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Calidris mauriwestern sandpiper

By Haley Mullins

Geographic Range

Western sandpipers (Calidris mauri) are subarctic nesters that breed in western Alaska on the Yukon-Kuskokwim Delta, extending from the tundra north of the Delta to the Seward Peninsula. After breeding is complete, they begin to travel south to Pacific coastal feeding areas.

Around the beginning of the fall season, western sandpipers migrate south along the Californian coast. However, the nonbreeding range of western sandpipers is not exact. It ranges from the Pacific coast along California, wraps around the southern coast along the Gulf of Mexico, continues along the southeastern coast of the United Sates, and northward along the Atlantic coast to New York. They also reside in the Caribbean and along the northwestern coast of South America, from Peru to Suriname. Other areas outside of the Americas that western sandpipers have been observed are east Siberia, parts of northern and western Europe, and one species was located in Russia.

Vagrant birds have been observed in parts of Europe such as France and Spain, further east into eastern Asia, and south in New Zealand. (BirdLife International, 2016; Franks, et al., 2014; Holmes, 1972)

Habitat

Western sandpipers spend their breeding season in subarctic Alaska in two habitats: drained, heath-covered tundra and low-lying marsh tundra. There are many water sources around the marshes, including lakes, streams, and ponds. Also, the marshes are mainly vegetated by grasses and sedges, serving as the primary feeding areas for nesters.

During the nonbreeding season, western sandpipers are found in coastal areas that contain sandy and muddy surfaces. These birds are also found near salterns, areas designated for making salt, and deserted shrimp farms during their migrating and wintering months. With sex and age dominating isolation patterns, males and adults are more prevalent at sites with higher food abundance and habitats with fewer predators. Fernandez and Lank (2006) found that western sandpipers also frequent briny flats, mangroves, and cattail (Typha spp.) marshes during the nonbreeding months. Also, during winter months, Howell and Webb (1995) recorded western sandpipers to be in elevations up to 2500 meters. (Fernández and Lank, 2006; Franks, et al., 2014; Holmes, 1971; Holmes, 1972; Howell and Webb, 1995)

  • Range elevation
    0 to 2500 m
    0.00 to 8202.10 ft

Physical Description

Western sandpipers range from 14-17 centimeters in length and weigh 22-35 grams. Their wingspan ranges from 35-37 centimeters and their wing bar is narrow and white. Their tails are primarily black, except for the white outer retrices. They have a long, black bill that is somewhat curved downwards with a fine tip. Their legs are black, and they have small webbed toes.

Western sandpipers undergo a five-step molting cycle every year: prejuvenile, prebasic, first prealternate, definitive prebasic, and definitive prealternate molts. The color of the feathers depends on which step of the molt the birds are undergoing. By the last step, the western sandpipers’ feathers are a mixture of black, white, tan, and reddish-brown.

Other than males having a brighter chestnut color on their upper body and more streaks on their underparts than females, the main difference is their wing morphology and size, with females usually being larger and heavier. The bills of females are also longer than that of males by about 15 percent.

At hatching, western sandpipers are precocial and have natal down. The bodies of young western sandpipers are mostly black and grayish yellow with white spots, with the ventral side being white. Their head is brown and white with a spot of rusty brown on the crown of the head. (Franks, et al., 2014; Holmes, 1972)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • male more colorful
  • Range mass
    22 to 35 g
    0.78 to 1.23 oz
  • Range length
    14 to 17 cm
    5.51 to 6.69 in
  • Range wingspan
    35 to 37 cm
    13.78 to 14.57 in

Reproduction

Western sandpipers are monogamous, sustaining a strong pair-bond throughout the breeding season. Holmes (1973) stated that their monogamous bond was adapted so that the young would have both parents present for protection. Some pairs mate for consecutive years. Around mid-May, once the snow has melted on their breeding grounds, western sandpipers arrive on the Yukon-Kuskokwim Delta in Alaska. After feeding and establishing territories, male western sandpipers begin attracting females while defending their territories.

While looking for mates, male western sandpipers emit a call that Holmes (1973) describes as “brrrt, brrrt.” Competition between males will occur while on the breeding ground in attempts to impress females. Males will also use wing-up displays and tail-up postures to communicate with a potential female pair. Females are initially unreceptive to the males’ behaviors and choose to feed instead. After a few days of the males courting the females with their wing-up displays and courtship stances, the females will begin to affiliate with them. Next, males begin their nest-scraping and preening behaviors, where they lead the females to their nest, scrape and settle their nest to attract them, and preen their necks and chests. Males can have a few nest-scraping sites, and females will visit more than one over a few days. Finally, females choose their sites, and after additional courtship and preening behaviors from the males, copulation begins.

Males are protective of their mates, and often follow them while they are in flight. They also defend their nesting site very heavily until the eggs are laid. Some females lose their eggs to predation or weather; therefore, they will attempt to lay a second clutch. Holmes (1972) found that females that had a successful first clutch do not lay a second. After a few days of this behavior, almost all male western sandpipers have pair-bonded and mated. Within a couple of days of mating, female western sandpipers lay their first egg, and then continue to lay the rest of their clutch over a span of 24 hours. (Holmes, 1971; Holmes, 1972; Holmes, 1973)

The breeding season of western sandpipers is typically from the end of May to the beginning of July. Copulation occurs between mated pairs on multiple occasions for roughly 21 (range 20.5-22) days until the clutch is laid.

On average, most clutches hatch around mid-June and contain four eggs (range 2-5). The mass of hatchling western sandpipers ranges from 4.4-5.4 grams. Within 12-24 hours, all the eggs have hatched, and the young leave the nest, with assistance from their parents, to forage on surface insects. Within two to three weeks, juvenile western sandpipers have fledged and are independent from their parents. The sexual maturity of both male and female western sandpipers is around a year, and only a few young will return to the same breeding grounds the next year. (Blomqvist, et al., 2002; Brown, 1962; Holmes, 1971; Holmes, 1972; Holmes, 1973)

  • Breeding interval
    Western sandpipers breed yearly during the summer months.
  • Breeding season
    End of May-Beginning of July
  • Range eggs per season
    2 to 5
  • Average eggs per season
    4
  • Range time to hatching
    20.5 to 22 days
  • Average time to hatching
    21 days
  • Range fledging age
    2 to 3 weeks
  • Range time to independence
    2 to 3 weeks
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Parental investment begins during the incubation period, where males and females alternate responsibility. Females incubate from the evening to morning and male western sandpipers take over throughout the day. As hatching approaches, males devote more time to incubating the clutch. Once the clutch has hatched, both parents attend to the young. After all the eggs have hatched, the adults help the young leave the nest to forage. The young are capable of foraging on their own within 24 hours after hatching. During the period before fledging, the adults guard the brood from weather and predators. Once the young have fledged, the family breaks apart and joins separate flock for migration. (Holmes, 1971; Holmes, 1973)

Lifespan/Longevity

There is no information on the expected lifespan in the wild, the longest lifespan in captivity, or expected lifespan in captivity for western sandpipers. The longest lifespan recorded in the wild for a western sandpiper was found to be 9 years and 2 months. Fernandez et al. (2003) reported that survival rates for adult males were 46.9-48.9% annually, while that of juveniles were 8% lower than male adults. Western sandpipers have a higher mortality rate when they are younger, and it decreases as they age. Factors that affect survival for young western sandpipers include hatching mass, relative threat of predation, and length of parental supervision. (Fernández, et al., 2003; Franks, et al., 2014; Ruthrauff and McCaffery, 2005)

  • Range lifespan
    Status: wild
    9.17 (high) years

Behavior

Western sandpipers begin to arrive at their breeding grounds in Alaska as soon as the snow begins to melt, typically in mid-May. After breeding has finished and young have fledged, western sandpipers leave the Delta and move into coastal California. This occurs around mid-July for adults and a month later for juveniles. From there, they continue to move south, staying near the coast, and moving north along the Atlantic coast as well. Western sandpipers reach their wintering grounds and stay there from roughly September to the beginning of May.

Western sandpipers use calls and songs as a way of communication, mating, and other behavior. Males have a song or call when trying to attract a mate, alerting conspecifics when danger is near, and when in competition with another male. Females mostly perform the alarm call when in distress or in danger.

Male western sandpipers become territorial during their breeding season, often fighting with other males. Males have different postures leading up to these altercations: hunched posture, rail-run, and wing-lifting. Territorial males also chase one other.

Brown (1962) found that western sandpipers display distraction behaviors. Both parents perform obvious, eye-catching behavior to draw predators away from their young. For example, western sandpipers will pretend to be injured or mimic a rodent running to distract a predator.

Western sandpipers are a social species that migrate in flocks during the day. Also, despite being territorial over their breeding and feeding grounds, their home ranges often overlap. (Brown, 1962; Fernández and Lank, 2006; Holmes, 1973)

  • Range territory size
    2000 to 3000 m^2

Home Range

The home range of western sandpipers is reported as their territories. While on the breeding ground, territories of western sandpipers are evenly distributed. These territories are usually 2000-3000 square meters. Food within the locality of the nest and community water sources serve as the main foraging sites for nesting western sandpipers. Adults do not stay away from their nest for longer than an hour at a time to protect the eggs.

Once the eggs have hatched, the family will leave the nest to forage on drained tundra and marsh areas. After fledging, both the young and the parents leave the nesting site and relocate to the marshes to feed.

According to Warnock and Takekawa (1996), western sandpipers stay within roughly 22 square kilometers of their foraging and resting sites on nonbreeding grounds in the San Francisco Bay. They also found that, on average, there are only about 2 kilometers separating western sandpipers’ foraging and roosting sites. While most aggressive, territorial behavior occurs on the breeding grounds, western sandpipers will still defend their feeding sites while on nonbreeding grounds. (Holmes, 1971; Warnock and Takekawa, 1996)

Communication and Perception

Western sandpipers have a suite of calls, as well as a song. Their song (only made by males) consists of an eight-note tune, beginning “t-e-e-e” and followed by a low pitch buzzy trill (Holmes, 1973). Both sexes also make alarm calls while nesting, and the calls are described as quick, trilled sounds. Holmes (1973) also found that when in flight, male and female western sandpipers give a call note that sounds like “bbeet” to communicate with other western sandpipers. Adults can interact with their nestlings by emitting freeze, brooding, and gather calls.

Western sandpipers use vision as a form of communication with one another. Males use display flights, paired with a song, over their breeding grounds to make their arrival in the area known. Another form of display shown by western sandpipers are wing-up displays, which are physical mechanisms used by males to announce their arrival from a flight or chase. Wing-up displays are also used when males are proposing a challenge to another bird of the species, towards females when mating, and in response to potential predators.

During the breeding season, male western sandpipers participate in chases near their territories. Physical altercations between these birds take place when on the ground. Males charge one another, using their beaks and wings for assault, often causing loss of feathers. (Franks, et al., 2014; Holmes, 1973)

Food Habits

Adult western sandpipers consume benthic invertebrates, spiders, and insects when on breeding territories or inland stopover sites. Also, Holmes (1972) found stones and seeds in adult western sandpipers’ stomachs during the summer months. During the nonbreeding months or when on coastal stopover areas, they eat mainly marine benthic invertebrates, including some crustaceans. Also, polychaete worms and molluscs serve as food for western sandpipers during winter. Kuwae et al. (2008) found that western sandpipers migrating northward to their breeding grounds often feed on intertidal biofilm and it contributes half of their energy supply per day.

Between 12 and 24 hours after hatching, young western sandpipers begin foraging on insects mainly active on the surface, such as adult flies and beetles. However, after fledging, their diet does not significantly differ from that of the adult western sandpipers.

Adult western sandpipers more often forage in wet mud with either a high concentration of silt, or a combination of silt and sand in inland freshwater habitats. Freshwater ponds along with the tundra are foraging sites for these birds. On nonbreeding grounds, males with shorter bills frequent shallower areas than longer-billed females. Fernandez and Lank (2006) found that western sandpipers forage in briny flats, mangroves, and cattail (Typha spp.) marshes during the nonbreeding months. Males and adults have a higher prevalence during the winter in foraging sites that have higher food abundance and have fewer predators. (Franks, et al., 2014; Holmes, 1972; Kuwae, et al., 2008; Pomeroy and Lindstrom, 2006)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • aquatic or marine worms
  • other marine invertebrates
  • Plant Foods
  • seeds, grains, and nuts

Predation

Known predators of western sandpipers on breeding grounds in subarctic Alaska include red foxes (Vulpes vulpes) and two seabirds: long-tailed skua (Stercorarius longicaudis) and Arctic skua (Stercorarius parasiticus). These predators prey on western sandpiper eggs and juveniles. While on nonbreeding grounds, known predators of western sandpipers include two species of falcons, peregrines (Falco peregrinus) and merlins (Falco columbarius), and northern harriers (Circus cyaneus).

On nonbreeding grounds, adult western sandpipers have a few anti-predator behaviors. Their flock size will vary depending on the threat level of the area and how covered it is. The safer the area, the smaller and tighter the flock, and vice versa. Also, western sandpipers are more attentive in areas that have a higher danger potential compared to areas that are safer.

On breeding grounds, Brown (1962) found that western sandpipers use distraction behaviors as anti-predator adaptations when their nest is disrupted. They can pretend to be injured or mimic a rodent running away. They also have an alert posture and squatted run, usually accompanied with a high-pitched squeal used as a form of disruption. (Brown, 1962; Fernández and Lank, 2006; Fernández and Lank, 2010; Holmes, 1972)

Ecosystem Roles

Parasites of western sandpipers include tapeworms (Dicranotaenia amphitrica, Aploparaksis clerci, Aploparaksis diagonalis, Trichocephaloides megalocephala, Aploparaksis bulbocirrus, Aploparaksis leonovi, and Aploparaksis stricta). They also include roundworms (Skrjabinoclava bakeri, Skrjabinoclava pusillae, Skrjabinoclava tupancinca, and Stellocaronema skrjabini).

In a study conducted in Texas, Canaris and Munir (1991) found western sandpipers to harbor Trichocephaloides megalocephala in the fall, Skrjabinoclava bakeri in the spring, and Dicranotaenia amphitrica, Aploparaksis clerci, and Aploparaksis diagonalis in both the fall and spring. On breeding grounds, western sandpipers serve as hosts to Aploparaksis bulbocirrus, Aploparaksis leonovi, Aploparaksis stricta, and Stellocaronema skrjabini. (Canaris and Munir, 1991; Franks, et al., 2014)

Commensal/Parasitic Species
  • Tapeworm Dicranotaenia amphitrica
  • Tapeworm Aploparaksis clerci
  • Tapeworm Aploparaksis diagonalis
  • Tapeworm Trichocephaloides megalocephala
  • Roundworm Skrjabinoclava bakeri
  • Roundworm Stellocaronema skrjabini
  • Tapeworm Aploparaksis bulbocirrus
  • Tapeworm Aploparaksis leonovi
  • Tapeworm Aploparaksis stricta
  • Roundworm Skrjabinoclava tupancinca
  • Roundworm Skrjabinoclava pusillae

Economic Importance for Humans: Positive

For sandpipers in general, a positive economic importance is ecotourism at a stopover site in the Bay of Fundy in Canada. Kane (1996) states that during the summer, people visit to observe the large population of shorebirds. (Kane, 1996)

Economic Importance for Humans: Negative

There is no negative economic importance of western sandpipers on humans.

Conservation Status

Western sandpipers have been listed as a species of “Least Concern” on the IUCN Red List, are protected under the US Migratory Bird Treaty Act, and have no special status on the US Federal List, CITES, and State of Michigan List. However, on the US and Canada Shorebird Conservation Plans, they have been listed as high concern due to several factors: limited breeding grounds, large amounts of their population being depleted due to their large migratory flock size, climate change, and harm due to human contributions.

Deterioration of habitat grounds is considered the most urgent problem facing western sandpipers. Due to urbanization and agricultural factors, the marshes that western sandpipers inhabit are being drained, contaminated, and altered. Oil spills and runoff on both breeding and nonbreeding grounds pose a threat to western sandpiper populations. Dangerous chemicals that are present near stopover areas could also be harmful. Buchanan (2003) found that invasive cordgrass (Spartina alterniflora) has heavily invaded estuaries in Washington state that are inhabited by western sandpipers, contributing to population decline. Additionally, the increased usage of water sources vital to western sandpipers by humans is a potential threat because, when feeling threatened, they perform defense mechanisms that exert a lot of their energy. Because western sandpipers are subarctic breeders, climate change could heavily affect their breeding grounds. For example, the increasing sea level and melting ice could potentially interfere with their breeding schedule. Several avian diseases could also jeopardize the wellbeing of the western sandpiper population, such as avian botulism, avian malaria, West Nile Virus, and avian influenza.

Steps have been taken to manage these threats to western sandpipers, such as the Western Hemisphere Shorebird Reserve Network, which dedicates conservation sites throughout the Americas to protect their habitats. In a conservation plan constructed by Fernández et al. (2010), restoring and bettering western sandpiper habitats is the main goal, and they proposed ways to do so: raising awareness, rehabilitating salt ponds into tidal marshes to support living conditions, and installing more nationally recognized safe areas for western sandpipers to inhabit. ("Conservation plan for the western sandpiper (Calidris mauri)", 2010; Buchanan, 2003; Fernández, et al., 2003; Franks, et al., 2014)

Contributors

Haley Mullins (author), Radford University, Alex Atwood (editor), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Karen Powers (editor), Radford University, Joshua Turner (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Nearctic

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.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

bilateral symmetry

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

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.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

female parental care

parental care is carried out by females

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

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).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polar

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.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

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).

terrestrial

Living on the ground.

territorial

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

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

tundra

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.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Western Hemisphere Shorebird Reserve Network. Conservation plan for the western sandpiper (Calidris mauri). Version 1.1. Manomet, Massachusetts: Manomet Center for Conservation Sciences. 2010.

BirdLife International, 2016. "Calidris mauri" (On-line). The IUCN Red List of Threatened Species 2016: e.T22693376A93401409. Accessed February 04, 2018 at http://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T22693376A93401409.en.

Blomqvist, D., B. Kempenaers, R. Lanctot, B. Sandercock. 2002. Genetic parentage and mate guarding in the arctic-breeding western sandpiper. The Auk, 119/1: 228-233.

Brown, R. 1962. The aggressive and distraction behavior of the western sandpipers Ereunetes mauri. The Ibis, 104/1: 1-12.

Buchanan, J. 2003. Spartina invasion of Pacific coast estuaries in the United States: Implications for shorebird conservation. Wader Study Group Bulletin, 100: 47-49.

Canaris, A., N. Munir. 1991. Helminth parasites of the western sandpiper, Calidris mauri (Aves) from El Paso and Hudspeth Counties, Texas. The Journal of Parasitology, 77/5: 787-789.

Fernández, G., H. Cueva, N. Warnock, D. Lank. 2003. Apparent survival rates of western sandpiper (Calidris mauri) wintering in northwest Baja California, Mexico. The Auk, 120/1: 55-61.

Fernández, G., D. Lank. 2010. Do sex and habitat differences in antipredator behavior of western sandpipers Calidris mauri reflect cumulative or compensatory processes?. Journal of Ornithology, 151/3: 665-672.

Fernández, G., D. Lank. 2006. Sex, age, and body size distributions of western sandpipers during the nonbreeding season with respect to local habitat. The Condor, 108/3: 547-557.

Fernández, G., D. Lank. 2007. Variation in the wing morphology of western sandpipers (Calidris mauri) in relation to sex, age class, and annual cycle. The Auk, 124/3: 1037-1046.

Franks, S., D. Lank, W. Wilson Jr.. 2014. "Western Sandpiper (Calidris mauri)" (On-line). version 2.0. In The Birds of North America (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY. Accessed February 19, 2018 at https://doi.org/10.2173/bna.90.

Franks, S., R. Norris, K. Kyser, G. Fernández, B. Schwarz, R. Carmona, M. Colwell, J. Sandoval, A. Dondua, R. Gates, B. Haase, D. Hodkinson, A. Jimenez, R. Lanctot, B. Ortego, B. Sandercrock, F. Sanders, J. Takekawa, N. Warnock, R. Ydenberg. 2012. Range-wide patterns of migratory connectivity in the western sandpiper Calidris mauri. Journal of Avian Biology, 43/2: 155-167.

Holmes, R. 1971. Density, habitat, and the mating system of the western sandpiper (Calidris mauri). Oecologia, 7/2: 191-208.

Holmes, R. 1972. Ecological factors influencing the breeding season schedule of western sandpipers (Calidris mauri) in subarctic Alaska. The American Midland Naturalists, 87/2: 472-491.

Holmes, R. 1973. Social behaviour of breeding western sandpipers Calidris mauri. Ibis, 115/1: 107-123.

Howell, S., S. Webb. 1995. A Guide to the Birds of Mexico and Northern Central America. New York, NY: Oxford University Press.

Johnson, M., J. Walters. 2008. Effects of mate and site fidelity on nest survival of western sandpipers (Calidris mauri). The Auk, 125/1: 76-86.

Johnson, M., J. Walters, S. Aref. 2008. Parent-offspring communication in the western sandpiper. Behavorial Ecology, 19/3: 489-501.

Kane, R. 1996. "Ecotourism and conservation" (On-line). New Jersey Audborn. Accessed March 22, 2018 at http://www.njaudubon.org/SectionConservation/NJASOpinionsandPositionStatements/EcotourismandConservation.aspx.

Kuwae, T., P. Beninger, P. Decottignies, K. Mathot, D. Lund, R. Elner. 2008. Bioflim grazing in a higher vertebrate: The western sandpiper, Calidris mauri. Ecology, 89/3: 599-606.

Norris, D. 2007. Trace element profiles as unique identifiers of western sandpipers (Calidris mauri) populations. Canadian Journal of Zoology, 85: 579-583.

O'Hara, P., G. Fernández, F. Becerril, H. Cueva, D. Lank. 2005. Life history varies with migratory distance in western sandpipers Calidris mauri. Journal of Avian Biology, 36/3: 191-202.

Pomeroy, A., J. Lindstrom. 2006. Tradeoffs between food abundance and predation danger in spatial usage of a stopover site by western sandpipers, Calidris mauri. Oikos, 112/3: 629-637.

Pomeroy, A., D. Seaman, Acevedo, R. Butler, R. Elner, T. Williams, R. Ydenberg. 2008. Feeding-danger trade-offs underlie stopover site selection by migrants. Avian Conservation & Ecology, 3/1: 86-101.

Ruthrauff, D., B. McCaffery. 2005. Survival of western sandpiper broods on the Yukon-Kuskokwim Delta, Alaska. The Condor, 107/3: 597-604.

Sutherland, T., P. Shepherd, R. Elner. 2000. Predation on meiofaunal and macrofaunal intervertebrates by western sandpipers (Calidris mauri): Evidence for dual foraging modes. Marine Biology, 137: 983-993.

Warnock, S., J. Takekawa. 1996. Wintering site fidelity and movement patterns of western sandpipers Calidris mauri in the San Francisco Bay estuary. The Ibis, 138/2: 160-167.

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