “The Neck,” a summer hotspot for Johnny Rooks.

Rooks waiting to feed at the Settlement. The rook on the rail at the far right is a juvenile.

Rooks waiting to feed at the Settlement. The rook on the rail at the far right is a juvenile.

When I arrived on Saunders on the 18th of May the overwhelming majority of birds, and almost all of the young birds-of-the-year, still were at the Neck and consuming an unusually large number of dead Gentoo Penguins that had washed up along drift lines surrounding the Gentoo breeding colony. It wasn’t clear what had killed the penguins, but more than 100 rooks were taking advantage of the carcasses nevertheless. And so were several dozen Turkey Vultures. Indeed, there was so much food laying around that the rooks and vultures were feeding relatively amicably without the normal food-fighting that characterizes most of their feeding events. And most of the rooks had clearly bulging crops suggesting that they were “filled to the rim” with penguins.

Within a week, however, things began to change. Cold, southerly winds blowing in from Antarctica chilled the island with the first dose of winter weather, the penguin food largess shrank, and the birds began their mini-migration toward the Settlement.

They did so in a way that surprised me. Groups of four to 10 rooks–overwhelming young-of the year—took several days to make the 10-mile journey, moving about two to six miles each day and sampling habitats along the way. Relatively little in the way of food exists in the treeless Patagonian steppe between the Neck and the Settlement, and after several days of meandering, the birds arrived. In a manner of speaking, the birds seemingly “settled in” for the winter. By the time I left Saunders Island on May 28, more than 60 of the rooks had made the autumn transition during a period in which temperatures dropped below freezing for the first time since the last austral winter.

I had not given it much thought but the onset of cold weather and the lack of available food immediately shifted the birds’ behavior. Until the first freeze, rooks and vultures were feeding together at carcasses. The day after the freeze, gangs of rooks dominated Turkey Vultures at food resources as they normally do in mid-winter. The change literally happened overnight. Unfortunately I was not there to see if the situation reversed itself when warmer temperatures returned the day I left, but the switch was obvious.

Boise State University graduate student Anna Autilio and I were conducting observations of feeding behavior at experimental goose carcasses we had arranged for the birds. The observations will form a main part of Anna’s master’s thesis.The afternoon after autumn’s first frost, rooks feeding on the goose were noticeably ravenous, much more so than they had been in the days leading up to the arrival of cold front. It was as if a physiological trigger had gone off and the birds clearly were in “feeding frenzy” mode. For many of the individuals involved it would have been the first frost of their life… and something of a “difficult learn.”

Anna and I had conducted a survey of rook distribution and abundance in the area immediately surrounding the settlement earlier in the day. As we began the survey on our all-terrain vehicles at the edge of the settlement, a first-year rook flew up and perched several meter away. The bird then proceeded to walk up to a puddle of ice-covered water along the track in front of us and tried to skim a drink from it. As its beak skidded across the ice that glazed the puddle I couldn’t but help imagine what was going through its head.

Without parental guidance, the first-year hadn’t a clue how to drink from the ice-covered puddle. The bird flew off several seconds later and I spent the next hour and half on the survey aiming my ATV at the frozen-over puddles that dotted our route. I couldn’t help but break the ice, making the water below potentially available to the young rooks, thinking all the while about what was in store for these youngsters as their first winter approached… a time of the year when as many as a third or more of them would perish.

Everyone faces a number of challenges in life, but the longer I study Johnny Rooks the more I appreciate just how lucky we humans are compared with our raucous avian friends.

Keith

By Keith L. Bildstein, Ph.D.
Hawk Mountain Sanctuary
20 May 2015

Studying the movement ecology of a vanishing species is quite new to me.

Throughout my professional career, which stretches back more than 40 years, almost all of the raptors I have worked with have been relatively widespread and common. And indeed, most have been abundant. Even the endemic striated caracaras, or Johnny Rook, a species that I now study on in the Falkland Islands, are reasonably abundant there. Simply put, none of the species I have spent time studying has been ranked as Globally Endangered by the International Union for the Conservation of Nature (IUCN).

None of them, I should say, until I started working with Africa’s hooded vulture in 2013.

With a world population estimated at fewer than 200,000 birds and with numbers in many part of its range shrinking as I write this vanishing species clearly is in trouble. Although populations of hooded vultures remain healthy in parts of West Africa, in parts of Central, East, and southern Africa they in rapid decline. As a result, my work with hooded vultures not only focuses on gaining insights into the species’ basic biology and movement ecology, but also on understanding the many factors that threaten its existence in Africa.

The causes for hooded vulture declines are many. Both targeted and unintentional poisoning rank high, as does the use of body parts in “muti” and other types traditional medicine. On top of that, in many places hooded vultures are shot and trapped for “bush meat.”

Like other vultures, “hoodies” feed on dead animals including elephants and rhinos, two species that are themselves declining catastrophically due to poaching. Evidence suggests that 30 to 40,000 elephants are being poached annually. If this keep up, they will be functionally extinct in 20 years. The numbers differ somewhat for rhinos, but the story is the same. Unless things change, they too, will be functionally extinct in two decades.

The author near an elephant carcass in South Africa.

The author near an elephant carcass in South Africa.

But what about the vultures?

In the short run it would seem that hoodies and other vultures are living in a land of plenty. Lots of dead elephants and rhinos, however unfortunate ecologically, can’t be a bad thing for the scavenging birds of prey, right? But wait a minute…humans are involved in the wildlife slaughter for horns and tusks, and things are not as simple as they appear.

Poachers break the law when they shoot wildlife and in many places in Africa, poachers themselves are shot when game protectors attempt to apprehend them. Flocks of vultures circling over freshly poached carcasses often lead game wardens to these criminals while they they can be caught in the act. For this reason, the poachers have taken to lacing the elephant and rhino carcasses they poach with poisons to kill carcass-feeding vultures in an attempt to remove them as useful sentinels of poaching activity. Because hundreds of vultures can feed at a single elephant or rhino carcass, lacing several dozen carcasses with poison can remove thousands of vultures from entire landscapes.

This is exactly what is happening in parts of Africa.

Our work with hooded vultures began in September 2013 when Hawk Mountain Research Associates Drs. Corinne Kendall, Marc Bechard and I, working together with local Gambian conservationists, placed satellite tracking devices on four hoodies in The Gambia, a stronghold for the species in equatorial West Africa. Since then, colleagues have placed additional units on four individuals in Ethiopia, an East African stronghold, and on eight individuals in and near Kruger National Park in northeastern South Africa, a region with far fewer hoodies than The Gambia and Ethiopia.

One of our South African hoodies, a juvenile named Ngotso that was tagged in August 2014, has a club-shaped home range that stretches for just over 400 kms (250 miles) from northeastern South Africa into southern Zimbabwe. It turns out that Ngotso is, quite literally, living on the “front line” of vulture conservation in the region. Its movements, which we have now tracked for 10 months, clearly illustrate its use of areas within Kruger National Park and several protected areas in southern Zimbabwe (see movement map below), as well as its avoidance of areas in bordering Mozambique, where poaching has eliminated most of the large game regionally. He has even been re-spotted in the field a few times (see photo below courtesy of Andre Botha).

Movements of Ngotso from August 2014 to March 2015

Movements of Ngotso from August 2014 to March 2015

NGOTSO 2 Resighting

Ngotso resighted by Andre Botha

Unfortunately, poachers from Mozambique recently have moved into Kruger and are now poaching there as well. In fact, one of the trap sites we used in December 2014 was the carcass of a poached elephant well inside the National Park. Preliminary results from our Pan-African studies suggest that densities of hooded vultures are more than 500 times greater in The Gambia than in Kruger National Park and that their home ranges are more than four times larger in Kruger than in The Gambia. Part of this geographic difference in abundance clearly results from the fact that Kruger supports higher densities of larger and competitively superior species of vultures that out compete the smaller hoodies at carcasses.

A significant part of the difference, however, is due to human activities. In The Gambia, the hoodies live in harmony with people, both in natural and in human-dominated landscapes. Whereas in South Africa, the species usually is not tolerated by people and is now restricted to ranging in large protected areas.

The larger home ranges in South Africa are particularly unfortunate as expansive foraging areas substantially increases the risk. A single poaching event coupled with poisoning of the resulting carcass can kill a large proportion of a regional population of hooded vultures.

Our preliminary results, which we recently shared with African conservationists in the field, should help colleagues there better protect this this critically important avian scavenger. The plan is to expand our studies of hoodie movement and home-range ecology in other parts of Africa including Zimbabwe, Tanzania, and Uganda, and to extend our use of camera traps at nest sites to better assess their breeding success both within and outside of protected areas. We believe that the information we are now gathering and sharing with colleagues will help us and them to better protect this species. That said, expanding our efforts is essential.

All of this costs money…actually, a lot of money. Camera traps cost several hundred dollar each and satellite tracking devices cost $4,000 each to buy and an additional $600 per device per year to download the data they collect. And then there are travel costs associated with fieldwork. So far the project has cost close to $100,000. We estimate that expanding and completing our work will cost an additional $150,000.

If you or someone you know has the capacity to help us in this effort, please contact me via email bildstein@hawkmountain.org, by phone at 1-570-943-3411 ext. 108, or via regular mail at Keith L. Bildstein, Hawk Mountain Sanctuary, Acopian Center, 410 Summer Valley Road, Orwigsburg, PA 17961.

Expect additional updates soon.

Keith

28 April 2015
By Keith Bildstein, Ph.D.

From its humble beginning in the early 1980s, Hawk Mountain’s internship program has grown into a fully-fledged graduate-student level Traineeship, which, over the years, has offered academically rigorous training to more than 380 students in 75 countries on six continents.

The proof of success they say is “in the pudding,” and as I sit in the Johannesburg Airport in South Africa this evening pouring over VULTURE NEWS–the official publication of the International Conservation Union for Nature’s Vulture Study Group–I am reminded of just how far and wide our training efforts have taken root.

Volume 67, the current issue of VULTURE NEWS, has two main articles, four short communications, and several reports that run for a total of 80 pages. Both main articles in Volume 67 were co-authored by former Sanctuary trainees, two from Kenya, and one each from Nepal and New York. And as if that were not enough, one of the four Short Communications in Volume 67 was coauthored by three Sanctuary Research Associates and me.

The first major article, Assessment of the occurrence and threats to Hooded Vultures in western Kenyan towns, was coauthored by former Sanctuary trainees Martin Odino– now of the Raptor Working Group of Nature Kenya–and Titus Imbomba–now of the National Museums of Kenya– and conservation colleague Darcy Ogada. The paper confirms significant recent declines in the currently globally endangered Hooded Vulture in western Kenya, where large numbers of “hoodies” once foraged in local slaughterhouses and city dumps. This species is the object of my current efforts here in South Africa,  and although there was little evidence of exploitation of the birds for witchcraft in Kenya–something that is common in other parts of Africa–the introduction of modern closed-system (i.e., sanitary) slaughterhouses and the widespread and increasingly popular poisoning of stray dogs is thought to have contributed to the declines, which appear to have been underway for about 15 years.

Martin Odino stands second from left in a “trainee class” photo taken in Kenya in 2009.

Martin Odino stands second from left in a “trainee class” photo taken in Kenya in 2009.

The authors surveyed elders in eight towns, and although attitudes there are largely neutral, little in the way of local protection is underway. The authors call for a vulture awareness campaign to help and possibly reverse the declines. This this is exactly what needs to be done and the Sanctuary hopes to help.

The second main article in the NEWS, Population and breeding success of Red-headed Vultures and Egyptian Vulutres in central west Nepal was coauthor by former Sanctuary trainees Tulsi Subedi (see photo below), now of Himalayan Nature, and Robert DeCandido of New York City. Although both species of vultures currently are doing fine in Nepal, both are in catastrophic decline in other parts of their ranges. In India, for example, declines in Red-headed Vultures are estimated to be at 44% annually and those of Egyptian Vultures at 35% annually. The veterinary drug diclofenac has been implicated in the precipitous population falloffs. Subedi and DeCandido’s monitoring efforts offer baseline data for a continuing monitoring effort.

Tulsi Subedi in his native Nepal

Tulsi Subedi in his native Nepal

The short communication, Avian Scavengers, but not conspecifics, feeding on the carcasses of storm-killed Turkey Vultures on the Falkland Islands was coauthored by me and Sanctuary research associates Micky Reeves of Falklands Conservation, Melissa Bobowski of Michigan, and Anna Autilio of Boise State University. The piece reports on winter-time observations of opportunistic scavengers including Variable Hawks and Striated Caracaras feeding on the carcasses of two storm-killed Turkey Vultures.

The author (upper right) with Sanctuary research associates Micky Reeves (upper left),  Marc Bechard (lower left), and Melissa Bobowski.

The author (upper right) with Sanctuary research associates Micky Reeves (upper left), Marc Bechard (lower left), and Melissa Bobowski.

Although flown over regularly by at least six other Turkey Vultures from a nearby roost, the carcasses were not fed upon by these conspecifics. This intriguing natural-history note describes an honor of sorts among this, the world’s most common and widespread obligate avian scavenger. The article, which represents the 250th Sanctuary contribution to conservation science since 1992, is, in fact, the tiny tip of a very large “iceberg of information” contributed by the Sanctuary and its colleagues across the years. It also suggests that the training of young conservationists at Hawk Mountain is having its intended effect.

Next month I will accompany former trainee Anna Autilio to The Falkland Islands as she continues her studies of the feeding and social behavior of the globally near-threatened Striated Caracara. Stay tuned for update on this exciting project.

Keith L. Bildstein

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