Feeds:
Posts
Comments

Posts Tagged ‘ornithology’

 

aerial-view-of-dakar

Ariel view of Dakar, Senegal, a city of 3.5 million people and no traffic lights

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

11 November 2016

I began my studies of the world Critically Endangered Hooded Vulture in The Gambia in September of 2013, when colleagues and I placed four tracking devices on individuals in the exurbs of Banjul, the capital of that country.  Almost immediately thereafter, I thought about investigating their populations in Senegal as well.  Senegal, the western most mainland country in Africa is a much larger nation that completely encircles The Gambia–except for the latter’s small Atlantic coastline– and is an ecological  transition zone between the humid tropics farther south, and the Saharan desert of Mauritania to the north.

countyrside

The country-side along our survey routes

This year’s meeting of the Pan African Ornithological Congress in Senegal’s capital, Dakar, gave me the perfect excuse to follow up on this.  After attending the Congress and the important Second Pan African Vulture Summit associated with it, my colleagues and I tried to capture several “hoodies” in hopes of placing satellite tracking devices on them.  We also conducted three roadside surveys of vultures to learn more about the distribution of Hoodies and other vultures in the country.

Two mornings of trapping attempts at the Dakar Zoo produced no captures, and our attention on Sunday, the 23rd of October turned to leaving Dakar and traveling north to the small city of Louga, where three of us, Drs. Lindy Thompson, Rien Van Wijk, and I, planned to meet with a group of other European and African vulture biologists who also planned to survey vultures populations.

All went quite smoothly until we reached the town of Thies, Senegal, where our low-cost rental car overheated, forcing us wait on the curb for 6 hours for a replacement, which arrived only after darkness fell.  Driving at night in Africa is never easy–livestock, pedestrians, aggressive drivers, and potholes, see to that–and it was past midnight when we reached Louga, long after our colleagues had gone to bed.

Hoodie near a ruppell's nest.jpg

A Hooded Vulture perched near a nesting of Ruppell’s Vultures

A breakfast meeting the next day resulted in a decision to head southwest to the village of Dars, and then southeast on to the city of Mbaké, slightly more than 200 kilometers away, while surveying vultures en route.  Our colleagues would survey other routes.  We saw 169 vultures along the way, including 17 hoodies, 47 Ruppell’s Vultures, 71 White-backed Vultures and 34 Gyps vultures that we could not identify to species.  The route took us through open habitats not unlike those we survey in South Africa, except for the fact that all of the ungulates we saw on the way were domestic livestock (i.e., sheep, goats and cattle), rather than wild antelopes and other native mammals.  We spent the night in a small, and somewhat questionable, hotel on the outskirts of Mbaké, where a small red light over our beds confirmed our suspicions concerning the facility’s hourly rates of stay.

The next day involved following a meandering survey route to the city of Kaolack, which our travel guide referred to as the “armpit of Senegal. ”  Unfortunately, Kaolack turned out to be aptly named.  Our approach to the city included skirting the edge of a primary sewage treatment facility, which quickly cleared our nasal passages of the dust they had accumulated over the course of the day.  Our hotel and the opposite side of town proved to be something of an oasis, even if the highlight of its view-shed was an enormous

hoodie-at-the-hotle-parking-lot-in-dakar

A Hooded Vulture perched at the gate to our hotel’s parking lot in Dakar, Senegal

mountain of salt excavated from the adjacent hypersaline estuary. The day’s route included good looks at 46 Hooded Vultures, together with lesser numbers of Ruppell’s, White-backed, and Lappet-faced Vultures, along with several impressive multi-thousand bird flocks of White Storks.  Our third and final survey route, which took us back to Dakar, produced an additional 69 Hooded Vultures, a number of which were sighted in Dakar itself, together with smaller numbers of African White-backed and Ruppell’s vultures.  Although we were not sure of what to expect, the numbers of hoodies, in particular, were more that I imagined, albeit much less than 10% the density of those we had seen on similar surveys in The Gambia in 2013 and 2015, in more moist wooded habitats, about a hundred kilometers farther south.

Although we collected our data in a traditional fashion using our odometer to indicate the locations of all birds we sighted, we later entered our counts into the newly developed African Raptor Databank (ARDB).  The brain child of my good friend Dr. Rob Davies, the ARDB aims to ascertain the conservation status of raptors and their habitats across Africa, and to help build the local expertise needed to monitor these species in the future and implement a sound strategy for their effective safeguarding.

The ARDB will be completed in two phases. The first involves building a database over a period of five years (2013 – 2018). The second involves distribution modelling of each species in relation to the availability of its habitat and production of a conservation atlas for African raptors, online and hard copy. The project which received initial support from Hawk Mountain Sanctuary, is managed by habitat INFO, and is currently co-funded by The Peregrine Fund.

Given our initial experiences in Senegal, I plan to return early next year to conduct additional road surveys, as well as trap and affix tracking devices to two or more hoodies.

Importantly participants at the Second Pan African Vulture Summit I attended agreed to foster additional roadside surveys of African Vultures, the majority of which, including Hooded Vultures, are globally threatened or endangered.  Hawk Mountain plans to help in this effort every way possible, so that we can better assess vulture abundances and distributions, and, in so doing, formulate practical and effective conservation action plans.

Stay tuned as we continue to do so.

For information on how you can help, contact me at bildstein@hawkmtn.org.

Read Full Post »

kerri-with-a-nestling

Hawk Mountain collaborator Kerri Wolter holding a tagged nestling Hooded Vulture in Olifants River Private Game Reserve, October 2013

By Keith L. Bildstein, Ph.D., Sarkis Acopian Director of Conservation Science
and Lindy Thompson, Ph.D., Hawk Mountain Research Associate
Hawk Mountain Sanctuary

10 November 2016

Yes, I admit it. We name our satellite-tracked vultures.

Some of our colleagues disagree with this, arguing that naming one’s study animals “personalizes” them in ways that make our observations less scientific.  But primatologist Jane Goodall and Nobel Prize laureate Konrad Lorenz named their study animals, and I have never doubted the scientific rigor of their work.  Naming animals as individuals makes their individual behavior easier to remember.  With more than 75 vultures tracked by satellite so far, numbers or alpha-numeric codes simply do not work as well, as names help to separate and categorize the birds in question and keep the stories of their movements in mind.

“Homebody,” a South African Hooded Vulture, is a case in point.

As a nestling, Homebody was fitted with a GSM satellite tracking device by Walter Neser and Kerri Wolter at the Olifants River Private Game Reserve in northeastern South Africa just west of Kruger National Park on the 19th of October, 2013.  Unfortunately, the unit never worked, and we decided to try to re-trap and refit Homebody with a new unit in the summer of 2014.  Trapping a vulture once is relatively easy.  We have caught hundreds of them.  Trapping the same bird twice, however, is a different matter entirely.  In 2004 we caught and placed data loggers in the body cavities of six Turkey Vultures to record their heart rates and core body temperatures.  The following year the birds needed to be recaptured and their data loggers removed to retrieve the accumulated data.  It took then graduate student and now Dr. Jamie Mandel, hundreds of hours during much of the next spring and summer to recapture four of the birds.  The other two were never recaptured.

 

nobuhle-with-homebody

Hawk Mountain trainee Nobuhle Mabhikwa holding the retagged Homebody in the Olifants River Private Game Reserve in June 2014

We had allotted a week of field time to recapture Homebody to replace its malfunctioning unit with a working one.  Three days unsuccessfully attempting to do so had us at wits end.  Hooded Vultures defer to larger African White-backed Vultures at carcasses, and Homebody, even though present at our trapping site, hardly ever got close to the carcass, let alone the snares that we had set around it.  But then something happened that one only dreams about.  We were late getting to our trap the fourth day of field work, and lo-and-behold Homebody and several other Hoodies were already at the site picking up small pieces of the bait that remained from the previous day.  Disappointed by their early arrival we drove our Land Rover toward the birds, flushing all of them into the air.  Miraculously, Homebody, after taking off to escape our approach, flew into a thorn bush and became entangled on one of the lower branches, which had slid between its body and the backpack harness we had used to attach the tracking device.  Within seconds we ran to the bush and hand-grabbed Homebody, disentangled it, and brought it back to base camp.  We then removed the malfunctioning unit and placed a new, fully functional unit on it.  Within 45 minutes of its miraculous recapture, we were celebrating our “lucky day” over a couple of beers.  A once-in-a-million event allowed us finally to satellite track the young vulture that had been tagged eight months earlier.

 

satellite-united-recovered-from-homebody

Tracking device recovered from Homebody in October 2016

This alone makes for a great story.  But Homebody’s epic journey does not end there.  Last week–and more than two years later–we received an email from Colin Rowles, game warden at the Klaserie Private Nature Reserve.   Colin said a staff member on fence patrol had found Homebody dead at an impala carcass. When Colin went to collect the transmitter, he found that a Martial Eagle had consumed most of the Hooded Vulture.  Jackal tracks at the carcass lead him to believe that a jackal had killed Homebody.   We hope to place Homebody’s unit, which is still working, on another Hooded Vulture as early as this December.

 

homebody-movements-2016-10-27

Homebody’s movements 2014-2016

Even though the story ended tragically for Homebody, we have placed similar units on other Hoodies, both in The Gambia and Ethiopia, as well as in South Africa.  Although several of these birds have died, most are still alive and transmitting important information.  The data we are now gathering will allow us to offer advice on how best to protect these birds, as well on the factors that most threaten them.  Costs associated in doing this are not inconsequential.  Homebody’s unit cost four thousand US dollars and download information from the unit cost us close to 600 dollars per year.  The information, however, is “priceless.”  Understanding the ecological neighborhoods of Critically Endangered Hooded Vultures is key to protecting them.

To learn more about our work with Hooded Vultures and other species of scavenging raptors, or want to support our field efforts financially, contact me at Bildstein@hawkmtn.org.

My next blog will describe our recent field work in Senegal, where Hooded Vultures remain very much in evidence.

Read Full Post »

Johnny Rooks digging for kelp maggots on the Falkland Islands.

By Keith L. Bildstein, Ph.D., Sarkis Acopian Director of Conservation Science
and  Katie Harrington, Hawk Mountain Research Associate
Hawk Mountain Sanctuary

29 August 2016

Bear with me on this; it is really quite exciting…

Kelp maggots are the larvae of coastal dipterid flies that feed on rotting seaweeds, including kelp that drifts up along sandy shorelines.  In the northern hemisphere, these larvae (aka maggots) are themselves fed upon by shorebirds and passerines, including crows, which excavate them from kelp wracks that accumulate along the shorelines of sandy beaches.  Although studied little south of the equator, kelp maggots also inhabit the rotting kelp that drifts up along the shorelines of the Falkland Islands, including those on Saunders Island, a 49-square mile landmass in the northwestern part of the archipelago.

Neck Maggot Feeding Summer

Johnny Rooks digging for kelp maggots

For more than four years, we and our colleagues have watched the Striated Caracaras (aka Johnny Rooks) that we have been studying on Saunders Island, digging and probing beached kelp adjacent to penguin colonies there, and have wondered if these largely scavenging birds were receiving ecologically significant amounts of nutrition from the buried invertebrates.  In February of this year, we began to study this feeding behavior in detail using a protocol that allows us to quantify the rate at which individual caracaras secure maggots.  Our observations involve counting the numbers of maggots individual birds catch and consume during 30-sec feeding bouts.  We continued to collect data using this protocol on our most recent trip this August to assess the extent of seasonal differences in feeding rates.  We also collected maggots and weighed them to determine their individual mass, allowing us to determine their nutritional value. Our results, albeit preliminary, suggest that although birds capture maggots at higher rates in austral summer than in austral winter, in both seasons they manage to do so at rates of capture that are high enough to provide substantial nutrition for the birds engaging in this behavior for several hours or more daily.

The dogged determination and methodic nature with which the rooks dig is impressive, with many birds digging alternately with their left and right feet five inches or more into the rotting kelp while securing dozens of maggots over brief periods.  Clearly, more study is needed, but our initial observations suggest that this nutritional resource plays a significant role in the life of Striated Caracaras year round.

Summer maggots

Exposed kelp maggots

Intriguingly, on the most recent trip we also saw groups of rooks digging in upland pastures where they were feeding on what appeared to be small earthworms and grass grubs, with about the same rate of capture as when they were catching kelp maggots.  On our next trip in February 2017, we plan to expand our observations considerably.  In the interim, we will be presenting preliminary results of our work at the annual meeting of the Raptor Research Foundation in Cape May, New Jersey, in October.

Of course, insect eating is not unknown in raptors.  Kites, American Kestrels, and many other falcons routinely do so, as do larger birds including Steppe Eagles overwintering in Africa.  However, digging in the ground for insects is relatively uncommon among birds of prey.  Honey buzzards reportedly do so, and kites and Common Buzzards dig for earthworms in recently plowed fields in Europe.  That said, at least some rooks appear to do it routinely as well, and not only on Saunders Island.  In August 2013, during a short trip to Steeple Jason, a tiny island in the Falklands more than 50 kms from Saunders Island, one of us saw large numbers of caracaras digging for earthworms in peaty soil at the base of the island’s steep escarpment.

Our work with caracaras indicates that they are severely food stressed in winter on the Falklands.  Digging in the ground for invertebrates at first may not seem “raptorly,” but beggars cannot be choosers, and the taste of a live invertebrate may beat that of a rotting vertebrate anyway.

Read Full Post »

Red-backed rescue - cropped

Keith rescuing the female Red-backed Hawk from a pack of Striated Caracaras.

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

24 August 2016

With an extensive open-country distribution throughout much of southern South America, Red-backed Hawks are the functional equivalent of North America’s widespread Red-tailed Hawk. The mid-sized Buteo—red-backs weigh in at just over one kilogram, or roughly the same body mass of a Red-tailed Hawk—feeds mainly on small birds and small mammals across much of its continental range.  But on the Falkland Islands, where the species also is common, red-backs focus on Upland Geese, a large terrestrial goose that weighs 3.5 to 4.0 kilograms, or more twice the body mass of a Red-backed Hawk.  Given this rather unusual predator-prey size relationship, red-backs, which are non-migratory on the Falklands and remain paired-bonded throughout the year, hunt geese together in male-female duos with one hawk distracting the goose while other surprises and “takes down” the un-suspecting waterfowl.  In many instances, both members of the pair kill the goose before feeding on it simultaneously, with both gorging themselves and often returning to the carcass for a day or more as they strip every last piece of edible tissue from it.

This cooperative feeding routine works well for the red-backs on the main islands of East and West Falkland, where there are few if any Striated Caracaras to worry about, but such is not the case where the two species co-occur on the smaller, peripheral islands.  Our principal Striated Caracara (aka Johnny Rook) study site, Saunders Island, which is inhabited by several dozen Red-backed Hawks, as well as over 80 Striated Caracaras, is a case in point.  On Saunders Island as elsewhere, caracaras may be incapable of subduing and killing Upland Geese on their own, but they are not above competing for a dead goose once a pair of red-backs have killed it.

Such was the case on Saunders last week when my colleague Katie Harrington and I came upon a pair of Red-backed Hawks feeding upon a recently killed Upland Goose in a sheep meadow at the eastern end of the island one morning earlier this month.  Both hawks, but especially the female, had already gorged themselves on the carcass while cooperatively fending off several dozen, mostly juvenile caracaras that were attempting to partake in the feast. As we approached the group to read the bands on the caracaras—we have fitted more than 1,100 of Johnny Rooks with individually numbered rings as part of our long-term studies of the species—the male red-back took off. The female tried to do the same but was unable to do so given an enormously over-filled crop, which made it impossible while she was being attacked by more than a dozen caracaras that had pinned her down on her back and were feverishly “footing” and pecking at her.  Sensing that she was not long for this world, I jumped off my ATV and ran her down after she broke free from the swarming caracaras.

Keith with red-backed

A close-up of Keith holding the female hawk, with it’s bulging crop.

My decision was instantaneous, our initial approach, which had spawned the male’s successful departure, had left the female vulnerable, and although interfering in nature is not something I typically do, in this case our approach had tipped the competitive balance in this ongoing interaction, and my rescue attempt was aimed at minimizing the consequences.  The carcass was a little more than a kilometer from our cottage at our farm-settlement headquarters, and I remounted my ATV, cradling the hawk in my left hand while steering and thumb-throttling the ATV with my right.  We reached the settlement several minutes later where I placed the female in a dog kennel to give here time to digest her crop peacefully.

Four hours later I released the hawk, who by then had digested about half of food in her crop, but to no avail, as a group for more than a dozen caracaras appeared as out of nowhere and proceeded once again to pin her down in what appeared to be a death grip.  Once more I sped toward the hawk, ran her down, and re-rescued her, placing her back in the kennel with a plan to release her the following morning.

By the time I had grabbed her from the kennel the next day morning, the distended crop was no longer visible, and although half-a-dozen caracaras again initially pursued her, this time they kept their distance, as the lack of a crop most likely signaled them as to the danger in approaching too closely.  After flying off and perching on a fence post for about 5 minutes, the hawk flew off un-pursued in the direction of the goose carcass and her mate.  She was re-sighted at the settlement several days later holding her own against a group of caracaras fighting over a goose carcass that had been fed to the farmer’s pigs.

The sharper talons of the predatory Red-back Hawk make them formidable opponents to the less predatory and less well-armed caracaras—at least when not encumbered by an over-filled crop.  However, when they do have a large crop, the interspecies-competitive relationship changes, and in mid-winter (austral-winter August is the equivalent of boreal-winter February) when both species are hard-pressed for food, it becomes something of a raptor-eat-raptor world on the Falklands Islands where things can change rapidly for individual birds.

Stay tuned… next week I will blog about yet another potential dietary item for food-stressed Johnny Rooks: kelp maggots.

Read Full Post »

Skyline drive survey

Our survey vehicle on Skyline Drive in the Shenandoah National Park during our initial survey in the summer of 2005

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

20 July 2016

I realize that I am running a risk with this column in talking about raptor monitoring. Indeed, when I begin to talk about monitoring, my audience often begins to doze off.  If I continue to talk long enough, some may even fall asleep.  Nevertheless, monitoring not only is a useful tool in raptor conservation; it is an essential tool.  When we in raptor conservation fail to monitor populations of birds of prey we often pay a steep and, in some instances, an irreversible cost.

Consider the current plight of the Indian Long-billed and Asian White-rumped Vultures, two species that 40 years ago ranked as the world’s most abundant large raptors.  Both species were then common and widespread throughout southeastern Asia.  When populations of both species crashed by more than 95% in Bharatpur, India in less than two decades in the late 1900s, the problem was thought to be pesticides.  But when similar reports were received for other populations elsewhere in these species wide ranges, a lack of earlier population monitoring made it difficult initially to ascertain the actual magnitude of the declines.

Two vultures that had once been so common that no one thought to monitor the sizes of their populations were now so uncommon that some conservationists were suggesting that they were in the “fast-lane” to extinction.  Half of a very large number is still a very large number, and by the time people were paying attention to these formerly species few knew what their once very large numbers had been.

Eventually conservationists learned the problem was an FDA approved drug, diclofenac, then in use on livestock.  Diclofenac, a non-steroidal anti-inflammatory substitute for aspirin that, while non-toxic to humans, turned out to be highly toxic to vultures in the genus Gyps.  But without proper population monitoring, we had reached a point where expensive captive breeding was necessary to reverse the trends.  Had we been monitoring these populations earlier, such extreme measures would not have been necessary.

Which brings me to my point.  Monitoring populations of raptors—even common and abundant species—is a critical component of practical and effective raptor conservation.  This is why Hawk Mountain decided to begin doing so with two species of common and widespread New World vultures in 2005.  As of late 2015, the Sanctuary has surveyed Black, Turkey, and other vultures in 23 locations throughout the Americas: from central western Canada in northcentral North America all the way south to Tierra del Fuego in southern South America and the Falkland islands in the South Atlantic.

Our surveys include both winter and summer counts totaling more than 24,000 miles of road counts across 14 United States, 4 Canadian provinces, and 6 central and South American countries.  Surveys are conducted by a driver and one official observer along secondary routes at 30 to 40 miles an hour on rain-less and fog-less days.  Counts begin at nine in the morning and end at four in the afternoon after and before most of the birds have roosted for the evening. In addition to Black and Turkey vultures, all other scavenging birds of prey are counted as well, including all other vultures, condors, and caracaras.

When we began the counts in 2005, the plan was to survey both Turkey Vultures and Black Vultures in representative areas across much of their geographic ranges and to redo the surveys once a decade in both winter and summer, so that populations of both migratory and resident populations of these common scavengers could be monitored routinely. Declines in numbers could be assessed in a timely fashion, and conservation action taken as necessary, before populations had declined catastrophically.

Black bear scvenging a road-killed deer

An unexpected “non-vulture” scavenger feasting on a road-killed deer along Skyline Drive during our second round survey in the summer of 2016.

Round two of our surveys began in early July 2016 when three Summer Field Experience Interns and I redid two day-long road counts in northern Virginia that were originally undertaken in the summer of 2005.  One of the routes was a mountainous 195-kilometer meander along Skyline Drive in the Park Service’s Shenandoah National Park and the northern-most section of the Blue Ridge Parkway.  The other was a 211-km route that followed the eastern shoulder of the upper Shenandoah Valley.  The numbers of vultures sighted were encouraging.  During two days of field work this summer, we counted a total of 253 Tukey Vultures and 14 Black Vultures, versus 124 TVs and 9 BVs seen on the summer 2005 counts.

Although this initial field effort was a modest one, we will ramp-up counts this winter to include 6 routes totaling 963 kilometers in western and central Panama, along with the two winter counts in northern Virgina.  Over the next five years, we plan to re-conduct all of our surveys from west-central Canada south to Tierra del Fuego.  We hope to find that all populations previously surveyed are stable of increasing.  However, if they are not, we plan to put conservation actions into play that will determine the cause or courses for the declines and begin work to reverse them.

Vulture perform important ecological services in the ecosystems they inhabit, not the least of which include nutrient recycling and reducing the likely spread of diseases including botulism, anthrax, and rabies.  Protecting their populations is a critical aspect of Hawk Mountain’s mission, and we plan to stay on top of this.  Our next surveys in Virginia are scheduled for December 2016.  We plan to redo our winter surveys in Panama in January 2017.  Once we have conducted them I will be in touch.

Between then and now let me know if you have any questions on this monitoring effort and how you can support the Sanctuary financially in carrying out this crucial part of our mission. Feel free to email me at Bildstein@hawkmtn.org or call me at 570 943 3411 ext. 108.

Read Full Post »

The team pauses to take a self: From left, Jean-Fancois Therrien, Marc Bechard, Jennie Duberstein and Keith Bildstein.

The team, from left, Jean-Fancois Therrien, Marc Bechard, Jennie Duberstein & Keith Bildstein.

By Keith Bildstein, Ph.D.
Sarkis Acopian Director of Conservation Science, Hawk Mountain Sanctuary
May 26, 2014

I have just returned from field work on the northernmost population of North America’s southernmost race of turkey vultures, Cathartes aura aura, a diminutive and largely tropical sub-species that weighs only two-thirds as much as other North American turkey vultures.  Our field team was made up of Hawk Mountain Research Associate Dr. Marc Bechard of Boise State University, former Sanctuary trainee Dr. Jennie Duberstein of the U.S. Fish and wildlife Service, me, and Hawk Mountain’s Senior Research Biologist Dr. Jean-Francois Therrien.

Our work in the approximately 100,00-square-mile Sonoran Desert in southern Arizona which included placing satellite tags on both turkey vultures and black vultures, turned out to be—as  often is true of field work–full of surprises.  Our new trapping site at a pair of dairy farms on the outskirts of Buckeye, Arizona, southwest of Phoenix, was far better managed than many of the farms we had visited before, and its owners were gracious beyond belief. One of the potential trap sites offered little in the way of clear views of any traps we might put out, but a second site near a massive ossuary, or boneyard, proved to be perfect.

A bone pile provided an ideal trapping site in the Sonoran Desert west of Buckeye, Arizona.

A bone pile provided an ideal trapping site in the Sonoran Desert west of Buckeye, Arizona.

Our plan was simply enough to trap and tag six turkey vultures and four black vultures, conduct a few day-long roadside counts, and spend a day looking for several of the individual vultures we had tagged in May 2013. We had nine days to accomplish all of this and, as there was no rain in the forecast, the plan seemed quite reasonable.  In the past, our experience with trapping turkey and black vultures has been that the latter species is easier to trap than the former, in part because black vultures dominate turkey vultures at carcasses, and in part because of the black vulture’s more social nature (i.e., if you catch one you are likely to catch many).

But not this time around.

The first six birds we caught were turkey vultures!  Blacks, although relatively common in the area, rarely showed up at our trap site, and were more skittish than the turkeys. We did catch one on the sixth day of trapping, but decided to turn to road surveys on the seventh day, as the likelihood of trapping more black vultures seemed rather low.  Presumably most black’s in the area were feeding somewhere else, and unfortunately, we never found that location.

A perched turkey vulture along one of our survey routes near the ghost town of Ruby, Arizona.

A perched turkey vulture along one of our survey routes near the ghost town of Ruby, Arizona.

We spent the next two days counting vultures along two road-survey routes that covered more than 300 miles of Arizona secondary roads south of Gila Bend and Tucson Arizona, mainly in the Tohono O’odham Indian Reservation and the Coronado National Forest.  Unlike the counts we conducted in January, the routes were filled with single and small groups of turkey vultures, many of which appeared to be searching the roadways for road-killed carrion, including snakes. Overall, we saw more than 10 times as many birds as we had seen along the same routes in winter, suggesting that the bulk of the population migrates south from the region in winter.

We spent the final day in the field searching for the five vultures we had tagged last May. The first one we searched for was “Jennie,” a vulture that, having migrated about 250 miles into Mexico last October, returned to Arizona less than a week later and overwintered in the area south and west of Gila Bend.   Unfortunately, Jennie was roosting in the Barry M. Goldwater Air Force Range, a bombing range south of Gila Bend that was off bounds for us, and was feeding at a dairy farm west of Gila Bend that the owners would not allow us to enter.  The next three birds were roosting and hunting closer to Maricopa Arizona and we set out in search of them just before noon.

The last known location of the next bird, “Desert Rat,” took us to a roosting site in a nut grove across the street from a large dairy farm.  Although we did not actually see the bird, we did find a number of molted feathers under a nut tree, confirming the presence of vultures at the site.

Keith and Linda Wallace-Gray with her vulture namesake in May 2013.

Keith and Linda Wallace-Gray with her vulture namesake in May 2013.

The next bird we looked for was “Julie,” who had last been sighted over a recently cut  north of Stanfield, Arizona.  Although we failed to see Julie, we did see another tagged vulture, “Linda” feeding together with six other birds on a road-killed jackrabbit at the edge of the hay field. Linda’s transmitter had been “misbehaving” and was sending signals episodically, with the last fix being recorded more than a month earlier in early April.  She was close to where she was then, and our sighting of her helped explain the episodic nature of her signals.  Although her tracking device was still in place on her back, the antenna for it was missing, a fact that almost certainly explained the spotty nature of her signals.  Given that we had seen close to 100 birds the day we were searching for the tagged individuals, and that as many as 500 birds almost certainly were using the area, our visual sighting of Linda, albeit without her antenna, was like winning the lottery … a “grand finale” of sorts for our field work.

Our plans are to revisit Arizona next January, not only to finish our tagging efforts there, but also to conduct additional road surveys. Although we are but one year into our studies of Arizona’s Sonoran Desert vultures, we already have learned much about their ecology.  Equally importantly, we also have learned to expect the unexpected in this population, which gives me reason to believe we need considerable additional monitoring to understand this most-southern race of North America’s most common and widespread avian scavenger. So please stay tuned.

Read Full Post »

Keith holding a satellite tagged juvenile Hooded Vulture

Keith holding a satellite tagged juvenile Hooded Vulture

By Keith L. Bildstein, Ph.D.
Sarkis Acopian Director of Conservation Science
3 October 2013

As readers of this blog know all too well, Africa’s vultures are in trouble … big trouble. Nine of 11 species are “Red Listed” by the International Union for the Conservation of Nature, either as Near Threatened, Vulnerable, Endangered, or Critically Endangered, and many regional populations face the immediate threat of extirpation. Hooded Vultures, whose movement ecology Hawk Mountain decided to study in detail in 2012 are no exception (the species is now considered Endangered globally), and many populations in both East Africa and South Africa appear to be in steep decline.

With critical support from the Wallace Research Foundation and North Star Science and Technology, Hawk Mountain and its colleagues in Africa are in the process of placing satellite tracking devices on individual Hooded Vultures in many parts of its African range. Indeed, if all goes according to plan, two or more tracking devices will be placed on Hooded Vultures in Ethiopia, Kenya and South Africa later this autumn.

Earlier this week my colleagues and I placed four units on Hooded Vultures (three juveniles and one adult) in The Gambia, a small West African nation surrounded on all sides except for its Atlantic Coast by Senegal. The work went extremely well and what I learned during my short visit to this African nation has lifted my spirits considerably.

Clive Barlow, an intrepid Gambian colleague and new friend, has been watching Hooded Vultures for decades in The Gambia, and his willingness to partner with Hawk Mountain allowed me and raptor specialists Dr. Marc Bechard of Boise State University and Dr. Corinne Kendall of Columbia University to conduct a series of road surveys in The Gambia, as well as catch and tag four individuals for satellite tracking. Clive who has worked in The Gambia as an ornithologist for 30 years, co-wrote the book on Gambian birds with Dr. Tim Wacher ZSL UK (Barlow, et al. 1997. A field guide to Birds of The Gambia and Senegal), and l laid the ground work perfectly.

Our first day on the ground included meeting our counterparts inthe Gambia Department of Parks and Wildlife Management, including its director Mr. Momodou L. Kassama, and explaining how we intended to proceed with our work and discussing the details of our permit. The second day included baiting a trap site that Clive had been “pre-baiting” for weeks and sitting back and waiting for the vultures to arrive.

And arrive they did.

Part of a large communal ground roost used by Hooded Vultures near the national airport in The Gambia.

Part of a large communal ground roost used by Hooded Vultures near the national airport in The Gambia.

We placed the bait–a recently killed domestic chicken–out and set the trap at 9:30 a.m. Within two hours our first birds (two adults and a juvenile) dropped down and within a minute, we had trapped our first two Hooded Vultures: an adult we named Makasutu after the privately protected forest we had caught it in, and a juvenile named Mandina-Gambia, after the Mandina Lodge, the ecotourist facilty we used as base camp. In addition to placing tracking units on the birds, we collected a small amount of blood from each of them for sexing and eventual genetic analysis, weighed them, and released them back into the wild in short order. It is unusual to trap two birds simultaneously so we were confident about our great start.  The next day we caught and tagged another juvenile in the Department of Parks and Wildlife Management’s Abuko Nature Reserve about 20 kilometers away, and named it Abuko in honor of the reserve. We also conducted the first of three roadside counts along a 24-kilometer route during which we saw an astounding (at least to us) 654 Hooded Vultures. Two days later we caught a second juvenile at Abuko and named it Tan Hoodie … “Tan” meaning “vulture” in the local Wolof language. Two additional road surveys later in the week suggested that in western-most Gambia, at least, populations of approximately 20 birds per square kilometer were the norm, which is far more than any of us had anticipated. Indeed by comparison, I had only a few dozen hoodies during five weeks of work in the Masai Mara region of southern Kenya in 2011 and 2012.Why the birds are doing so well in The Gambia remains something of a mystery, but studying the movements of these birds, and comparing them with those of birds in decline populations elsewhere promises to be an important first step in understanding the species ecology in different parts of it range, which, in turn, should help us better assess where the threats to this species lay, and how we might better design effective strategies for their survival.

Several adult Hooded Vultures at a trapping site.

Several adult Hooded Vultures at a trapping site.

Unfortunately, one week in the Gambia is but a tiny step in the right direction.  Additional work, including satellite tagging many more birds is needed. The task will not be easy but for the rationale for doing it is plain. If we don’t learn more about this species ecology and behavior, and we don’t learn it quickly, we may lose ecologically functional populations of this the most widespread of all African vultures.More field work will require more funding, of course. But my trip to a haven for Hooded Vultures has only served to rejuvenate my enthusiasm for this important project. The loss of ecologically significant populations of vultures in southern Asia has brought with it dramatic increases in scavenging feral dogs, which, in turn, has resulted in rabies in humans skyrocketing in many places. We simply can’t afford to let that happen in Africa, the center of Old World Vulture diversity.Hawk Mountain plans to be in this good fight for the duration. If you want to help Hawk Mountain in this truly worthwhile effort, please contact me.

For information about how you can help, contact: mailto://bildstein@hawkmtn.orgor 570-943-3411 x108.

Acknowledgements:  Mawdo Jallow & Lamin Sanyang (DPWM) , Lawrence Williams , Linda English & staff Mandina Lodges @ Makasutu, Dr Tony Fulford & Dave Montrieul (road surveys & photographs)

Read Full Post »

Older Posts »