Thursday, April 30, 2015

Birdsong at Sunrise

Dawn at Ninepipe National Wildlife Refuge is for the birds. Literally. Bird activity starts at dawn and really picks up when the sun crests the Mission Mountains. It's interesting that males do most of the singing here in the temperate latitudes while females sing just as much in more tropical areas. In addition to our love of bird song, there are lots of different reasons for birds to raise their voices.

The sunrise song of a Western meadowlark turns to steam as he sings at dawn among backlit spider webs 
Western meadowlarks (above) are our state bird. Males sing to establish a territory for a month before the females arrive. So in this case, their song is primarily a territorial announcement to other males. The quality of his song also helps females judge how fit or healthy he is. Most males have two females nesting in their territory, and he will help deliver food to the chicks in both nests.

Male red-winged blackbird sings at dawn
Male red-winged blackbirds also sing to exclude other males from his territory. But in this case, the females are picking a male based on the quality of the nesting habitat within his territory. An older, studly male might have 15 females nesting within his territory while a young male on the fringes might not attract any females.

Wilson's snipe making a warning call to his hidden mate
Male and female Wilson's snipes both make a range of calls during the breeding season. But this changes subtly once the female starts nesting. She sits quietly on their nest hidden in thick grasses while the male takes up a conspicuous post to watch for intruders. When a potential threat approaches (a skunk, a photographer, etc.) he gives a sharp call to let her know. If the threat continues, his calls get louder and more frequent, and she sneaks away through the grass to distance herself from the nest. That way, she won't give away her nest location if she has to flush from the ground. When the eggs hatch, the male raises the older two chicks and the female raises the younger two, and the single-parent families do not mix.

Killdeer turns broadside to the morning sun and warms up while resting on one leg
The killdeer name comes from one of their most common vocalizations. Males give this loud kill-deer call over and over in flight while displaying to a female. Males and females both give a range of sharp warning calls, but they are also well-known for bluffing predators away from their nests. They tempt some predators into following with their broken wing act, all the while leading them away from the nest. For larger animals like cows or horses, killdeer fluff up their feathers to appear larger and bluff charge, running straight at the unsuspecting animal. The killdeer will usually scold the animal at the same time.

Just like us, birds make many different sounds for many different reasons. Spring is a noisy time of year for most of our avian neighbors, and a good time to stop and watch and try to put the bird calls into context with their behaviors.