Monday, June 8, 2009

A bird to watch for in CT: Arctic Tern

In a recent post I mentioned a few rarities that tend to show up in June, for those who might enjoy the task of searching for rare birds. One of those species was Arctic Tern. This pelagic tern is exceedingly rare in Connecticut despite being regular on Long Island and breeding in very small numbers as close as Massachusetts.

Why so scarce in our coastal state? CT's sheltered coastline and lack of open ocean (thanks to Long Island) are just not very attractive to these terns. Arctic Tern breeds to our north and winters well to our south, but they generally head straight out to sea for migration. Long Island Sound just doesn't cut it.

There are a few mechanisms by which this species might be found in CT:
1) Tropical Storm - A late-summer cyclone could conceivably dump any pelagic species into LI Sound, and Arctic Tern can be (and already has been) seen in CT following one of these storms.
2) Spring migration - This species is occasionally seen in our region during mid-late May, often during an out-of-season nor'easter or other inclement weather.

And, what I really want to talk about:
3) Early-summer immatures

While adult Arctic Terns spend their summers breeding to our north, one-year-old birds are not yet of breeding age. These individuals may spend their first summer well south of the species' breeding range. These young birds look a lot like adults in non-breeding plumage, sporting incomplete black caps, black bills, and blackish legs.


My blurry photo of a first-summer Arctic Tern (right) next to an adult Common Tern, taken at South Beach, Cape Cod, MA on 5 Jul 2005.

These individuals occur regularly on Long Island and Cape Cod, usually among flocks of Common Terns. They peak from mid-June to early-July. For instance, in 2008 there were 8 Arctic Terns seen on Long Island during this time period (mostly immatures).

I've done some thinking about where to find such birds in CT. I think your best shot would be a Common Tern roost as far east as possible. The site that always comes to mind for me is Griswold Pt in Old Lyme at low tide, where Common (and Roseate) Terns often roost during the summer months. Milford and Sandy Pts also come to mind, but both sites are currently tern-less.

Can anybody else think of a spot that has roosting Common Tern flocks, particularly in the eastern part of the state?

Checking such a site regularly over the next 6 weeks could yield one of these beauties. Keep an eye out for first-summer Common Terns as well, which occur in small numbers at this time of year. The separation of Arctic from Common Tern relies more heavily on structure than on plumage details (although plumage, especially wing pattern, is important), so if you're lucky enough to see some one-year-old Common Terns this month, take the extra time to study them closely.

- NB

7 comments:

  1. I remember THAT picture. That was my life Arctic Tern! 8-)

    You had just finished explaining the field marks we should be looking for maybe ten minutes before I asked you "What about this one?" About the only field mark I still remember is the short legs.

    ReplyDelete
  2. Ohh...cool...will be in ct..for the month of July...will check out that area...
    not far from where we stay in Ledyard..
    thanks for the heads up...

    ReplyDelete
  3. here I am again..
    We are Planning a Birders who Blog,Tweet and Chirp bird outing...several people interested so far
    Christopher from Picus blog
    Dan from Nature observances by forestal
    Bev from Behind the bins
    Jeff and myself
    We are currently Tweeting about the event.
    let us know if you are interested..
    we are looking for a nice area to bird for a day possibly two..but one would be fine..
    let me know what you think and if you may be interested.
    thanks

    ReplyDelete
  4. I am not a stalker...LOL..

    Check out my blog..another event planned for July 11th Milford, CT..Luke from Under Clear Skies will be leading our group.
    its free and it a fun way to mean other Bird/nature bloggers.
    leave a message on my blog if you are interested.
    wouldnt mind seeing a roseate tern..

    ReplyDelete
  5. Hi Dawn, I might actually be able to make that. Sounds like a lot of fun. My weekend schedule is still up in the air though. I'll let you know as we get closer. Thanks for the invite!

    ReplyDelete
  6. Oh and by the way, Luke is the man...great guy, birder, etc... you/we will have a great time.

    ReplyDelete
  7. So glad you might be able to join us..I am putting you on the list on my blog post of maybe attending..let me know if things change.

    http://dawnandjeffsblog.blogspot.com/2009/06/birders-who-blog-tweet-and-chirp-outing_21.html

    ReplyDelete