The killdeer, an interesting and atypical plover that nests in coastal open areas with sparse vegetation, is one of my favorite birds. I devoted a column to this species back in March 2021. So when Tanya Stum, a frequent walker around the Oak Bluffs waterfront, notified my employer on May 12 of a killdeer behaving strangely on the hillside overlooking Sunset Lake, I wasted little time in responding.
While BiodiversityWorks may be best known for its work protecting state and federally listed shorebirds and terns (the killdeer has no special legal status beyond that afforded to all migratory birds), we lend a hand where we can.
The behavior Stum described, a seemingly distressed or injured bird calling piteously and limping along, means only one thing: An actively nesting adult bird with eggs on the ground, or chicks, is protecting its offspring by trying to lure a perceived threat away. Called a “distraction display,” this is one of the many behavioral tools that shorebirds use to protect their vulnerable young.
I quickly determined that the land the bird was on is in an Oak Bluffs park, and I called the Parks and Recreation Department to ask permission to provide some protection for the birds. A quick return call from Tony Lima put me on my way to Sunset Lake to find the nest and erect some fencing around it as a buffer against people and dogs.
Killdeer are not subtle birds, and finding the nest took about 20 seconds; a binocular scan of the area from which Stum reported the birds revealed the head of a sitting plover sticking up above the closely mown grass. While their choice to nest in such a heavily used park may seem strange, it’s worth remembering that the birds arrived in late March or April, when human activity here was limited. At the time, the sparse, low vegetation promised ideal nesting conditions for this species.
A salient fact of shorebird reproduction is that the young are precocial — that is, they hatch already covered with down, and within hours of hatching are fully mobile, leaving the nest to begin exploring and foraging under close parental supervision. Having a mix of eggs to incubate and mobile young to tend would overload the adults, so shorebirds generally begin incubating only after they’ve laid all their eggs (almost invariably four of them, in the case of the killdeer). Deferring incubation ensures that all the young hatch almost simultaneously.
These eggs hatched between my visit on the morning of Sunday, May 18, and the following morning, when I found the nest empty, without even eggshells to mark its location. Initially discouraged, and assuming the nest had been predated, I was relieved to find both adults defending three lively chicks as I walked back to my car! I left the fencing up, figuring the birds might regard the protected square as a safe refuge.
From the sparse, open grassland of the hillside, the adults moved their chicks into the yard of an unoccupied seasonal home on Greenleaf Avenue, where Chris Seidel, the cartographer and Geographical Information System (GIS) wizard for the Martha’s Vineyard Commission, relocated them. All three chicks survived a wicked coastal storm on May 22, and the next day, seeing that the birds showed no interest in their former nest site, I removed the fencing.
The family was back on the grassland on May 26, but unfortunately, that appears to have been the last sighting of the chicks. An expanded search of the area a couple of days later turned up nothing.
It’s possible, however, that the family had simply moved. Plover parents often relocate their families to avoid threats or improve food availability, and adult killdeer such as the Sunset Lake pair undoubtedly have a detailed mental resource map of a wide radius around their nest. A move of a half-mile or more would not surprise me.
Barring the rediscovery of the family somewhere in the area, there is no way to know for certain what became of the chicks. They may be happily maturing in some hidden patch of habitat; or they may have been eaten, conceivably along with one or both of their parents, by dogs, raccoons, gulls, or — perhaps the most likely culprit — a flock of crows.
I did, though, hear a high-flying adult calling over Sunset Lake, the adjacent hillside, and the Oak Bluffs Harbor on June 1. Assuming that was one of the original adults, such behavior would be odd if there were still chicks to protect; both adults usually stick close to home, sharing defensive duties. Nothing is impossible. But the most likely explanation for such a display flight is that the chicks and possibly the other adult had been lost, and the displaying bird was starting the process over, claiming territory and advertising its presence to potential mates.
The outcome is sad, but not unexpected. Nest failure is common in birds of all kinds, and is a basic fact of shorebird population dynamics. But although it was unsuccessful, this was a good effort by the adult killdeer, boosted by cooperation from Parks and Recreation, Stum, and Seidel, and many members of the public who gave these birds a little space to do their thing.
