each year, billions of birds undertake a long journey between distant habitats in order to breed. the coolest part, to me, is the fact that you can observe this phenomenon from basically anywhere.
let’s get the self indulgent part out of the way: i’m writing this post because, on top of needing it to build my newsletter’s lore, i recently spotted my apartment’s hundredth bird species since i started keeping track, a cape may warbler. some of these birds i’ve seen because i live between two patches of good habitat (prospect park and new york harbor) and i have old native oak trees on my street. but the vast majority of those birds weren’t commuting from the park to the sea, or stopping to feed in the trees; they were just flying over as part of their migratory journey.
birds migrate to and from every single continent, even antarctica. presumably, they do this because they have wings, and they can use those wings to find a more favorable place to feed or raise their young, based on resources or competition changing as the seasons change. they seem to use instinct, geographical cues, the stars, and even the earth’s magnetic field to navigate during these treks.
you can observe migration passively by simply noticing the birds around you. some of the most common birds disappear in the autumn and reappear in the spring. laughing gulls—the abundant black-headed seagulls of the us east coast—depart nyc in the fall to winter in the gulf of mexico and the caribbean. in the winter, white-throated sparrows move in, singing their awkward songs from basically any green space they can find.
you can watch migration actively, too, with just a little bit of planning—by tracking the winds. winds from the southwest in spring give northward-migrating birds a boost and push them into nyc. northwest winds in fall do the same, with the added effect that they push some birds to coastal long island, forcing them to retrace the south shore beaches westward back to the mainland.
when i first started watching birds from my apartment window, i focused on the conspicuous migrating hawks. they’re most active during midday, relying on pockets of warm air called thermals to help them float effortlessly along their journey. but once i got permission from my upstairs neighbor to start going to the roof, i unlocked a new kind of migration: morning flight. many songbirds migrate at night—but when the sun rises, they descend to find a refueling spot. those that find themselves over the ocean must reorient and head back to the closest point of land. on a day with good winds, i’ll head up about 15 minutes before sunrise to just look up and listen.
bird migration can be hard to predict, but there are tools that make it easier. migrating birds show up on doppler radars, and cornell’s birdcast uses weather forecasts plus machine learning to make predictions of how many migrants there’ll be each night, where migration will be good, and even gives you a dashboard to see how active migration is over your county.
once you start noticing the birds flying over, the biggest challenge is figuring out what species they are. but there are hints. as songbirds migrate, they make repeated flight calls, probably to signal themselves to other birds they’re migrating with. you can recognize many of these calls with practice: robins make a “rup rup rup” kinda sound, grackles go “chuck chuck chuck,” and goldfinches say “potato chip,” for example. many also have a distinctive shape and flight style, and birdcast will tell you which species are most likely to be flying overhead on a given day.
migrating birds tell a totally different story than birds on the ground. bald eagles are a spectacle when they show up in a nyc park, but from my roof, they’re a pretty regular migrant. bobolinks may prefer grasslands, but they have to fly over apartments to get there. uncommon or scarce nyc birds like rusty blackbirds, red-shouldered hawks, and even dickcissels are basically a guarantee if you keep your eyes and ears open at the right time. i also encounter tons of migrating insects like green darners and monarch butterflies.
of course, there are better places than your roof to observe these birds, places that concentrate migrants into small patches of habitat. in nyc, that includes city parks, coastal locations, and narrow spits of land—or the ground in front of big glass buildings, since small birds can’t tell the glass from the sky, crash into those buildings, and often die. elsewhere, people swear by patches of trees in otherwise treeless spots, basically any habitat that juts out into the sea or into a patch of inhospitable habitat, breaks in mountain ranges, etc.
but people watch these birds from everywhere. i recently wrote about the foreman’s branch bird observatory in maryland which censuses migratory birds in pretty unassuming habitat. check the ebird profile for any migrating bird species and you’ll see them widely distributed, often in habitats that are very different from their preferred breeding or wintering habitats.
in short, if you look up long enough you’ll eventually see cool birds fly over. and i kinda wish more people knew that birds are migrating everywhere, not just over good habitat, and actually used that info to make the world a safer place for those birds.
postscript:
i have lots of nature walks i’m leading this week!
sept 6 i’m leading a free walk at prospect park at 5:30pm, meeting at the stranahan monument, going til 7pm. my friend efua is also leading a walk at central park at 5:30, meet at w81st and central park west.
sept 9 i’m leading a free walk at riverside park in manhattan, meet at 120th and riverside drive at 5:30pm, going til 7pm.
sept 10 i’m leading a free walk at the marine park salt marsh nature center in brooklyn, meet at the flagpole just west of the visitor’s center at 10am, going til 11am.
and here’s a very cute video of a stuck semipalmated sandpiper