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Citizens Concerned About the Future of the Etobicoke Waterfront

Updated: Oct. 20, 2014

June 2007 Birdwalk

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Don Burton led our June 2007 bird walk on a beautiful sunny day in Colonel Sam Smith Park. It was great weather for a walk in the park, but unfortunately, not ideal for seeing a lot of birds. Despite that, we managed to find 33 species, including great looks at Warbling Vireo, Black-crowned Night-heron, and Baltimore Oriole. An Orchard Oriole also put in a brief surprise appearance.

This will be our last walk in September. The date is still t.b.a., but it will be at Sam Smith Park as well.

Here are some photos of the birds and birders:

 Main Bird Walk Page

_MG_1932r
Watching-a-Spotted-Sandpiper

Watching a Spotted Sandpiper on the beach.

Mute-Swan-Family

The local Mute Swan Family

In-the-meadow-at-Sam-Smith
Warbling-Vireo

This warbling Vireo gave great views of his lack of field marks.

Cowbird-pair

A Pair of Cowbirds

Baltimore-Oriole

Male Baltimore Oriole

Black-Duck

American Black Duck

Common-Tern

Common Tern

DC-Cormorant-Drying

Double-crested Cormorant drying

(for more on drying, click here)

Two-Night-Herons

Two Black-crowned Night Herons, well camouflaged on the rocks.

Black-crowned-Night-Heron
Eastern-Kingbird

Eastern Kingbird (nothing else has the white band across the end of the tail).

RW-Blackbird03

Male Red-winged Blackbird

So, what was that Cormorant doing with his wings spread?

This was the source of some discussion during the walk. I found the answer (maybe) in this essay from The Birder’s Handbook (Originally published by Simon & Schuster Inc. Electronically published by Thayer Birding Software Copyright © 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.)

Some birds adopt characteristic poses in which they extend and often slightly droop their wings. This behavior is commonly described as "sunbathing" or "wing-drying." Cormorants and Anhingas frequently assume these postures, which are also seen in both Brown and White Pelicans, as well as in some storks, herons, vultures, and hawks.

The structure of cormorant and Anhinga feathers decreases buoyancy and thus facilitates underwater pursuit of fishes. Hence their plumage is not water-repellent, but "wettable." It has been suggested that the function of the spread-wing postures in these birds is to dry the wings after wetting. Biologists once thought that deficient production of oils from the preen gland necessitate wing-drying behaviors. We now know, however, that the degree of waterproofing of feathers is primarily due to their microscopic structure, not to their being oiled. In addition to helping wing feathers to dry, other suggested functions for these postures include regulating body temperature ("thermoregulation"), realigning of feathers, forcing parasites into motion to ease their removal, and helping the perched bird to balance.

Spread-wing postures may serve different purposes in different species. Anhingas, for example, have unusually low metabolic rates and unusually high rates of heat loss from their bodies. Whether wet or dry, they exhibit spread-wing postures mostly under conditions of bright sunlight and cool ambient temperatures, and characteristically orient themselves with their backs to the sun. Thus, it appears that Anhingas adopt a spread-wing posture primarily for thermoregulation -- to absorb solar energy to supplement their low metabolic heat production and to offset partly their inordinately high rate of heat loss due to convection and (when wet) evaporation from their plumage.

Cormorants, in contrast, apparently use spread-wing postures only for drying their wings and not for thermoregulation. Although cormorant plumage also retains water, only the outer portion of the feathers is wettable, so an insulating layer of air next to the skin is maintained when cormorants swim underwater. This difference in feather structure may explain why cormorants can spend more time foraging in the water than Anhingas, and why cormorants can inhabit cooler climes, while the Anhinga is restricted to tropical and subtropical waters.

Spread-wing postures appear to serve for both thermoregulation and drying in Turkey Vultures. These birds maintain their body temperature at a lower level at night than in the daytime. Morning wing-spreading should provide a means of absorbing solar energy and passively raising their temperature to the daytime level. Field observations indicate that this behavior is associated with the intensity of sunlight and also occurs more frequently when the birds are wet than when they are dry.
 

[June 2007 Birdwalk]

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