The Nature Writers of Texas

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

Sunday, October 17, 2004

Are Green Jays Moving North?
By Ro Wauer

Two green jays suddenly appeared in my yard last week. Although I wasn't home, wife Betty and son, Brent Nichols, were present, and they watched the two birds come to one of my birdbaths to drink. These new "yard-birds" were in the company of at least one blue jay, probably part of a group that visits my yard on a regular basis. And then several days later, Brent observed two green jays in Victoria, 15 miles to the east of my Mission Oaks residence.

The first question that comes to mind is why green jays would come this far north at all. It is a common bird in the United States throughout most of deep South Texas, from the Lower Rio Grande Valley to Loredo and northward into Bee County. And wandering birds occasionally have been reported northward as far as Victoria and Calhoun counties. So maybe my green jays are little more than strays that will eventually find their way back to their southern home. But finding two sets of birds suggests a small resident population. If any of my readers are finding additional green jays in Victoria and surrounding counties, please let me know at rwauer@viptx.net. Thanks.

For those of you who do not know a green jay, it is one of the easiest birds to identify. Slightly smaller than a blue jay, but without a crest, green jays possess a green back, yellowish underparts, and blue-and-black head with a black throat. A spectacular bird.

It is not unusual for many kinds of birds to wander after nesting, behavior know as post-nesting dispersal. That apparently is a way in which species discover new niches where they are able to breed and expand their range. This also is the case, to a lesser degree, for butterflies. While most birds that find suitable new environments, containing essential food, mates, and nesting sites, are often able to stay year-round, that is not often the case for butterflies. Birds are warm-blooded creatures that are able to survive north of their "normal" range even during cold winters. Butterflies, on the other hand, persist only so long as conditions remain favorable. But when one or more very cold winters occur, the temporary colonies often disappear.

Wanderings of birds and butterflies are different. Post-nesting dispersal of birds seems to be a purposeful behavior in that they, especially males, simply strike out in various directions. While most post-nesting males head south toward their wintering grounds, others can appear hundreds of miles north, east, or west of their breeding grounds. Scissor-tailed flycatchers, a typical bird of the Southwest, have appeared in Maine, and our South Texas buff-bellied hummingbird regularly is recorded in Louisiana in the fall and early winter.

Some butterflies also wander after breeding, usually mating immediately after emergence near their larval foodplant, and can fly in any direction. Some species also are able to find proper foodplants out of their normal range for females to lay her eggs, and colonies can occur far from their breeding grounds. The majority of far-wandering butterflies usually are aided by wind. The vast majority of these northward wanderers die before being detected, so their presence is never recorded. But occasionally, especially with so many people getting involved with butterfly-watching, species known only in Mexico or South Texas are reported far away in north Texas, the Great Plains, or even beyond. Some of the more exciting discoveries in recent years probably are related to global warming.

Many recent northern recordings of more tropical bird species, such as green jays, kiskadees, and ringed kingfishers, may also be the result of global warming. But habitat loss and strong storms may be involved with their northward dispersal as well. Cave swallows, groove-billed anis, Couch's kingbirds, and buff-bellied hummingbirds were unknown along the Coastal Bend 50 years ago. Their presence today can hardly be the result of wind and stormy weather. The residency of white-tipped doves, brown-crested flycatchers, and Audubon's orioles in the Coastal Bend may only be a matter of time.

1 Comments:

At 10:32 PM, Blogger Genie said...

Learned anything more about Green Jays possibly moving northward? We live in Brackettville, Texas, 168 miles north of Laredo, and hubby spotted a Green Jay this week. Well, we're pretty sure it was a Green Jay at any rate, nothing else looks like it.

 

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