Drake Canvasback at Fresh Pond on November 8, 2011. Photograph by the author.
Fresh Pond in Cambridge, Massachusetts, has for decades been a reliable location for urban birders to see many species of waterfowl during the autumn migration (Robinson 1975, Barton 1995). Notably, Fresh Pond has been perhaps the best place in all of New England to see Canvasback ducks (Aythya valisineria), particularly at close range (see photo). When we first arrived in Massachusetts from San Francisco in October 1988, one of the first places my wife Kathleen Buckley took me was Fresh Pond. On this first walk around the pond, we saw dozens and dozens of Canvasbacks, a bird I have loved to see since I first encountered them on the lakes near my hometown of Spokane, Washington.
Since that first trip in 1988, I have returned every autumn to Fresh Pond, always coming on multiple days to observe the migration. During these almost thirty years, I, along with many other observers, have noted that the number of Canvasbacks has gradually dropped so that in the past three seasons only a handful has been seen. For example, as noted by Rines (2017) regarding November and December 2016:
There was a time when Fresh Pond in Cambridge was one of the best places in the state to find Canvasbacks, with counts over 100 in the 1990s. Numbers have dwindled since then, with only one seen during this reporting period.
This essay describes my attempt to understand why Canvasback numbers have decreased so markedly at Fresh Pond over the last two decades.
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