November 23, 2024
ON THE WING

Snow, cold have negatively impacted birds

As I write this, I’ve noticed the forecast for this weekend calls for sunny skies with temperatures in the 60s. The storms and rain will soon be just a bad memory.

However, there is some concern within the birding community that the early spring cold and snow cover may have greatly impacted migrating birds.

Anecdotal reports of our early arrivals have described birds in distress due to the harsh conditions. Robins, which normally forage for invertebrates in the soil or consume the berries of certain fruit-bearing trees, have been observed visiting backyard feeding stations and consuming sunflower seeds, suet, and corn. Eastern phoebes, known as “flycatchers,” feed themselves by catching insects on the wing. But one birder observed a phoebe probing for marine invertebrates in the mud along a pond shore – something only shorebirds would do.

On a more dire note, late last week I received an urgent e-mail from Bill Sheehan.

“A few people in Maine are reporting finding dead tree swallows,” Sheehan wrote, “but to our south in the middle Atlantic and southern New England states, the swallows have apparently been creamed. Andy Weik from USF&W Service sent me an e-mail from a biologist on a national wildlife refuge in upstate New York this week. The biologist reported finding hundreds of tree swallows had piled into bluebird boxes on the refuge to stay warm. Apparently they were then too weak (from lack of food) to get back out and perished.

“Likewise it seems the phoebes and early sapsuckers reported across the middle and southern sections of the state have dropped out of reports recently. I’m afraid they are lost. Other species may be having problems as well.”

In a more macabre and bizarre account, a birder was observing several juncos and some crows foraging over bare ground in her yard. Suddenly, one of the crows grabbed a junco and flew off with it; this person happened to see this yet a second time.

Although crows are very opportunistic and have been known to prey upon songbird nestlings and fledglings, it isn’t often they are able to nab an adult bird.

Normally, our early spring migrants do take a bit of a gamble with the weather. Birds that arrive abnormally early are quickly weeded out of the population through natural selection. Regarding birds that arrive more or less on schedule, harsh weather tends to separate the weak individuals from the strong, ensuring that only the fittest survive to pass on their genes.

However, widespread, severe weather during this time can have a devastating effect. Birds already stressed from the journey, unable to rest and refuel the way they could in decades past due to increasing habitat loss, may more easily succumb to harsh conditions. It all depends upon what percentage of the population was affected, as well as the timing of the event.

As I recall, a few years ago our populations of swallows seemed to be in trouble as well. An unusually mild, late winter was followed by weeks of spring cold and rain. The vanguard of swallows that had arrived and begun nesting vanished. However, later arrivals – which would normally have lost out on all the good nesting sites – experienced a boon. They had prime nest sites to choose from and an abundance of insects that had hatched as a result of such a wet spring (as well as no competition for them). The early summer weather remained favorable, and they lost no time in reproducing. The result was a virtual population boom.

Will this be the case with this year’s migrants? How many have been affected? It’s too early to tell, but ornithologists are trying to gauge the impact of our early spring cold and snow spell.

“In order to judge the impact here in Maine,” Sheehan requests, “I’d like to hear from anyone finding stressed birds or individuals that might have perished from the cold/lack of food during this recent cold/snowy spell.”

Please send any reports to Sheehan at lsheehan@maine.rr.com.

BDN bird columnist Chris Corio can be reached at bdnsports@bangordailynews.net


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