by Linda de Kort
Several years ago our neighbor and I stopped by West Valley Ponds on a sunny May morning. The ponds were filled with migratory waterfowl and shorebirds. I immediately recognized two of my favorites: Ruddy Ducks with their distinctive blue bills and American Avocets with boldly patterned black and white wings and upturned bills. I tried in vain to describe them to my friend and then remembered our Montana Audubon License Plates. I wiped off the mud stains and there were the clear images; she then knew immediately what to look for.
We have spotted American Avocets on their wintering grounds in Baja, Mexico as well. Unlike the breeding birds seen here in Montana in spring and summer with rusty necks and heads, the non-breeding birds have a grayish white head. They generally have this winter plumage from September to February. The males and females in both plumages can easily be distinguished because the female’s bill is shorter and curvier. These handsome birds stand 16-20 inches tall and have very long grayish blue legs. They can weigh up to 11 ounces and have a wingspan of around 28 inches.
American Avocets fly from their wintering grounds in Mexico and the southern U.S., defying border walls and edicts, arriving in our valley around the end of April to the end of May. The return flights in the fall are generally from the first of September to the first of October. Their breeding range stretches from Texas to Canada. Some of the Avocets we spot in our valley will stay here, breed and raise their young. They seem to prefer shallow alkaline wetlands; West Valley ponds, waterfowl production areas and Conservation Easements along the north shore of Flathead Lake are prime nesting habitat.
Courtship displays are quite elaborate involving crouching and bowing; the male will then preen himself with water and splash frantically. It is quite a spectacular dance, and following copulation, they briefly cross their bills and/or intertwine their long necks. They stay together for a single breeding season and raise one brood together. Both male and female build the next, incubate eggs and care for the young. They nest in areas with little vegetation and seem to favor islands. They make a scrape in the ground and line it loosely with vegetation and feathers. The female will lay 3-4 greenish brown spotted eggs in sequence, and both parents will incubate for 23-25 days. The chicks hatch at the same time and already have down, open eyes and within a day are able to walk, swim and dive under water to escape predators. At four weeks, they acquire feathers that look like non-breeding adults and are then able to fly.
The call of the Avocet is loud and shrill, especially when an intruder (such as skunk, fox, harrier, raccoon) approaches their nest. They crouch on the ground to distract the intruder from the nest; if that doesn’t work, they fly directly at the intruder with outstretched necks. They often nest in colonies so several adults might be involved in these noisy attacks.
Diet is varied and consists mainly of water beetles, midges, brine flies, fairy shrimp, daphnia, amphipods and seeds. They have also been seen to consume fish. They have several feeding methods. They can use their long pincer like beak to pick prey from the water surface or mud. They also forage by touch in murky water, sweeping their long bill rhythmically from side to side, filtering the smaller prey. In deeper water, Avocets can be seen up-ended like a duck to reach the food below. They are also adept at snatching flying insects from the air.
Avocets have been known to live 9 years in the wild. Their main threat, even more so than predation, is habitat loss. Wetlands were drained extensively in the twentieth century, and this species was completely eliminated from its eastern range. Some of our remaining wetlands are contaminated with selenium that leaches from the soil following irrigations; this can reduce hatching success. Methlymercury, associated with the burning of coal, may also lead to chick deaths.
Audubon scientists are predicting that with climate change, the breeding range in Montana would move north into Alberta and Saskatchewan. In addition to these threats, human presence at nesting sites can cause abandonment so use your binoculars and observe them from a distance.
We look forward to spotting many Avocets during the Montana Audubon Festival in June. While there, sign up for a Montana Audubon License Plate so that you can help your neighbor keep a look out for these extravagant birds.