Purple sandpipers are the northernmost wintering shore birds. Their winter range in the Americas consists of the coast of Quebec and Newfoundland, coastal New England, as far south as South Carolina, and rarely, as far south as Florida. Some are seen along eastern coasts of the Great Lakes. Outside the Americas, their range consists of Greenland, Iceland, Norway, and from northern Norway to southern Belgium. They can also be found in Palearctic locations, including the Faeroe Islands, Britain, Ireland, Norway, Murmansk Russia, theBaltic coasts, Denmark, western and northern Germany, the Netherlands, and Belgium. (Boere, et al., 1984; Buxton, et al., 1985; Payne and Pierce, 2002)
Purple sandpipers are migratory birds that migrate to warmer climates in order to breed. In the Americas, their breeding range consists of islands in high Canadian arctic, south to the eastern shore of Hudson Bay. They may also breed west to Banks Island, Melville, Bathurst, Devon, Bylot, Baffin Island, Southampton and Belcher Islands, North Twin Island, James Bay, Banks and Prince Patrick Islands and southern Ellesmere Island. Outside the Americas, their breeding range consists of Greenland, Iceland, northern Europe, coastal northern Russia, northwestern and central Siberia. (Boere, et al., 1984; Buxton, et al., 1985; Payne and Pierce, 2002)
During the breeding season, purple sandpipers in the High Arctic are found around sea level, whereas ones in the low arctic breed inland and at elevations greater than 1000 m. They feed in the rocky intertidal zones of the tundra. During migration, they can be found on rocky shores, and their preferred winter habitat consists of rocky shores or sandy beaches. In Britain, some populations have been found to stay at the breeding site if it does not freeze, and only migrate if it does. (Atkinson, et al., 1978; Payne and Pierce, 2002)
Adult purple sandpipers have dark gray plumage on their wings and backs and white plumage with gray speckles on their bellies. Their underwing plumage is white. During breeding, their feathers have a mixture of buff gray and light brown feathers. Their plumage changes slightly in the non-breeding season, where they have darker gray feathers with a purple sheen that can only be seen at close distances. This hardly-noticeable purple tinted plumage is where their common name comes from. Purple sandpipers are 20 to 22 cm long, have a wingspan of 42 to 46 cm, and weigh 60 to 75 g. (Payne and Pierce, 2002; Sutton and Parmelee, 1955)
Purple sandpipers are sexually dimorphic in that females are larger in mass and in bill length. Some possible causes for this sexual dimorphism include competitive displacement, so that males and females would be able to eat different sizes of food and thus would not have to compete with each other. Other possibilities are that females need to be larger in order to lay large eggs, or that males are smaller so that they can allocate more energy to parental care instead of body mass or feeding. (Buxton, et al., 1985; Summers, et al., 1990)
Purple sandpipers are monogamous and show very few instances of extra-pair copulation. Males do not exhibit behaviors such as increased copulation with their mate or guarding of their mate while she is fertile, which shows that extra-pair copulations must not be frequently attempted. This is probably because there are no benefits for the female. This also shows that the reason for extensive male investment in breeding is not in defense against extra-pair copulation. Although females and males both share in the incubation of the eggs, the male assumes parental care after hatching and the female leaves the nest and migrates. (Pierce and Lifjeld, 1998; Pierce, et al., 2010)
Males establish and defend a territory and use courtship displays to attract a mate. Courting displays include aerial displays, ground-chasing, announcement-song flights, flight chasing, and nest-scraping. (Payne and Pierce, 2002)
Purple sandpipers breed annually after migration to their breeding habitat. The males arrive first and begin to defend a territory between May and June. The females come afterward and find their mate and help to start a nest. Females lay one clutch, generally consisting of 3 to 4 eggs. The young weigh 9.1 g at birth, on average. Pairs rarely make a replacement brood for lost clutches. Both sexes have a brood patch and help with incubation for the 21 to 22 day period. The chicks can fly in 21.6 days on average and are independent of their parents after 19 to 33 days. Males and females reach sexual maturity at 1 year old. (Payne and Pierce, 2002; Pierce and Lifjeld, 1998; Pierce, et al., 2010)
Males perform most of the parental care. Females help incubate the eggs, but migrate soon after they hatch. Within 24 hours of hatching, chicks can walk and forage. The male forages with them and directs them to adequate feeding sites, but does not forage for them. The male stays with the brood for an average of 22 days, where he protects his brood from other adult birds. (Payne and Pierce, 2002)
The process of exclusively male parental care has been studied using mate-removal experiments and it was found that the cause of this mate dynamic is not due to desertion of the female or because the female is not capable of parental care. When the male was removed, the female assumed parental care of the fledglings and did not suffer ill effects from the extra energy cost. The cause of this selection for solely male parental care, then, may be because of male territoriality and that the male excludes the female from the nest, instead of the female deserting on her own. (Pierce and Lifjeld, 1998; Pierce, et al., 2010)
Purple sandpipers have relatively long lifespans and commonly breed for four consecutive years, starting in their first or second year. Some birds have been found to breed until they are 8 years old, and the oldest observed breeding male was 13 years old. The expected lifespan of purple sandpipers is 5 years, and the oldest individual observed was at least 20 years old. (Payne and Pierce, 2002)
The highest risk factors for survival are exposure and predation, specifically in eggs, nestlings, fledglings, and first year birds. Experience is a determining factor in survival, which explains why first year birds have a higher mortality rate than second year birds. Cold temperatures do not decrease survival because purple sandpipers have adaptations to withstand these conditions. They have heavy body plumage and large breast muscles. They have also been found to have only a marginal increase in weight during winter and less fat stores than other waders. This may be due to their extensive digestive systems, which are efficient in digesting and absorbing nutrients, allowing them to meet their energy demands for thermoregulation. (Dierschke, 1998; Summers, et al., 1998)
Locomotion includes walking, hopping, flying, and swimming. Purple sandpipers are agile when walking and hopping around intertidal rocks in order to forage. During the non-breeding season, they will be seen swimming along the shores where they forage for mussels and other aquatic invertebrates. Chicks, led by the male, will also swim in order to forage. In general, except during migration, they are not quick to fly and mostly flutter around rocks. When they do fly, they fly with fast and full beats of their wings. (Payne and Pierce, 2002)
Males maintain relatively large territories, which are used for attracting a mate, foraging, and maximizing conditions for nesting. Territories are claimed by males performing aerial displays and are maintained by extensive presence and patrolling. Announcement-song flight is also used in order to make a male's a territory known. Males are territorial of their breeding grounds immediately after they arrive from migration and will display antagonistic behaviors if intruders are present. Males will 'fence' each other by running alongside each other and thrusting out their beaks. This sometimes leads to fighting. Both sexes will chase away other birds from foraging and breeding territories. Dominance hierarchies are present and generally consist of males with broods being dominant. Also, larger and older males are dominant over younger males. Males in general are dominant over females. (Payne and Pierce, 2002)
Females migrate to their wintering location shortly after chicks hatch and the males and chicks follow once the chicks can fly. Purple sandpipers are faithful to their wintering locations and return to the same one each year. This may be because they feed on rocky shores, where their food source is less affected by waves and sand erosion, and thus more dependable. (Burton and Evans, 1997; Sutton and Parmelee, 1955)
During the breeding season, pair bonds form and the only social interactions between other pairs are territorial. During the wintering season, winter flocks form with size varying between populations. During high tide and nighttime, birds will roost in large groups, and each bird remains faithful to the same roost site. (Burton and Evans, 1997)
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)
During the breeding season, the home range in which they forage does not exceed a 2 km radius around their nest. Winter home ranges are larger and more variable in size, but most birds return to the same one each year. (Payne and Pierce, 2002)
A major form of communication in purple sandpipers is by vocalization. Males use their song while performing an aerial display in order to court a female. His song is also used during territorial displays. The song is not very well described because it is long, intricate, and variable. However, it is known that it starts with a trill and ends with several long pulsed elements. The trills start at a low frequency and then shift to a higher frequency. The song is rarely repeated in succession. The male also uses other calls besides song. Monotonous, rhythmically repeated display-flight calls are used during aerial displays and cricket-like ground calls are used in the breeding territory. Males also produce the high frequency, mouse-like squeal, called the 'rodent run' call, while doing a performance to lead predators away. Males and females both use a low and rapid chatter during the breeding season in response to intruders. This call is only used until the chicks hatch. (Miller, 1996; Payne and Pierce, 2002)
Visual displays are also used, mainly for territorial interactions. Males and females both exhibit wing-lifting behaviors, where they lift one wing up straight overhead and facing the intruder, exposing the white plumage underneath. This display is also sometimes used during courtship. Males will also chase and fight each other over territories. The wing-lift is sometimes used during these aggressive interactions. (Payne and Pierce, 2002)
Purple sandpipers are generally molluscivores, although they also eat insects and algae. They mainly eat winkles (Littorina littorea), mussels (Mytilus edulis), dog-whelps (Nucella lapillus), and sea snails (Rissoa interrupta). During high tide when the waves cover the molluscs, purple sandpipers eat larvae, pupae, and adult kelp flies (Coelopa frigida). They also eat crustaceans, annelids, spiders, aphids, seeds, leaves, and berries. Purple sandpipers eat molluscs whole, and female birds have been found to eat larger molluscs than males because they are larger and have longer bills. (Payne and Pierce, 2002; Summers, et al., 1990)
Predation is the leading cause of nest failure during the breeding season. Top predators during this time are arctic foxes (Vulpes lagopus) and jaegers (Stercorarius parasiticus). During the winter, large birds of prey such as Eurasian sparrowhawks (Accipiter nisus), northern goshawks (Accipiter gentilis), and gyrfalcons (Falco rusticolus) attack adults. (Payne and Pierce, 2002)
When approached by a predator at the nest, the incubating bird will lower its head and try to stay on the nest as long as possible. If the predator continues to get closer, the purple sandpiper will first give an alarm call and then go into a 'rodent run', leading the predator away from the nest while ruffling its feathers and making a squealing noise. Once the male leaves, the chicks stay frozen in place. If the chicks are older, they will scatter and then crouch in a hiding place. If the predator finds them, then they will run away quickly in zigzag motions. (Payne and Pierce, 2002)
Purple sandpipers are predators of shore mollusks. This allows for increased biodiversity because the population sizes of the mollusks are kept in check so that one species will not out-compete the others for space. Purple sandpipers are hosts to the same strain of gapeworms (Syngamus) carried by chickens raised for poultry, which means that purple sandpipers may also assist in the spread of these parasites. (Campbell, 1935)
Purple sandpipers in wintering flocks will also benefit from alarm calls of other shore birds, such as dunlins (Calidris alpina), snow buntings (Plectrophenax nivalis), and arctic terns (Sterna paradisaea), and these birds benefit from the alarm calls of purple sandpipers. (Mouritsen and Poulin, 2002; Payne and Pierce, 2002)
Purple sandpipers do not have a big impact on humans. They were hunted, along with other shorebirds, for food in North America in the twentieth century and eggs were sometimes also collected for food. However, in 1918, the Migratory Bird Treaty Act made hunting these birds illegal. (Payne and Pierce, 2002)
Purple sandpipers are found in the arctic, where there are not large populations of humans, and thus cannot have many negative effects on humans. However, they have been found to carry the strain of gapeworms (Syngamus) that is found in chickens, which could be harmful for the poultry industry or for anyone who owns chickens. (Campbell, 1935)
Purple sandpipers are listed as least concern by the IUCN Red List of Threatened Species. Their habitat in the tundra is not occupied by many humans, and thus does not suffer from much human degradation. Water pollution from pesticides and oil spills have the greatest effects on these shorebirds, and could potentially lead to a more concerning conservation status. (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.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
either directly causes, or indirectly transmits, a disease to a domestic animal
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
A substance that provides both nutrients and energy to a living thing.
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
parental care is carried out by males
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.
specialized for leaping or bounding locomotion; jumps or hops.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.
uses sight to communicate
young are relatively well-developed when born
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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.
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