Fall Equinox and Flocking Birds

With the fall equinox this week, the days will begin to grow shorter. Birds get ready to migrate when shortening days and changing weather conditions trigger internal hormone responses. They then begin to eat great amounts of food in order to store fat for their long journeys. Keep an eye out as waterfowl begin to flock together and stopover at Sunset and Minister Lake. You're likely to see sandhill cranes, geese, mallards, loons, and maybe even trumpeter swans.

Why do birds migrate? Birds that rely on such food as aquatic creatures, insects, or mammals that hibernate must move further south to find prey as winter approaches.

Migration operations: Most small insect-eating birds like sparrows, warblers, wrens, thrushes, and vireos migrate at night using circumpolar (visible year-round) constellations to guide them. Flying at night reduces the threat of predation and overheating for these avians. Herons, gulls, waterfowl, and hawks migrate during the day and use the position of the sun to direct them.

High-flying hawks: The second week of August is the peak migration time for many raptor species. Keep an eye toward the skies and you might be lucky enough to see one of these graceful birds:

Accipiters: hawks with short wings and long tails that hunt between trees and shrubs, such as sharp-shinned and Cooper's hawks.

Buteos: hawks with wide wings designed for soaring, such as the broad-winged hawk.

Falcons: raptors with slim tapered wings meant for speed, like the American kestrel and the merlin.

Fast Food: Scientists have noticed that American kestrels tend to migrate at the same time as green darner dragonflies. These clever falcons snack on a moving insect feast as they travel.

Kettles of Birds: Broad-winged hawks often migrate in groups called kettles. These groups soar on high wind currents, expending as little energy as possible.

Learn More: Hawkridge

Wild Grapes are Ripe

This week at CWES look for the fruit of wild grape vines in wooded areas, as well as near the shores of Sunset and Minister Lakes. These creeping vines are capable of covering trees and shrubs, blocking their light, and killing them. However, the plant also has many good qualities. Small bees and flies visit its tiny white flowers early in summer,and several moths feed on its leaves. Its fruit is a favorite of both birds and mammals, who disperse the 2-6 oval seeds found within it.

Learn more: Cofrin Center for Biodiversity

Gray Squirrels Stockpile Food

These crafty critters bury their food in the fall, typically one nut at a time. They then find their buried treasure in the winter and spring by smell, sometimes digging through a foot of snow to get to it. The acorns that are overlooked will grow into new oak trees, a benefit for both parties. Besides nuts, gray squirrels eat tree buds, fruit, mushrooms, insects, and sometimes even bird nestlings.

These familiar creatures use their multi-purpose tails for rudders when climbing, insulation when tucked around them in the winter, or as an umbrella from falling rain and snow. In the approaching cold months they will search for a tree cavity in which to shelter. If one isn't found, they will build leafy nests, called drays, that we often see high in bare trees. These nests provide protection from harsh winter elements.

Learn more and view pictures of skulls and tracks: Animal Diversity Web

Amazing Acorns

Acorns are an important crop for many creatures. Squirrels, blue jays, woodpeckers, and insects love to eat the protein-rich morsels. One creature even lays its eggs inside acorns: the acorn weevil. A few days after the eggs are laid, grub-like larvae emerge and feed on the acorn meat. When fall arrives, they chew their way out of the acorn by creating a small circular hole. Then, they burrow into the soil to pupate (similar to a butterfly's chrysalis stage) over the winter. In summer the adults will emerge from the pupae and begin the whole process over again. After the acorn weevils are done with the nut, other insects may make it their winter home. Look for these tiny shelters strewn along the trails at CWES.