Wednesday, May 15, 2013

Spring migration begins!

We have had a very difficult spring in terms of passerine migration across all of Connecticut. In 2012 and other recent years it seemed that the beginning date for heavy migration of neotropical birds was somewhat around April 20 with the bulk passing through by May 20. This year we have had very little moving into our state except breeding birds returning to territory. This is partly because we have had a normal April in terms of temperature unlike the previously mentioned last year where it was much above average. The other aspect coming into play has been the constant easterly flow overwhelming southern New England during the first week of May. The easterlies began in the last few days of April with a blocking high in place pumping this marine air over us and literally pushing birds away from Connecticut.

Think of southern New England with a big arrow pointing west - that is where the birds stayed unless they are breeders who want to return to territory within our borders. This means you may have seen a Yellow Warbler or two, your neighborhood Baltimore Oriole, or perhaps a Red-eyed Vireo. What you likely did not see were many more of those nesting species in terms of the typical high quantity (as some stay and some keep going north) and birds that live exclusively to our north like the Cape May Warbler I found on Friday. They had no reason to enter our area against the winds and would have stayed away. Nevertheless, plenty were bottled up to our south. There's perfect harmony to how our cooler temperatures and these winds correlated to keeping the birds away or south of us as most trees have only started leafing out now. This is right on schedule for the birds.

For the most part all of this is exactly on schedule. The very average temperatures we have been having seem to correlate well to the perfectly average (in comparison to the long-term and not recent years) arrival dates for many birds in Connecticut. The bulk of them should be passing through now from around May 10 to May 25, with the last stragglers pushing through May 31. This is the way it used to be with the late teens or possibly the early twenties of May being the peak of the spring migration birding season. We will see how the rest of the year plays out but, for now, it is entirely normal...despite the fact it does not feel like it!

Scott Kruitbosch
Conservation Technician

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