A tributary flows into the Canterbury Brook next to the Boston Nature Center in Mattapan. Trash from storm drains and other sources covers its banks. Photo by Pete Stidman

On March 23, 1901, a letter from a young man who grew up in Uphams Corner was printed on the front page of the weekly newspaper the Dorchester Beacon. "Save a few free fields, save a few of the beautiful woodlots," wrote Frank Birtwell from Albuquerque, New Mexico. "Let the flowers bloom."

He seemed homesick, and described his favorite Dorchester nature spots at length. Birtwell's voice was part of a growing preservationist movement, echoing into a city building over its remaining wilderness at a breakneck pace. He once led the charge against the house sparrow, an invasive species, under Mayor Josiah Quincy III. The Beacon's editors no doubt appreciated his message, but it was the last letter he wrote to his hometown paper.

"He was considered at that time to be one of the great upcoming naturalists," said Dan L. Fischer, 75, author of 'Early Southwest Ornithologists, 1528-1900.' "Elliot Coues, probably the most prolific writer in that period on birds, thought he was fantastic."

Ornithologists like Birtwell were not timid fellows with binoculars and cameras hanging from their necks at the time, hiding in bushes and making fervent notes in spiral notebooks. Back then, bird-geeks packed rifles. They shot the birds they were interested in and stole their nests, eggs and all.

"There were all these guys trying to find birds and new species and they went to a lot of effort to do so," said Fischer.

The eggs of a buff-breasted flycatcher or a yellow-rumped warbler might send them out on branches a squirrel would weigh down, reaching with one hand, gripping a rope with the other. More often than one might think, curious ornithologists died in the line of duty.

Birtwell fared well while still in his hometown, however. He was a native of London who came to Boston at an early age, eventually attending Roxbury High School and later the Bussey Institute at Harvard University. He mother Rosina brought him up with five brothers and sisters in big house at 80 Glendale Street - now standing empty after a recent foreclosure.

The Back Street Woods, no doubt a childhood haunt of his, was what he argued to save in his last letter. The old span of those woods includes what is now the Boston Nature Center, but also rolled out to Blue Hill and Morton Streets and likely on up to the borders of Franklin Park and the Forest Hills Cemetery.

"These woods are a grand temple," he wrote, "finer far, than man ever fashioned. None such fretwork was ever carved in stone nor placed on ceiling; such vaulted arches and aisles defy effort, and the mosaic carpet - ferns, mosses, leaves and flowers, mixed in that delightful confusion only possible to wildness - makes a floor as grand as it is beautiful."

The floor of the swamp in the heart of what remains of the Back Street Woods was covered with a thick layer of plastic trash this week: water bottles, candy wrappers, even a car bumper and a basketball. The state-owned Canterbury Brook carries the debris in during medium to heavy rains from storm drains and other sources throughout the watershed, said BNC director Julie Brandlen.

In Birtwell's time, the brook ran right through the watershed, but now channeled, the brook sees daylight beginning in a spot near Morton and Harvard Street (known as Back Street in 1901). It then travels through the BNC and along American Legion Highway into Roslindale, where it eventually disappears again near a Scrub-a-Dub Carwash.

The Boston Water and Sewer Commission (BWSC) is looking into flooding problems in the area, spokesperson Tom Bagley told the Reporter. Bagley added that they would also look into the trash in the brook. BWSC chief engineer John Sullivan was out of town at press time.

"They've done a good job helping us get this brook as clean as it can be," said Brandlen about the city agency's efforts to catch the debris in special grates, admitting that the brook still isn't very clean at all. To address the problem, she has applied for grants to hold a water summit that would bring together state and city agencies and neighbors to discuss ways to improve the brook's hydrology and water quality.

Despite having to share space with discarded soda bottles and popsicle sticks, mallards, great blue herons and wood ducks do occasionally take to the water, and dozens of species are still attracted to the area, even if only for a moment's rest.

"The loss of breeding species is amazing, not unexpected, but amazing," said Andrew Birch, an avid birder in the area and former BNC employee. Birch read Birtwell's description, which cited around 25 bird species, with great interest. "No longer are these breeding grounds, they are considered migrant traps," said Birch. "Exhausted, they look down on this concrete jungle and see one green spot. These birds funnel into these small park areas. It's a bonanza for birders."

At the Nature Center, 159 different species have been sighted since 1999, said Brandlen. The heaviest migration month is May, but early arrivers can already be seen.

"We've got the grackles coming through, the brown-headed cowbirds and the redwing blackbirds," said Birch. "I saw my first Eastern phoebe this weekend."

If his writing can be taken for evidence, Birtwell would be horrified at what the Back Street Woods have become. "Let the reader himself go afield - go before too late," he warned the neighborhood, "before the bird and plover haunts of Dorchester are of the past. They are going quickly and the city draws nearer - good, in its place, but never as the idol and complete sphere of existence."

Birtwell might have stayed on to protect "the fairest spot in the world" personally, if it weren't for a discovery he made while studying a pair of screech owls he had captured. He was trying to prove that their feathers changed color based on their diet, without molting. He was way off base there, according to today's science, but he did find that he had contracted tuberculosis.

He was forced to cut his studies at the Bussey Institute short in 1899, leave Harvard's esteemed Nutall Ornithological Club, and set free the one owl that still lived under his care. In New Mexico, he could benefit from fresh, dry air, said to be good for his disease.

After two years of study in his new home, he began working on his thesis "The Ornithology of New Mexico," at the Territorial College of Agriculture. This, of course, involved a great deal of gawking at birds.

One such bird was the evening grosbeak. The e.g. is a large, robust finch that nests in conifer forests. The male bird is bright yellow, the female grey with a yellow neckband. It was his interest in this bird's nesting habits that brought Birtwell to his doom.

Birtwell went bird hunting with his new wife Olivia Morton, who he had married in May, 1901. It was she who copied and completed his final notes for an article in The Auk, which ran in the same issue as his death notice.

"Our last finds to-day were the most important I have ever made, ornithologically," wrote Birtwell June 20, noting the discovery of a trio of nests perched high in the pines behind the couple's cabin. "The climb is risky and I am married. Unless I am forced I shall not attempt to collect the set but will secure specimens of young later on."

Yet he couldn't resist. He collected two nests with eggs, the second of which he carried in his teeth while suspended from a rope 40 feet from the ground.

The third nest was higher, and when Birtwell called for help from 75 feet up, according to his New York Times obituary, his wife ran for help. Two men tied several short ropes together and tossed them up to him. He fastened the rig over a limb and began to descend, but one of the knots in the rope got caught in the fork of a tree branch. He jerked one arm out of the loop while attempting to free the knot, and "the rope tightened around his neck. He was unable to lift his body… and slowly strangled to death."

He died June 28, 1901, at 21.