These are strange times indeed for birding on Cape Cod. Seasonally confused times. While the expected winter fowl have arrived on schedule with December, and Snowy Owls are setting up shop on our increasingly chilly beaches, it’s still possible to find Neotropical warblers, tanagers, and grosbeaks that should have departed for Central and South America two months ago.
Winter and summer are colliding in the beaches and thickets of the Cape and Islands. So what exactly is happening?
About a month ago, I talked about something called “reverse migration”, a phenomenon that brings unsuspecting migrating birds far north of their intended destination. It happens when a cold front moves though the southeast concurrent with northwards tracking low pressure offshore, which happened twice back in October. Birds in Florida were enticed to migrate by the light northwest winds associated with the cold front, only to get caught in a northerly flow offshore, eventually finding themselves a couple of days later in coastal New England or Nova Scotia instead of Belize or Columbia. The Cape was loaded with these reverse migrants a month ago. The question was, what would happen to these unlucky travelers? Would they pack up and try to head south again? Based on reports from local birders, it’s clear that they are actually sticking it out here in Massachusetts, and setting late date records with every passing day.
A Blue-winged Warbler seen in Eastham this week is the only one reported this side of Cuba in the last couple of weeks, and the Yellow-throated Vireo reported in Falmouth on Saturday is the first December record for this species north of Florida. The list of lost birds goes on – Prairie Warbler, Wilson’s Warbler, Northern Waterthrush, Tennessee Warbler, Northern Parula. A Rose-breasted Grosbeak lingering at Wellfleet Bay sanctuary. White-eyed Vireos turning up left and right. All of these should be rubbing elbows with sloths and monkeys in tropical jungles two or three thousand miles away right now, not shivering their way through a December night on Cape Cod.
Last week, I got to experience a bit of the reverse migration action in my own yard. I looked out my window one morning to see a bright yellow Summer Tanager sitting on a big wasp nest in my front tree, looking quite out of season among the bare branches. Summer Tanagers eat a lot of bees and wasps, including both adults and larvae, so I suspected it was breaking into that wasp nest for a snack. Sure enough, there were big holes in the nest, and the neighborhood titmice were now able to get at the juicy larvae inside thanks to the tanager. So remember this story when you’re going for that can of raid to dispatch a wasp or hornet nest in your yard, and think of the poor lost Summer Tanagers you might be starving. Yeah, my wife probably wouldn’t buy that either.
At the same time were are knee deep in seasonally confused neotropical migrants more typical of our summer months, our wintry visitors have arrived from the north, including Razorbills, Dovekies, and murres, those flying footballs of the northern oceans. All have been seen in Provincetown in the last week, to the delight of winter birding aficionados. And that king of Arctic birds, the Snowy Owl, is starting to show in good numbers on barrier beaches around the area. More on those Snowy Owls another week – it’s shaping up to be an above average year, and I expect there will be lots to say about them soon. In the meantime, please behave yourselves if you look for them, which means don’t trample the dunes or get so close in pursuit of a photo that the owl flushes. I suspect there will be enough owls to go around, so be patient.
And don’t forget to check your local thickets and even your backyard feeders for wayward warblers and vireos, and let me know if you find any. We can’t really get them on the next flight to Costa Rica, but we should at least enjoy them while they’re here.