Bonaparte's Gulls - different from Franklin's Gulls

Bonaparte's gulls have black beaks and more of the head is dark on the adults.

I have always been uncertain when seeing a black-headed gull as to whether it is a Franklin's or Bonaparte's gull.  One of the key differentiators is beak colour.  Both 1st and 2nd year Bonaparte's gulls have black bills, while Franklin's gulls have reddish bills.  There are other differences as well, such as the white crescent around the eyes in the Franklin's, which is absent or relatively minor in Bonaparte's.  Franklin's gulls also have red legs that are darker than Bonaparte's.

That's the thing about bird identification.  It comes down to specifics.  There is general information, such as type of bird (heron vs chickadee, for example), and then there is specific information that allows you to narrow down identification further.  I have written about my dislike of identifying gulls in the past (click here to see what I mean), so I won't go into my rant on the subject.  However, the process still holds true.  

When I am uncertain, I use the computer's search algorithm to help me out.  Even then, there is certain chance that it may get it wrong, so it is always wise to verify.

Another thing I refer to are maps.  Regarding the above two species, for example, Bonaparte's gulls can be found in salt water whereas Franklin's gulls are strictly birds of the interior.  Their ranges do overlap, which is why I started having this problem in the first place.  I frequently visit central and northern Alberta where both species are present.  However, Bonaparte's gull ranges into Alaska and south of the 48th parallel, whereas Franklin's does not.  This becomes moot when the birds are migrating as sighting may occur all over the place.  In general, though, I find maps helpful in verifying species.  Unless, of course, you have a transient.

Thanks for reading.

Eric Svendsen     www.ericspix.com