An online resource based on the award-winning nature guide – maryholland505@gmail.com

Birds

Wild Turkeys Feeding and Making Burdock Balls

Almost every response to this Mystery Photo was spot-on, but “myip2014” was the first NC reader to recognize the signs left by a Wild Turkey feeding on Common Burdock (Arctium minus) seeds. A variety of plant material is eaten by Wild Turkeys in the winter: white pine and hemlock needles and buds, evergreen ferns, lichens, moss, and buds and stems of Sugar Maple, American Beech and American Hophornbeam trees. Especially when there is deep snow, Common Burdock is a favorite due to having seeds that are within reach and usually above the snow.

Turkeys consume these seeds in such a distinctive manner that one can recognize what animal has been feeding on burdock, even if tracks and scat are not present. The burdock burrs, or fruits, are plucked off the plant by the turkey, opened and the seeds are eaten. The burrs end up nearly inside out as a result of the turkey prying them open to get the seeds, and often are stuck together and form “burdock balls.“  The presence of these balls is a sure sign that turkeys have dined on the seeds they once contained.

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.


American Tree Sparrows : Winter Visitors

One of New England’s common winter visitors from the far northern tundra is the American Tree Sparrow (Spizelloides arborea), often spotted in large flocks in weedy, snow-covered fields moving from one spot to another as they feed..  These seed-eating sparrows are known to beat weeds with their wings and then fly to the surface of the snow beneath the weeds to retrieve seeds they have caused to fall.  

Their common name is a misnomer, for American Tree Sparrows feed on the ground and often breed and nest on the ground above the treeline.  They apparently reminded European settlers of the Eurasian Tree Sparrow (Passer montanus), a cavity-nesting bird which has very different habits than the American Tree Sparrow. 

In part because of the loss of weedy old fields and other open habitats, the American Tree Sparrow population has declined by 53% over the last 50 years.  Even so, they are a common sight during the winter in fields, on road sides and at feeders throughout the northern half of the United States.

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.


White-winged Crossbills Foraging

Most of New England is privileged to see White-winged Crossbills (Loxia leucoptera) only during the winter, when these nomadic birds forage south of their far northern boreal forest breeding grounds for conifer seeds during poor cone crop years. 

Spruce seeds are the preferred food of White-winged Crossbills. Their crossed mandibles allow them to pry open cone scales and they then extract the seeds with their tongue.  Individuals can eat up to 3,000 conifer seeds a day!

These birds have been documented nesting every month of the year.  As long as they can find a source of food that is sufficient for egg formation and that is likely to remain for the next month or so when they’ll be feeding nestlings, they will breed.  The larger the spruce cone crop, the longer a span of time crossbills typically nest.  Nesting usually declines by November although young do occasionally fledge in December and January. (Photos of a male White-winged Crossbill by Erin Donahue.)

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.


Birds Gathering Grit On Dirt Roads & Roadsides

Birds compensate for their lack of teeth with a two-parted stomach, the first of which (proventriculus) secretes digestive enzymes and the second of which (a muscular gizzard) grinds the food they’ve eaten into small digestible bits.  Birds that eat hard seeds and nuts tend to have thick, muscular gizzards, while those species that eat very easily-digested foods such as soft-bodied insects, soft fruits, or nectar often have very small and thin-walled gizzards.  Many birds whose diet consists of hard substances, including seed-eaters, swallow grit (often why you see them on dirt roads or the sides of plowed roads where dirt has been exposed) to enhance the gizzard’s ability to pulverize food.

At this time of year, American Goldfinches, Common Redpolls, Snow Buntings, Tree Sparrows and Eastern Bluebirds (among others) can be found swallowing roadside grit to help grind up the seeds that they consume.  (Photo:  While a majority of their summer diet is insects, Eastern Bluebirds consume many fruits (containing hard seeds) during the winter, a change in diet that allows them to remain in northern New England throughout the year.)

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.


Snow Buntings Feeding

Congratulations to Kathie Fiveash, the first NC reader to correctly identify the tracks and feeding sign in the latest Mystery Photo as those of Snow Buntings (Plectrophenax nivalis).  These birds began arriving in the northern half of the United States from their summer home on the northern tundra last fall and will remain here until March, when they begin migrating back to their breeding grounds.

In the winter, 97% of a Snow Bunting’s diet is weed seeds, including those of knotweed, ragweed, amaranth, aster, goldenrod, grasses and grains. These birds forage on the ground, collecting seeds from the protruding stems of tall weeds, occasionally reaching or leaping up to take seeds from taller stems, jumping against stems to scatter seeds or bending stems over by stepping on them. (Birds of the World, Cornell Laboratory of Ornithology)

While foraging, Snow Bunting flocks are constantly restless, frequently flushing rapidly and low over the ground for short distances.  A flurry of birds, much like snowflakes, fills the air nearest the ground for a few seconds while they relocate to a new area. Birds at the back of the flock fly forward to the front, creating the impression that the flock is rolling along.

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.


Fish are a primary, but not exclusive, food source for Bald Eagles

Hands down, Bald Eagles (like the 2nd year immature bird pictured) prefer fish over other prey — roughly 56% of the diet of nesting Bald Eagles consists of fish such as salmon, herring, shad, and catfish.  However, eagles are opportunistic foragers and over 400 species of prey have been recorded, half of which are waterbirds. Reptiles, amphibians, invertebrates such as crabs and crayfish, and small mammals such as squirrels, rabbits, muskrats, young beavers, fawns and raccoons are also subject to Bald Eagle predation.

During their first year, until they learn to be proficient hunters, Bald Eagles frequently feed on carrion. Even as adults, eagles regularly consume roadkills and deer that have died as a result of being stranded on ice. Whatever food is available and requires the least amount of energy to capture is usually high on their list.

Although not considered a primary source of food, domestic pets are subject to occasional predation by eagles. A discovery made by Fish & Wildlife personnel engaged in banding Bald Eagle nestlings may be of interest to cat owners who allow their pets to roam free in the great outdoors.  Upon reaching one nest, they found, among the detritus, over 20 cat collars.

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.


The Feathered Legs & Feet of Snowy Owls

Snowy Owls, inhabitants of the Arctic, are not only well camouflaged but well insulated with their feathers. Their exceptional density make Snowy Owls North America’s heaviest owl.  Weighing in at about four and a half pounds, they are about a pound heavier than Great Horned Owls and almost twice the weight of Great Gray Owls (North America’s tallest owl).

Most species of owls have densely-feathered legs (exceptions being owls living in southern regions such as Barn Owls, Burrowing Owls, and some tropical species).  Snowy Owls have exceptionally thick feathering on their legs and feet. The toe feathers of a Snowy Owl are the longest known of any owl, averaging 1.3 inches – in comparison, the Great Horned Owl’s (which has the second longest toe feathers) are a mere .5 inch. In addition to their insulative quality,  the feet and leg feathers may also serve to sense contact with prey and to protect against prey that might bite when seized.

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.


Owls & Eyelids

All birds have three eyelids – like humans, they have an upper and lower eyelid.  Owls are among the only birds that have a larger upper eyelid than lower eyelid. They are the only birds that blink like humans, by dropping their upper eyelids. But when owls sleep, they close their eyes the way other birds do—by raising the lower lids.

Beneath the two outer eyelids birds have a translucent nictitating membrane, sometimes called a “third eyelid.”  This membrane sweeps across the cornea from the inside corner of the eye to the outer edge of the eye. It moistens and cleans the cornea, especially in flight.  It is also drawn across the eye when there is a chance the eye might be scratched or damaged such as when capturing prey, flying through brush or feeding their young.

In summation, one could say that owls have three eyelids for each eye: one for blinking (upper), one for sleeping (lower), and one for keeping their eyes clean and protected (nictitating). (Photo: Snowy Owl sleeping, with lower eyelids raised.)

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


Northern Cardinal Nests: Safety in Numbers

This is the time of year to keep an eye out for bird nests that were hidden by leaves all summer. Their location can reveal more than one might guess.  As with many bird species, the female Northern Cardinal does most of the nest-building herself, usually selecting a site that is in dense shrubbery, often in a tangle of vines.  Frequently there are two broods, but rarely is a nest reused.  Instead, a new nest is built for the second clutch of eggs, and it can intentionally be located quite close to the first nest.

The two pictured Cardinal nests were both built this year, only four feet apart in a grape vine-covered stand of Staghorn Sumac. Two different birds would not have nested so close to each other due to territoriality; thus, the same bird most likely built both nests. Ornithologists feel that the presence of old nests may function as protection against predation.  They found that when they placed an empty Cardinal nest adjacent to a Cardinal nest containing plastic eggs, there was significantly less predation than with single Cardinal nests. (Thanks to Jody Crosby for photo opportunity.)

(NB:  Even though most songbirds only use their nest once and then abandon it,  one needs a federal permit to collect bird nests.)

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.


White-crowned Sparrows Migrating

White-crowned Sparrows (Zonotrichia leucophrys) breed north of New England and overwinter south of New England.  The only time we get to admire their elegant plumage is during migration, primarily in May and October. 

White-crowned Sparrows are strong migrators (A migrating White-crowned Sparrow was once tracked moving 300 miles in a single night.) but they do have to stop and refuel along the way.  Because they are now passing through New England, you may see what at first might appear to be a White-throated Sparrow, but is a White-crowned Sparrow.  Their bold black-and-white striped crowns are one quick way to tell one species from another. (Immature birds have brown and gray stripes.)  Look for them foraging in weeds along the roadside or in overgrown fields.  About 93% of their diet is plant material, 74% of which is weed seeds.

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.


Yellow-bellied Sapsucker & European Hornet Sign

Congratulations to “mariagianferrari,” who came the closest to solving the Mystery Photo when she correctly guessed that the missing bark was the result of a partnership between an insect and a Yellow-bellied Sapsucker (Sphyrapicus varius).  The sapsucker arrived first and pecked the vertical rows of rectangular holes in the trunk of the tree in order to obtain sap as well as the insects that the sap attracts.  (Usually these holes are not harmful, but a tree may die if the holes are extensive enough to girdle the trunk or stem.)

The second visitor whose sign is apparent between the sapsucker holes is the European, or Giant, Hornet (Vespa crabro).  This large (3/4″ – 1 ½ “) member of the vespid family was introduced to the U.S. about 200 years ago. Overwintering queens begin new colonies in the spring and the 200-400 workers of a colony then forage for insects including crickets, grasshoppers, large flies and caterpillars to feed to the larvae. 

In addition, the workers collect cellulose from tree bark and decaying wood to expand their paper nest, which is what has occurred between the sapsucker holes, effectively girdling the apple tree.  The nutritious sap that this collecting exposes is also consumed by the hornets. We don’t often witness this activity because most of it occurs at night.

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.


Snowy Owls Starting Their Return To The Arctic

Every year in North America some Snowy Owls migrate southward during Arctic winters while some remain in the Arctic.  (In some winters — not this one — we see large numbers, or irruptions, of young owls in the Northeast which is thought to be a result of food and weather conditions further north.)  Individuals that spend the winter in New England usually can be found near large, open terrain that resembles their Arctic breeding grounds. Agricultural fields, coastal dunes and airports provide them with an ample diet of small mammals and birds.  Overwintering Snowy Owls begin to head northward in March and April. Occasionally a few owls linger on wintering grounds well into spring and summer (records of Snowy Owls exist in May in Massachusetts and June in New Hampshire).

Much has been learned about the migratory flights of Snowy Owls due to satellite tracking. According to Birds of North America, in February 2012, a transmitter attached to a female at Logan Airport in Boston, MA tracked an owl to Nunavut, Canada. The owl migrated north along Hudson Bay’s eastern shore during spring migration and returned south along Hudson Bay’s western shore during the autumn migration. It eventually returned to Logan Airport the following November, having completed a 7,000 mile round trip.

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.


Admirable Qualities of the Canada Jay

Most of New England never sees Canada Jays (formerly called Gray Jays), but in the northern reaches of the Northeast this bird is familiar to most boreal woods walkers.  It’s not hard to find something to admire about the cleverness of Canada Jays.  Admirable traits include their habit of using their sticky saliva to glue bits of food behind bark or in other vegetation during the summer (as well as the ability to be able to find it again when hungry in the winter), their use of forest tent caterpillar cocoons to hold their nest of twigs together, and their ability to incubate eggs in -20°F during their late winter nesting season.

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.


Bird Nests Revealed

Deciduous leaves have fallen, revealing bird nests that were right under our noses all summer without our even knowing it.  In addition to building in specific habitats and constructing different sized nests, each species of bird uses a combination of building material that is slightly different from every other species. Because of this, the material a bird uses to construct its nest can be diagnostic as far as determining what species built the nest.  Is the nest lined with rootlets? Are grape vines incorporated into the nest? Is moss covering the outside of the nest?  Is there a shed snake skin woven into the nest? The answer to these questions and others can help narrow down the list of possible builders.

This is the time of year to look for nests and try to determine, with the help of a good field guide such as Peterson’s Field Guide to Bird Nests, the identity of the birds that built them.  (Be aware that possession of a bird nest, egg or feather of most migratory birds, even for scientific research or education, is illegal if you do not have a Federal Migratory Bird Scientific Collecting Permit.)

Sometimes you’ll find material in nests that surprise you — some contain man-made, as well as natural, materials. Among the most unusual examples of this are a nest built solely out of barbed wire by a Chihuahuan raven in Texas and the pictured clothes hanger nest built by a crow near Tokyo and photographed by Goetz Kluge.

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


Spruce Grouse Foraging

While Ruffed Grouse are plentiful throughout most of New England, one has to go to northern Vermont, New Hampshire or Maine to see its cousin, the Spruce Grouse.  Associated with boreal forests, this largely herbivorous bird feeds primarily on the needles of pine, spruce and fir (a small amount of animal matter is consumed in the summer as well as ground vegetation). Especially in the winter, a large volume of conifer browse is consumed in order to meet energy demands.

The grouse holds the needle between the tips of its mandibles and breaks it off by flicking its head.  This action, and the fact that Spruce Grouse feed exclusively on needles in the winter, leads to the wearing off of the tip of the bird’s upper mandible by spring.

If you are searching for a Spruce Grouse, you might want to concentrate in the middle of the crowns of trees, as this is where the birds tend to forage. Theories for this preference include the fact that needles in this location have higher nutritive value, branches provide sturdy support, and grouse can see approaching avian predators while remaining partially concealed. (Birds of North America, Cornell Lab of Ornithology). (Photo: male Spruce Grouse browsing on Tamarack needles and (inset) looking for grit on the ground.)

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.

 


Birds Molting Old Feathers And Growing In New Ones

With birds, molting refers to the loss of old, worn feathers and the growth of new ones.  A molt can involve all of the bird’s feathers (complete molt), or just some of them (such as wing or tail feathers – a partial molt). Most birds have a complete molt once a year (chickadees, hummingbirds, owls, etc.), or one complete molt and a partial molt before the breeding season (buntings, tanagers, warblers, etc.), or two complete molts per year (Bobolinks, Marsh Wrens).

Complete molts often occur in late summer and early fall, after the breeding season is over. When you think about it, the timing of this “prebasic” or “postnuptial” molt makes a great deal of sense. Growing new feathers takes an inordinate amount of energy; food is plentiful now, the demands of breeding are over and for many birds, migration isn’t quite under way. It is the perfect time to look for molted feathers on the ground.  (Photo:  molted Red-tailed Hawk tail feather)

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.

 

 


Juvenile Least Bitterns Foraging

The Least Bittern is the smallest member of the heron family, measuring 11-14 inches in length with a 16-18 inch wingspan.  It is so secretive and well camouflaged that it is heard far more often than seen. A soft cooing song is sung by the males in spring, and a variety of calls are given on their breeding grounds. (You can hear both types of vocalizations at www.allaboutbirds.org/guide/Least_Bittern/sounds.)

This elusive bird of freshwater and brackish marshes is foraging for itself soon after it leaves its nest at two weeks of age.  Long agile toes and curved claws enable the Least Bittern to climb and grasp reeds while it looks for frogs, snakes, salamanders, leeches and other prey from on high.

Like its relative the American Bittern, the Least Bittern freezes in place when alarmed, with its bill pointing up, turns both eyes toward the source of alarm, and sometimes sways to resemble windblown marsh vegetation. (A few wisps of white down still remain on young Least Bitterns at this time of year, as is evident in photo.)

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 Loon Chicks Riding High

July on a lake occupied by nesting Common Loons is a birder’s slice of heaven.  Eggs are hatching, day-old fluff balls are riding high on their parents’ backs, parents are busy catching and delivering small fish and crayfish to their chicks, and survival lessons are being given. Recently while watching a pair of two- or three-day-old chicks whose parents were off obtaining their offspring’s next meal I observed a juvenile Bald Eagle, known predator of Common Loon chicks, soaring overhead.  Within a split second both loon chicks dove and stayed submerged long enough for the eagle to give up the ghost. Nature or nurture?

To see a related entertaining phenomenon, go to https://loonproject.org/2019/06/29/unlikely-allies/?fbclid=IwAR0po44dJaElcyYpqKqLwaz9A6gs7RxWfhJRkoB-QleC7sUGnjgElksR5G4.

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.


Changing of the Guard: Pileated Woodpecker Parents Share Parenting Duties

7-1-19 male and female pileated 0U1A0116Recently I had the opportunity to observe nesting Pileated Woodpeckers, and I thought I would devote this week’s Naturally Curious posts to different aspects of my observations. I would like to thank Amber Jones and Dave Bliven for generously sharing their Picidae residents with me.

From start to finish, both Pileated Woodpecker parents are involved in raising their young and all that it entails. Together they excavate a nest cavity, usually in a dead or dying tree. Both have brood patches (areas on their undersides that lack feathers and are well supplied with blood vessels, allowing efficient transfer of body heat to eggs), and both incubate the eggs during the day (the male has night duty). The parents take turns brooding the nestlings and providing them with food. And finally, once fledging take place, both parents provide and help their young find food for several months. (Photo: male Pileated Woodpecker in nest cavity; female Pileated Woodpecker on nesting tree)

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.


Why Do Birds Turn Their Eggs?

5-31-19 C. goose turning eggs 1B0A8783It’s common knowledge that birds periodically turn their eggs when they are incubating them, but have you ever stopped to ask why they do this. One assumes that if this action weren’t critical to the incubation process, it wouldn’t be practiced, and science bears this out. According to Audubon, birds turn their eggs to make sure the embryo gets enough albumen – the white part of the egg that contains water and protein and provides essential nutrients to the developing embryo. Too little albumen leads to an underdeveloped and often sickly chick. (Photo: Canada Goose turning eggs)

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.


Hungry Barred Owls Near Feeders

3-4-19 barred owl _U1A2992Over the past few weeks many people in northern New England have discovered Barred Owls perching near their bird feeders during the day. At this time of year, with snow on the ground, food is harder to find and owls are forced to hunt during the day as well as at night. Bird feeders are a sure source of food, as mice and voles are coming out to feed on spilled seed (most often at night).

The owls we see are relying primarily on their sense of hearing to locate small rodents. Their ear openings are asymmetrically placed, which means that sounds reach the owl’s ears at different times. This helps them zero in on the exact location where the sound is coming from, both when they are perched as well as in flight.

Although Barred Owls can detect the sound of a mouse scurrying through tunnels two feet beneath the snow, this winter has been more challenging for them than many. Almost every snow storm has been followed by rain, which has created multiple layers of icy crust. Although sound may be heard through solid, liquid, or gaseous matter, one wonders if these multiple layers of crust compromise an owl’s ability to hear. In addition, these conditions can’t help but impede an owl’s ability to reach its target as quickly as it normally does.

A dear friend whose compassion for creatures big and small is unmatched was going to great lengths (coating balls of hamburger with hair cut from her dog’s coat so they would bear some resemblance to small rodents) to help a resident owl in a time of need. Some would argue that nature shouldn’t be interfered with, but those readers with a desire to come to the aid of a hungry owl could let a little seed fall on the snow that’s packed down around the feeder in hopes that a large supply of accessible food might attract more rodents which might fill more owl stomachs.

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.


An Owl’s Digestion Process

11-26-18 -barred owl coughing up pellet2 _U1A1839Most owls do not bother to tear small prey such as mice and voles apart but instead swallow them whole.  After eight to sixteen hours, all the nutrients available in the eaten prey have been absorbed by the bird.  Owls cannot digest the fur, feathers, bones, teeth and nails of their prey, so these parts remain in the bird’s gizzard (specialized organ that grinds up food in most birds but serves as a filter for holding indigestible parts in birds of prey).  This accumulation of indigestible parts takes on its pellet form (which is the shape of the gizzard) about eight hours after ingestion, but is sometimes retained by the owl for another six hours or so before being coughed up. As a rule, bones are on the inside of the pellet, and the fur and feathers form a soft coating on the outside.

The stored pellet partially blocks the entrance to the digestive system so it must be ejected before the owl can eat again.  This process takes anywhere from a few seconds to several minutes.  The owl appears to “yawn” several times before regurgitating the pellet.  Note that the pictured Barred Owl has prey (a Deer or White-footed Mouse) in its talons, but out of necessity is getting rid of a pellet before devouring it.

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


Lingering Great Blue Herons

11-12-14 great blue heron2_U1A1373

Most fish-eating birds that breed where most bodies of water freeze over in the winter migrate further south in the fall, including Great Blue Herons.  Movement of this large wading bird takes place largely from September to mid-October. According to Christmas Bird Count data, the Great Blue Heron has the widest wintering distribution of any heron species in North America.

While the number of Great Blue Herons in the Northeast is greatly diminished in November and December, it’s not uncommon to spot lingering birds at this time of year.  Come January, when most bodies of fresh water are inaccessible to herons, sightings become rare until they begin returning in March.

Where open water remains in the Northeast, those Great Blue Herons braving the cold continue to consume fish, insects, amphibians and crustaceans.  Small mammals, especially voles, and birds remain a warm-month delicacy, when mammal hair is cast in pellets and bones are digested.

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


Ospreys Migrating

10-15-18 osprey 014

Banding birds, and the retrieval of these bands, has provided valuable information on the movement of birds. Today we also have the benefit of satellite telemetry, in which a bird carries a tracking device and its location is calculated via satellites that orbit the Earth.  The following is just a sample of what this tracking technology has revealed about the migration of Ospreys.

There are significant differences in male and female timing of migration (females leave up to a month before males), distance traveled and overwintering locations.  There is strong fidelity to overwintering sites as well as to migration flyways.  Breeding pairs of Osprey do not migrate or overwinter together, and adults do not migrate with their offspring.  Ospreys rarely migrate at night over land but inevitably migrate at night when undertaking longer (more than 12 hours) water crossings.

Subtle insights into migratory behavior can be gained by the findings of satellite telemetry, as well.  Their first flight south by juvenile Ospreys is often largely over water. A majority of juveniles migrating over the Atlantic Ocean from Massachusetts to the Bahama Islands flew as many as 1,500 miles over a period of up to 58 hours. The fact that no adults or 2nd year birds took this route over water suggests that juvenile Ospreys learn the coastal migration route during their first trip north.

Overwintering habitat preferences have also been assessed.  Of 79 Ospreys tracked by satellite, 30.4% overwintered on coasts, 50.6% overwintered on rivers, and 19% overwintered on lakes or reservoirs, with differences based on both sex and region of origin.

These few facts don’t begin to exhaust the information gathered from banding and satellite telemetry on Ospreys, much less many other species. They just serve to illustrate how modern tracking technology compliments and increases the information formerly gathered by firsthand observation and banding.

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