Sunday, January 11, 2015

Common Redpolls - Winter 2015

Common Redpoll by Phil Brown

When I see Common Redpolls, I immediately think of the low-Arctic tundra, the land
with short, dwarf-like shrubs that includes willow, alder, birch, all of which support
the Common Redpoll. These abundant, boreal and taiga region breeders share this
habitat with foraging Willow Ptarmigans and patrolling Parasitic Jaegers.

Common Redpolls feed often upside down, hanging on small branches, using their
feet to hold food items.  As winter visitors to our area, they're interested in our thistle
feeders too.  They are social birds that are often associated with catkin-bearing trees
in brushy and weedy  areas.

Redpolls are rotund and fluffy, sporting a tiny, yellow bill. Their characteristic features
include dark lores, a black throat and chin and a red fore crown. The dark brown of the
wings and tail along with the brown streaking  of the nape, back, breast and flanks are
offset by the whitish belly.

Pete Dunne refers to this bird as "...effervescent pipsqueak of a finch with a small red
beret and a black gotee."  What a clever way to remember the field marks!

Redpolls have been observed on twigs, feeding each other by passing seed from conical
bill to conical bill.  The sexes are discernible ~  the male has pink on the chest and is less
streaked; the female lacks that rosy hue and is heavily streaked. Their tails are forked,
and in flight, the wingspan is 7 - 9 inches.  They weigh less than a half an ounce.

Recently, I reread Kathleen S. Anderson's article on Cumberland Farms in a 1996 issue
of "Bird Observer" that has Barry W. Van Dusen's illustration of Common Redpolls on
the cover.  In that issue, I found in W. E. Davis Jr.'s account of  Common Redpolls that
they have a specialized "pocket" in the neck area known as an esophageal diverticulum.
A diverticulum is a sac or pouch arising from a tubular organ; crossbills also have this
storage ability. This is like having an in-flight cupboard for storing seeds.   This seed
stockroom and the specialized winter-feeding behavior enable this songbird to survive
colder temperatures.  "The Birder's Handbook" by Ehrlich, Dobkin and Wheye [page 641]
refers to this partially bi-lobed pocket as analogous to the crop of gallinaceous birds.

Thermal regulation is also key to their survival.  When in a sheltered area, redpolls fluff
up their feathers to maximize heat retention.  Frank Gill's "Ornithology" states that
Common Redpolls sleep in snow tunnels during the long Arctic night to conserve body
heat.  These winter visitors will feel more at home in New England with snow cover
when they can insulate themselves against the cold air temperatures.

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