TERRORISTS IMPACT THE NATURAL WORLD (7/05/02)

Of late, we have all been overwhelmed by the talk of terrorist activities. I’m not sure that we can take any comfort from the fact that humans aren’t the only ones who have to learn to live with the prospect of terrorist attacks, since terrorism can take many forms in the wild. Following are some examples:

A squirrel observed at the intersection of Rts I-93 and 3 at the South Shore Plaza appeared to be contemplating running the gauntlet. Above it was a crow looking down at the critter. The observer writes, “This scene intrigued me. Traffic being light at that hour of the morning, I was able to watch the drama unfold. The squirrel made little movements toward the center strip. Finally, it made its move. Right behind it, the crow dropped down and was just a few feet behind and, or course, a little above the cars. The car several yards ahead of me ran over the squirrel. The crow immediately dropped on it!

“Now, I have to believe that this was a learned behavior by the crow. The crow chose the light stand closest to the squirrel. When the mammal made its decision, fatal as it was, the bird immediately lit out after it, definitely tracking it. The squirrel did manage to get 3/4 of the way across. The crow's movements suggested that it had seen this scenario before. Chances are, there was a free meal soon to be available.”

Here’s another story. “As I was driving down the road, I noticed a squirrel by the side of the road. On the lawn toward the house were two crows facing the squirrel. As I approached, both crows hopped toward the squirrel and it ran out into traffic. I managed to miss the squirrel, but what about next time? Were they using my car as a tool similar to the story from a few years ago about crows chasing starlings into a glass building in Yonkers, where, of course, they broke their necks?”

Ornithologist John Terres suggests that corvids (including crows) have probably achieved the highest degree of intelligence to be found in any birds. Scientists have performed many studies of corvids and their abilities to show thought. One study asked, “How can birds learn and remember without an elaborate cerebral cortex?” The answer was contained in the avian brain, built on its own unique plan.

Instead of relying on the cortex, birds have developed another part of the forebrain, the hyperstriatum, which mammals lack, as their chief organ of intelligence. The larger the hyperstriatum, the better birds fare on intelligence tests, and as you probably can guess, the corvids are tops among birds for overall brain size. The brain-to-body ratio of crows, ravens and magpies equals that of dolphins and nearly matches humans.

Remember this: “If men had wings and bore black feathers, few of them would be clever enough to be crows.” Rev. Henry Ward Beecher, mid 1800s

Another terrorist at work: While walking in a cemetery, a couple observed two Red-tailed Hawks perched near the top of a tall spruce tree. The pair flew out of the spruce and glided through an open grove of maples and oaks. The lead hawk grabbed a squirrel from a branch, took it to the ground and "footed" it until it stopped moving. Over the next 30 minutes they observed the redtail eat the squirrel. The second hawk was perched nearby but did not share in the meal. After half an hour the redtail moved the squirrel carcass to a low branch and continued feeding.

Is this the accidental terrorist? In Charleston, WV, a female kestrel got into a Lowe’s warehouse. Store employees and natural resource personnel tried to get her out, but apparently the resident English sparrows kept her from being “saved.” Since kestrels hunt from a perch, the rafters were a good substitute. The sparrows were observed to be quiet and trying to hide. Will the kestrel ever desert her sanctuary?

Here’s a different form of terrorism. As many of you already know, cowbirds parasitize other, smaller birds by laying their eggs in other birds’ nests, often those of thrushes, sparrows or warblers. More times than not, the cowbird young hatches before those of the host birds. In the bird world, it’s the bird with biggest mouth that gets the worm, so cowbird babies often eat well while their nest mates starve.

If this is all there were to the situation, it would just be one of those interesting facts of nature that we all gather as we go through life. Unfortunately, that’s not the whole story. Cowbird numbers have increased dramatically in the last couple of decades, not because of Mother Nature but from man’s activities.

Houses and other structures built in wooded areas have created more open areas and subsequent edges around these. This edge effect benefits cowbirds but has had detrimental consequences for birds that would ordinarily have nested in more extensive woods. While song sparrows and yellow warblers, two of the most common cowbird eggs’ hosts, are not deep woods birds, these small songbirds are unable to compete with the wildly proliferating numbers of cowbirds. The wood and hermit thrushes and their cousin the veery have taken a severe hit from the cowbirds, so that they are on the brink of becoming endangered species.

I would not argue that male cowbirds are truly handsome birds with their glossy brown heads that contrast sharply with their black backs, but I guess I’m of the school that feels, “Handsome is as handsome does.”

Crow photo courtesy of Joe Brown Photography