On Martha’s Vineyard, the conclusion of the Agricultural Society Fair in late August signals the unofficial end of the busy summer season. For the BiodiversityWorks field staff, it similarly marks the unofficial end of the beach-nesting bird breeding season. The transition is most apparent on the 22 beaches we monitored this summer: these beaches are now largely inhabited not by the breeding species we monitor (piping plovers, least terns, American oystercatchers, etc.), but by migratory species travelling through from their breeding grounds further north (like the black-bellied plover, dunlin, and dowitcher seen below), some coming from as far as the Arctic Circle.
Photo: Jeffrey Bernier
Photo: Lanny McDowell
Photo: Jeffrey Bernier
Now that the youngest chicks have fledged and our productivity data have been finalized, we can take a step back and summarize the 2025 season.
| Species | Nesting Pairs | Fledglings | Productivity |
| Piping Plover | 60 | 43 | 0.72 (fledglings/pair) |
| American Oystercatcher | 21 | 20 | 0.95 (fledglings/pair) |
| Least Tern | ~170 | ~24 | Poor |
A piping plover fledgling. Photo: David Meen
Piping Plover:
This was a poor year for the piping plovers we monitor. 0.72 fledglings/pair is the second lowest productivity we have seen since BiodiversityWorks began in 2011. Last month I wrote about the ill-timed Nor’easter and the challenges faced by all the plover families forced to restart in the wake of that storm. These challenges, compounded with high levels of predation on re-nests, resulted in our highest number of nests lost (70 nests) and a chick survival rate (0.45) slightly below our all-time average (0.48).
Another point of interest is that 60 nesting pairs is the most BiodiversityWorks has ever monitored (and by a large margin: the previous record was 49 pairs, last year). While this is certainly an encouraging sign, we want to temper our excitement. With the high incidence of nest loss this season, some of these pairs likely included adults who experienced unsuccessful nest attempts elsewhere and decided to swap sites and/or mates midway through the season. These movements, which are hard to detect on unmarked birds, could inflate pair numbers. In fact, this past June we recorded a banded plover swapping sites, the subject of this blog post.
A banded American oystercatcher with a fledgling. Note the fledgling's bi-colored bill. Photo: Lanny McDowell
American Oystercatcher:
Oystercatchers generally nest slightly before piping plovers, and as a result many pairs had already hatched their first nest attempts by the time the big Nor’easter hit our shores in late May. Most of the precocial chicks, though very young, were able to navigate the high winds and tides of the storm. As a result, the oystercatchers we monitor fared better than the piping plovers. A productivity of 0.95 fledglings/pair is right in line with our all-time average (0.93 fledglings/pair), and 20 fledglings is the second most BiodiversityWorks has seen since 2011 (our record is the 31 fledglings recorded last year).
A least tern with a nearly fledged chick. Photo: Jeff Bernier
Least Tern:
Least terns nested at eight of the 22 sites we monitored this year, though only six of these sites actually hosted colonies (Lambert’s Cove and West Tashmoo each had one solo nesting pair). These six colonies ranged in size from seven to 93 nesting pairs, and only two of these colonies managed to fledge any chicks (Lighthouse Beach and Little Beach). The colony at Lighthouse Beach might have been the highlight of the season for me, as the 14 pairs there fledged at least 18 chicks and was the most successful tern colony I have seen since I joined BiodiversityWorks in 2022.
There is much more to our conservation work than the direct monitoring of birds on our beaches that I discuss here. We collaborate closely with other beach-nesting bird programs on the island; we feed detailed reports to regulatory agencies; and we work closely with ornithologists up and down the western Atlantic flyway to study bird populations and movements. But the time we spend on our beaches, tracking and protecting the birds we're responsible for, remains a central part of our organization's work. And it's as rewarding as it is challenging. Each season is unique, and even as we're closing the books on 2025, we're learning everything we can from this year's results as we start to prepare for the coming season.
