Ninety-eight percent of a Killdeer’s diet consists of animal matter. Beetles, insect larvae, earthworms, grasshoppers and crayfish make up the majority of what a Killdeer eats. In the summer, adult beetles (see photo) and beetle larvae make up almost half of what they consume.
Much of the time we observe Killdeer they are running, stopping, waiting and then running again. This is typical feeding behavior. Another method of obtaining food consists of patting the ground or the bottom of a pond in shallow water with one quivering foot. Killdeer also engage in probing into mud and chasing prey, and they have been known to follow tractors in search of earthworms.
Food normally passes through a Killdeer’s digestive tract in about two hours, but the spore-bearing structures of some ferns that it eats take five to sixty hours. All birds have gizzards, where food is ground up. Some birds swallow grit to aid in the grinding process, and the Killdeer is one of them. It has been proposed that the sporocarps take longer to pass through a Killdeer because they are retained in the gizzard where they function as grit.
Over the past decade or so, there appears to be a trend of increasingly early American Woodcock arrivals on breeding grounds in Vermont. It used to be that when March arrived, you started looking for the very first returning migrants. Now you need to keep your eyes open for this forest-dwelling shorebird in February.
The start of the Woodcock migration northward and the rate of their progress is said to be greatly influenced by photoperiod and weather. With the unusually warm weather we had in February and early March this year, American Woodcocks, as well as several other migratory species, have been returning earlier than normal. Since their return, we have had early thaws interspersed with hard frosts and several days in a row staying below freezing which created a hard crust on what snow remained. This was followed by a storm that dumped one to two feet of snow on the ground and colder than usual temperatures.
Migration is demanding enough on birds, but those fortunate enough to reach their destination then have to find food and stay warm. It is most challenging for those species with a fairly limited diet, such as Woodcocks, whose diet consists primarily of earthworms. In a typical year there are frequently brief freezes after Woodcocks return, and even storms that leave several inches of snow. But it warms up relatively quickly and there are usually ditches and wet, thawed areas where long bills can probe the soil for life-sustaining food. Not so this year – a deadly combination of early arrivals and late frigid weather spells disaster for American Woodcocks.
The Raptor Center, a wild bird rehabilitation center in New Jersey, reports that during a recent 24-hour period, they admitted more Woodcocks than in all of 2016. After flying hundreds of miles, these birds are exhausted and very hungry when they arrive on their breeding grounds. Should you find one in distress, you can locate a wildlife rehabilitator that accepts birds (in all states) by going to www.owra.org/find-a-wildlife-rehabilitator .
Special thanks to Maeve Kim and Ian Worley for the data and information in this post.
Killdeer that breed in the southern half of the U.S. are year round residents, and do not migrate, but in the northern half of the U.S. killdeer are migratory. Their wintering range extends across the southern tier of states, through Mexico and the Caribbean and along the coastal regions of western South America (Columbia, Venezuela, Ecuador and Peru). Killdeer that breed in the Northeast overwinter in Gulf and southern states that border the Atlantic Ocean.
The first returning killdeer have been sighted in Vermont. While the spring migration of killdeer is early, it is also prolonged, peaking in late March or early April in New England. Killdeer migrate during the day as well as at night, in flocks of 6-30 birds. When they stop to rest and/or forage, the birds typically do not go within 13 to 20 feet of each other, and are met with aggression from other flock members if they do. Once on their breeding grounds, killdeer are even less tolerant of each other. The courtship behavior in one pair often elicits aggressive behavior from neighboring pairs.
Now is the time to keep ears and eyes open for this inland-nesting shorebird. Corn fields, lawns and parking lots are a good place to start. For a perfect example of onomatopoeia, listen to Lang Elliott’s killdeer recording: http://www.langelliott.com/mary-holland/killdeer/ (Sound recording © Lang Elliott – langelliott.com)
Least Sandpipers are the smallest shorebirds in the world, weighing only an ounce and measuring 5 – 6 inches long. Their fall migration has already begun, with individuals leaving their breeding grounds in the subarctic tundra and far northern boreal forest for their wintering grounds in Central and South America. Banding has revealed that the eastern population of Least Sandpipers undertakes nonstop transoceanic migrations of about 1,800 to 2,500 miles from the Gulf of St. Lawrence and New England to northeastern South America. Not much bigger than a sparrow, this common but declining shorebird can be seen refueling on mud flats throughout New England during its fall migration.
Many of the shorebirds that overwinter in Central and South America, as well as southern North America, migrate through New England during the month of May, on their way north to their Canadian breeding grounds. Although Greater Yellowlegs (pictured) are more solitary than most shorebirds, they tend to migrate in small flocks as they head for the bogs and coniferous forests of northern Canada and southern Alaska. They are recognizable by their upright stance, bright yellow legs and piercing alarm calls (nicknames include “telltale,” “tattler,” and “yelper”). During the early 20th century, before they were protected, Greater Yellowlegs were considered an important game bird, and according to Arthur C. Bent, an ornithologist at the time, this species was often shot “by an angry gunner as a reward for its exasperating loquacity.”
Spotted Sandpipers are a relatively easy shorebird to identify, with their spotted breasts, their constant body-bobbing/teetering and the stiff beat of their wings. Although they are a shorebird, they can be found near freshwater ponds and streams throughout North America. Spotted Sandpipers differ from most birds in that the male and female roles are completely reversed when it comes to breeding – from courtship to parental care. The females establish and defend their territory, often arriving on nesting grounds before the males. Females court the males, performing display flights as well as strutting displays on the ground. Males, usually less aggressive and smaller in size, do the lion’s share of incubating the eggs and brooding the young chicks.
This is the time of year when it pays to watch where you walk – there are a number of ground nesting birds, some of which, including killdeer, may choose your lawn or even your garden to build their simple “scrape” nest. Typically killdeer nest on the shoulders of roads, gravel roof tops, fields and gravel parking lots. The nest is very primitive, and there’s actually very little to it — killdeer scrape a slight depression in the ground, to which they often add bits of material, including white objects such as shells and bones. Their pigmented eggs are extremely well camouflaged. The young precocial killdeer chicks are on their feet and feeding themselves as soon as their down feathers dry. (Photo by Sadie Richards)