Migrating Birds Are All Around

Aug 14, 2019

 

Credit Scott Heron / bit.ly/2P7sPcx

Almost exactly a year ago, the bird report was about a rare stowaway on a boat off the Cape and Islands, a Brown Booby that hitched a ride on a boat heading into Mnemsha on Martha’s Vineyard. Last weekend I received a text message from naturalist and local radio personality Dennis Minsky letting me know that history had repeated itself, sort of, when a Brown Booby landed on a whale watch boat somewhere off of Provincetown. This bird, perhaps a young adult, spent a half hour sitting atop this boat packed to the gills with people, providing an extra treat for the bird-oriented folks aboard.


Brown Boobies are a warm-water relative of our familiar Northern Gannets – both dive for fish in spectacular fashion, with Brown Boobies hitting the water at a shallow angle rather than straight down. They’re widely distributed in the world’s tropical oceans, which do not include the Gulf of Maine last I checked. There were only four records of this species in Massachusetts prior to about 8 years ago. But starting in 2011 with a long-staying bird first discovered in Dennis, Brown Boobies have turned up more years than not, and it’s hard to say why. While ocean waters, especially those in the Gulf of Maine, have been clearly and rapidly warming, I’m not sure this explains the sudden increase. It could be that a couple of birds that first turned up as juveniles later returned as adults, thus inflating the records a bit.

 

Even so, there’s no question that Brown Boobies have gone from near zero to near annual in a very short time. Could there be a population boom going on? Probably not – researchers estimate that populations have declined by as much as 90% over historic levels thanks to human disturbance and introduced predators on their once remote nesting islands. Maybe it’s a food thing – Brown Boobies are especially fond of flying fish, those fantastical bird-fish chimeras that glide over tropical seas. It could be that flying fish are increasing in the Gulf Stream and, more importantly, the warm water eddies it spins toward shore. Incidentally, these eddies bring young tropical fish to our inshore waters, things like Snowy Grouper and Spotfin Butterfly Fish – these are the rare vagrant birds of the fish world.

 

Whatever the reason Brown Boobies are showing up here, you now have a higher chance of finding one somewhere around the Cape and Islands than you did 10 years ago, so look sharp at any gannet-like seabirds that don’t seem quite right.

 

Back on terra firma, some other southern, fish-eating birds have been turning up several places, mainly Little Blue Herons, Yellow-crowned Night-Herons, and a young Tricolored Heron that showed up at Forest Beach in Chatham. These skinny, colorful herons are among the rarest of the southern wading birds here. Little Blue Herons, small dark wading birds with a two-toned bill, are uncommon but more expected, and have been sighted five different places from Sandwich to Wellfleet this week. Young birds are white and closely resemble much more common Snowy Egrets, but a shrewd birder will check the leg and bill color to tell them apart.

 

I’d need a lot more time to cover everything going on in the bird world right now, but whether you’re here for that week that you look forward to all year, or you’re a local like me, you should make a point to get out on an organized birding tour, a whale watch, a seal cruise, or just on your own, because the Cape and Islands are awash in migrating birds and marine creatures from literally all corners of the globe right now. I guarantee you won’t regret skipping one more morning at the beach to take in this fleeting wildlife spectacle while it lasts.