Thursday, September 13, 2012

Flights of Yellow

Yellow wings flash and click knee-high next to my bike. Up ahead, several sets of yellow wings flap quickly up to the trees. A gentle breeze releases yellow sugar maple leaves from their twigs, and they flutter gracefully to the ground. This sunny gravel road glimmers with the yellows of late summer.

The first yellow wings belong to the Carolina grasshopper. While not especially numerous, they are probably the most common grasshopper you notice. Not only do they prefer roadsides, weedy lots, and the Museum’s outdoor classroom, yellow bands along the edge of black hind wings do a great job of catching our attention.

The grasshoppers’ yellow wing bands flash briefly as they make short flights to escape from predators (or us). When flushed, they fly at a right angle to the predator’s line of travel, then hunker down and use their mottled brown body and front wings to disappear. (This seems like a better strategy than Great Blue Herons, who I have followed for miles down a river in a canoe before they flew out and around us.)

To find food, Carolina grasshoppers make lazy, bobbing flights about 2 feet off the ground, and are often mistaken for butterflies. To find mates, males rise almost vertically from the ground to heights of 3 to 6 feet, occasionally higher, and hover for 8 to 15 seconds. Then they flutter down to the ground near where they started. Late summer is their mating season, and the eggs will hatch next JuneMales, and sometimes females, produce sound in flight. The snapping, crackling, or buzzing sound is made by rubbing the under surface of the forewings against the veins of the hind wings. The short flights attract both females and other males. They remind me of frogs calling each other in to a vernal pool in the spring, or prairie chickens displaying on a dancing ground.

The second group of yellow wings belongs to Yellow-shafted Northern Flickers. As the migrating flock spooks off down the road in front of me, handsome yellow feathers are visible under their wings and tails, and yellow feather shafts show through from above and below. Their white rump patches flash brightly and give another vibrant identification clue.

These woodpeckers spend most of their time feeding on the ground, where their smooth brown back with black bars and dots blends in well with soil and leaf litter. They catch ants and other insects (but not grasshoppers!) with their long, sticky tongues, and dig up anthills to access tasty larvae. Ants are not just food, but also pest control. Flickers rub formic acid from the ants on their feathers during preening to help prevent parasites.

When flushed, flickers make short, undulating flights up to low branches, and often perch like robins instead of clinging to the trunk like most woodpeckers. The courtship flights of the Northern Flicker in spring are noisy and lively, as three or more birds of both sexes perform a comical dance, nodding and bowing or chasing each other through the branches of a tree. Instead of the snapping sound of grasshoppers, the song of the Northern Flicker is a loud wick-wick-wick-wick or a squeaky flick-a, flick-a, often accompanied by a long continuous roll of drumming on spring mornings.

This time of year, flickers head south. (They are one of the only migratory woodpeckers.) Warblers continue on toward Central America in their mixed flocks. Soon harsh frosts will silence the grasshoppers, and maple leaves will have all made their own journey to the forest floor. The wings of fall are bringing beauty and change to our wonderful northern home.

Whose wings have you seen lately?

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