At least, there have been far fewer birds than usual in our part of South Texas. Is this going to be a “silent winter” reminiscent of the “silent spring”? In 1962, Rachel Carson published Silent Spring. This book was pivotal in convincing us that DDT, pesticides and pollutants were destroying bird populations at an alarming rate. Carson wrote “Imagine a spring with no birdsong.” We did imagine it ,and we took note. Subsequent environmental awareness and conservation has helped the birds.
Now, it seems again the birds are telling us something is wrong. Like the proverbial “canaries in the coal mine,” birds can indicate changes in the environment even before we are affected personally by those changes.
This year, we are seeing both fewer kinds as well as lower numbers of birds around Beeville. Perhaps you have observed this at your feeder. Fewer cardinals, not many sparrows, a bare sprinkling of goldfinches. What is going on?
The consensus is that the drought of the past couple of years has had a detrimental effect on bird populations. The number of wintering birds arriving here is low. Is there not enough food? But how could they know that without first coming to check it out? Surely we would have seen them before they left again. Most of us in Bee County agree that some of the birds we’ve expected to arrive have not arrived at all.
When I walked around my farm these past few months, I have seen no White-crowned Sparrows. My records for previous years indicate that they are normally here from October to March. No Hermit Thrushes have shown up. Even Olive Sparrows, which are year-round residents of the brush country, are in short supply. I have not seen or heard one since last summer.
Of course, the only valid way to determine if bird populations are down is to count. This is where the Audubon-sponsored Christmas Bird Counts provide solid data. Christmas Bird Counts are carried on at hundreds of locations during the “season,” which runs from Dec. 14 through Jan. 5 each year. Each location is a circle, 15 miles in diameter, with a precise center point. Within this circle, all the birds are identified and counted during a single day, midnight to midnight. The observations are made by teams of bird-watching volunteers. The data are submitted to the Audubon Society and are compiled into an ongoing database.
The first counts were done in 1900. This year is the 113th year of Christmas Bird Counts (also known as CBCs). Most of the locations have been gathering data for decades. This means we have substantial information on wintering birds.
Looking at these CBC data, scientists have concluded that wintering birds aren’t going as far south as they used to. Over 56 percent of fairly common wintering bird species are staying an average of 35 miles north of where they usually went! This northward shift in the wintering ranges of birds has been correlated with warmer winters. Forty years of weather data indicate that the continental United States have had an increase in January temperatures by 4.6 degrees Fahrenheit.
Although many factors drive bird range changes, warmer winters in recent decades have played an important role in shifting many winter birds’ ranges to the north. The birds most affected by this shift are the species that occupy urban and suburban habitats. No wonder we are seeing fewer birds at our feeders!
Of course, you can’t have failed to notice the devastating effects of the drought on plants, particularly the wildflowers. If plants can’t grow, then the food base for wildlife is reduced. Insects and the creatures that feed on them become fewer. Animal populations, in general, are depressed.
A few weeks ago, on Dec. 15, the Bee-Picayune published a story on the effects of the drought in Texas. Along with the story were two maps of Texas. The one on the left was a satellite photo of Texas prior to the drought. It was mostly green. The one on the right was a photo of the state recently. It was mostly brown. If this much of a change is observable from space, imagine what is happening on the ground!
Warmer winter temperatures, droughts in some areas, floods and severe weather in others are all aspects of global warming. Or it could be just a natural cycling of the complex system we call weather. I hope that this is so.
But these changes may be permanent. It could be that we are witnessing only the beginnings of major climate change. The northward shift in bird ranges we are now observing is perhaps a preview of what’s to come.