Tuesday, September 5, 2017

Nighthawks on the Move

As summer winds down [the first day of autumn is just three weeks away] forests, fields and wetlands have fallen silent of bird song, and with another nesting season behind them, many of the bird species that nest in Vermont and north are either in the midst or preparing for their annual southward migration to winter ranges in the southern U.S., Caribbean islands, Mexico, Central and South America.  Warblers, flycatchers and shorebirds are currently on the move and can pass through unnoticed to the untrained eye.  Currently two bird species, Common Nighthawk and Broad-winged Hawk, are wrapping up and beginning their fall migrations, respectively, at our latitude.  Both birds undertake spectacular flights: Common Nighthawks passing through from mid August to late August or early September, and Broad-winged Hawks primarily in September.  The nighthawk is the focus of this post with more to be said of Broad-winged Hawk migration in a future post.

The Common Nighthawk is not a hawk at all but rather a close relative of the Eastern Whip-poor-will, both members of the taxonomic family Caprimulgidae (nightjars) which translates from Latin to goatsuckers, in its own right is a misnomer.  Nighthawks are insectivorous birds feeding nocturnally on the wing and almost exclusively on flying insects.

Photo taken by Lloyd R. Bunten and is used with his permission.
Although nighthawks during migration may be observed in early evening hours just about anywhere in Vermont but especially along river corridors, the very best location to see them in high numbers is at Westminster Station in Windham County, Vermont.  This location is located next to a migration corridor, the Connecticut River, and is an area dominated by open agricultural fields, both features favoring an abundance of insects.  Annual surveys to estimate nighthawk migration abundance have been conducted here since 2010 by Don Clark, the principal counter and an experienced and well respected Vermont birder and naturalist.  Below are count data collected by him over the eight years since monitoring began.


The summer range of the Common Nighthawk includes much of the lower 48 states of the U.S. and the southern Canadian provinces.  Winter range extends from southern Columbia to central Argentina, and migration distance between summer and winter ranges spans 2,500 to 6,800 miles.

Each speck in the above photo is a nighthawk migrating over Westminster
Station, VT.  Place cursor on image and tap to enlarge.  Photo taken by 
Lloyd R. Bunten and is used with his permission.

Observing a thousand birds over several hours, not to speak of the nearly 6,000 counted in one evening this year, is amazing.  So, if you haven't experienced a nighthawk fall migration, mark your 2018 calendar.  You won't be disappointed.

Tuesday, April 25, 2017

Atypical Broad-wing Feeding Behavior

Broad-winged Hawks are returning to Vermont since departing New England last September for their principal wintering range in northern South America.  The first report of 2017 was on April 11 from Putney.  Since then sightings have steadily increased.  This is our smallest breeding hawk of the genus Buteo with an average total length of 15 inches followed closely in size by the Red-shouldered Hawk (16 inches) and the Red-tailed Hawk (19 inches).


This is a relatively common hawk nesting in woodland habitats.  Its diet is varied consisting of small mammals, frogs, snakes, lizards, small birds, large insects, and earthworms.  Today I encountered a Broad-winged Hawk picking earthworms off the surface of a paved residential driveway (photos follow).  That the hawk was eating earthworms wasn't as much as a surprise as where it was feeding. The bird was observed consuming no less than a half dozen worms in an environment more expected of foraging robins.  After having migrated as much as 4,000+ miles on average between winter and summer ranges no doubt energy reserves are depleted and with nesting season approaching getting back into prime physical and physiological condition are critical.   Today's rainy and cool temperatures (40s) may not be prime conditions for encountering small mammals but earthworms are easy pickings at least for this hawk.



  

Saturday, April 1, 2017

Spring...Really?

March weather in Vermont this year has been sort of a roller coaster ride.  A spell of unseasonably warm daytime temperatures during late February through early March kicked off maple sugaring season and the northward bound hordes of Canada Geese and other waterfowl.  Ice covering the Connecticut River broke up and ice floes flushed out earlier than usual, and open-water conditions on rivers, streams and many of the larger lakes forebode an early spring, or so it appeared, and then a return to winter.  More snow was forecast for yesterday, and this morning we woke to 13 inches of new snow carpeting the yard.  No April Fools joke...just early spring in the Green Mountain State more or less as usual.

All winter we have had a flock of Wild Turkeys numbering between 26 and 31 birds making nearly daily visits to the yard to feed on cracked corn.  With increasing day length we observed this past week two toms come into season showing off their finest "attire" before the hens which seemed not to pay any attention to them but rather focus on consuming corn.  The following movie clip was taken from the dining room window.


The recent snow storm was followed by considerable bird activity at our feeders with 18 species tallied for today.  Of special note was an adult male Pine Warbler feeding on suet and seeds.  While shoveling snow, it could be heard singing (a high, musical trill) from the tall pines hear the house.




    

Tuesday, March 7, 2017

A Rare Visit from the "Gray Ghost"

When the sighting of an impressive Great Gray Owl in Newport, New Hampshire was announced last Monday, February 27, it generated considerable attention within the New England birding community.  Since then, birders have traveled lengthy distances to view and photograph this rare and unpredictable vagrant from the boreal forests of northern Canada.  Fortunately the owl has been very "cooperative" in rewarding its pursuers with awesome close-up views.  There has been an irruption of Great Grays south of their normal range this winter with birds being reported from Montreal and Ottawa, Canada, nearby northern New York, and northern Maine.  The last incursion of this species south of its normal winter range was eight years ago.  I have heard of several New England birders making extensive drives to these locations, some seeing multiple owls in a day; others striking out altogether. So when a Great Gray is discovered south of the border and so close to U. S. population centers, birders are going to jump at the opportunity to see this striking bird.

Eva and I made the short drive to Newport from our home in Vermont last Wednesday and upon arrival we saw about 40 vehicles parked along Oak Street at the Sugar River Rail Trail access. Walking the trail a short distance to the owl location we passed about a dozen departing happy birders, and at the site joined another 32 birders with scopes and cameras aimed at the owl as it perched on a low limb at the edge of a large field.  With observers as close as 30 feet or so to the owl, it appeared indifferent to all the attention and was content to doze off for minutes at a time presumably getting rest before its evening meal of small rodents.  During our brief visit, I took about 100 photos of the bird of which the following two are typical poses.




At one time something, possibly a vole or the like, below the owl's perch caught its attention (photo below) for only a moment before nodding off again.  As we walked out another 10+ birders and otherwise curious persons were going in to see the Gray Ghost or Ghost Owl, as this bird is sometimes called.


As the world's largest owl species, by length (27± inches) but not weight, it is known to make cyclical winter irruptions south of its boreal range.  Incursions into southern Canada and the northern Great Lakes states typically occurs every four years or so and correlates with low vole population abundance, the principal prey of such a large owl [1].  Appearances in New England are less frequent.  Sightings in New Hampshire occur on average every seven years [2].

As of the date of this posting, the owl continues to be seen and reported from the large field lying just east of the trail.  A Northern Shrike is also being seen at this location.

Citations:

[1] Chereau, M., Drapeau, P., Imbeau, L., and Bergeron, Y. 2004. Owl winter irruptions as an indicator of small mammal population cycles in the boreal forests of North America. Oikos 107:190-198.

[2] Masterson, E. A. 2013. Birdwatching in New Hampshire. University Press of New England, Lebanon, N.H.



Wednesday, February 8, 2017

Bizarre Pink Blue Jay

Back in January I heard of an oddly colored Blue Jay that had been frequenting a Unity, NH backyard feeder since early December.  I was shown a poor quality photo of the bird which stirred my curiosity having never seen such an oddity and questioning whether it was in fact an example of erythrism or had been artificially induced, such as dyeing.  I tracked down the homeowner (name withheld at request) to whom's feeder the bird was regularly being seen and who kindly permitted me the opportunity to view and photograph it firsthand. Shortly after my host placed fresh seed out at the feeding stations a group of 15 normal colored Blue Jays arrived and several minutes later the str pink bird flew in. Even though it's visit was brief, I did manage to get several photos including the one posted below.  In all respects the jay is typical except for the pale rosy-red overcast coloring most but not all of its plumage.  Bill, eyes, legs and feet are normally pigmented.


An internet search failed to turn up any similar variants in birds and particularly in jays with exception of a pink Blue Jay photographed in Canada.  That bird generated some discussion on Birdforum in May 2013, but the consensus was the image had been altered significantly or fabricated.  The Unity, NH bird photo posted here is as it appeared and is not a hoax.

The Cornell Laboratory of Ornithology was contacted to inquire whether any similarly colored jays are known to have been encountered and if so possible causes for the strange pigmentation.  While staff are unaware any such birds, two possible explanations were offered: (1) a genetic factor causing erythrism, or (2) some sort of environmental staining.  One respondent thought that it looks like staining, such as a fluorescent colorant having been applied for a science project.  Thus an actual cause for the pink plumage remains in the realm of speculation and is unlikely to be resolved without having feather samples from the jay to subject to analysis.

Diet-induced erythrism has been observed in other species of birds.  The introduction and spread of nonnative red berry bearing shrubs, e.g. bush honeysuckles Lonicera spp., is suspected of causing unusually red feathering in Baltimore Orioles occurring in southeastern Canada, and reddish House Sparrows reported in Scotland are thought to have been diet induced.

     

Friday, January 6, 2017

Some Observations of a Turkey Vulture Roost

Admittedly I'm a fan of Turkey Vultures despite their dietary habits.  The sight of a vulture effortlessly soaring overhead, wings slightly tilted upwards, gently rocking side to side makes me wish for such freedom and views of the landscape spread out below.  Andrew Wyatt's painting "Soaring" has long captured my interest.  Of course I could take up hang gliding or skydiving for a similar experience, but I prefer to keep both feet firmly planted on Earth and leave unconfined flight to my imagination and to creatures that have evolved to fly.  Some art critics have described the painting as dark and unsettling.  I'll venture to guess that they are not birders.

"Soaring" (1950) by Andrew Wyeth.  Shelburne Museum, Shelburne, VT.
This past summer I kept close watch on a Turkey Vulture communal roost located in North Springfield, VT.  The roost has been active for some years, and this summer was occupied by at least 35 birds.  At dawn vultures congregated in a large dead elm tree next to the Black River, spread their wings for a morning stretch and to absorb the sun's radiant energy.  By mid morning by ones and twos they took to the air rising on thermal currents, congregating once again in kettles drifting off in various directions presumably in pursuit of a meal of carrion.  At the approach of evening they gathered again at the roost tree before retiring to an adjacent conifer stand for the night.


What I found puzzling is that the number of vultures counted at the roost tree never varied by more than several birds on each of my visits conducted from late spring through the summer.  This seemed odd being they appeared to be all adults and I thought that they would have been incubating eggs and caring for young for much of that time rather than hanging out at a communal roost.  For a plausible explanation I delved into several references on vulture life history.

According to the species account given on the EOL website, Turkey Vultures at northern temperate latitudes lay eggs (typically 2) between May and June.  The incubation period is 32 to 41 days (average 35 days) and the young fledge the nest at 70 to 80 days of age.  There is little data from Vermont establishing when nesting typically begins; however, assuming a date of May 10, egg hatch would be expected to take place about June 14 with young fledged some time between late August and early September.  Both parents share in egg incubation and the care of the young.  This eliminates the possibility that the roost is comprised of mostly post-mating males.  Rather, sexual maturity is not attained until 3 years of age which suggests the vultures seen at the roost through the summer were likely sub-adult birds with the possibility of a few mature individuals that either failed to mate or experienced nest failure.

On the morning of September 30, my last count of the year, a total of 36 vultures were counted at the roost.  A few weeks later the roost tree was abandoned as the birds undertook fall migration to points south for the winter. Sometime around the last week of February or first week of March the first Turkey Vultures of the New Year can be expected to return to Vermont on steady outstretched wings riding spring air currents with seemingly little to no effort as captured by Wyeth.




Monday, January 2, 2017

2017 New Year's Resolution

Never having been one to make New Year's resolutions I am going to go out on a limb and make one this year.  Since starting this blog over eight years ago, I have become increasing lax in posting articles and keeping the site current.  For that I apologize.  I have learned that blogging takes time...a lot of time...and work to keep the site up to date, interesting and hopefully relevant.  My passion for observing, learning about, and enjoying birds, other wildlife, and the environment is as important to me as ever. What has changed as of the end of 2016 is my retirement from a 36+ year professional career as a fisheries biologist, and now find myself in the enjoyable position of having more time to pursue birding and other interests. So, my New Year's resolution is to commit more time to writing blog articles and hopefully become better at it.  In my pursuit of self-improvement I welcome feedback and constructive criticism from readers.

A New Year's Day treat in Swanzey, New Hampshire: male Varied Thrush, a
species that breeds in moist, coniferous dominated forests of the Northwest (Alaska,
western Canada, northwestern United States) and is a winter vagrant in the East.