Calidris Pusilla Class
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Calidris pusilla Class: Aves Order: Charadriiformes Family: Scolopacidae Genus: Calidris. Distribution A highly migratory species, after breeding in the Arctic regions Calidris pusilla breeds in the of North America these sandpipers begin to travel southwards Arctic and subarctic from in July. Birds that did not breed start out first followed quickly far-eastern Siberia, east by adult females and then males that did breed and are leaving across Alaska and northern their young. These juveniles remain a little longer. Some travel Canada to Baffin Island and with late adult migrants. There is a long and arduous journey Labrador. They spend the ahead especially for these young birds. Peak migration of adults Canadian winter in is late July and early August. Most western birds migrate south northern South America. through the interior of North America. Those having nested in Some western birds are the central and eastern Arctic migrate south non-stop until they found along the Pacific reach southern James Bay, the St. Lawrence estuary, and the Bay coast of Central America. of Fundy in Canada. This is a stop over stage for rest and Smaller numbers spend this recuperation before continuing south. The spring return season in the Caribbean. migration is towards the Atlantic then continues northward. Habitat While breeding, the semipalmated sandpiper builds its nest While in the north during amongst dry shrubby areas in upland tundra near small ponds, the early summer months lakes and streams. Ideal foraging habitat includes pools close to they occupy areas of wet lakes and rivers, shrubby river deltas, and sandy areas along the sedge or sedge- tundra. shore. Before migrating, it gathers in areas of shallow fresh or They select open habitats saltwater, along the edges of lakes, on muddy intertidal zones, or well-suited for breeding on soft silt or clay mudflats. Migration stopover habitats may displays and scrape nests. include wetlands, grassy fields, marshes, or edges of lakes and They generally are found rivers. At its wintering sites, the semipalmated sandpiper resides running along sandy on shorelines with mudflats bordered by shallow lagoons and shorelines, probing the dead mangroves. loose sand for food. Prey includes a variety of arthropods, molluscs and worms. Food It may wade belly-deep into water where it moves slowly and Small invertebrates rapidly probing at underwater burrows in search of prey. Reproduction The male excavates scrapes among sparse vegetation within his Early arriving males territory for females to choose from. The female makes her establish territories from selection. Mating takes place and she begins lining the scrape which to display to with nesting material. From June through to early July, four to incoming females. six days after pair formation, a clutch of usually four eggs is laid, Pairs often reunite. and then incubated by both parent birds for 20 to 22 days. Development These are amazing young birds. The chicks, being Young hatch within 24 precocial are not fed by their parents, they fend for hours of one another. themselves. They are periodically brooded or kept Chicks are extremely warm by a parent, during their first week. They independent from birth. begin to fly weakly at about 14 days of age and can They are born with open fly fairly well at about 18 days. Females leave their eyes and almost adult-sized broods within 10 days after they hatch in the care legs. As soon as they are of the male. She needs a period of recovery. Males dry, they begin to move usually leave the chicks at about the time the chicks about, pecking for insects. fledge, or take their first flight. These young birds are soon to begin their first long migration southwards. Characteristics During the breeding season, This small wading bird has long, stilt-like legs. It gets the the adult has rich reddish- name semipalmated from the webbing present between brown upperparts marbled its toes. The female is typically larger than the male. The with dark brown and black, juvenile is distinguished by varying amounts of reddish- a white throat and dark brown on the shoulders. Like other sandpipers, it has brown streaks along the relatively long wings, a long neck and a short tail. sides. At other times the Male bills are short and blunt, the longer bills of females plumage is more subdued, a have a tapered and slightly drooped form. Adult wing brownish-grey, with dark span 27-30 cm, body length 15-18 cm, weight 22-48 g, centres on the shoulder egg weight 8 g. Life span is up to 12 years. feathers, a thin, white wing- They form monogamous pairs for the season. Although stripe, white underparts breeding pairs migrate separately and probably spend the with dark barring on the winter apart, many pairs re-establish each year at the breast, and a white eye breeding area until a partner fails to return. If the previous year’s streak. nest was successful, a male will re-establish in the same area. Adaptations Males perform aerial displays at 5 to 9 m where they hover and These birds boost the produce "motorboat" calls. These aerial displays are well suited aerobic capacity of their to their relatively open habitat where visibility is high. flight muscles by eating They use a variety of other communication calls. The large amounts of food prior front toes are long and adapted to walking rather than to departure. On their long perching, making this bird adept at running on land, journey south they drop as well as wading and swimming if necessary. Their down into staging areas to cryptic plumage provides excellent camouflage. replenish these fat reserves. IUCN Red List - Near Threatened. They have Status/Threats undergone a moderately rapid decline over the past Natural predators include three generations (22 years). Over-exploitation in the non- falcons, gulls, owls and breeding range may be the principal driver of decline. foxes. These birds are now on the IUCN Red List. The Bay of Fundy is the most important staging site in eastern North America in providing food that enables the birds to Sightings in Nova Scotia accumulate fat to fuel their long flights. Birds may double their Readily seen during fall weight in less than two weeks by eating small shrimp-like migration. invertebrates which are abundant on the mud flats. .