Since I started keeping systematic records, the largest number of bird species I had ever recorded in January was 47. So I did not begin the month with high hopes. January is usually a good time to stay inside and think about the environment instead of being out in it, and this year started out that way. Snow was on the ground continually through the first half of the month, accompanied by temperatures that were below freezing most of the time. I bundled up and took my usual weekend walks, but never saw more than 25 species in any one day; yet the numbers mounted, and on January 16, I was surprised to record my 48th species. I had broken my record with the month just half gone.

No. 48 was a ringbilled gull that sailed in and perched on a light pole in the Food Lion parking lot in Taneytown, where I was waiting for my wife. Taneytown would not rank high on the list of places where most people would expect to find seagulls in January; in fact, when I started keeping records in 1979, gulls appeared in my notes only when I went to Baltimore. But one of the significant environmental changes of the past 20 years is the proliferation of multi-acre paved parking lots around malls and supermarkets; and those parking lots always come with a supply of garbage. When it comes to eating, seagulls are the avian equivalents of billy-goats. They root through open dumpsters with perverse glee; they relish cookies and hot dog fragments that kids didn’t have time to finish before their harried moms yanked them into the car; and they forage in the surrounding fields when early plowing and manure-spreading is done. They have discovered that it is at least as easy to make a living here in January as it is in their ancestral habitat along the Bay, and I have recorded them around here in each of the past four years.

A couple of the other birds on my list are the result of ecological phenomena 1,000 miles north of here—in a way, the stuff of legends. In the tundra regions of Canada, one of the most abundant small mammals is the lemming, which one of my favorite writers, Ed Deevey, has called "rat-sized hyperborean field mice." They are eaten in great quantities by a number of predators, particularly the Snowy Owl, a beautiful bird with a wingspan of about 4 ½ feet. Most people have heard the fantastical stories of lemmings committing mass suicide by migrating down the mountains in Norway and jumping into the sea… stories that are exaggerated, though not entirely untrue. In Canada, lemmings don’t migrate, but they do reproduce with remarkable enthusiasm, so that every three or four years there is a population explosion. Lemmings are everywhere. Snowy owls gorge on them, and produce large families of their own; the owl population surges upward also, and in the following year the lemming population declines under its impact (it’s really more complicated than this, but you get the idea). The result is that every few years there are more owls than the food supply can sustain; and rather than stay home and starve, they migrate south. This is apparently such a year. A snowy owl turned up near Buckeystown a few weeks ago; it was reported on the Internet, and I was one of several hundred birders who made the pilgrimage to see it. During the same week, alerted by some Audubon Society friends, I was lucky enough to see four short-eared owls, another boreal species that had wandered south to the Gettysburg area for the same reason.

The rest of my list was comprised of species I have seen regularly over the past two decades, though never before all in the same month. Perhaps the severe weather had something to do with that; birds need food and shelter, and they tend to concentrate where these things are available. The flood plain along Toms Creek is such a place, and I visit it frequently. This month it yielded a yellow-bellied sapsucker, numerous myrtle warblers and an extended family of bluebirds, in addition to the usual chickadees, titmice, nuthatches and woodpeckers.

Walking through the flood plain after a recent snow afforded the chance to watch mammals as well as birds—not directly, of course, because most mammals are nocturnal, but by the tracks that show their presence. After one of the most successful hunting seasons on record, there were still plenty of deer. Dogs and cats had been there; it’s a pity there is not a hunting season for them, because they are destructive to native wildlife. Squirrels are abundant this year, and there were the usual numbers of rabbit tracks. At least two kinds of mice, raccoons, beaver, foxes, a frostbitten possum, and what I am pretty sure was a weasel left their records in the snow. People had been there too; there will be fewer wildflowers next spring in the places where the soil was torn up by "4-wheelers."

I never walk through that area without thinking of Robert MacArthur. He was an ecologist who finished his doctoral work just as I was beginning mine; his research on the ecological niches of warblers provided the theoretical basis for my studies of crayfish, so he was one of my idols. At the height of his career, just before his untimely death in the early 1970’s, he wrote a book entitled Island Biogeography, which became a landmark for everyone concerned with the threat to biodiversity. He showed that a given amount of space (islands in the Caribbean, in his studies) could support only a limited number of species of plants and animals; that number depended on the size of the island and its distance from other islands. The smaller the islands and the farther apart they are, the fewer species they can sustain.

I was not nearly as smart as MacArthur, so it took a long while for me to understand that this concept applies to places other than islands in the ocean. But eventually, even I realized that places like the narrow strip of woodland along Toms Creek are islands, in an ecological sense. They are remnants of what was once a forest that stretched hundreds of miles; they are now isolated patches, separated by farmland, highways, suburban developments and supermarket parking lots. And as such, they are the only places in which native wildlife can find the food and shelter necessary to survive in harsh times like this winter.

As "progress" comes to the Emmitsburg area, we see more and more housing developments springing up, commercial concerns paving former farms and woodland, and megafarm complexes ripping out fence rows and trees to create larger fields for monoculture cropland. Our local natural islands are shrinking and becoming farther apart; the inevitable consequence will be a loss of diversity in wild plants and animals. The Toms Creek flood plain is a particular treasure in this respect; it houses a rich variety of native plants and animals, and it should be preserved and protected. The town could do this fairly simply by buying the land, declaring it a natural area, and banning motorized vehicles from it. It would require a few dollars and some courage and foresight on the part of local leaders; but it would be worth it. Nature would take care of the maintenance.