When It Comes to Migration, It’s a Global World

Sep 18, 2019

It’s a global world. You hear that a lot these days, and while this statement has all the keen insight of the equally inane modern cliché “it is what it is”, there is a certain amount of truth in it. And at no time is the natural world more “global” than during bird migration, especially on the Cape and Islands. You could spend an entire middle school geography course studying the countries of origin of the birds that pass through here. 

 


Cumulatively over the years, we’ve hosted off-course birds from Asia, Eastern Europe, and South America, along with birds that got lost trying to get to wintering grounds in Africa, like the Northern Wheatear. But on average, when we’re talking about our normal, work-a-day migrants, it makes more sense to think of it as a hemispheric world.

 

At this time of year, we host shorebirds from the Canadian Arctic en route to Chile and Argentina, and seabirds from Canada to the Caribbean basin and as far away as the southern oceans. Terns staging on our beaches right now come from breeding colonies in all parts of Eastern North America, and are trickling away each day to winter on waters at the mouth of the Amazon, off of Brazil. A Broad-winged Hawk breeding in Bourne could soon be in a cloud forest in the Peruvian Andes.

 

Right now, Blackpoll Warblers are making their way east across boreal Canada, and will soon be fattening up here in New England to prepare for a marathon, often non-stop flight to South America. As a clear reminder of how birds connect us to other biomes across the hemisphere, an outbreak of a single species of insect in remote Canadian forests has resulted in off-the-charts numbers of normally rare Cape May Warblers the last couple of weeks. While one is always a nice sighting, I saw six together at Wellfleet Bay sanctuary last week.

 

And on Monday, a wayward warbler from the Pacific Northwest arrived on the remote outpost of South Monomoy – a Black-throated Gray Warbler. Sporting the somber color palette of a Chickadee but for a bit of yellow by the eye, this species has turned up around here about a dozen times over the last 20 years. Of those records, four have been in Chatham, with three from seldom visited South Monomoy, a federally designated Wilderness Area. Luckily, a group of young ornithologists is staying at the lighthouse and banding birds this fall, where they noticed this prize bird flitting about the few trees remaining on this duney, storm-battered island.

 

The hemispheric connectivity doesn’t just apply to birds - we’re also a crossroads for migrating insects, with southern butterflies like the fast flying, startlingly chartreuse Cloudless Sulphur emigrating northwards along our coast right now, while at the same time Monarch butterflies and dragonflies like Common Green Darners and Black Saddlebags are passing them on their way to Mexico.

 

It’s this connectivity that explains the many partnerships between North American bird conservation organizations and organizations in the Caribbean and Central and South America.  Consider that in the course of a year, a single Whimbrel may spend time in Arctic Canada, New England, the Carolinas, the Caribbean, South America, and Texas. Conserving a species like that takes a holistic, hemispheric approach, with an understanding of breeding, wintering, and key stopover habitats and the unique threats they face.

 

So just remember, when it comes to migration, it’s a global world. Or maybe it’s just “a hemispheric world”. Whatever it is, I can say the following with absolute certainty: It is what it is.