Reflections on the century

Friends, there it is, the 100th species on my Somerville list:  the swamp sparrow. When I last wrote about the state of the species list, in February of this year, I had 71 species on the list.  At that time, I reckoned it would take me another six years to reach my goal of 100.  Instead, it took me not much longer than six months.  (And in fact, since I got to 100 with my dear friend the swamp sparrow, I've actually gotten three species more -- belted kingfisher, pied-billed grebe, and Cooper's hawk, plus eastern wood-peewee, misclassified earlier.)

So what to think about this?  Does it turn out that Somerville is actually a birder's paradise?  Even though, according to the Charles River Watershed Association, fully 77% of Somerville is paved over?

Well, the satellite doesn't lie.  There is precious little green in Somerville (and ironically enough, the largest green patch on this map has since been paved).  Here's a data point to consider:  at Mt. Auburn Cemetery (visible a bit below Fresh Pond on the lower left), there have been 218 species recorded, according to eBird.  It's nice and green there.  But it also has to be said that people -- and competent people at that -- have been looking much harder and longer in Mt. Auburn than they have in Somerville.  So forgive me if I think that 100 (or 104, really) isn't too disgraceful, given the material I have to work with.

In other words, while Somerville might look entirely hopeless from a birding perspective, it actually isn't. Its saving graces number no more than two, but they're important.

The first is the Mystic.  Degraded as this river is, and though mostly man-made in its current form, it still offers aquatic life, animal and vegetable, on which a certain number of birds depend.  And, because in Somerville the Mystic has both a freshwater and a saltwater piece, it serves two different bird populations, both of which have a large migratory component.  So as birds move south, or range up and down the coast in winter, the Mystic offers a sheltered stopover where they can rest and feed.  Further, the fringe of vegetation on the river bank, though rarely more than ten yards wide, gives shelter to a surprisingly large range of birds -- particularly various species of native sparrows.

The second saving grace is the migrant-trap effect.  Because Somerville, and the adjoining towns, are so paved, the few spots of green tend to concentrate migrants as they pass over.  This phenomenon is the secret to why Mt. Auburn sees so many species; but it's true for us as well, though to a much smaller extent. Prospect Hill, both the park and people's yards adjoining it, is the salient example of this phenomenon in Somerville.  The bike path, to a limited extent, has the same function, as does Alewife Brook.

Now, don't think I'm talking up Somerville as a birding destination.  It just isn't, particularly since within five miles of Somerville there are a number of vastly more plausible and rewarding birding destinations.  But for those of us who live here, there's something to be said for appreciating what we've got.

And what we've got, at the current hour, is 104 species.