How well do birds tolerate people?

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Turkey Vulture. Photo by Mark Gorges.

By Barb Gorges

Also published here: https://www.wyomingnetworknews.com/do-birds-tolerate-people

Every soaring bird I saw in early February along 1300 miles of interstate highway between Nashville, Tennessee, and Fort Lauderdale, Florida, was a black vulture or turkey vulture.

However near Vero Beach, Florida, where we were visiting Cheyenne snowbirds Karen and Fred Pannell, there was a black bird of a different shape, a magnificent frigatebird, a life bird for both me and my husband Mark.

But about those vultures, were they really more abundant along the interstate than away from it? Were they waiting for roadkill? We passed a couple landfill “mountains” that were big vulture magnets too.

We think wild birds go about their lives oblivious to people, or at least avoiding us. Except for birds coming to feeders. Or ducks at the park looking for handouts. Or Canada geese that enjoy eating the grass on park lawns and the leftover grain in farmers’ fields.

We know that some human activities are detrimental to birds. But how many are beneficial to them? Chimney swifts have experienced both. We took down the old hollow trees they used to build their nests in and they moved into our chimneys.

The speaker at February’s Cheyenne – High Plains Audubon Society meeting, Cameron Nordell, relayed interesting research results on nesting ferruginous hawks and their reactions to people. Nordell, Raptor Fellow at the University of Wyoming Biodiversity Institute, is with the Wyoming Raptor Initiative.

In his previous work in southern Alberta, Nordell and his colleagues experimented in part to see at what distance hawks would flush from their nests as researchers approached by vehicle or on foot to check the nests for other aspects of the study.

Southern Alberta is a mix of agriculture, oil and gas and other development. The farmers and home owners have planted trees on the prairie and the ferruginous hawks have found them to be great for nesting—they are a ground-nesting hawk otherwise. The trees give them better protection from predators.

However, along with people came another species that climbs trees—and raids nests—racoons. Barns and other structures have helped increase the population of great horned owls and they too prey on the nestlings.

Ferruginous hawks nesting near the busiest roads were more tolerant than birds that had not seen as much traffic. Approaching vehicles were tolerated better than approaching people.

Raptors have been shown to hang out by roads, looking for injured prey species. The problem is that they risk getting hit by vehicles too.

The Wyoming Raptor Initiative (see https://wyomingbiodiversity.org/Initiatives-Programs) wants to understand the state’s raptors better, including the road problem. It has two goals:

“(1) To synthesize our scientific understanding of raptors in Wyoming so that the public, scientists, land managers and energy companies will be better informed in developing and implementing future conservation strategies and land mitigation efforts.

“(2) To foster appreciation of raptors in Wyoming and the world through education and outreach efforts.”

Nordell and his colleagues will be looking at previous studies of raptors in Wyoming, gathering more data, talking to all kinds of people to get more information, and then they’ll relay what they learn.

What will they discover about Wyoming’s ferruginous hawks, for instance? What human activities help them or harm them?

Nordell also studied arctic peregrine falcons near Hudson Bay, where there were few direct human impacts. However, the weather was ferocious. Too much rain, and a young bird, poorly nourished, could succumb to the cold rainwater collecting in the cliff-face nest. Better-fed youngsters had better survival rates.

The next questions: What affects the availability of peregrine prey species and the peregrine parents’ ability to bring food back to the nest? Is there any human influence on their success? Are humans linked in any way to that Arctic location getting demonstrably rainier?

What will be discovered about peregrines in Wyoming? I watched one nail a duck on a ranch reservoir just outside Cheyenne once. The human-made lake attracted the peregrine’s food target—southeastern Wyoming doesn’t have many natural water bodies.

I look forward to answers from the Wyoming Raptor Initiative. I’m sure they will also discover many more questions.

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Turkey Vulture. Photo by Mark Gorges.

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Turkey Vultures return again

Turkey Vulture

Turkey Vulture, photo courtesy of U.S. Fish and Wildlife Service

Published Feb. 21, 2007, in the Wyoming Tribune Eagle, “This spring watch for ‘TVs’ soaring above the area.”

2014 Update: Keith Bildstein is still researching Turkey Vulture migration: http://www.hawkmountain.org.

By Barb Gorges

Do you know where Wyoming turkey vultures spend the winter? It could be Venezuela.

Keith Bildstein, director of the Acopian Center for Conservation Learning at Hawk Mountain Sanctuary in Pennsylvania, is working on a migration study in which turkey vultures wintering in northwestern Venezuela have been tagged. He predicts bird watchers in western North America will see them this spring and report back to him.

Little is known about the migration of the “TV,” as birders refer to it, and even though it is a species with a stable population that is increasing northward, it’s better to do your research in advance of problems, said Bildstein, when I talked to him recently. Also, sometimes the new information will translate to less fortunate species.

Bildstein studied raptors for his dissertation so it is quite natural to find him at Hawk Mountain, the famous place where so many hawks pass on migration. What bothered him was that observers would refer to “just another turkey vulture.” He thought they deserved more respect than that.

Turkey vultures in eastern North America don’t migrate much except to get out of the cold—it is hard to chip meat off frozen carcasses.

Bildstein said satellite studies show TVs travel independently and individual birds may not travel the same route each year. They stop along the way and share roosts and food with the local vultures. Maybe they pick up pointers on great Florida real estate.

Meanwhile, when birds of the western subspecies head south, they travel down through Mexico, Central America and into Columbia and Venezuela, possibly heading as far as Argentina. On the wintering grounds they raise the population of vultures to four times that of the year-round resident subspecies. The smaller resident birds are crowded into marginal habitat, Bildstein said.

Two of the places the “gringo” vultures like to hang out are the zoos in Barquisimeto and Maracay. Last winter zoo folks told Bildstein about a tagged TV they found, which turned out to be part of a study in Saskatchewan, Canada.

Bildstein and Adrian Naveda, a biologist from Maracay, put their heads together and designed the northward migration study, counting on the help of the legions of birdwatchers in North America.

It was easy to gather the visiting vultures. Zoo management cleared out one of the aviaries, stocked it with dead chickens from the market, waited for the vultures to walk in, closed the door and tah-dah, 100 vultures ready for tagging. However, grabbing birds with 67-inch wingspans probably wasn’t easy.

Bildstein has had one report of a tagged bird so far. It was found shot 45 miles north of the release site. The rest of the birds should be migrating along the coast. In early morning, the warm ocean creates small thermals near shore, giving the TVs an early start. Then it’s a matter of riding one thermal after another over land all day long, day after day. As many as 2,000,000 turkey vultures have passed by an observation point in one season.

Here in Cheyenne, we may see TVs as early as March and definitely will by April. They have favorite roosting spots in the Avenues and are often seen circling over the cemeteries. Recently they have been noticed far into the summer, however, the nearest nest is probably by Guernsey, according to Doug Faulkner, who is working on the definitive book about Wyoming birds for the University of Wyoming.

OK, this is where you come in. Let’s review TV i.d. The most common large birds flying over Cheyenne in the spring, summer and fall are the turkey vulture and the Swainson’s hawk, which, incidentally, spends the winter in Argentina and shares the vultures’ migration route.

As they soar overhead, look at the underwing patterns. The leading (front) edge of the Swainson’s is light and the trailing edge is dark. Turkey vultures have the reverse: dark on the leading edge and light, actually silvery, on the trailing edge. Seen up close, they have red-skinned, featherless heads.

If you see one of the marked birds, it will have either a red tag with white numbers or a blue tag with black numbers wrapped over the leading edge of the wing, visible from top or bottom.

If you see one of these birds, you need to make note of the date, specific location, color and number of the tag, which wing it is attached (the bird’s right or left) and the circumstances of the sighting, whether the bird was alone or in a group of vultures, flying, perched, feeding or roosting. Dead birds should also be reported.

Report sightings to: Keith Bildstein, Hawk Mountain Sanctuary Acopian Center for Conservation Learning, 410 Summer Valley Road, Orwigsburg, PA 17961; Bildstein@hawkmtn.org; 570-943-3411, ext. 108. All reports will be recognized and individuals reporting tagged birds will receive summary information about the study.

If you would like to print your own copy of the “Wanted” poster, go to http://www.hawkmountain.org.

The February issue of Smithsonian magazine tells of the demise of millions of vultures in India in just ten years due to ingestion of a new livestock antibiotic while they feed on dead cattle. It has led to a terrific increase of wild dogs and, in turn, human cases of rabies. Valuable time was lost puzzling it out and there is no guarantee vulture populations will ever recover.

Though turkey vultures are the widest ranging of the vulture species, from Canada to Tierra del Fuego, and probably the most numerous vulture species in this hemisphere, everything that can be learned about them helps keep them that way.

To learn more to marvel over about turkey vultures, such as their terrific sense of smell, the way the young protect themselves and the sounds they make, go online to All About Birds, http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Turkey_Vulture.