SIZE MATTERS

Comparing the bill lengths of the 30 species of shorebirds recorded on Chico Basin Ranch reveals an amazing difference in bill shape and length.

Wilson’s Phalarope – This shorebird is unusual in sex-role reversal, where duller plumaged males incubate the eggs and tend to the young after brightly colored females compete among themselves for available males. During migration, both males and females often feed in groups, spinning in circles on top of the water. The spinning action creates a vortex where aquatic invertebrates are drawn to the surface where they are consumed. Wilson’s Phalaropes also frequently forage with Blue-winged Teals and Northern Shovelers, feeding on the invertebrates stirred up by the ducks. Wilson’s Phalaropes also feed on land and in shallow water. In shallow water they rapidly scythe their bill for food items. On land, they can be seen with head held low, plucking prey items from muddy surfaces. Flocks are relatively small in Colorado, whereas flocks in other western states can range from hundreds to several thousand.

Black-necked Stilt – While most shorebirds are varying shades of brown to avoid detection by predators, the beautiful, slim, long-legged Black-necked Stilt is easy to spot. Their long legs allow stilts to feed in deeper water where they use their needle-thin bill to pick invertebrates and crustaceans off the water surface. They also eat small fish and frogs, feeding both day and night. Like other brightly colored shorebirds, Black-necked Stilts are loud, giving a yip-yip-yip-yip alarm call.

Long-billed Curlew – Aptly named, this very large shorebird with the extraordinary decurved bill is a stunner. Coastal birds use their long bill to extract Fiddler Crabs and crustaceans from deep burrows. A shortgrass and mixed-grass species, interior birds use their long bills to extract earthworms. In migration, like this bird, they often feed in irrigated fields. On their breeding grounds in eastern Colorado, male’s flight display is spectacular. He begins with a steep climb at a 45˚ angle using fluttering wing beats followed by a long descending glide. While in the air, this activity is repeated multiple times while giving haunting trills and whistles followed by a drawn out werr-EEEer call. Fascinating to watch and hear.

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