The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Thursday, July 30, 2009

Spotted Sandpipers, An Example of Avian Polyandry
by Ro Wauer

A recent visit to Lassen Volcanic National Park in northern California reminded me how different breeding spotted sandpipers appear from when they are over wintering in South Texas. They are a Jeckel and Hyde bird that sports a spotted breast on their breeding grounds but possess an immaculate white breast in winter. But what is most amazing about these little sandpipers is that they are one of nature’s most fascinating experiments. They are one of the few bird species in which the female is dominant. She will entice two or more males into her harem to incubate the eggs and care for the youngsters. She arrives on the breeding grounds first and selects and defends her territory and her mates. This example of avian polyandry is an apparent success story because spotted sandpipers are among our most widespread and abundant shorebirds.

Betty and I discovered a very defensive female near Manzanita Lake at Lassen. She flew about the little stream where we were searching for butterflies, perched on an adjacent tree, and constantly scolded us with shrill “peet-weep” calls. Then she would fly off again, flying stiff-winged in a sporadic flight-and-glide manner to the next landing spot. We did not search for a nest, but moved away so as not to disturb her or her mates who we assumed were sitting tight on a nest. She continued her frantic calls for a long time as we moved further away.

Spotted sandpipers are often finished with their nesting chores by late July, and some of the earliest birds can arrive on their winter homes soon afterwards. They normally utilize lake shores and streams where they wander about searching for insects and various other invertebrates such as worms, crustaceans and mollusks. But they may even catch small fish and on occasion feed on carrion. But whether they are on their nesting or winter grounds they are easily identified by their small size (smaller than a killdeer), long yellowish legs, yellowish bill, and unusual behavior of constant teetering.

The spotted sandpiper is the most widespread sandpiper in North America with a breeding range that extends throughout North America from coast to coast and from the extreme north Texas to Alaska. Because of its odd nesting behavior it can be characterized as a “pioneering species.” It “quickly and frequently colonizes new sites, emigrates in response to reproductive failure, breeds at an early age, and lives a relatively short time (breeding females live an average of only 3.7 years), lays many eggs per female per year, and has relatively low nest success,” according to “The Birder’s Handbook.”

“The maximum clutch size is four eggs, each of which weighs about 20 percent of the adult female’s body weight. Apparently, it is physiologically impossible for a female to increase the clutch size beyond four, but during the six-to-seven-week breeding season she can lay up to five complete clutches of four eggs each. Each clutch requires about three weeks of incubation, so a female would be hard-pressed to hatch and raise even two broods. Multiple males enable a female to increase her reproduction output by freeing her from the responsibility for incubation and care of the young.” Her free time at Lassen allowed her to properly chastise us for invading her territory.

Thursday, July 09, 2009

The Importance of Handouts
by Ro Wauer

Drought conditions significantly increase the importance of handouts and water for the wildlife that utilize our yards. Our yard in Mission Oaks has become a feeding and watering area for more wildlife than usual during the last few weeks. The birdseed in our feeders had been disappearing much quicker than usual, although the number of birds that were utilizing the feeders had not changed all that much. But then it all became clear when we discovered a white-tailed deer also taking advantage of the birdseed handouts, stretching for seed in the rather small feeders. This individual doe is probably the same mamma deer that had left her fawn in our yard a few weeks ago. But now she leaves her fawn hidden in a brushy area along the edge of the yard, not encouraging it to also take birdseed. We did get a distant sighting of the fawn a couple days ago, so we know it is still about. We wonder if it will join its mother at the feeders before long.

Another wild animal taking advantage of our bird feeders of late, besides the regular birds and squirrels, is a cottontail. This individual will sit underneath the feeders and feed on the various seeds that have been brushed off the feeders by the birds. It seems very content to take leftovers. Yet it also will eat grasses in other locations in the yard. Our cottontail seems to be a loner. We have not recently seen its mate that had been present a few weeks ago.

The birds currently utilizing the feeders include the ever present cardinals, chickadees, titmice, blue jays, as well as Inca, mourning, and white-winged doves. A male painted bunting has become a regular as well. During most summers the green female painted buntings will also take advantage of the birdseed handouts, but we haven’t seen the ladies yet this year. Maybe they are still nesting. But as dry as it is this year there is a good chance that they will not be able to produce young.

Drought conditions have also increased the use of our birdbaths. Water is always important for wildlife, but never as much as this summer. All of the mammals – the deer, squirrels, and cottontail - constantly drink from the birdbaths. And all the birds, not just those that utilize seed, spend an inordinate amount of time at the birdbaths. Mockingbirds, yellow-billed cuckoos, white-eyed vireos, eastern bluebirds, Carolina and house wrens, and blue-gray gnatcatchers also visit the birdbaths on occasion.

The two larger birds that seem to enjoy the birdbaths are the resident red-shouldered hawks and a barred owl. The hawks seem to think they own the yard, and they will settle down in one of the birdbaths for an extended stay; undoubtedly an extremely pleasurable experience on a hot day. But on a couple occasions in recent days, and for the first time in the years we have lived in our home, a barred owl has taken over the birdbath. It, too, like the hawk, will settle in to enjoy the cool bath. None of the smaller birds bother either the hawk or the owl during their afternoon baths. And their presence provides Betty and me a super opportunity to photographs these most welcome visitors.