2009

August 19, 2009

by Tony Klock, CU Treasurer

One flash of yellow then another darts among the leaves of a sweet gum, and just as quickly, seems to evaporate to be followed by another wave moving through the tree tops. Early autumn along the bayshore is the setting for many natural splendors, but among the most anticipated for birders and other naturalists, is the return, however brief, of the migrating wood warblers and other songbirds.

The early bird truly does get the worm, or more appropriately, the early rising birder gets the best views of these diminutive, colorful feathered gems. The wood warblers, and their compatriots, the vireos, flycatchers, tanagers, orioles, thrushes, etc. are what are referred to as Neotropical migratory songbirds. These amazing creatures are the long distance travelers of the animal world. Early in the spring they set out from their tropical jungle and other habitats in central and South America and begin an arduous journey to the north. They come to find suitable habitat to find mates and raise young. The ancestors of these migrants through the millennia have developed a survival strategy that allows them to take advantage of the relative openness of the northern forests and to forego the need to compete for food and nesting sites in the intensely crowded tropics.

So beginning in late March and continuing through the month of May the rivers of migrations flow northward over land and sea, many individuals making a perilous nonstop leap over the Gulf of Mexico. Peterson describes sixty species of North American warblers, but in our area, and east of the Mississippi, one might see closer to thirty types. Often called the “butterflies of the bird world” for their intense coloration, these incredibly tiny metabolism machines are often a blur as they move through the canopy snatching caterpillars and other larvae from the undersides of leaves. In the spring, their foraging may be accompanied by the males' distinctive songs; the females don't sing. However, during fall migration, often the birder's only clue to their presence is a nondescript "chip" note. Over a dozen species breed here on the bayshore, but the others continue on to the northern forests of New York, New England, and the Canadian taiga, all of which are under intense developmental pressures.

What are best times to see these amazing creatures and to witness this awesome, yet subtle spectacle? Watch for cold fronts that pass through the region in late August and through the month of September. The migrants make use of the winds to aid in their migration. On cool clear mornings, be in the field, with your binoculars as the first rays of sunlight touch the edge of a woodlot or hedgerow. The birds come to the edges to gain warmth as well as to avail themselves of the bounty of insects that also awake in the warming sunshine. The activity often subsides by eight-thirty or nine o'clock. Water fountains and misters draw migrants to your garden as the birds settle in after a long night's flight and are attracted to moving water. Naturalistic plantings and berries can also be a real magnet for desperately hungry birds searching the landscape for sustenance. If you are able to leave a portion of your landscape in a somewhat wild state, you might be rewarded with some truly cosmopolitan visitors.

The past several decades have witnessed the precipitous decline of many of our Neotropical migrants, and predictably, the culprit is habitat loss, both in the tropics and in the north. It is critical that we endeavor to protect these areas if we wish to pass on to future generations the legacy of biological diversity that we are blessed with today.

CU on the River!