The World Outdoors: Identifying look-alike birds can be tricky
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As we welcome the official start of spring and head out to see early migrants, it makes sense to key in on particular aspects of bird identification.
From scaup species to accipiters, there are lots of birds that leave us scratching our heads. Brushing up on difficult pairs makes it easier when you’re out in the field.
A perennial challenge for the spring is identifying yellowlegs. The greater and lesser yellowlegs are both good-looking shorebirds and they are a lot alike.
Field guides remark that the greater yellowlegs has a more angular body and a more heavily streaked breast, however these observations are only helpful if both species are conveniently posed beside one another. Even then, there is a range in markings within a single shorebird species depending on age and season.
A quicker diagnostic technique is to compare the bird to itself. For example, the beak of the greater yellowlegs is definitely longer than its head. If the beak on your bird is shorter or even if you’re not quite sure, you are probably looking at a lesser yellowlegs.
As with most species, the timing should also give you a good clue. Greater yellowlegs arrive here in late March and the lesser yellowlegs migrate through in May.
Downy and hairy woodpeckers represent another frequently confused species pair. The hairy woodpecker is about 5 cm. bigger than a downy in length, but it’s often difficult to get a sense of scale if a bird is partly obscured by a limb.
Like the yellowlegs however, you can key in on the woodpecker’s bill. The hairy’s is as long as its head. The downy’s bill on the other hand is short.
Scaup are certainly challenging, especially considering that greater and lesser scaup fly through Southwestern Ontario at about the same time. This is a difficult pair.
When looking at the males, focus on the head. The greater scaup typically has a rounded head and nape, and in sunlight there may be a sheen of green on its dark head. The male lesser scaup will usually have a peaked crown and in sunlight you may notice a purplish sheen.
I struggle mightily with common terns and Forster’s terns. These two birds can be seen in good numbers by the Great Lakes. The adults of both species are similarly sized, both have jaunty black caps, and both have black-tipped orange bills.
The common tern, however, has dark grey upper wings unlike the Forster’s tern, which has white upper wings. The grey primary feathers of the common tern can also be seen when the bird is just sitting. Also notice this bird’s short tail if it is sitting. Its wingtips extend past its tail.
There are good challenges in the raptor world as well. Much has been written about the distinguishing characteristics of sharp-shinned hawks and Cooper’s hawks. Both are in the accipiter family, both are seen across Southwestern Ontario, and while sharp-shinneds tend to be a little smaller, their size alone isn’t a defining characteristic.
The sharp-shinned has a small head and its tail is squared off. Look for a big head and a rounded tail on the Cooper’s hawk.
There are some less common yet still challenging identification pairings. We all know the Canada goose, but diligent birders will check each individual in a flock, hoping to see a cackling goose.
London birder Tim Arthur was doing exactly that last Sunday and found a cackling goose at Greenway Park. This bird has the same markings as a Canada goose, but the former is close to the length of a common merganser and it has a very round head with a short beak.
Nature notes
Lambton Wildlife invites bird enthusiasts to join a birding hike at 8 a.m. March 28. Participants will meet Eric Marcum at the Canatara Park roundabout parking lot near the Sandy Lane entrance. There is no charge. See lambtonwildlife.com
Eric Marcum maintains an excellent Facebook presence for Lambton Wildlife with fresh and wide-ranging postings about the natural world.
Paul Nicholson can be reached at g.paul.nicholson@gmail.com
Twitter @NicholsonNature