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Wednesday, March 14, 2012

Barn Swallows often make a home at your home

Barn Swallow

Barn Swallows, which nest around here, used to nest in natural caves, rock crevices, even splintered trees. These things are mostly gone from developed environments now. By the middle of last century they were only seen nesting in human-made structures like bridges, highway overpasses and so on. Around Denton (where I live) I see often under an overpass on Loop 288 - their mud nests lined up fastidiously. They even nest under the eaves of certain houses.The mud (which requires water of course) is a sure sign that there's a body of water nearby.
Barn Swallow

.............................................................................. Certainly Purple Martins (a type of Swallow) have a pleasant song. Adult males will fly into the sky around dawn for "dawnsinging".  Aided by the unique acoustics of that time of day, the Purple Martin's song may cover at least 30 square miles.
Purple Martins

Sunday, March 11, 2012

Birds' eggs hide in plain sight

Killdeer eggs

Almost all ground-feeding birds have eggs that are difficult to see. They're camouflaged by nature. In north Texas, that includes the Killdeer (among many other ground-feeding birds). The Killdeer's eggs are speckled with random brown spots (see pic above) to blend with its customary ground "nest".
adult Killdeer
Thus, a predator (which includes humans) could walk right by the nest, and not notice it.

On the other hand, most birds that nest in cavities (like birdhouses) or in trees or shrubs, lay brightly colored eggs which could be easily spotted if they were on the ground. In this case, the brighter the egg, the healthier the chick; since an egg's brightness indicates plenty of nutritious food - hence a healthy mother.

BIRDS DINE ON COLOR. A bird's intensity of coloring (such as the bright red of a male Cardinal) usually comes from nutrients and pigments ingested in its food. That's a reason why birds seek out the freshest food. It's also a sign of the male bird's fitness to propagate, to rear baby chicks and to defend a good territory (thus, a nutritious food supply).