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US (MA) Birder Needs Help from Folks Familiar with “Commic” Terns (1 Viewer)

Lunada_Z

New member
Hello All,

This bird was seen on an island south of Cape Cod, Massachusetts on 19 July 2020. Common, Roseate, and Least terns all breed in this area, while Arctic Terns are exceedingly rare at any time of year. This individual caught my eye because of the overall gray breast. Then I noticed the teeny tiny legs. It seems to be a SY or TY (i.e. second- or third-summer) “Commic” tern. Other than the short legs, it doesn’t really seem structurally different than the nearby Common Terns, and the one local birder with whom I shared the photos thought it was probably a Common in what they used to call “portlandica” plumage. But he allowed that he was not very familiar with Arctic Terns.

Would any tern mavens like to weigh in here? I’m thinking that UK birders who are more practiced at separating Common and Arctic Terns might be able to help me out. (Note: When it comes to aging terns and gulls, I am not totally up to speed on the latest molt terminology, so please dumb it down for me if you can.) I do have a few more photos from slightly different angles (but none of the bird in flight, unfortunately.)

Thanks in advance! :)
7548A36A-90D5-41E7-888B-9E60B4C48744.jpeg 60CCEE3B-D49E-4491-BEC2-5A4F437EF954.jpeg 5179827D-CFCC-456C-8496-B31EEA1A9FA0.jpeg BB9699F7-EA56-452C-8187-3F4D8C8E42BF.jpeg
 

Deb Burhinus

Used to be well known! 😎
Europe
The bill and head pattern looks like a fairly typical 1st/2nd summer Arctic imo - sometimes posture can make them look long legged (as in the last image)

Just to expand a little:
  • The bill is comparatively short with a deep base (longer and less spiky on CT) #1/#3
  • The head pattern, with the eye being fully masked with dusky borders extending onto the ear coverts is quite typical of 1st/2nd s - SY/TY
  • The tail streamers look long #1 - they appear dark grey which would indicate a SY not TY I believe - (outer retrices are moulted in mid-winter so a TY would have more whiter, adult looking streamers)
  • The head nice and rounded with relatively steep forehead #3
  • Clean very white underwing trailing edge on the secondaries #4
  • Noticeably short legs in some of the images
  • Weak carpal covert bar #4
Btw Welcome to Birdforum

Given the significance of a record, I strongly advise getting more opinions - I am by no means any kind of expert here!
 
Last edited:

Deb Burhinus

Used to be well known! 😎
Europe
Given the significance of a record, I strongly advise getting more opinions - I am by no means any kind of expert here!
Bump!

The fact that no one has commented or agreed with Arctic, might suggest I am completely barking up the wrong tree here so I am awaiting for someone to say why this is a Common Tern - this really isn’t my area of expertise!
 

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