After school last Monday, as I pedalled my bike to the main gate at Hilton Pond, I looked casually toward a bluebird box near the driveway. That quick glance was enough to convince me that I had arrived at my York property about five minutes too late.

The birdhouse that caught my attention was nailed to a shortleaf pine in the spring of 1983, and has produced four broods of Eastern Bluebirds since then. The shortleaf died two years ago after an assault by pine beetles, and the bark has been peeling off in larger and larger pieces. Perhaps I should have felled the tree when it died, but after Brown-headed Nuthatches excavated a nest hole near the top last spring, I decided on a laissez-faire policy.

Loose, flaking bark provides hiding places for various animals from lizards to bats to insects, and I have seen all these animals coexisting with Eastern Bluebirds that used the nest box during the past three years.

This spring a bluebird pair built their customary nest in the box and the female laid five eggs, the first of which hatched the last weekend in April. I was looking forward to banding the nestlings before they fledged, but--as I already mentioned--on Monday I arrived home about five minutes too late.

It's not that I didn't get there early enough to band the young before they fledged on their own, but I WAS too late to deter the four-foot Black Ratsnake with its head poking into the entrance hole of the nestbox. The snake had taken advantage of an easy climb along the loose pine bark, and apparently made a quick meal of the nestling bluebirds despite the agitation of the mother bluebird in the tree above.

As non-poisonous constrictors, Black Ratsnakes (Elaphe obsoleta) suffocate prey by squeezing more and more tightly until the prey can no longer inhale. They don't crush their food, which usually consists of small mammals and birds, but they do have fairly strong longitudinal muscles that also provide considerable agility for climbing. The ascent to the bluebird box was only a minor feat for the snake, and it probably even swallowed the defenseless nestlings alive without having to constrict them.

I'm sure many of my fellow bird lovers would have gone into a frenzy at the sight of a Black Ratsnake halfway into a bluebird box, and I fear that some of them would have taken the garden hoe to this predatory reptile. My own response was to remove the lid from the box, shoo away the serpent, discard the old nest material to encourage the bluebirds to start over again, and sit back to ponder what else that blacksnake might have eaten in the four or five years since it hatched from an egg itself.

These Black Ratsnakes are all very efficient at seeking out rodents, and a six-footer can easily down a cotton rat or several house mice. The biggest one I've ever seen was just under seven feet long; the longest known was measured at 8' 5", making it the largest kind of snake found in the Piedmont. This species is also called "Pilot Blacksnake" after its mythical habit of leading rattlesnakes to winter denning areas.

Several times I have seen Black Ratsnakes up to six feet in length sitting in shrubs, peering intently into the nest of a bird or squirrel; once I observed a half-dozen Blue Jays buzzing and bombing one at the top of a small persimmon tree. And then there was the day in my yard when I saw two entwined (i.e., mating) blacksnakes crashing down from about 30 feet up in a turkey oak tree. It's pretty startling to watch a pair of smooth, shiny black serpents with blotchy gray and white chins bounce down from tree limb to tree limb, eventually landing unharmed in the leaf litter below.

We've had a five-foot Black Ratsnake living in the attic of our old Hilton Pond farmhouse for at least the past two years; however, the snake doesn't spend all its time in the attic since it has to descend for water every now and then. Our third-grader, Billy, enjoys watching it get back to a small entry hole by spiralling up a dogwood tree whose limb extends onto a porch roof leading toward the attic. I'm not about to expel any acrobatic ratsnake that keeps my house free of mice that might otherwise gnaw the socks and heirlooms.

Besides, I've been importing Black Ratsnakes to Hilton Pond over the years to release them in the crawlspace under the house. They have been excellent mouse exterminators, and a pair lives in and around my bird banding shack. This structure also houses my stock of sunflower seeds, cracked corn, millet, and other bird food, and I'd probably have a lot of trouble from seed-spoiling rodents without my trusty watchsnakes.

sI have a feeling there are readers who think the only good snake is a dead snake, especially one that eats baby bluebirds. I'd disagree strongly, of course, particularly since those bluebirds wouldn't have been around in the first place if I hadn't manpulated nature and put up an artificial nestbox. Who am I to interfere further with the natural feeding habits of a hungry and resourceful Black Ratsnake?