Migratory Warblers of May

May 23, 2018

Credit skuarua / https://bit.ly/2s4uB3H

It’s the sweetest time of year for us songbird enthusiasts – the warbler wave has arrived. While at least some migrant warblers have been around since late April, starting on Friday, a swarm of at least 24 species of these colorful forest songbirds were reported by local birders over the subsequent four days.

 Assuming it continues, a single morning’s trip to hotspots like the Beech Forest in Provincetown or High Head in North Truro should now net you 15 or 17 species of warbler, most of them fresh in from the tropical forests of Central and South America. But like May itself, most of them won’t stick around long, so you need to enjoy them while you can.

 

So who are these delightful and elusive woodland sprites? When we say warblers here in the Americas, we are talking about a colorful family of insectivorous woodland songbirds, and specifically, the ones that breed in the northern half of North America who mainly winter in Central and South America. In Europe, the family of birds they refer to as warblers are not closely related to ours, and are dull colored and maddening to identify, so the Europeans tend to be jealous of our warblers. Many species have impressive migrations, like the Blackpoll Warbler who migrates from Canada to South America each fall over the Atlantic ocean, often via a 1500 mile non-stop flight. Not bad for a bird that weighs as much as a ball-point pen. In spring, listen for the ultra high-pitched squeaky wheel song of male Blackpolls from oak tops anywhere.

I was very lucky to have some of the more sought after spring warblers passing through my yard over the 4-day migration wave. Uncommon and gorgeous birder favorites like Cape May Warbler, Bay-breasted Warbler, and Blackburnian Warbler spent hours probing the new leaves and flower clusters of the neighborhood oaks. Every birder looks forward to their first good look at a male Blackburnian in May, with its burningly orange throat, and distinctive song that usually ends on a note so high that you almost need your dog to hear it for you. On Monday, my three-month-old son was fairly drooling at the sight of his first Blackburnian Warbler as it foraged in the oak above our deck. Though he’s pretty much always drooling, so it may have been unrelated.

There’s another of our transient warblers with a distinctive enough song that even beginners may be able to pick them out of the crowd, the Black-throated Green Warbler. One of their buzzy songs has a rhythm that sounds a lot like trees, trees, murmuring trees, and another that just sounds like zee zee zee zoo zee. They tend to forage in one spot for a while and sing ad nauseam, giving you plenty of time to learn the song. Just now, as I characteristically struggled to finish this report on deadline, I was briefly distracted by a male Black-throated Green who was singing and foraging at eye level above my deck, picking wriggling little green caterpillars from the clusters of new leaves.

While I’m focusing mainly on warblers that pass through for a limited time in mid-May, a few of them do stick around to breed, and many of those have been on territory for a couple of weeks. Any Cape and Islands woodland hike right now will likely be soundtracked by our two most common forest-breeding warblers, the ubiquitous Pine Warbler, with its short, liquid trill, and the Ovenbird, with its endlessly repeated “teacher teacher teacher”. This odd, thrush-like warbler struts around on the forest floor, where it builds a domed nest, shaped like an old clay oven. The sharp ones among you just figured out how the Ovenbird it got its name. 

There are a couple of other locally breeding species that I’ll cover another time – I don’t want to distract you from seeking out the ephemeral, living jewels of the treetops that are the migratory warblers of May.