Purple sandpipers have dark gray feathers on their wings and backs, and their bellies are white with gray speckles. Their wings are white underneath. In the breeding season, their feathers are brownish gray and light brown. Their feathers change a little bit in the winter. Their feathers turn darker gray with a purple shine that can be seen from up close. They get their name from this tint in their feathers, which is hard to see. Purple sandpipers are 20 to 22 cm long, their wingspan is 42 to 46 cm long, and they weigh 60 to 75 g. (Payne and Pierce, 2002; Sutton and Parmelee, 1955)
Female purple sandpipers are larger than males and have longer bills. This might allow them to eat foods that are a little bit different in size, so they don't compete with each other as much. Females might need to be larger so they can lay bigger eggs, or males might be smaller so they can use their energy to care for their young. (Buxton, et al., 1985; Summers, et al., 1990)
Purple sandpipers live farther north than any other birds that stay on the shore in the winter. In the winter, they are found from the coast of Quebec and Newfoundland in Canada to the coast of New England, as far south as South Carolina, and other times as far as Florida. Sometimes, they are found along the eastern coasts of the Great Lakes. Outside the Americas, they live in Greenland, Iceland, Norway, and from northern Norway to southern Belgium. They also live in parts of Europe, including Faeroe Islands, Britain, Ireland, Norway, eastern Russia, the coast of the Baltic Sea, Denmark, western and northern Germany, the Netherlands, and Belgium. (Boere, et al., 1984; Buxton, et al., 1985; Payne and Pierce, 2002)
Purple sandpipers travel to warmer areas in the summer to reproduce. In the Americas, they spend the summer on islands in the High Arctic in Canada and south to the eastern shore of Hudson Bay. They may also be found on many of the very northern islands of Canada. In Europe, they breed in Greenland, Iceland, northern Europe, along the coasts of northern Russia, and in northwestern and central Siberia. (Boere, et al., 1984; Buxton, et al., 1985; Payne and Pierce, 2002)
In the summer, purple sandpipers that live in the High Arctic stay near sea level. Farther south in the Low Arctic, they reproduce inland above 1000 m in elevation. They find food in the rocks between high and low tide. When traveling between summer and winter locations, they are found along rocky shores. In the winter, they prefer to live on rocky shores or sandy beaches. In Great Britain, some of groups of purple sandpipers stay at their breeding spot if it doesn't freeze over, and travel to a warmer spot to spend the winter if it does. (Atkinson, et al., 1978; Payne and Pierce, 2002)
Purple sandpipers form pairs of males and females, and usually don't try to reproduce with other sandpipers that are not their mate. Males and females share the responsibility of keeping the eggs warm. Afterwards, males take over parental care while females leave their nest and travel to their winter location. (Pierce and Lifjeld, 1998; Pierce, et al., 2010)
Male purple sandpipers find a territory and defend it. They attract a mate using courtship displays. These can be flying displays, chasing females on the ground, making announcement songs, chasing them in flight, or scraping out a nest. (Payne and Pierce, 2002)
Purple sandpipers reproduce every year after traveling to their summer location. Males arrive first and start to defend a territory between May and June. Females lay one group of 3 to 4 eggs. It's not common for pairs of chicks to replace a group of eggs if they lose them. Both males and females help keep the eggs warm for 21 to 22 days until they hatch. When they hatch, the chicks weigh 9.1 g on average. They are able to fly in 21.6 days on average, and are independent of their parents after 19 to 33 days. Males and females are able to have their own young after they are 1 year old. (Payne and Pierce, 2002; Pierce and Lifjeld, 1998; Pierce, et al., 2010)
Males are mostly responsible for caring for the young. Females help keep the eggs warm, but leave for their winter location soon after they hatch. Chicks can walk and search for food within 24 hours. Males look for food with them and show them places to find food. Males stay with the group of chicks for 22 days on average, protecting them from other adult birds. (Payne and Pierce, 2002)
Researchers have studied parental care by taking away males from a pair of a male and a female. When the males were taken away, females took over caring for the chicks and didn't have a problem caring for them. This might mean that the reason that males take care of the chicks is because they drive the females away from the nest with as they defend their territory. (Pierce and Lifjeld, 1998; Pierce, et al., 2010)
Purple sandpipers live a long time compared to most birds, and most of them live about 5 years. They are able to reproduce for about 4 years, starting in the first or second year of their lives. Some birds reproduce until they are 8 years old, and the oldest male found still breeding was 13 years old. The longest a purple sandpiper ever lived was 20 years. (Payne and Pierce, 2002)
Purple sandpipers are at risk of getting eaten by predators, especially when they are eggs, chicks, and in the first year of their lives. Once they have more experience avoiding predators, they are less likely to get eaten. They are adapted to living in the cold, so temperature isn't a threat to their lives. They have thick feathers on their bodies and large muscles on their breasts. They only get a little bit heavier in the winter and don't store as much fat as other birds that wade in the water. This might be because their digestive systems are very good at getting nutrients out of their food. (Dierschke, 1998; Summers, et al., 1998)
Purple sandpipers move around by walking, hopping, flying, and swimming. They are good at walking and hopping around rocks between low and high tide to find food. Outside of the breeding season, they are found swimming along the shores where they look for mussels and animals in the water. Males lead chicks through the water searching for food. They don't fly very often except when they migrate, and most of the time just flutter around in the rocks. When they actually fly, they are fast and beat their wings all the way. (Payne and Pierce, 2002)
Females travel to their winter location shortly after the chicks hatch. Males and chicks follow them after the chicks can fly. Purple sandpipers go back to the same place every year in the winter. They group together in flocks in the winter, and each spend the night in the same spot every night. In the breeding season, they form a mating pair. The only time they interact with birds that are not their mates is to defend their territory. (Burton and Evans, 1997; Sutton and Parmelee, 1955)
Males use their territories to attract females, search for food, and find a good spot to nest. They claim their territories by flying around in a special way, making a call to announce their territory, and patrolling them. Males and females chase away other birds from their food or breeding spots. Sometimes, males run next to each other while sticking out their beaks, which is called fencing. They might start fighting afterwards. Males have social hierarchies where larger and older males are dominant. They usually dominate over females as well. (Payne and Pierce, 2002)
In the summertime, purple sandpipers stay within 2 miles of their nest in any direction. In the winter, the area where they live is larger and can sometimes be a lot larger. Most purple sandpipers go back to the same spot every year. (Payne and Pierce, 2002)
Songs and noises are important in communication between purple sandpipers. Males sing their song while flying as part of courting females and marking their territories. The song of purple sandpipers is long, complicated, and can sound very different. It begins with a trill that gets faster and then ends with several long pulses. The song is not usually repeated. In addition to songs, male purple sandpipers make other calls during flying displays, as well as different calls when they are on the ground that are used in the territory where the sandpipers are breeding. Males also make a squeal like a mouse at called a "rodent run" that helps chase away predators. Both males and females respond to intruders in the breeding season with quick chatter in a low tone. They only do this before their chicks hatch. (Miller, 1996; Payne and Pierce, 2002)
Purple sandpipers also use displays to communicate about their territories. If there is an intruder in their territory, males and females both lift up one of their wings straight over their heads facing the intruder. This displays the white feathers underneath. They also do this as part of their courtship ritual at times. Males also chase each other and fight over territories, and will use the wing lift behavior for this as well. (Payne and Pierce, 2002)
Purple sandpipers eat mostly molluscs, and also eat insects and algae. Some of their common foods are winkles, mussels, dog-whelps, and sea snails. Purple sandpipers eat molluscs whole, and females can eat bigger molluscs because they are larger and their bills are longer. When the tide is high and the molluscs get covered by the water, they eat larvae, pupae, and adult kelp flies. They also eat crustaceans, ringed worms, spiders, aphids, seeds, leaves, and berries. (Payne and Pierce, 2002; Summers, et al., 1990)
The most common reason that chicks do not survive is that they are eaten by predators. Their common predators are arctic foxes and jaegers. In the winter, large birds of prey like Eurasian sparrowhawks, northern goshawks, and gyrfalcons try to eat the adults. (Payne and Pierce, 2002)
When predators come near the nest, the parent lowers its head and tries to stay on the nest as long as it can. If the predator comes closer, the parent gives an alarm call and then does a "rodent run." This means that they lead the predator away from the nest by ruffling their feathers and squealing. The chicks stay frozen in place. If the chicks are older, they go in different directions and then hide. If the predator follows them, they run away in zigzag directions. (Payne and Pierce, 2002)
Purple sandpipers eat shore mollusks. This improves the diversity of mollusk species by making sure that one species doesn't take over all of the others. Purple sandpipers get infected with the same kind of gapeworms that infect chickens raised by humans. This means purple sandpipers might also spread these parasites. In the winter, groups of purple sandpipers benefit from hearing alarm calls of other birds living on the shore like dunlins, snow buntings, and arctic terns. These same kinds of birds also benefit from alarm calls of purple sandpipers. (Payne and Pierce, 2002)
Purple sandpipers are found in the Arctic, where the number of humans is very small. They do carry the same kind of gapeworms found in chickens raised by humans. (Campbell, 1935)
Purple sandpipers were hunted or their eggs eaten by humans in North America in the 1900s. This became illegal in 1918 when the Migratory Bird Treaty Act was passed. (Payne and Pierce, 2002)
Purple sandpipers are not threatened or endangered. They don't live close to very many humans, so they are not bothered by humans. They are most threatened by water pollution from pesticides and oil spills. (Payne and Pierce, 2002)
Sydney Hope (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Catherine Kent (editor), Special Projects.
Atkinson, N., M. Davies, A. Prater. 1978. The winter distribution of Purple Sandpipers in Britain. Bird Study, 25/4: 223-228.
Boere, G., K. Roselaar, M. Engelmoer. 1984. The breeding origins of purple sandpipers Caldris maritima Present in the Netherlands. Ardea, 72: 101-109.
Burton, N., P. Evans. 1997. Survival and winter site-fidelity of Turnstones Arenaria interpres and Purple Sandpipers Calidris maritima in northeast England. Bird Study, 44/1: 35-44.
Buxton, N., R. Summers, M. Nicoll. 1985. The populations and biometrics of purple sandpipers in the Outer Hebrides. Ringing & Migration, 6/2: 87-92.
Campbell, J. 1935. The Gapeworm (Syngamus) in Wild Birds. Journal of Animal Ecology, 4/2: 208-215.
Dierschke, V. 1998. Site fidelity and survival of Purple Sandpipers Calidris maritima at Helgoland (SE North Sea). Ringing & Migration, 19/1: 41-47.
Miller, E. 1996. Acoustic differentiation and speciation in shore birds. Pp. 241-257 in D Kroodsma, E Miller, eds. Ecology and Evolution of Acoustic Communication in Birds. Ithaca, New York: Comstock/Cornell University Press.
Mouritsen, K., R. Poulin. 2002. Parasitism, community structure and biodiversity in intertidal ecosystems. Parisitology, 124: 101-117.
Payne, L., E. Pierce. 2002. "Purple Sandpiper (Calidris maritima)" (On-line). The Birds of North America Online. Accessed September 24, 2012 at http://bna.birds.cornell.edu/bna/species/706 doi:10.2173/bna.706.
Pierce, E., J. Lifjeld. 1998. High Paternity assurance behavior in the purple sandpiper, a species with high paternal investment. The Auk, 115/3.
Pierce, E., L. Oring, E. Roskaft, J. Lifjeld. 2010. Why don’t female purple sandpipers perform brood care? A removal experiment. Behavioral Ecology, 21/2: 275-283.
Summers, R., S. Smith, M. Nicoll, N. Atkinson. 1990. Tidal and sexual differences in the diet of Purple Sandpipers Calidris maritima in Scotland. Bird Study, 37/3: 187-194.
Summers, R., T. Piersma, K. Strann, P. Wiersma. 1998. How do purple sandpipers Calidris maritima survive the winter north of the arctic circle?. Ardea, 86: 51-58.
Sutton, G., D. Parmelee. 1955. The purple sandpiper in southern Baffin Island. The Condor, 57: 216-220.