Event:
The Rio Grande Delta Audubon Chapter will
hold their monthly meeting
on Monday, March 5, 2007, 6:30 p.m. at the Historic Brownsville
Museum at 7th and Madison Streets.
Presentation...
This month's guest speaker will be Jimmy Paz,Director of Sabal
Palm Sanctuary,giving a talk on "Teaming up with Wildlife".
His talk will include the trip to Washington,D.C.
to request grant money for wildlife in Texas.
Let's come out and hear the outcome of this trip,and
show our support for Texas Wildlife.
|
Summer
heat can take its toll on birds. Combine that situation with
drought, and you've got a dangerous and deadly combination.
Birds are particularly affected because they are small and
have a greater surface area to weight and a higher body temperature
than humans," said Juan Carlos Atienza, a biologist at
the Spanish Ornithological Society. "If it's very hot
birds don't fly around during the day which cuts down their
feeding time."
Unlike people, birds lack sweat glands and
so cannot sweat to cool themselves down. Black vultures and
wood storks, for instance, use a highly practical, if not
pretty method: they defecate on their unfeathered feet and
legs. As the moisture in the excretia evaporates, the bare
skin cools quickly, sucking heat from the bird¹s body.
Vultures and other large soaring birds also cool themselves
by riding thermals to several thousand feet up in the atmosphere
where the air may be 50 degrees cooler than on the ground.
A bird in flight produces from 9 to
15 times as much heat as a resting bird. They also simply reverse
their heating tactics: Instead of fluffing up their feathers,
they compress their plumage to retain as little body heat as
possible. And, they increase circulation to unfeathered parts
that will radiate heat from their blood to the outside air.
When air temperatures rise over 100 degrees,
many birds - pant, stepping up their breathing rate to expel
hot, moist air from inside their bodies. The influx of dry
outside air also cools the bird evaporatively from within by
vaporizing water in its lungs and its air sacs, a system of
balloon-like extensions of the lungs that fill most of the
extra space in a bird¹s body, including some of its bones.
Most birds can dissipate about half of their resting heat production
by panting.
In addition to panting, some birds - like the perched white-winged dove - pulse
the skin of their throat in and out, and at the same time, increase the blood
flow to their throat skin. Like a car radiator cooling the hot water from the
engine, the fluttering skin radiates the heat of the bird¹s blood to the
air.
By Susan Tweit http://www.southernnewmexico.com. |
