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Updated: Jul 21, 2022

To some, Peeps are those colourful marshmallow chicks sold to candy-lovers at Easter time. To birdwatchers, peeps are a collective nickname for small shorebirds called sandpipers that include about a half dozen species, named perhaps because many of them make a “peep” like sound when calling. It actually sounds more like “creeep” but what a sadly unsuitable name that would be! I love peeps because they remind me of being at the seashore. There’s not a lot of seashore in the London area, so it may be surprising that we can find shorebirds in so many different habitats here. One might see one of these small waders anywhere there is a mud flat or muddy shoreline, including flooded agricultural fields, sewage lagoons, sod farms, along the Thames River or even a neighbourhood stormwater pond.

We don’t get the huge numbers of peeps that gather in staging areas along coastal beaches, but wetlands here are important rest-and-feed stopover areas for weary bird migrants. London is a good half way point between Lake Huron and Lake Erie and a welcome spot for birds to “fall out” in bad weather. Six species of “peep” may stop for refueling in our local area. There are also small waders called plovers which may feed side by side with peeps, but I’ll save that discussion for another blog.

Sandpipers in the genus Calidris embody the magic of migration. Twice a year, these little flyers, some the size of a sparrow, embark from South America to their nesting grounds in the arctic or sub-arctic and then back again. That is a journey of over 3000 km... times two. Many traverse open ocean waters between the continents. Spring migration is condensed into a critical few weeks, with a peak for most species in the last two weeks of May. Birds are in a hurry to arrive north when the tundra is snow-free but long daylengths allow for maximum feeding and nesting time. Fall migration is a bit more leisurely and extended from mid-July to post-autumn solstice. I’ve always been amazed that some early fall migrant shorebirds head south in late June only a week or two after the last spring migrant stragglers pass on their way north. In some locations there can even be an overlap.

Peeps can be an identification challenge extraordinaire. They are often at some distance which means a spotting scope is a useful element in your birding arsenal. Birds seen during spring migration are adults with partial or complete adult breeding plumage. Returning fall migrants include the new generation of juveniles, which show brighter colouring, sometimes with a buffy infusion or rusty/rufous edged fresh feathers. Then there are the non-breeding adults in more neutral toned, drab plumage, becoming paler and drabber as late summer progresses. There is much to examine when trying to determine species on the grassy mudflat.

For identification, let’s start with the most common peep migrant here. Least Sandpiper is the world’s smallest sandpiper, which means it can be easily overlooked, even at close range. It’s back feathers are the same warm brown tone as a mudflat, affording great camouflage from eagle-eyed predators. The belly and undertail are white and the species has a brown-washed, lightly streaked bib which fades as summer moulting progresses. The legs are yellow but not the most reliable field mark alone. Feeding in a gooey, brown substrate can coat the yellow with dark, mucky “leggings”. Sometimes yellow is still visible where the legs meet the underbody and remains clean. Least Sandpipers have a somewhat elongated, thin black bill, slightly downturned at the tip. If there are other peeps nearby, its good to compare relative size and shape of the bill and body. Least Sandpipers have been reported on eBird at many of the water retention ponds around the city, especially during fall migration. Their feeding posture is a hunched, tentative probing and they prefer drier, upper shoreline margins edged with low vegetation.

Most commonly confused with Least Sandpiper is the Semipalmated Sandpiper. Semipalmated refers to the partial webbing between its toes, a fleeting field mark that I’ve only ever seen on a bird walking past me on an ocean beach, captured and reviewed from a photo. No need to look for that! The ID differences between the two species do seem frustratingly subtle. Semipalms are only ½ inch longer bodied than a Least. Other field marks to check for are black legs, a shorter, blunt-tipped black bill and grayer feather colouration overall, mottled with black on the back. Fall migrants can have a gray, streaked “collar” or incomplete breast bib. Their gray tones make them stand out somewhat from the brown mud surface compared to a Least and they stand upright more when feeding.

A Pectoral Sandpiper is like a Least on steroids! It shares some of the same field marks, such as yellowish legs, medium length slightly decurved bill, and juveniles which sport tiger-toned back feathers...however it’s three inches larger. The bill is more robust with an ochre paleness at the base. The field mark of note, however, is a densely streaked bib. It’s the first thing I look for after size. The streaks meet the upper belly in an abrupt transition, a demarcation from fine lines to white belly. The bib often extends lower on the front than on other peeps.

The last two peeps I’ll describe are later migrants, so chances are good that if you see a peep in July it is one of the three species already mentioned. Baird’s Sandpipers start arriving in August with mid-August being an optimal time of the month to see one. White-rumped Sandpipers pass through even later during fall months and it seems I’m usually bundled up in cold weather clothes when I see this migrant. They are regular visitors here in SW Ontario, but in smaller numbers so it’s always exciting to find one of these two long-winged peeps. Both Baird’s and White-rumps have wings that extend beyond their tail, to a degree that their wing tips can cross over each other while standing. The body behind the legs also appears to be elongated compared to a Semipalmated Sandpiper.

With White-rumps, a few field marks to look for are the blocky head, streaks or chevrons that extend down the sides below the wings and a white supercilium that flares up like a comma just behind the eye. Then, of course, there is the completely white rump, which isn’t always easy to see. In locations with sticky muck though, such as at the Strathroy Lagoons, the rump can quickly become obvious. The birds spend a lot of time flapping their wings as they navigate walking over the residual goo and “presto”, there is your field mark!

I’ve never seen a Baird’s during spring migration but have been lucky to see a few in August. The juveniles start moving through then and show some striking field marks. The back feathers are scaly looking, which means that each scapular feather on the back has a white fringe or margin. It contrasts against the black centre of the feather and the whole appearance looks scalloped. The head and bib area are infused with a soft buffy beige and the eye is set against a pale face which gives the bird a surprised look. Both of the long-winged peeps have black legs and a longish bill. Size is intermediate between Semipalmated Sandpiper and Pectoral.

The last bird to highlight in the Calidris group is the Dunlin. This species is 8 ½ inches long, similar in size to a Pectoral Sandpiper. Luckily, spring birds in breeding plumage have an unmistakable field mark to help identification—their striking black belly which looks like an ink blot. Contrasting with their upperside which shines a bright cinnamon speckled with black, these waders are charismatic and photogenic. Its always a bit of shock and awe to see them on their return migration as adults are nearly unrecognizable. While on arctic breeding grounds, they moult into a dull beige/gray unpatterned "dun" plumage. One has to look hard at a fall migrant to see that it has the long, down-curved bill and plump body shape of a Dunlin. Juveniles retain a hint of colour and the beginnings of a belly blot.

Shorebird identification is a challenge to all birders, but that’s what makes it fun and engaging! Migrant bird plumages transition between breeding and non-breeding and the partial moults in between. Variation within some species can also be confusing. For example, the eastern female Semipalmated Sandpiper fooled me once into thinking it was another peep species because it had a long, nearly downturned bill, not so short and blunt as ones I'd seen elsewhere. Its good to weigh all field marks together. It's also much easier to attempt identification when there is good lighting on the bird. Find a time of day when birds aren't backlit silhouettes.

To learn peeps, start small. During the dog-days of summer, try to pick out a Least Sandpiper from one of many storm water pond shorelines in the city or one of the many sewage lagoons beyond. Scan the mud with binoculars for any small birds poking around. Take photos, if possible, and study traits on the bird that might help you skip Merlin app the next time. Get out and enjoy the “peep show”. The magnitude of effort and energy these long-distance migrants expend to perpetuate their species deserves our utmost appreciation.

** Photos from top: Semipalmated Sandpiper, Least Sandpiper, Pectoral, White-rumped, Baird's and a fall Dunlin showing some residual orange back feathers.

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