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Birds

Ruffed Grouse Flying Into Windows

1-25-16 dead ruffed grouse by Eve BernhardThose of us who feed birds are well aware of the hazards that windows and glass doors present to birds. The latest research shows that roughly 988 million birds are killed each year in the United States from hitting windows. Migratory birds and songbirds are the most common victims, but Ruffed Grouse, especially in the fall and winter, are very apt to collide with glass windows. (This phenomenon is not the same as the aggressive behavior towards glass that a bird’s reflection can promote, especially by males during the breeding season.)

Many of the grouse victims are first-year birds. Often, inexperienced young grouse, frightened by a predator, crash into buildings, trees or windows in a so-called “crazy-flight.” Hard, transparent glass is not something grouse recognize as a barrier, due to the reflections it creates. There are a number of things one can do to reduce the chances of this happening. Netting, decals, window film and tape hanging from the top of the window can help. One of many creative new products available are window panes that have external patterns that birds can see from the outside, but that are invisible from the inside. On a national level, legislation and bird-friendly buildings are gaining traction. For more window crash-prevention ideas, go to http://www.birdwatchingdaily.com/featured-stories/15-products-that-prevent-windows-strikes/. (Photo by Eve Bernhard)

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Great Horned Owls Courting

Great Horned Owls are staking out territories and beginning courtship rituals in northern New England. Their “songs” are typically given with their beak closed, as they lean forward and cock their tail up (see photo). When calling, their white throat feathers are pronounced as their throat swells.

The hooting of a Great Horned Owl can be compared to the sound of a distant foghorn – it is soft, and somewhat subdued, with no strong accent on any one hoot. Pairs often synchronize their deep sonorous territorial songs, a custom which is referred to as “duetting.” The higher-pitched female calls a six or seven-note song and the male responds with a deeper five-note song during or within a few seconds after the female’s song.  The chances of hearing a Great Horned Owl are somewhat greater after midnight than before. To hear Great Horned Owl territorial calls and duetting go to https://www.allaboutbirds.org/guide/Great_Horned_Owl/sounds. (Thanks to Vermont Institute of Natural Science for photo op.)

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1-19-16  great horned owl calling 289


American Crow Bills Used As Tools

1-13-16  American crow tracks 147American crows obtain most of their food on the ground as they walk along in search of seeds, insects, frogs, snakes, bird nests and small mammals. Their hunting techniques are varied and most involve the use of their bill. In search of invertebrates, crows will probe the soil with their bill, flick aside leaves, dig in the soil and even lift cow paddies. They fish for tadpoles and dig nearly an inch deep with their bill for clams. In winter, their foraging continues and as these tracks indicate, when the snow is only a few inches deep they will walk around and around in a given area, probing tufts of grass for hibernating insects, mice, voles, or any other form of life these opportunists find.

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The Short Life Span of Ruffed Grouse

1-8-16  fisher and grouse 177Ruffed grouse typically have a short life span; few live to be three years old. By mid-August about 60 percent of the grouse hatched that year are lost to predators, weather extremes, disease, accidents (such as flying into windows) and hunters. Less than half of the surviving young survive through the winter to have a chance to breed in the spring, and less than half of those that survive long enough to breed make it to a second mating season. The hazards for a ruffed grouse are many, with predation at the top of the list.

Birds of prey, especially the goshawk and great horned owl, take many grouse, but terrestrial hunters such as foxes, coyotes, bobcats and fishers also take advantage of this plentiful food source. Along with hares, porcupines, squirrels, mice and voles, grouse are one of the fisher’s preferred foods. A fisher managed to capture a ruffed grouse in the pictured scene, leaving only tracks and a few tell-tale feathers to tell the story.

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Uropygial Gland

1-8-16  anhinga 1411Yesterday’s unusual-looking structure was, as the feather quills next to it may have indicated to you, located on the body of a bird, specifically, a Barred Owl. Usually hidden by feathers, this oil gland, known as a uropygial or preen gland, is found just above the base of a bird’s tail and contains fatty acids, fat and wax. The shape of the gland varies greatly among species. Its nipple-like projection (papilla) can have between one and five openings and in many species is covered by a tuft of specialized feathers.

The uropygial gland plays an important part in feather conditioning. Birds preen, or groom, their feathers with their bill in order to keep their feathers in good condition. The act of preening removes dust, dirt and parasites from feathers and aligns each feather in the optimum position relative to adjacent feathers and body shape. Preening is also the means by which oil from the uropygial gland is applied to a bird’s feathers, feet and legs. The act of preening induces the flow of the secretion from the nipple of the uropygial gland. By manipulating the gland with its bill and rubbing it with its head, a bird accumulates oil and then transfers this oil from its bill and head to the rest of its body.

Ornithologists theorize that the uropygial gland serves different purposes in different species of birds. While the secretions contain beneficial bacteria, and keep a bird’s bill, legs and feet in good condition, waterproofing is the primary function of this gland (which is especially well developed in water birds). Both the water-repellent secretions as well as the act of applying them to feathers through preening serve to protect a bird’s body from water and the resulting heat and flight loss. Some birds lack uropygial glands but have specialized feathers that disintegrate into powder down, which serves the same purpose as preen oil. (Photo: Anhinga preening with uropygial gland secretions; thanks to Joan Waltermire for yesterday’s Barred Owl uropygial gland photo op)

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Opportunisitic Bird Nest Builders

12-3 northern mockingbird nest IMG_6363Several winters ago I discovered a Northern Mockingbird nest in downtown White River Junction, Vermont. Like all birds, mockingbirds are opportunists and utilize whatever material is available when building their nests. Even though it is not a booming metropolis (population roughly 2,500), White River’s relatively dense population is reflected in the building material that these songbirds used. Because they often nest in urban and suburban areas where trash tends to be more concentrated, mockingbirds often line their nests with bits of plastic, aluminum foil, and shredded cigarette filters (see photo). The male constructs the twig foundation while the female makes most of the lining. He often begins building several nests before the female chooses one to finish and lay eggs in.

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Female Purple Finch or House Finch?

12-2-15 female purple finch IMG_0523While the eastern population of Purple Finches has declined significantly since the invasion of House Finches (a few California individuals released from a pet store in New York City in 1939 as well as natural expansion of its western range resulted in a population explosion of House Finches in the east), both species can appear at feeders. Without fail, every winter I have to relearn the field marks that distinguish these two birds. Both males and females of these respective species are quite similar, but it is the drab and sparrow-like females that send me flying to a field guide.

Three features stand out as most helpful in distinguishing female Purple Finches from House Finches. The female Purple Finch has short, dark streaks on her breast, whereas the House Finch’s breast streaks are quite blurry. The female (and male) Purple Finch has a distinctly notched tail; the House Finch’s tail is just slightly notched. Finally, and most obvious, are their respective head patterns. Female Purple Finches have a conspicuous light eyebrow stripe that contrasts with a solid, dark brown ear patch, both of which the House Finch lacks.

Being seed eaters, Purple Finches are attracted to sunflower seed feeders, and if you feed birds, this provides ample opportunity to observe these field marks. While doing so, you may notice that Purple Finches can be fairly aggressive with each other when vying for this source of food. Surprisingly, more often than not, the female prevails. (photo: female Purple Finch)

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