Wild Side: The Breeding Bird Survey

The macro view is also informative.


For about 20 years now, I’ve spent one morning every June running the Vineyard’s Breeding Bird Survey (BBS) route. Coordinated by the U.S. Geological Survey, the BBS is a continent-wide, long-term monitoring program for breeding birds. Prompted by concerns over the impact of insecticides such as DDT on bird populations, the BBS was launched in 1965; today, about 3,300 routes are surveyed each year, each one consisting of 50 three-minute stops at predetermined points along a 25-mile route. During each stop, the observer tallies every bird heard or seen within a quarter-mile radius.

BBS observers follow a carefully designed procedure to ensure that results can be compared year to year with confidence. The vast majority of routes are covered by amateur birders like me, contributing their time and skills to help keep an eye on bird population trends.

The Vineyard route runs from Lobsterville around Moshup Trail, along State Road to the Menemsha Crossroad, on North Road back to State Road, down Old County Road, and then east for its final four stops along the Edgartown–West Tisbury Road. In keeping with standardized procedures, I start the route at precisely 4:37 am every year, wrapping it up a little more than four hours later, tired but always satisfied, on the roadside south of the State Forest.

In recent years, finding traffic noise to be an increasing complication, I’ve been running the route exclusively on Sundays. Even so, the last 15 stops or so are difficult because of the number of passing cars — as many as 20 at a couple of stops this year. In an effort to keep my data as comparable, year-to-year, as possible, I try to run my route on the Sunday closest to June 10. This year, though, so as not to waste a perfect weather forecast, I opted to do my survey on the early side, June 5.

The BBS is a very different exercise from birding for pleasure, though it uses the same detection and identification skills. With stops at specified locations, there is no opportunity to poke around in promising habitat: You take what you find. And with only three minutes of active observation at each stop, there is no time to pause and appreciate an especially interesting or well-seen bird. These days, I waste as little time as possible, knowing that any delay at an early stop is likely to translate into more traffic noise at the end of the route. One typically hears many more birds than one sees, so the focus is on instant recognition of songs and call notes, with visual identification being much less important.

Given the constraints of the BBS, most of what I find tend to be common species, birds numerous and broadly distributed on the Island. Finding a true rarity is almost unheard-of on a BBS, though each year, it seems, produces a few mildly unusual birds. This year, the highlight was a blue-gray gnatcatcher, singing from a wet thicket near Priester’s Pond. It’s the first time I’ve tallied this species, which is an uncommon migrant and very rare breeder on the Vineyard. But it’s a species that has increased dramatically in Massachusetts in recent decades (though the Cape and Islands appear to be lagging behind on that score). So finding one on a BBS was probably an overdue event, and this is a species I anticipate finding more regularly.

Whether this individual was actually breeding is a good question. The date suggests it (gnatcatchers are rather early migrants, and you’d expect the transient ones to be gone by now). And the habitat was suitable. But my gut reaction is that it was a lingering migrant, singing in promising habitat in an increasingly desperate attempt to find a mate. In any case, I’ll check the spot in a week or so and see if it, and possibly a female, are present.

Unfortunately, most of this year’s other surprises were depressing ones. For instance, I failed to hear a single wood thrush, once a species I could expect at three or four up-Island stops. This melodious singer is declining in much of its range, with the drop in numbers across the Cape and Islands especially pronounced. Part of the problem is likely on the tropical wintering grounds of the species. But wood thrushes prefer large tracts of unbroken woodland, and the loss and fragmentation of habitat due to residential development is likely driving much of the local decline of this species. I worry that the wood thrush’s days are numbered as a regularly breeding bird on Martha’s Vineyard.

One day in the field, of course, only tells you so much. The whole point of the BBS is its scale, with many years of data across a huge geographical area. But still, doing this survey takes me through a lot of habitat, and represents two and a half hours of focused observation. It’s a high point of my year because it offers a chance for a very broad look at what’s up with Vineyard birds.