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Backyard Birder

Birds leave for  warmer climes

The leave-taking has begun. Tree swallows are long gone. No longer coursing over local fields and waterways, they gather by the thousands along the seacoast, sweeping low to dunes. And then one day they take off, southward bound.

Shorebirds lead the annual leave-taking when adults head south early in August or even in late July. They leave their young to feed and strengthen up on their own. Birders are on the alert to watch for shorebirds on Thorndike Pond in Jaffrey where dam repairs require a water-level drawdown that soon will expose mudflats.

Last summer dam repairs in Bennington caused a very low tide on Powdermill Pond. Shorebirds passing overhead dropped down when they saw an irresistible expanse of shoreline terrain ripe for their probing.

In backyards, hummingbirds keep sugar-water feeders busy as they work to double their weight before they take off, adult males first. Juveniles are the last to leave.

Last Saturday evening, in response to an email appeal from New Hampshire Audubon for help finding roost chimneys for migrating chimney swifts, I headed for downtown Peterborough.

Eventually 15 swifts showed up, small and speedy, careening overhead as they fed in typical swift fashion. At times I could hear their tick-tick vocalizations. In West Peterborough I saw another 10. The old mill building there lacks the big chimney I hoped to find, as does the Noone Falls mill building, another stop on my search.

I didn’t find the migratory crowds of a hundred or more that gradually compress into a funnel of birds that pours down into huge chimneys for an overnight roost.

Pam Hunt’s Audubon email appeal cites roosts of more than 100 in Concord and Lebanon and years back a roost of 300 in Exeter. I remember well a swarm of swifts over Peterborough on Aug. 28, 2003, as Dennis Kucinich spoke from the porch of Harlow’s Pub. Too many to count, for sure, ticking low over the downtown.

If you see swifts over your town as light fades at day’s end, please count and let me know — Here’s Pam Hunt’s description of what to watch for: “Find a highish vantage point downtown from which to start watching swifts as early as 7 p.m. They are often most active over the general areas were the roosts are going to be, and as dusk approaches they tend to ‘congeal’ more closely to roosts. They then start circling fairly low and fast near the roost, perhaps covering a radius of 1-2 city blocks, and eventually start peeling off to go down the chimney. It might take a couple of visits — and ideally multiple observers — to nail down the roost, but this low circling behavior is a good clue. As the days get shorter, chimney entry is happening earlier, with some birds now entering the roost as early as 7:30. Peak numbers at a Concord roost last night (Aug. 15) entered just after 8.”

I suspect that the swifts I saw Saturday were locals not yet heeding the migratory urge that will take them all the way to South America.

Highlight of the vigil actually came early, at 7:10 p.m., before the swifts showed up: common nighthawks high overhead, as graceful and leisurely in flight as chimney swifts are frenetic.

More and more emerged into view from beyond the street maples. Forty was my count, rounded up a bit as I’m not a good counter when birds swirl around the way nighthawks do when feeding on an insect hatch.

Ants of many common species develop wings this time of year and form large swarms. Common nighthawks and chimney swifts take full advantage of the seasonal bounty.

The birds soon merged into a more orderly progression that headed in a southerly direction towards the Contoocook River, a north-south flyway that attracts many migrants.

Along with careening chimney swifts, watch in late afternoon for the elegant nighthawk so long of wing. Flocks vary from less than 10 to well into the hundreds.

New Hampshire Audubon tracks nighthawk populations. Once common in the state they now are a threatened species. Last year only three confirmed nests were documented in New Hampshire, including one in Keene where a total of five birds was counted — the same number as this year. Knowing a species is declining in numbers adds to the pleasure and the poignancy of their viewing.

As a perhaps too-poignant footnote, along with the leave-taking there is an arrival that didn’t occur this year. The butterfly bush outside my desk window just now hosted three hummingbirds but not one monarch butterfly. Typically this time of year I’m distracted all day long by monarchs probing the abundant flowers for nectar. I’ve seen just one monarch — weeks ago. Very few swallowtails. Not one painted lady. A few common wood nymphs. Some great-spangled fritillaries.

Butterfly numbers fluctuate naturally, but it’s highly unusual to have so few of all the common backyard garden species.

I scan the many plants selected just for butterflies, often finding not a one. It’s a stunning absence.

Backyard Birder by Francie Von Mertens appears every other week in the Monadnock Ledger-Transcript.

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