Like many New Yorkers, I love the magnolias and cherry blossoms that drape the city in spring. But for me, the parks’ yellow sprays of spicebush, rubbery red skunk cabbage, and the conquerees of red-winged blackbirds are my favorite harbingers of the season.
Last Saturday, Sarah and I went to Alley Pond Park for the start of spring migration. We found the woodlands waking to the calls of spring peepers, and spied a few early migrants, including an eastern phoebe and two pine warblers—one with bright breeding plumage.
When living in the age of eBird, where rare birds are charted in digital wilds, we can easily forget to allow nature to be our guide. Neither of us expected to see a life bird that afternoon, so we were very fortunate when we stopped to take a second look at the birds foraging in the shallows of Decadon Pond. They were black, but with brown brindling and startling yellow eyes. They had buffy eyebrows and the voices of droids. They were rusty blackbirds.
I know that rusties are not uncommon in New York City’s parks, but had never seen one, myself. They are seasonal visitors—some overwintering, others stopping over on their way from Southern swamps to their breeding grounds in the Canadian muskeg. They are also among the most rapidly declining bird species in America. Using the Audubon Christmas Bird count and Breeding Bird surveys as a reference, scientists estimate that their numbers have declined by staggering 85% (or more) since the mid-1900s.
The reasons for their plunging population are poorly understood, but habitat loss is suspected as a primary cause. Other North American blackbirds have adapted to diverse breeding habitats and even flourish near human settlement, where they feast on waste grain in fields and pastures. In contrast, the rusty blackbird is reliant on secluded forest wetlands. In the southeastern US, wetlands sheltering overwintering birds have been fragmented by logging and agricultural development, while breeding habitat in Canada has been degraded by oil sand mining.
Of additional danger is the blackbird’s breeding diet, which consists almost entirely of aquatic snails and insect larva. Not only are these species vulnerable to pollution, but they also accumulate toxic methyl-mercury, which threatens developing young.
The small flock in Alley Pond Park were lively, giving bubbly calls and eagerly flipping wet leaves and rooting in the mossy bank of the kettle pond. We submitted the sighting via eBird to the Rusty Blackbird Spring Migration Blitz, an initiative of the International Rusty Blackbird Working Group. I am crossing my fingers that we will see them again next year.