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Raptors

Snowy Owls Headed North

4-21-14 flying snowy 046The record number of Snowy Owls that spent the winter in New England are turning up in all sorts of new locations now that they are on their way back to their breeding grounds on the open tundra and stopping to refuel along the way. Although many were young birds, and won’t breed this year, the adult owls will when they reach the Arctic in a few weeks. First, the males perform aerial and ground displays. After mating, the female selects a nest site. In addition to having a sufficient food supply, the site must be snow-free, not subject to flooding, and command a view of its surroundings. The latter is achieved by making their nest on a hummock, or slightly raised surface of bare ground. The female scrapes a shallow depression in the earth with her claws, twirling around to make a form-fitted hollow. No insulating material is added to this depression – no vegetation, no feather lining. Eggs and nestlings are totally dependent upon the mother’s warmth, transmitted via the large, featherless, pink patch of skin on her belly known as an “incubation patch.” The female alone incubates the eggs and broods the young chicks while the male provides food for his entire family.

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Barred Owls Frequenting Feeders

4-4-14  barred owl with suet IMG_5432The number of Barred Owls seen near bird feeders recently makes one question whether these birds are, in fact, in dire need of food. Certainly the extended period of deep snow this winter has made finding prey challenging. Fortunately, the local bird rehab center (Vermont Institute of Natural Science) has not been inundated with starving owls, which indicates that other factors may be involved in the increased number of sightings near homes and feeders. One of these factors could be that Barred Owls are currently laying and incubating eggs, and a few early nesters may even be providing food for young owlets. Whatever the reason, the accessibility of rodents that are attracted to feeders and the food itself that’s in the feeders allows us an all-too-rare glimpse of this common owl. (The mystery of repeatedly finding my suet feeder on the ground every morning was finally solved when I took this photograph – look closely at what the Barred Owl is clutching in its talons.)

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Snowy Owl Pellet

3-25-14 snowy owl  203Your knowledgeable ID skills regarding yesterday’s Mystery Photo were most impressive!

Snowy Owls are the heaviest owls in North America, weighing roughly 4 pounds (a Great Gray Owl is only 2.4 pounds). A lot of fuel is needed to power this magnificent raptor. In the Arctic, where they live, lemmings are their preferred prey — one owl may eat more than 1,600 of these small rodents in a single year. This winter the Northeast has experienced record numbers of visiting Snowy Owls. A banner year for the Arctic lemming population followed by prolific nesting success for Snowy Owls resulted in an unprecedented “irruption” of these owls further south this winter.

While we do have lemmings in New England, they are uncommon, so Snowy Owls have relied on our small rodent, squirrel, rabbit and hare populations for food. Those owls wintering on the coast, where dunes and moors closely resemble their tundra habitat, have also taken advantage of the large number of sea ducks. As witnessed and described by Nantucket ornithologist Edie Ray, the owls fly up to great heights over the sea, spot waterfowl and then plummet down to just above the surface of the ocean where they sink their talons into a “sitting duck.” As a result, the indigestible bones, teeth and nails of prey are protectively wrapped in feathers as well as fur in the large pellets coughed up by these owls. (Snowy Owl locators: Edie Ray and Sadie Richards; Snowy Owl pellet finder: Sadie Richards)

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Bald Eagles Refurbishing Nests

3-13-14 bald eagle on nest IMG_8514Bald Eagles in New England are repairing and adding to their nests, even as snow and cold temperatures continue. They often reuse their nest year after year – a nest in Ohio was used 34 years before the tree blew down. Although most don’t reach the record-breaking dimensions an eagle nest in Florida did (9 1/2’ wide, 20’ deep, weighing almost 3 tons), they are impressive structures, averaging five feet and three feet deep. Typically eagles will choose one of the biggest trees in an area in which to build their nest. Because their nests will be used for many years to come, eagles often choose living trees (which will remain standing longer) in which to build them. The nest is usually located in the top quarter of a tree, just below the crown. Both male and female eagles collect sticks for the nest, either finding them on the ground or breaking them off nearby trees. In parts of Alaska and northern Canada where trees are scarce and short, eagles often nest on the ground.

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Snowy Owl Invasion

2-4-14 lemmings-at-nest4In a typical winter, sightings of snowy owls are a regular occurrence in the Northeast, but this winter, as most New Englanders are aware of, we’re experiencing a banner irruption year, with individuals appearing in greater numbers from the north than they have in decades. In the past, hunger and lack of prey in the Arctic have been the accepted explanation for this influx of northern predators, but this year that theory has been put to a test, as 2013-14 visitors are arriving in excellent condition. Last summer the lemming population (snowy owls’ food of choice, with one owl eating up to 1,600 lemmings in a year), as well as other prey species, exploded in northern Quebec. It’s thought that snowy owls amass to nest in areas where prey is abundant, and it appears that this is exactly what happened in Quebec. The rodent explosion resulted in exceptionally large broods (up to 12 chicks per pair of owls). In part due to competition with older owls, this large first-year population of owls moved south this winter, and we are the beneficiaries. To see the movement of this year’s irruption, go to http://www.projectsnowstorm.org, where this photograph of a 70 lemmings/8 voles-lined snowy owl nest by Christine Blais-Soucy originally appeared.

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Great Horned Owls Thaw Cached Prey

1-13-14 great horned owl l MH_20091001_225056_4Great Horned Owls are one of the earliest species of birds to nest in the Northeast –some are already sitting on eggs. Female Great Horned Owls do the lion’s share of incubating the eggs, while the male hunts for and brings her food. While they do eat small rodents, which they swallow whole, the diet of Great Horned Owls also consists of rabbits, hares, opossums, squirrels and skunks, which must be torn into small pieces before being swallowed. Great Horned Owls often kill more than they can eat at one time, and cache the extra food for later consumption, when food is scarce. Needless to say, during winter months the cached prey freezes, and if the prey is large, its consumption is challenging for a bird with a bill that’s designed for shredding and tearing. To solve this dilemma, Great Horned Owls sit on their frozen prey until it thaws, and then proceed to tear it into bite-size pieces.

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Bald Eagles Year Round in Vermont

1-2-14 bald eagle2  033Biologists estimate that there were up to 500,000 Bald Eagles (Haliaeetus leucocephalus) in North America when the first European settlers began arriving. Seventy-five years ago you wouldn’t have seen a single Bald Eagle in the state of Vermont. Thanks to the banning of DDT in North America, an effective reintroduction program in Vermont between 2004 and 2006, and the protection of Bald Eagle breeding and wintering habitat through the Endangered Species Act, Vermont now has a healthy breeding population of eagles. This summer 16 Bald Eagles nested in Vermont and 26 young eagles fledged. Winter records of Bald Eagles reflect this increase as well – 24 eagles (13 of which were immature birds) were found in the 2013 annual Midwinter Bald Eagle Survey in Vermont, with the largest numbers occuring near open water, such as Lake Champlain and the Connecticut River, where the eagles have access to fish. (You can also find them at frozen lakes where there generous ice fishermen.) Eagles are still listed as endangered in Vermont, but they are off the national Endangered Species list, and biologists say they should soon be off the state endangered list as well.

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Northern Hawk Owl

n. hawk owl3- 231The Northern Hawk Owl is a bird of the remote Alaskan and Canadian boreal forests. Its name reflects the fact that this diurnal owl has both the appearance and behavior of a hawk, specifically, an accipiter. Although the Northern Hawk Owl winters throughout its breeding range, it periodically erupts southward into southern Canada and the northern United States. Sightings of this bird are rare in Vermont, but in recent winters, including the current one, there have been some. As with Snowy Owls, the magnitude and extent of these winter irruptions are thought to correlate with high reproductive success followed by severe winter conditions and decreased prey availability, but much remains to be understood about their winter dispersal habits. What we do know is that the Northern Hawk Owl’s skills as a hunter are very impressive. It can detect prey (small rodents, grouse, hares) by sight at a distance of half a mile and just using its ears can find prey under a foot of snow.

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Interpreting a Kill Site

12-18-13 hawk kill IMG_4136When there’s snow on the ground and you come upon a site where a predator successfully caught prey, there are usually signs that will help you determine who the main players were. In the above scene, remnants of red squirrel fur confirm the identity of the prey. If you look at the top of the image, you can make out a faint wing impression. Although not in this case, both wings of an avian predator often touch the surface of the snow, allowing you to measure the wingspread, and this information can help to eliminate some species of raptors. Birds of prey often defecate at a kill site. In the lower left corner of the photograph, as well as to the left and right of the packed area where the squirrel was eaten, you can see white (uric acid) bird droppings. Given that it is a hawk or an owl, knowledge about their respective evacuation habits will allow you to narrow down the possibilities even further. Owls tend to let their droppings do just that – drop, leaving small plops on the ground. Hawks, on the other hand, tend to forcefully eject their droppings some distance away. The long, thin streaks at this site were definitely propelled outwards, making it likely that the predator was a hawk. Familiarity with the hawks that overwinter in your area can help pinpoint which species it could be.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Common Raven Defends Nesting Territory

4-5-13 raven chasing red-tail2 IMG_8693Common ravens are known for their aerial acrobatics, often doing rolls and somersaults and other amazing tricks.  According to Cornell Lab of Ornithology, one bird was seen flying upside down for more than a half-mile. Young birds are fond of playing games with sticks, repeatedly dropping them and then diving to catch them in mid-air.  The pictured raven, however, was much too busy to be doing cartwheels in the sky.  It has a nest with eggs nearby, and during its morning patrol encountered a red-tailed hawk which it drove out of sight in a matter of seconds.  Although small mammals make up most of a red-tail’s diet, they are known to also prey on smaller birds, including defenseless nestlings, which the ravens will have in the next few weeks. (Because of the angle, the  24-inch-long, 53-inch-wingspread raven looks disproportionally larger than the 19-inch-long, 49-inch wingspread red-tail.)


Red-shouldered Hawks Building and Refurbishing Nests

4-5-13 red-shouldered hawk nest IMG_8573With winter temperatures still upon us, it can be challenging to find signs of spring in the hills of Vermont.  However, subtle signs do exist if you know where to look!  Notice the fresh greenery in this nest – it confirms that recent refurbishing has taken place by returning red-shouldered hawks.  Roughly two feet in diameter, a red-shouldered hawk’s stick nest is lined with moss, lichen, bark and conifer sprigs.  Other  items that have been used as building material for these raptors include ears of corn, corncobs, corn husks, tissue paper, nests of songbirds, straw, mullein, leaves, twine, various deciduous tree leaves, entire plants, dried tent caterpillar webs and plastic grocery bags. The pictured nest will serve as a nursery for two to five red-shouldered hawk chicks in about a month’s time, and as the nesting season progresses, sprays of conifers such as the hemlock sprigs you see here will continue to be added.


Mourning Dove Remains

3-13-13 mourning dove remains IMG_5958A cooper’s hawk made short work of a mourning dove near my bird feeder recently, killing and apparently, given the large number of feathers scattered on the snow, plucking the dove on a nearby snow bank. If you look closely you can see whole sunflower seeds in amongst the feathers. These came from inside the mourning dove’s crop. Mourning doves generally feed quickly, filling their crop with seeds which they digest later, when they’ve found a safe spot in which to roost. Unfortunately for this particular dove, it didn’t live long enough to have that opportunity.


Juvenile Bald Eagles

2-13-13 juvenile bald eagles IMG_3152Raucous crow and raven calls alerted me to the fact that something, most likely a bird of prey, was in the area (crows and ravens often mob and harass hawks and owls). Through the trees I got a glimpse of a raven flying beside another bird that dwarfed the raven. Soon there were two of these large birds, dipping and diving in the wind, seemingly enjoying themselves no end. They turned out to be juvenile bald eagles, last year’s young. Perhaps they were practicing for the acrobatic courtship flight displays they’ll be performing in three or four years.


Sharp-shinned Hawk

1-25-13 sharp-shinned hawk2 IMG_1977If the majority of your diet consisted of one type of food, and that food was concentrated in certain spots, it would make sense to frequent those spots. Bird-eating predators, such as the sharp-shinned hawk, are frequently seen at bird feeders for this very reason. Although not very large — roughly the size of a blue jay (the female is a third again larger than the male) — this accipiter is a formidable predator, and one which causes feeder visitors to either disappear or become motionless for a considerable amount of time. The sharp-shinned hawk is the smallest hawk in North America and derives its common name from the sharp-edged “shin” on the lower part of its legs. Its long tail and short wings make it extremely adept at flying through dense woods in search of small birds.


Bird of Prey Kill Site

1-24-13 bird of prey kill by SRichards IMG_6546Dramatic stories are not limited to the snowy woods of northern New England! This photograph was taken in Jamaica Plain, a neighborhood of Boston, Massachusetts. It tells the story of a small bird being killed by a relatively small bird of prey, most likely a Cooper’s Hawk or a Sharp-shinned Hawk – both are accipiters and predators of small birds (as well as other prey). Because their wingspans overlap, there’s no way to unequivocally state which of these raptors left this imprint, but whichever it was, it was successful, judging by the feathers and blood that remain. Both of these hawks are listed as Massachusetts Species of Special Concern, with the Sharp-shinned hawk sighted most often in the western part of the state. (Photograph by Sadie Richards)


A Great Christmas Present!

If you’re looking for a present for someone that will be used year round, year after year, Naturally Curious may just fit the bill.  A relative, a friend, your child’s school teacher – it’s the gift that keeps on giving to both young and old!

One reader wrote, “This is a unique book as far as I know. I have several naturalists’ books covering Vermont and the Northeast, and have seen nothing of this breadth, covered to this depth. So much interesting information about birds, amphibians, mammals, insects, plants. This would be useful to those in the mid-Atlantic, New York, and even wider geographic regions. The author gives a month-by-month look at what’s going on in the natural world, and so much of the information would simply be moved forward or back a month in other regions, but would still be relevant because of the wide overlap of species. Very readable. Couldn’t put it down. I consider myself pretty knowledgeable about the natural world, but there was much that was new to me in this book. I would have loved to have this to use as a text when I was teaching. Suitable for a wide range of ages.”

In a recent email to me a parent wrote, “Naturally Curious is our five year old’s unqualified f-a-v-o-r-I-t-e  book. He spends hours regularly returning to it to study it’s vivid pictures and have us read to him about all the different creatures. It is a ‘must have’ for any family with children living in New England…or for anyone that simply shares a love of the outdoors.”

I am a firm believer in fostering a love of nature in young children – the younger the better — but I admit that when I wrote Naturally Curious, I was writing it with adults in mind. It delights me no end to know that children don’t even need a grown-up middleman to enjoy it!


Barred Owl Pellet

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Having posted a barred owl regurgitating a pellet, it only seemed fitting to post the pellet itself.  Many birds, not just birds of prey, form pellets that consist of the indigestible parts of prey they’ve eaten – fur, feathers, claws, teeth, fish scales, exoskeletons of insects and crustaceans and parts of plants.  In general, the larger the bird, the larger the pellet – the pellets of most birds of prey are an inch or two, and they’re roughly half an inch for a small songbird.  With birds of prey, likely spots to find pellets are beneath roosting and nesting sites.  In addition to getting rid of indigestible matter, the casting of pellets is thought to improve the health of a bird by scouring its throat, or gullet.  It takes anywhere from 6 to 16 hours after a hawk or owl has eaten for it to cast a pellet, and it may be necessary for the bird to do so before it eats its next meal.  Dissecting pellets is an effective way of determining a bird’s diet.  The pellet of a golden eagle in Oregon contained a leg band that had been placed on an American wigeon (a species of duck) about four months previously, a thousand miles away! (Pictured are a 1 1/2-inch barred owl pellet and the contents, minus the fur, of several pellets.)


Juvenile Broad-winged Hawk

Broad-winged Hawk chicks spend their first five or six weeks in the nest being fed small mammals, toads, nestling birds and a variety of invertebrates by their mother. They then fledge, but for the next two weeks these young birds continue to use the nest as a feeding (food is still being provided for them) and roosting site. At about seven weeks of age they begin capturing their own prey, and remain on their parents’ territory for the next month or two — just enough time to learn the ropes before migrating south for the winter, which they are doing right now (peak migration is mid-September).


Great Horned Owl Fledglings

Hardy birds that they are, Great 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’re ten or twelve weeks old, the fledglings follow their parents around and continue to be fed and cared for by them until the fall. These two fledglings were sticking close together as they made their raspy begging calls from high in a white pine. Both their calls and the down that was visible on their heads told me that they were this year’s young.


Striped Skunk

Although you would think that no predator would think of preying on, much less eating, a striped skunk, there are a few mammals, including coyotes, foxes and bobcats, that do just that, but only if they are in danger of starving.  One predator that routinely dines on skunks is the great horned owl.  One summer night I made out the silhouette of an owl flying in my direction, and as it flew by me its identity was confirmed by the skunk-like odor that accompanied it. 

 


American Kestrel

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The American Kestrel, formerly known as the Sparrow Hawk, is about the size of a Mourning Dove, making it the smallest falcon in North America.  It typically perches on tall trees, or telephone lines and poles, surveying surrounding fields in hopes of finding insects or small mammals to eat.  This female American Kestrel (her wings are rusty colored, males’ are slate-blue) flew down to the ground, captured an insect and returned to its telephone pole perch where it consumed its meal.  If you look closely at the perched kestrel, you’ll see a notch in its upper bill.  Many falcons have this notch which is thought to be an adaptation for severing the spinal column of vertebrate prey. 


Red-tailed Hawks on Eggs

The red-tailed hawk nest that produced two chicks last summer is once again occupied by a pair of red-tails.  A conifer sprig adorning the outside of the nest was the first clue that a second brood might be in the works.  Yesterday I saw both male and female return to the nest carrying strips of bark, which the female applied to the lining of the nest.  Mid-March is when red-tails typically are building or refurbishing their nest and laying eggs.  They begin incubating as soon as the first (of 2 – 3) egg is laid, with the male and female both participating.  This photograph was taken at the changing of the guard.


Turkey Vultures Return

Right on time, the second week of March, Turkey Vultures are back in central VT/NH. Recognizing them is not too hard – they’re bigger than any other raptor in New England except for eagles.  At a distance Turkey Vultures look all black, but a closer look reveals that the undersides of the flight feathers, along the trailing edge and wing tips, are lighter in color than the rest of the bird, giving the wing a two-toned appearance. (Black Vulture wings are solid black with silvery tips.)  The feathers at the wing tips are often separated, which some birders refer to as ‘fingers.’   In addition, vultures hold their wings slightly raised, forming a ‘V’ or dihedral shape in the sky when viewed head-on.   Turkey Vultures soar in circles as they ride the thermals, using their sense of smell to locate tasty carcasses on the ground.  

 


Red-tailed Hawk

Given the right lighting, it’s very easy to see how red-tailed hawks (Buteo jamaicensis) got their common name (although the tail of juvenile red-tailed hawks is brown for their first two years).  Central Vermont and New Hampshire is at the northern end of the red-tailed hawk’s year-round range – if they live much further north, they usually migrate south for the winter.  This common bird of prey typically inhabits open areas interspersed with trees.   It is usually observed soaring in wide circles over a field, or perched high in a tree, where it sits and waits, keeping an eye out for prey such as mice, voles, rabbits and hares.  Once it spots a small mammal, as the red-tail in this photograph just had, it quickly takes off and uses its talons to capture its next meal.

 


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