Warbler wrapup, Spring 2020

I made a discovery this spring: the more time I spend in my yard, the more warblers I see.

In years past, I've worried about declining warbler numbers, at least as they manifest locally.  I've blamed house sparrows, and while it's true that sparrows compete with warblers for food, and on occasion harass them, I've come to doubt that there's a tight linkage between the number of sparrows and the number of warblers that pass through.  There are a ton of other factors that affect how many warblers I see, starting with level of effort, of course, but including such things as weather, overall population numbers, and even local vegetation patterns (for example, this last year I lost my apple tree, which was a bit of a bird magnet).

Just taking what I saw in and from my yard, I counted the following:

Black and white, 10
Black-throated blue, 2
Cape May, 2
Magnolia, 2
Ovenbird, 6
Northern parula, 1
American redstart, 3
Wilson's, 1
Yellow, 3
Common yellowthroat, 9
Yellow-rumped, 1

There are a few others I was unable to identify, or only heard singing, and some of these birds may have been continuing birds that got counted twice, but in general, I feel like this was a pretty representative year:  11 species, across five genera.  Ovenbird was the curtain-raiser, on May 3, and American redstart brought the season to a close on June 1 -- rather later than usual.

I also spent some time at the Mystic and Alewife Brook, and saw some species there that I didn't see in my yard:  chestnut-sided, prairie, and Blackburnian.

All taken in all, I saw the species I expected to see, with a few exceptions:  blackpoll, palm, and pine.  And I even added a new one for my Somerville list, in Blackburnian warbler.