Environment : Notes about your surroundings.

WAYWARD BIRDS--The thousands of birds that return each fall to spots such as the wetlands of Bolsa Chica and Upper Newport Bay are part of an uncannily regular cycle of migration whose mechanisms scientists are only beginning to understand. But sometimes birds show up where they’re not expected, and it is these deviations from the cycle that often spark the most interest among veteran bird watchers.

Several birds that normally migrate along the East Coast have been seen in Orange County recently. The county’s first recorded worm-eating warbler was spotted in Huntington Beach’s Central Park earlier this month and may spend the winter there. A scarlet tanager also was seen at the park for about a week, and an Eastern phoebe was spotted near Turtle Rock Community Park in Irvine. Such “vagrants” may have been blown off course by a storm or, as some bird experts believe, may simply lack the genetic ability to navigate correctly.

Also, several bird species that normally spend their lives in the pine forests of the local mountains are appearing in Southern California’s coastal lowlands. Birds spotted in the county include mountain chickadees, white-breasted and pygmy nuthatches, red crossbills and white-headed woodpeckers. Scientists believe that such “invasions” may be a response to weather conditions or a food crop shortage, birder Doug Willick said. There is no apparent cycle to these events--the red crossbill was not seen in the county for 20 years until an invasion two years ago, and now it is back again.

Thick-billed kingbirds are tropical birds rarely seen locally, but an individual bird has returned to the same eucalyptus grove in Lemon Heights to spend its sixth consecutive winter. This confused bird is an example of “reverse migration,” said Willick. While the rest of the species heads toward the Equator to spend each winter, this bird heads north. But it does retain enough navigational skill to find the same grove of trees, a trait scientists call “site faithfulness.” Another example of this trait is a male harlequin duck that has returned to spend its fourth consecutive winter at Bolsa Chica--far south of the bird’s normal range.