An online resource based on the award-winning nature guide

Raptors

Red-tailed Hawks Building & Refurbishing Nests

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Red-tailed Hawks are on eggs, or soon will be.  Whether their nest is in the canopy, on a building ledge, transmission tower or elsewhere, it usually has a commanding view of the surrounding area and unobstructed access from above.

Both members of a pair share in nest site selection, which is often in mixed woods adjacent to open fields. They build their nest together, working most diligently in the morning, and construction is completed within four to seven days. If a nest is re-used, which it often is, it is refurbished with sticks and greenery. Red-tails are very wary during this nest-preparation period and may discontinue nest-building if humans are detected, so should you come upon a nest during this stage, best to remove yourself quickly.

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Rare Winter Visitors – Great Gray Owls

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Great Gray Owls are impressive birds – at 27” in length, they are our largest owl (Great Horned Owl – 22”, Snowy – 23”) but at 2.4 pounds, not our heaviest (Great Horned Owl – 3.1 pounds, Snowy – 4 pounds). The feathers that make a Great Gray Owl look so massive are what keep it warm during winters in the northern boreal forests where it resides.

Most of a Great Gray Owl’s diet consists of rodents, and some winters, when prey is scarce, individuals wander south to southern Canada and northern U.S. to sustain themselves. Sometimes Great Gray Owls are highly irruptive, and the number of sightings in the Northeast is high. In the winter of 1978-79 there were over 150 sightings in New England and Quebec. While there were numerous sightings in southern Canada this winter, northern New England was visited by only a few individuals, including the one pictured (in central New Hampshire).

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Great Horned Owls & Striped Skunks

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Striped Skunks do have predators other than Great Horned Owls (bobcats, foxes and coyotes-fishers have been known to prey on skunks, but very infrequently), but these predators have to be pretty desperate before they will prey on a skunk.  Automobiles and disease kill more skunks than all of their predators put together, but Great Horned Owls have the distinction of being the primary predator of Striped Skunks.

Being a nocturnal hunter, a Great Horned Owl necessarily consumes prey which are nocturnal. Striped Skunks are active at night and are consumed by Great Horned Owls with regularity, even though a skunk can weigh up to three times as much as a Great Horned Owl (average GHO weighs a little over 3 pounds) and has a potent way of defending itself.

For many years scientists assumed that birds had a poor sense of smell because the area of a bird’s brain involved in smell is relatively small compared with the area found in mammals.  However, recent research reveals that birds have a high number of active genes that are associated with smell, and many species may have an excellent sense of smell.  It’s fairly safe to assume, however, from its consumption of skunks, that the Great Horned Owl’s sense of smell is not very well developed. In addition, if a skunk sprays, much of the odor is absorbed by the Great Horned Owl’s leg feathers, which extend down to its talons.

A favorite memory of mine is walking through a field at dusk and suddenly noticing a strong skunk-like smell coming from above, not below, me. A Great Horned Owl silently flew overhead, with only the tell-tale smell of a recently-captured skunk announcing its presence.

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Snow Conditions Making Life Challenging For Barred Owls

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There has been an unusually high number of Barred Owl sightings reported in northern New England and New York this winter, primarily from the road and near bird feeders. This phenomenon, particularly with owls, is usually attributed to either a current lack of food or an abundance of food during the most recent breeding season resulting in a dramatic increase in the owl population.

In the case of Barred Owls, it is the former. Unlike Snowy Owls, which vary the size of their clutch depending on food availability, Barred Owls typically have two young, regardless of the size of the rodent population. Thus, a plethora of progeny can be eliminated as a viable explanation for the abundance of Barred Owl sightings this winter, which leaves a scarcity of food as the primary reason.

For several weeks there has been a thick crust on top of the snow, which makes hunting for mice and voles difficult for raptors. Because they are very territorial, Barred Owls rarely wander outside of their territory, even when food is scarce. Thus, especially in the past few weeks, they have been desperate to find small rodents. Roads are one reliable spot where mice, voles and shrews are exposed, and bird feeders are most definitely rodent magnets. Hopefully weather conditions will allow birds of prey access to the subnivean layer (space next to the ground where small rodents travel, shelter and breed) before too many more Barred Owls starve to death. (Source: Joan Collins, NYS Ornithological Association, UV-BIRDERS List) (Photo:  Barred Owl with recent Northern Red-backed Vole catch.)

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Small Birds Beware of Sharp-shinned Hawks

coopers-and-blue-jay-by-jeannieShort, powerful, rounded wings and a relatively long tail enable Sharp-shinned Hawks to maneuver in dense cover in pursuit of small birds, which compose 90% of their diet. Small mammals and insects are consumed, but not nearly as frequently as birds. The size of the birds eaten range from hummingbirds to Ruffed Grouse. Long legs and toes (especially middle toes) enable individuals to reach into vegetation and large eyes enhance its ability to catch fast-moving prey.

Sharp-shinned Hawks are familiar sights to those of us with bird feeders – this species is responsible for 35% of 1,138 predation incidents reported at feeders in continent-wide survey. In this photograph, a Blue Jay is successfully warding off an attack by a juvenile Sharp-shinned Hawk. (Photo by Jeannie Killam.)

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Bald Eagle Eyesight

7-26-16  juv. bald eagle2 026The eyesight of a Bald Eagle is impressive.  Part of the reason for their excellent vision is that these birds of prey have two centers of focus (foveae), which allow them to see both forward and to the side at the same time. Cone cells, one of three types of photoreceptor cells in the retina, perceive color, fine detail and rapid movement.  In a human, the fovea has 200,000 cones per millimeter; in the central fovea of a Bald Eagle’s eye, there are about a million cones per millimeter. An eagle’s eye is almost as large as a human’s, but its sharpness is at least four times that of a person with perfect vision.

Bald eagles are capable of seeing fish in the water from several hundred feet above, while soaring, gliding or in flapping flight.  (They locate and catch dead fish much more rapidly and efficiently than live fish, because dead fish float with their light underside up, making them easier to see.)  It is very likely that a Bald Eagle can identify a rabbit moving almost a mile away. This would mean that an eagle flying at an altitude of 1000 feet over open country could spot prey over an area of almost 3 square miles from a fixed position. (photo: recently fledged, juvenile Bald Eagle)

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Great Horned Owl Fledglings Still Being Fed By Parents

great horned owls-first year IMG_1616Great Horned Owls are one of the earliest nesting birds — you can find them on nests in January, February and March, even in northern New England. Eggs are incubated for about a month, typically in March or April with young usually hatching in May or June. The nestlings remain in the nest for six or seven weeks before fledging. Unable to fly until they are ten or twelve weeks old, the fledglings follow their parents around and continue to be fed and cared for by their parents until fall. In late summer, when they have fledged but are still begging their parents for food, you can hear their distinctive calls. To know what to listen for, go to http://langelliott.com/mary-holland/great-horned_owl.mp3 (Sound recording © Lang Elliott – langelliott.com & miracleofnature.org.)

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