Wednesday, February 11, 2009
All About Eagles
A dedicated raptorphile, I once said that if I could see a wild Harpy Eagle in the South American jungle, I would die a happy woman. Harpia harpyja is the only member of the genus Harpia. It is the largest and most powerful raptor found in the Americas, inhabiting tropical lowland rainforest in the upper canopy layer, where it preys on sloths, monkeys, and other tree-top dwelling animals.
Throughout the world, there are 46 species of eagles, including fish eagles, to which our national bird, the Bald Eagle, belongs, and booted eagles of the family Aquila which includes the other well-known North American eagle, the Golden Eagle. There also is a large group of hawk eagles, none of which might be found in the United States. While many birding afficionados consider only the bald and golden native to our land, another eagle, even larger than the bald occasionally graces Alaska and the northern seacoast with its presence, the Stellar’s Sea-eagle. This species which can weigh up to 20 pounds dwarfs our eagles which rarely weigh more than 10 pounds. It normally nests on the east coast of Russia, but often takes to open water during the non-nesting season, sometimes straying as far as North America.
Our beloved national symbol, the Bald Eagle is probably the most instantly recognizable raptor in the world. However, despite its symbolism, the species has suffered from persecution, and until recently was a federally listed species. At one time Bald Eagles occupied almost all of North America and estimates placed the population prior to 1800 at more than 250,000 individuals. However, as humans began to expand our range on this continent, eagle populations began to decline. In the American West, Bald and Golden Eagles were considered vermin and were shot in the mistaken belief that they were a threat to livestock.
In 1940, the Bald Eagle Protection Act made it a federal offense to kill Bald Eagles everywhere except Alaska. In America’s frontier state, however, they still offered a bounty for eagle carcasses as late at 1953. Then, in 1967, they were listed as endangered under the original version of the Endangered Species Act.
Although direct persecution diminished, the species still suffered from low reproductive success. As a top predator, they were a victim of bioaccumulation. Because most of the bald’s prey is aquatic, either fish or waterfowl, toxins from pesticide residues built up in their systems, causing thinning eggshells and reproductive failure. Populations of Bald Eagle, along with Osprey and Peregrine Falcon crashed as a result of DDT and related toxins. Essentially, these large predators were the ‘canary in the coal mine’ that warned us of these pesticide hazards.
Bald Eagle numbers have rebounded thanks to a more enlightened citizenry, the banning of DDT, and laws that protect not only the birds, but also their nests. Now, in many areas, an active Bald Eagle nest is cause for celebration, and eagle watches and eagle cams are the rage. When it comes to nesting, Bald Eagles may just be downright hospitable. Other smaller species sometimes build their nests in the massive structure that the eagles improve upon each year. These smaller birds receive protection from the presence of the larger predator, and the eagle doesn’t necessarily view a small-medium sized songbird as a food item. At one eagle’s nest along Puget Sound, three live nestling red-tails were found. Because the hawks were younger than the eaglets they could not have hatched from eggs laid before the adult eagles arrived. It is likely that the adults brought the chicks to nest to feed their young. But, they were not killed. Under the right conditions, if a nestling makes a food begging call, the parents treat it as just another mouth to feed. Two of the three red-tail chicks fledged from their surrogate eagle’s nest.
Although Bald Eagles have rebounded, much concern remains about the Golden Eagle population in North America. Some biologists believe that golden numbers are as low or lower now than the Bald Eagle was when it was listed. Goldens face some of the same threats to survival, persecution from shooting and also electrocution on power lines. With their large wingspan of 6-1/2 feet, they can easily span the distance between energized components on utility structures.
There is a thriving black market for raptor feathers in North America, especially eagle feathers. While Native Americans can legally possess feathers under permits issued by the U.S. Fish and Wildlife Service for use in religious ceremonies, collectors often pay exorbitant prices for feathers, feet, and skulls. Ironically, some of the largest documented eagle-poaching rings have involved Native Americans.
International trade in raptors is a continuing threat worldwide, and more than 120 countries have signed the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES), the most comprehensive wildlife conservation agreement ever created. Appendix I includes some 700 species of plants and animals that are critically endangered, including the Bald Eagle, and no legal trade is permitted in these species. Appendix II includes 3,000 animals, including the Golden Eagle, and 21,000 plants that would be threatened by uncontrolled trade, and only limited trade is allowed under certain circumstances. Appendix III includes species already protected by existing laws of signatory countries, but not included in the other two appendices. I
Which brings us back to the Harpy Eagle which was listed on Appendix I in 1975. For me, this species epitomizes the ultimate birding challenge: rugged conditions, bugs and snakes, potentially unstable politics, and the other hazards of travel in a country with only my marginal grasp of the language. I never for a moment thought that one day I might actually have an opportunity to see one of these magnificent creatures. That is, until the day my friend, Sam, called and said, “Jim Black is leading a tour to Venezuela to look for Harpy Eagles! Wanna go?” So, what could I say, except, “You betcha!” Sam and I are off later this week, along with 6 other birders, on a special quest to see our dream bird. Oh, and the several hundred other species that reside there! So, there won’t be a bird article in the March 1 issue of the Thunder. Hopefully, I’ll have the rest of the story for you in mid-March! Bien Venidos.
Tuesday, February 10, 2009
Gallant in Gray: Townsend's Solitaire
Townsend's Solitaire photograph by Jerry Oldenettel
Although it was winter, he jealously guarded his turf and its bounteous crop of juniper berries. In fact, his very life depended on the berries so ferociously guarded, for they made up about 95% of his winter diet. It would take between 42,000 and 84,000 juniper berries, depending on berry size, to survive the winter season. He had won the right to this particular berry patch in the fall with up to six fights per hour with others of his kind who would usurp the territory. Now, with winter territories firmly established, he could relax his guard, albeit slightly.
Both sexes of Townsend’s Solitaires establish individual territories around patches of junipers in the autumn, and fiercely defend them until late winter. Territories range from very small, containing as few as two junipers, to quite large, up to 12 acres, containing several hundred junipers. Almost all territories hold more berries than necessary to sustain their owner throughout the long winter. Boundaries are sharply defined, and protected even from members of the opposite sex. Individuals are strongly site faithful to their winter territories, returning to defend the same set of trees each year.
By March, as daylight hours increase, this slender gray thrush experiences the hormonal surges that drive males and females to pair up and establish nesting territories. Like other thrushes, the male sings a complex, hauntingly beautiful song during a display flight, similar in some ways to other members of this family, which includes American Robin, Hermit Thrush, and Mountain and Western Bluebirds. After attracting a female to the territory, he cements that season’s relationship by either regurgitating food to the female, or offering berries. During the spring and summer, spiders and insects, particularly moths and butterflies make up a large portion of their diet.
However, domestic bliss may not reign supreme in solitaire land, as both males and females have been known to indulge in extra pair copulations. By mating with more than one individual, each clutch has a higher degree of genetic variability, essentially a safety net to produce the most fit offspring. Females also have been documented laying eggs in the nests of other solitaires, thus increasing their chances of producing successful offspring with little extra energy demands.
Like other members of thrush family, immature solitaires are heavily spotted. Each feather is edged in black giving the young bird the appearance of a heavily ornamented scallop design on its body. The first time that I saw a juvenile solitaire, many years ago in Bandelier National Monument, I was at a complete loss as to how to identify it. On closer inspection though, the bold white eye ring that both youngsters and adults show, helped me to figure out the identity of the bird.
Because of its specialized winter diet, Townsend’s Solitaire is heavily dependent on juniper woodlands, a particularly under-appreciated habitat type. Throughout the West, many grassland restoration projects focus on large-scale removal of juniper in an attempt to create more forage for cattle and other browsing animals. Loss of mature trees and their berry crops affect not only the solitaire, but also other pinyon/juniper dependent birds such as Gray Vireo, Juniper Titmouse, Pinyon Jay, and both species of bluebirds. Although populations of solitaire appear to be stable currently, there is growing concern about the entire suite of birds dependent on pinyon/juniper woodland.
To learn more about Townsend’s Solitaire, including the song and “Tew” call, visit www.birds.cornell.edu Look at the menu bar across the top of the page, and click on Bird Guide. This will bring up a search page where you can enter any North American species. Generally, for each species account, there is an audio clip.
I would like to thank Jerry Oldenettel for providing the photograph for this article, and I look forward to sharing more of his wonderful photographs in the future. You can view more of his nature photos on his website.
Birds of Winter - Rosy Finch
One wouldn’t ordinarily think that birding the high mountains in the dead of winter would be a good idea. First of all there is all that snow: it makes the basics of getting around challenging as well as noisy, and stealth downright impossible. It would seem that all birds might flee with the advance of a large two-legged mammal crunching along through the snow. Such is not the case however, at least in certain parts of New Mexico.
Several years ago, a friend and I stumbled upon three new life birds while cross-country skiing along the open waters of East Fork of the Jemez River. Being neither quiet nor stealthy, we encountered a smallish flock of rosy-finches was feeding on the rock walls that line the canyon. They seemed oblivious to our presence as they flitted over the rock face searching for food. Among the flock were individuals that appeared to be markedly different. Indeed, in recent years, they have been classified as three separate species: Gray-crowned Rosy-Finch, Black Rosy-Finch, and Brown-capped Rosy Finch.
In summer, the Gray-crowned Rosy-Finch is distributed from coastal and western Alaska and British Columbia to the mountains of Idaho, western Montana, and northern California. The Black Rosy-Finch breeds high on scattered mountaintops in the Great Basin, and the Brown-capped Rosy-Finch is limited to the southern Rockies. In winter, the three species may be found together at high elevations in Colorado and New Mexico, most reliably at ski resorts such as Loveland, Colorado, and Taos, New Mexico.
Of the three species, the Black Rosy-Finch (Leucosticte atrata) is the least studied of all birds found on our continent, due to its choice of nesting locations. Only three people known to recorded scientific literature had ever found a nest of the Black Rosy-Finch before 2002. With Global Information Systems (GIS) technology and strong mountaineering skills, a University of Wyoming student became the fourth – when she discovered a nest at an elevation of nearly 12,000 feet in Utah's Uinta Mountains. The difficulty of exploring the Black Rosy-Finch breeding habitat has severely limited scientific study of the birds and made finding one of the nests a rare event.
In late spring, the alpine birds migrate to their nesting grounds above the timberline. There, among the tundra tussocks amid craggy cliffs, the rosy-finches build their nests inside cliff crevices and among the large boulders found on talus slopes. At an elevation of 10,000-13,000 feet, generally in the most remote regions of the Rocky Mountains and on the edges of the Great Basin, these hardy finches set up housekeeping and rear their young in nature’s most challenging environment.
On the nesting grounds, males defend a floating territory around their mates, rather than an area with a defined boundary. As a result, males constantly chase other males that approach their mates too closely. The best way to locate females is simply by watching the center of all the fighting.
In winter, the feisty, territorial birds assume a more gregarious lifestyle, and can be found in large mixed flocks of all three species of rosy-finches. The birds roost in large communal sites in caves, mine shafts, on rafters of barns, and in clusters of old Cliff Swallow nests.
It had long been known that one might find rosy-finches at the well-stocked feeders of the condos near the Taos Ski Area, but elsewhere they were considered to be rare, appearing only sporadically in the dead of winter. There was no reliable site where the birds might be found. This changed when birders Ken and Mary Lou Schneider responded to a Rare Bird Alert in the dead of winter and drove to the top of Sandia Peak (10,678 feet). The skies were clear and the winds calm on that day, and 40-50 rosy-finches of all three species were present foraging along the edges of the parking lot.
Thus began a fledgling plan that has, today, grown into one of the premier winter birding locations in North America. With the blessing of the US Forest Service and the staff of the Crest House, the feeders are always stocked much to the delight of birders that travel here from throughout the world to bag three different lifers in a single day. What is even more remarkable is that many of the feeders are within easy viewing of the tables in the coffee shop, eliminating the need to brave the elements. The dedicated folks that manage this site also run a banding station to track the birds’ movements, and they also maintain an extensive website www.rosyfinch.com The rosy-finches arrive in November and can stay as late as March, although the latest sighting occurred in April.
While I would love to direct you to a more local site in the Jemez Mountains to view these remarkable birds, your best bet to check off all three rosy-finches would be to drive up to the top of Sandia Peak on the next sunny, calm day, buy a cup of hot chocolate or two, park yourself next to the window near one of the feeders and wait. I might just see you there!
Several years ago, a friend and I stumbled upon three new life birds while cross-country skiing along the open waters of East Fork of the Jemez River. Being neither quiet nor stealthy, we encountered a smallish flock of rosy-finches was feeding on the rock walls that line the canyon. They seemed oblivious to our presence as they flitted over the rock face searching for food. Among the flock were individuals that appeared to be markedly different. Indeed, in recent years, they have been classified as three separate species: Gray-crowned Rosy-Finch, Black Rosy-Finch, and Brown-capped Rosy Finch.
In summer, the Gray-crowned Rosy-Finch is distributed from coastal and western Alaska and British Columbia to the mountains of Idaho, western Montana, and northern California. The Black Rosy-Finch breeds high on scattered mountaintops in the Great Basin, and the Brown-capped Rosy-Finch is limited to the southern Rockies. In winter, the three species may be found together at high elevations in Colorado and New Mexico, most reliably at ski resorts such as Loveland, Colorado, and Taos, New Mexico.
Of the three species, the Black Rosy-Finch (Leucosticte atrata) is the least studied of all birds found on our continent, due to its choice of nesting locations. Only three people known to recorded scientific literature had ever found a nest of the Black Rosy-Finch before 2002. With Global Information Systems (GIS) technology and strong mountaineering skills, a University of Wyoming student became the fourth – when she discovered a nest at an elevation of nearly 12,000 feet in Utah's Uinta Mountains. The difficulty of exploring the Black Rosy-Finch breeding habitat has severely limited scientific study of the birds and made finding one of the nests a rare event.
In late spring, the alpine birds migrate to their nesting grounds above the timberline. There, among the tundra tussocks amid craggy cliffs, the rosy-finches build their nests inside cliff crevices and among the large boulders found on talus slopes. At an elevation of 10,000-13,000 feet, generally in the most remote regions of the Rocky Mountains and on the edges of the Great Basin, these hardy finches set up housekeeping and rear their young in nature’s most challenging environment.
On the nesting grounds, males defend a floating territory around their mates, rather than an area with a defined boundary. As a result, males constantly chase other males that approach their mates too closely. The best way to locate females is simply by watching the center of all the fighting.
In winter, the feisty, territorial birds assume a more gregarious lifestyle, and can be found in large mixed flocks of all three species of rosy-finches. The birds roost in large communal sites in caves, mine shafts, on rafters of barns, and in clusters of old Cliff Swallow nests.
It had long been known that one might find rosy-finches at the well-stocked feeders of the condos near the Taos Ski Area, but elsewhere they were considered to be rare, appearing only sporadically in the dead of winter. There was no reliable site where the birds might be found. This changed when birders Ken and Mary Lou Schneider responded to a Rare Bird Alert in the dead of winter and drove to the top of Sandia Peak (10,678 feet). The skies were clear and the winds calm on that day, and 40-50 rosy-finches of all three species were present foraging along the edges of the parking lot.
Thus began a fledgling plan that has, today, grown into one of the premier winter birding locations in North America. With the blessing of the US Forest Service and the staff of the Crest House, the feeders are always stocked much to the delight of birders that travel here from throughout the world to bag three different lifers in a single day. What is even more remarkable is that many of the feeders are within easy viewing of the tables in the coffee shop, eliminating the need to brave the elements. The dedicated folks that manage this site also run a banding station to track the birds’ movements, and they also maintain an extensive website www.rosyfinch.com The rosy-finches arrive in November and can stay as late as March, although the latest sighting occurred in April.
While I would love to direct you to a more local site in the Jemez Mountains to view these remarkable birds, your best bet to check off all three rosy-finches would be to drive up to the top of Sandia Peak on the next sunny, calm day, buy a cup of hot chocolate or two, park yourself next to the window near one of the feeders and wait. I might just see you there!
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