Silencing tanks and muffling oil wells so a little bird might sing

First, I heard the bird's clear song, loud and low: several staccato notes, then a higher-pitched sound, then a roll of rapid, ringing notes, then an abrupt stop.

Then I saw it, a Kirtland's warbler perched on the topmost branch of a jack pine deep in a forest in northern Michigan - a plump little bluish-gray bird with a blackish mask and yellow breast, the sides of its breast and back sprinkled with black spots.

I was so close, I could see the pulse in its throat as it sang. I was spellbound to have found so rare a bird in the thousands of dense acres of prickly, scraggly jack pines.

The bird sang again and again - a brave song, for the Kirtland's warbler is an endangered species, teetering on the brink of extinction.

Only 200 singing males were counted in the 1982 spring census, with a comparable number of females assumed to be quietly nesting nearby. That's less than half the number there were in the '50s and '60s, and devoted followers worry that without care, this native Michigan bird could disappear altogether.

About 10 years ago, a Kirtland's Warbler Recovery Team was organized as a cooperative venture of Michigan's Department of Natural Resources (DNR), the US Department of Agriculture's Forest Service, US Fish and Wildlife Service, Michigan Audubon Society, and private citizens who offered their expertise. The team is headed by retired DNR biologist John Byelich.

The team has been so zealous in protecting the warblers during their nesting season that it commands nearby oil well drillers to muffle their machinery. Army tanks on maneuvers from a Reserve training camp must be rerouted so the bird won't be disturbed.

That's a lot of authority on behalf of a little bird, but the DNR's Raymond Perez, a wildlife habitat biologist in charge of the warbler program in the Grayling area, says it's worthwhile.

''We won't know the results of much we are doing for another 10 years,'' he says, ''but when do we decide to act before it's too late? We've lost so many birds, plants, and animals already for failure to act soon enough. Personally, I would like to see this little bird make it.''

The Kirtland's warbler (Dendroica kirtlandii) breeds in only one range in the world - a six-county area in Michigan about 100 miles long and 60 miles wide in the upper middle and eastern portion of the lower peninsula.

Recovery team projects are carried out on almost 128,000 acres of state land and in the Huron-Manistee National Forest. Here, the arid, sandy soil yields the special habitat the warblers require for breeding - dense stands of jack pines. For this reason, the birds are frequently dubbed jack pine warblers.

But there is a complication: The warblers will build nests only under the protecting limbs of the low-growing branches which the trees sprout when they are from 4 to 18 feet tall. When the trees get older and taller, the low-growing branches disappear and the warblers leave.

But were can they go? They can't just move ''next door'' or to ''another subdivision'' like displaced householders, because new stands of jack pines with low-growing limbs haven't been available in recent years.

The only way jack pines reproduce is through fire, which heats their rock-hard cones, causing them to explode and disperse their seeds. This gives the bird another name - bird of fire.

During the early lumbering era in Michigan, this was no problem. Loggers routinely took only the trunks of trees and burned off the branches and cones (slash) left on the ground, so new stands of jack pines were continually springing up. With the passing of this era, however, and with greater control over forest fires, the jack pine population began to shrink, and so did the warblers that nested under them.

To remedy this problem, the recovery team carries out a systematic program of ''controlled burns'' under the supervision of the US Forest Service, which has the best firefighting equipment for the job. The burns are usually done in the spring and fall.

''We have commercial loggers cut the timber, so no trees are burned,'' Mr. Perez explains. ''They leave the slash where it falls and when wind conditions and the humidity are right, we burn the slash and do some replanting. The plan is to have new growth in each area every 10 years. Then when jack pines in one area become too tall, there's a neighboring area the birds can move to.''

Always cautious, the team is even more so since a burn two years ago in the Mack Lake area was suddenly fanned by high winds. Before it was brought under control, it burned 25,000 acres including oak and aspen forest, destroyed some farms and cottages, and took the life of a forest service biologist. Public reaction was swift and angry.

''In the DNR alone, we've carried out about 30 burns successfully in the last 15 to 20 years,'' Mr. Perez explains. ''Some were in large areas, some small. Most have been since the '70s, with four to six a year at the most. There's no doubt the Mack fire deeply affected us. We've done a few burns since without complaints. If we don't continue the burns, of course, we could lose the birds.''

There are other threats to the Kirtland's warbler besides the loss of its habitat. Early investigators found that the parasitic cowbirds often laid their eggs in warbler nests. The cowbirds hatched first, and being bigger and more aggressive, took the most food. Then, for example, instead of four warbler fledglings in the nest, only two might survive.

The recovery team devised a cowbird control program supervised by the US Fish and Wildlife Service which sets up 15-foot-square wire cages throughout the nesting area to trap and hold cowbirds when they swoop in for the food and water provided for them. Since this program began, cowbird eggs have rarely been found in warblers' nests.

''Because the birds are easily startled by noise and will desert their nests if they are inadvertently disturbed by people, we post and patrol the area from May 1 to Aug. 15,'' Mr. Perez explains. ''Then, when the birds have left for their wintering grounds in the Bahamas, we return the area to the recreationists - hikers, hunters, snowmobilers, and cross-country skiers, though we still supervise it.''

Another project involves the taking of an annual census of the Kirtland's warblers in early June, during the peak 10 days when the males sing their loud and persistent songs to signal the defense of their territories during courtship and nesting.

During this time, experts say there is an 85 percent probability that a territorial male will sing at least once during any five-minute period between sunrise and 11 a.m., in good weather. The song can be heard up to a quarter of a mile away under ideal conditions. The birds spread themselves out from one another so separate birds can be easily distinguished; and since there are most often slight variations in their calls, experienced census takers can pick out the same bird from year to year.

Studies of banded warblers show they return to the same general area every year, often to the same mate. This, too, makes the census more reliable.

Dr. Ted Black, a retired DNR biologist in Okemos, Mich., is one of the volunteer census takers who assist the government agencies. He has participated in almost every census. He credits famed ornithologist Harold Mayfield of Toledo, Ohio, with the census concept, explaining:

''Harold Mayfield felt that since the Kirtland's warbler has a distinct, loud song and breeds in big, loose colonies under scrubby jack pines on burned-over land, it would be possible to count their entire world population - and it is.''

The census in Kalkaska and Crawford Counties, under the supervision of Raymond Perez, is taken in six warbler management plots. About six persons from the DNR and the US Fish and Wildlife Service, plus volunteers like Dr. Black, walk through each plot, following aerial maps with x's marked where sightings were reported in previous years.

There is always a special tension until the results are announced for all six counties by the DNR's L. A. Ryel, who directs the total census effort. In 1961, the tally was 502 pairs, based on that number of singing males who were heard. The number gradually dropped to a low of 167 pairs by 1974. Then, as recovery operations took hold, it was boosted to 242 pairs in 1980. But it was 232 in 1981 and 200 pairs this year, a 14 percent drop from the previous year.

Funding for the recovery program is in jeopardy. Federal matching funds were put back to $150,000 this year, matched by $50,000 from the state in the form of personnel allotted time to plant jack pines. The outlook is for still deeper cuts. The state DNR's annual appropriation for endangered-species programs is $ 60,200 from the fish and game protection fund, just enough to maintain an office with one staff member and a secretary.

That's not much, officials say, for such an extensive program which receives so much support and enthusiasm from the public. Last spring, over 1,000 wildlife enthusiasts participated in free, guided warbler-watching tours conducted by personnel from the DNR office in Grayling and the US Forest Service office in Mio. ''We get people from all over the world on our tours,'' Mr. Perez says. ''About 99 percent see birds. We also give talks to schools and civic groups through the year. People respond. They care about this little bird and its fight for survival.''