12 April 2017. Stoney Creek Mountain, Hamilton ON. There are yellowlegs and there are yellowlegs; Greater and Lesser, two closely related and closely-resembling-each-other species. Thank goodness their common names tell everything you usually need to know to make a field identification; they have yellow legs and one species is noticeably smaller than the other. It’s (pretty well) all about size.
In the absence of some kind of yardstick it can be difficult to know whether you’re looking at a big one or a little one. There are some subtle differences and with experience you can usually make somewhere between an educated determination and a hopeful guess.
Experienced birders faced with uncertainty know to look at the length of the bird’s bill in relation to its head. The greater’s bill length is about one and a quarter times its head length whereas the lesser’s bill length is equal to its head length. The greater’s bill also shows an upturn towards the tip, it’s slight in some individuals and quite marked in others. Overall size aside, all the relative proportions, the external morphology, of the species are so similar as to make them indistinguishable ( to me anyway).
Today I had the rare opportunity of examining both Greater Yellowlegs and Lesser Yellowlegs side by side. In the photos above and below, the individuals show some slight differences in plumage but I think they only reflect slightly different stages in the individual birds’ spring moult. The difference in relative bill length is evident and with a bit of coaxing you might come to see the slight upturn of the greater’s bill.
These birds made my day. Otherwise I did rather too much aimless wandering looking for anything the spring winds had blown in. I watched a Peregrine Falcon in territorial display by an established nest site, a male American Kestrel and a couple of active Eastern Meadowlarks. But it was a bit unsatisfying so I opted instead to scout out a woodland where I’m scheduled to lead a nature walk early next month. Capturing shots of the emerging leaves of Wild Ginger and flowers of Blue Cohosh was every bit absorbing as the close study of two yellowlegs species. There’s always something to be learned outdoors.
