Calidris maritima

Geographic Range

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.

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.

• Biogeographic Regions
• nearctic nearctic
  • native native
• palearctic palearctic
  • native native

• Other Geographic Terms
• holarctic holarctic

Habitat

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.

• Habitat Regions
• temperate temperate
• polar polar
• terrestrial terrestrial

• Terrestrial Biomes
• tundra tundra

• Aquatic Biomes
• coastal coastal

Physical Description

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.

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.

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Reproduction

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.

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.

• Mating System
• monogamous monogamous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

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.

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.

• Parental Investment
• precocial precocial
• male parental care male parental care
• pre-fertilization
  • provisioning
  • protecting
    • male
• pre-hatching/birth
  • provisioning
    • male
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
    • male
  • protecting
    • male
• pre-independence
  • protecting
    • male

Lifespan/Longevity

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.

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.

Behavior

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.

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.

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.

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.

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.

• Key Behaviors
• flies
• saltatorial saltatorial
• diurnal diurnal
• motile motile
• migratory migratory
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Home Range

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.

Communication and Perception

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.

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.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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.

• Primary Diet
• carnivore carnivore
  • molluscivore molluscivore

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks
• terrestrial worms
• aquatic or marine worms
• aquatic crustaceans
• other marine invertebrates

• Plant Foods
• leaves
• seeds, grains, and nuts
• algae

Predation

Predation is the leading cause of nest failure during the breeding season. Top predators during this time are arctic foxes ( Alopex 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.

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.

Ecosystem Roles

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.

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.

Economic Importance for Humans: Positive

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.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

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.

• Negative Impacts
• causes or carries domestic animal disease causes or carries domestic animal disease

Conservation Status

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.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Sydney Hope (author), The College of New Jersey, Matthew Wund (editor), The College of New Jersey, Catherine Kent (editor), Special Projects.

References

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 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.