Wednesday 18 October 2017

Harrison’s Point 2017: Blackpoll Fall Out


October normally finds local birders, like myself, combing the wooded areas surrounding the old US Naval Base at Harrisons Point (HP), St. Lucy. This is in search of a bird weighing less than an ounce but has one of the longest and most impressive migrations of the animal kingdom.  These birds, Blackpoll Warblers(BLPW) (Setophaga striata), take off from their breeding grounds, in forests of northern North America from Alaska, through most of Canada, the Great Lakes region and New England, on a  journey  of up to 1,500 miles over the Atlantic to their winter grounds in South America. (See migration map).  A study in the 90s done by McNair, Massiah and Frost at Harrisons Point discovered that the area around HP is an important refueling station along the migration route of these birds.  On normal occasions you may see one or two birds but during bad weather the birds on the ground can number into the hundreds.  This is a phenomenon called “fallout”.  It is when adverse atmospheric conditions interrupt migration forcing birds to the ground.  The study by McNair et al. stated that among other things when the barometric pressure is low around the BLPOs peek migration period - between October 15th -25th - that fallout will occur at HP. Saturday 14th was just that, with a barometric reading of 1012mb (weatherforyou.com) along with winds from the SE and persistence rain.



I left home at 5:45am with my birding buddies, Jason and Sahara (my two children) for the 40 minute drive to HP in the north.  When we arrived, it was still raining and I drove onto one of the new access roads (that’s another story) and parked under a large Tamarind Tree (Tamarindus indica) in hope that it would offer some protection from the rain.  They were many birds around especially seedeaters, like Blackface Grassquits and Barbados Bullfinches who were attracted to the seeding Megathrsus maximus commonly known as Guinea Grass.  Shiny Cowbirds and Carib Grackles were also busy feeding on the grass seeds.  As I exited the car with an umbrella, I caught sight of my first Blackpoll Warbler in the Tamarind Tree.  It was a strange one, something I had never seen until then - this bird was still showing its breeding plumage.  I then saw another, and another and another and by the end of our trip to HP the tally was 15 BLPO warblers and I knew many more were around but after spending one hour  and a half it was time to go. 

I am hoping to visit HP again this coming Saturday. Hopefully the weather is better and the birding is good.

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