Feeds:
Posts
Comments

Posts Tagged ‘animal conservation’

L1290372

Dr. Keith Bildstein about to release one of the northern breeders this January.

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

17 March 2017

Most studies of bird migration focus on the movements of birds that ornithologists refer to as “complete migrants,” species whose global populations evacuate their breeding grounds each year while traveling to geographically distant wintering areas.  Although Arctic Terns, Black-and-white Warblers, and Broad-winged Hawks, along with a small percentage of other species of migratory birds, do follow this pattern, most migratory species of birds are “partial migrants,” species whose populations include both sometimes-migratory and non-migratory individuals, and whose migratory populations sometime overwinter in areas already occupied by non-migratory members of the same species.  It turns out that partial migration is a lot more complicated than complete migration, and although the former is little studied compared with the latter, its complexity makes it a lot more intriguing, as well as a lot more challenging, both to investigate and to understand.

New World Turkey Vultures are a good example of partial migrants, with some populations consisting entirely of migratory individuals, whereas other populations consist of both migratory and non-migratory individuals, and still other populations consisting entirely of non-migratory individuals.  The degree to which different populations of Turkey Vultures interact, and the effects they have on each other is not well known.  One place where such interactions have been explored is in the Llanos, the enormous freshwater wetland of central Venezuela, where Turkey Vulture migrants from western North America, which are larger and more massive than the region’s non-migratory, year-round residents, displace the latter from the best available habitats and gain weight after their arrival while the supplanted residents simultaneously lose weight.  Indeed, the so-called Llanos “residents” appeared to “migrate reciprocally” to avoid competing with of the larger North American birds.

But what happens in areas in which some breeders migrate south in autumn, whereas other stay put, while still others from more northern breeding sites migrate into the region and over-winter there?  Such is the case in the Sonoran Desert of southwestern Arizona, where members of the breeding population include both migrants and non-migrants of the aura race of Turkey Vultures, whereas as the winter-only individuals are migrants from the larger and more massive meridionalis race from farther north.  (Note: There are six subspecies of Turkey Vultures, three that breed in North America, along with two that breed in Central America, and three that breed in South America.)

L1290369

Keith and Hawk Mountain Sanctuary Senior Researcher Dr. Jean-Francois Therrien fitting a satellite to one of the norther breeders this January.

We began satellite tracking members of the Sonoran Desert breeding race in 2014 and have followed the movements of nine birds since then.  All but one have proved to be migratory, with some individuals overwintering consistently in Mexico, whereas other have overwintered consistently either in Guatemala, El Salvador, Panama, or Colombia.  In late January of this year my Hawk Mountain colleague, Dr. Jean-Francois Therrien, and I traveled to our tapping site outside of Phoenix and successfully trapped two winter-only individuals of the meridionalis race of Turkey Vultures.  Although we don’t know exactly where these two breed, as of early-March one was on Vancouver Island in south western most Canada, and the other was in Death Valley California in late March, with both north of their Arizona trapping site.

Tracking the movement of all of these Sonoran birds for several years will allow us to determine if the northern breeders crowd out the smaller year-round residents from Arizona, and if so, whether or not the smaller southern migrants leave in autumn in advance of the arrival of the larger northern migrants and time their returns to avoid the departing northern migrants in spring.

Although this may seem a bit esoteric to some, understanding the extent to which the two subspecies interact in the Sonoran Desert has important implication for conservation.  Suppose, for example, that in Arizona the larger northern breeders consistently dominate the smaller southern breeders.  If so, the size of the former’s populations could limit the size of the latter’s, particularly in winter when food may be limiting.  If so, the fate of the latter would be affected by the fate of the former.  Thus, if global change were to affect the former–either positively or negatively–the latter might “respond” as well, albeit indirectly, in-kind.  Although, all of this remains highly speculative, the extent, if any, to which populations of the two races merits examination, and I very much look forward to doing so over the course of the next few years.

I will keep you posted of the arrivals and departures of both our “northern” and “southern” Arizona migrants this summer.

Read Full Post »

 

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 »

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 »

keith releasing vulture may 2016

Keith releasing “Calm Lady” at the Buckeye dairy-farm trap site.

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

27 June 2016

We’ve all seen the Gary Larson cartoons of vultures perched or soaring above one or two desiccated cowboys insightfully expounding on something comical.  Truth be told however, vultures are rare inhabitants of most of the world’s deserts.  Fortunately, this is not so in the Sonoran Desert of the southwestern United States and northwestern Mexico.

The Sonoran, a fascinating and ecologically rich region, is an important go-to place for vacationing Canadian and US snow birds, as well as home to 10 species of amphibians, 100 or so reptiles, 60 mammals, and more than 350 species of birds, including the world’s most northern breeding populations of Cathartes aura aura, a largely Neotropical subspecies of Turkey Vultures.  Investigating raptors at the limits of their geographic ranges has been a fascination of mine for more than 40 years, and this explains why I traveled to Buckeye, Arizona, 30 minutes west of Phoenix on Interstate 10 just before midnight on the night of Tuesday 17 May 2016.

Hawk Mountain’s Senior Research Biologist Jean-Francois Therrien and I landed at Sky Harbor Airport in Phoenix with an ambitious agenda.  The following day I would travel two hours south to Tucson to give a talk on our vulture work at the world famous Arizona Sonora Desert Museum, while at the same time Jean-Francois would hook up with Rich Glinski, the editor of The Raptors of Arizona, and try to catch vultures at a dairy facility outside of Buckeye.  Dairy farms are large in Arizona, and still-born calves would be the bait at our desert trap site.

Both Black and Turkey Vultures occur in Buckeye, and although we had begun our studies in the state in 2014 focusing solely on the latter, we have recently expanded the work to both species, as both were feeding, interacting at, and fighting over at the same nutritional resources, and fully understanding the feeding ecology of two species was only possible if we studied both of these competitors.

My talk at the museum was set for noon and a group of 40-plus museum workers and volunteers were eager to what I had to say as the museum had open an exhibit featuring both Black and Turkey Vultures a few months earlier.  Half way through the talk my mobile phone vibrated in my pocket.  Unfortunately, I ignored it as I didn’t want to interrupt the presentation.  That was a mistake, as Jean-Francois was calling from Buckeye to let me know that he and Ron had just caught and placed a satellite tracking device on an adult Turkey Vulture they had decided to call “Moo Moo,” the name the young daughter of our host blurted out when she first laid eyes upon it.  (Most of our trapping sites are on private land, and we always make certain to engage the land owners in all aspects of our field work, including watching us place tracking devices on the birds we catch and tag and helping us name them.)  The next phone call came two hours thereafter when JF called to let me know that he and Rich caught and tagged a second Turkey Vulture named “Gash.”  Both individuals, while quite healthy, weighed less than 70% of the Turkey Vultures we catch in Pennsylvania, which were members of the considerably more massive septentrionalis subspecies.  Needless to say we celebrated the day over dinner at a “wings” restaurant close to our motel.  We had brought four tracking devices with us, and after just one day of the four that we had allotted to trapping and tagging birds, we were half way to our goal.  The pressure was still on, but reaching our goal certainly appeared doable, and we were pleased.

Keith and AZ bird May 2016

Keith with “Calm Lady” at the trapping site.

We caught Turkey Vulture number three, “Calm Lady,” early afternoon the next day, and caught our fourth Turkey Vulture, “Early Bird,” before eight the following morning.  Four birds after a little more than two days in the field.  Not bad… not bad at all.  We took time off from the field the rest of day three while planning our work for the remaining two days we had scheduled to be in Arizona.  When we first started working in Arizona in May of 2014, our plan was trap and tag at least a dozen Turkey Vultures, and the four we caught in May of 2016 brought our total 15.  We also planned to conduct a series of six seasonal road surveys totaling 1,061 miles in southern and western Arizona.  The surveys would allow us to estimate the sizes of the wintering and summering populations there, providing us with critical information on regional numbers.

The next morning we set off a 166-mile road survey that began at Gila Bend and meandered through the towns of Ajo, Why, and Sells Arizona, while circling back toward Tucson.  We counted 63 Turkey Vultures and 3 Black Vultures along the way.  After overnighting in Tucson, we conducted a second, 152-mile survey that began at Three Points and continued south to Nogales on the border with Mexico, before turning north to Continental.  On that survey we counted 30 TVs and 1 BV along this route.  After finishing the survey we scurried back to Sky Harbor Airport in Phoenix to catch a red-eye flight back to Newark, New Jersey.  It was then onto Hawk Mountain by car, where we arrived mid-morning on Monday the 23rd.

Although we had spent but five days in the field, we had managed to catch and tag four new Turkey Vultures and had conducted two full-day roadside counts.  Our next trip to Arizona will be in January 2017, when we hope to catch and tag at least three Black Vultures and conduct as many as six road surveys.  Although the work—if you want to call it that—might seem tedious to some, for me and my colleagues it was as close to heaven as one comes in raptor biology…  a chance to catch up on all things “vulture” while trapping and tagging a few birds, surveying an important regional populations of two species, and getting the word out to the public about why we are studying Turkey and Black Vultures and what we are finding out about them.

In my next blog, which I hope to have out in several weeks, I will update you on our Arizona findings to date.

To learn how you can help support our studies, email me at Bildstein@hawkmtn.org or call me at 570 943 3411 ext. 108.

Read Full Post »