1st and 2nd cycle Great Black-backeds can appear very very similar. So much so that I couldn’t find one that I was certain was a 2nd cycle bird so I used a photo from Ireland for img 2. So, to arrive at Great Black-backed from some other species; standing with the flock you would see that this guy is gigantic. You would think, “Wow, this thing isn’t just bigger than a crow, its bigger than a dang Red-tailed Hawk.” So, we don’t have much else to consider. The huge bill, very dark centers to the scapulars, and the overall brightness of the plumage’s white undertone (not as brown as most young gulls) are all also good Great Black-backed clues

So, why 1st cycle? Any gull with no adult-like patterned feathers (e.g. solid gray or white body feathers, or white-tipped primaries) is either in juvenile plumage or 1st cycle plumage of a 4 cycle species (some 2nd cycle birds may not have adult-like feathers either :). 1st cycle birds of 2 and 3 cycle species (remember the Ring-billed from class) have adult-like mantles and scapulars.

So, why not 2nd cycle? Note the nearly all dark tail, and nearly all dark bill. This individual’s bill tip approaches what is expected in 2nd cycle Great Black-backeds. The clincher for me on this bird given everything else is the evenly barred (brown and white) greater coverts. A 2nd cycle bird should have more mottled/speckled greater coverts (see img 2).

Virginia Beach VA
February 2011