Adults have black legs and a small, thin, dark bill. The body is dark brown on top and mainly white underneath, with brown streaks on the breast and a white rump. They have a white stripe over their eyes. This bird shows long wings in flight. In winter plumage, this species is pale gray above. This bird can be difficult to distinguish from other similar tiny shorebirds; these are known collectively as "peeps" or "stints".
One of the best identification features is the long wings, which extend beyond the tail when the bird is on the ground. Only the Baird's sandpiper also shows this, and that bird can be distinguished by the lack of a white rump.
Their breeding habitat is the northern tundra on Arctic islands in Canada and Alaska. They nest on the ground, usually well-concealed in vegetation.
They are a long distance migrant, wintering in southern South America. They are rare but regular vagrants to western Europe. The species is a rare vagrant to Australia.
These birds are not often spotted. In the summer they are rarely seen because they are in such an obscure breeding location. Similarly, in the winter they are rarely seen because they travel too for south for many birdwatchers. Therefore, the majority of sightings occur during the spring or fall in temperate regions and are generally in small numbers around water.
These birds forage by probing on mudflats or tundra or picking up food by sight in shallow water. They mainly eat insects, mollusks and marine worms, also some plant material.
Hybrids between this species and the dunlin are occasionally found in northeastern North America (see external link below); the white-rumped sandpiper is also suspected to hybridize with the buff-breasted sandpiper.
Firstly, the white-rumped sandpiper is placed in class Aves which is consistent for all birds. Being a shore bird places it in the order Charadriiformes along with gulls, alcids, plovers and oystercatchers. Its family Scolopacidae encompasses all sandpipers and being a stint classifies it in the genus Calidris. And finally its species is classified as calidris fusicollis which is more commonly known as the white-rumped sandpiper.
The white-rumped Sandpiper is a relatively small bird measuring only 7.8 inches. The top of its body is a dull grey-brown color and it has a white eye stripe. Its beak is of medium length and its legs are very dark. This bird is often mistaken with many similar looking sandpipers that live in its range or along its migration path.
Their plumage is much less distinct during the winter; however, during all seasons males and females remain similar in their appearance. For the adult alternate plumage the crown and face have a brownish tinge. The supercilium is pale, there are black feathers on the back and there are grey edges on the wing coverts. The breasts and flanks are streaked and finally the underparts are white. In the adult basic plumage the underparts are a dark grey and at the centers there are black feathers. The underparts are still white but the breast is now a dark grey. Finally, The supercilium is white while the crown and eyeline are darker. Juvenile plumage consists of black-based feathers on the back and wing coverts. These black-based feathers have brown edges towards the scapulars and whiter edges towards the wing coverts. The breast is finely streaked and there is a white “V” on its back. The underparts are white, as is the supercilium while the crown is a brownish color and the face is pale.
The two primary features used to identify this bird in the field are its long wings and its white rump. The white patch on the rump can be seen while the bird is in flight making it a useful identification tool. Its long wings wings extend beyond the tail by about a quarter inch, another unique trait helpful to set this bird apart. There is also a thin white stripe on the wing  and a row of marks on the flanks below the wings which can be useful traits in identifying this bird as well.
Habitat and Distribution
The white-rumped sandpiper inhabits relatively vegetated patches of the tundra. More specifically, they live in the marshy, heavily vegetated, hummocky arctic tundra of Alaska and Canada during the breeding season. It can be found in various types of wetlands while migrating. During the winter months it inhabits a variety of freshwater and saltwater habitats such as lagoons, estuaries and marshes. In general, it tends to avoid sandy beaches and fast moving water.
Shore birds spend up to 5–6 months on migration and in wintering grounds over the course of a year. The white-rumped sandpiper is one of the most impressive travelling the entire continent of North American in the span of one month. It is considered one of the most extreme long distance migrants in the world.
The white-rumped sandpiper is a nearctic migrant. While it breeds in northern Canada and Alaska, it flies over the Atlantic ocean to spend the majority of its non-breeding period in South America, particularly along the Patagonian coast in both Chile and Argentina. It also frequently visits fracasso beach. Many shorebirds concentrate in this area due to the abundance of intertidal invertebrates - especially clams. In addition to this popular location, the white-rumped sandpiper has been spotted in Venezuela, Suriname, Brazil and Paraguay during its migration. Dozens have even been seen in Europe.
The birds migrate with both nonstop and short distance multiple stop flights. During their migration from North to South the white-rumped sandpipers fly over the Atlantic ocean. They gradually travel along the northeastern coast of South America before they head inland towards the islands. This travel generally takes about one month. On their migration from South to North the white-rumped sandpiper follows a similar path as with North to South, but does it much more quickly. This migration is done in a fast series of long flights without stopping. One nonstop flight can be as long as 4,200 km.
Weather patterns play a crucial role in determining the migration route. Birds like to travel so that the temperature, pressure and humidity work with the tailwinds. Strong winds can blow birds off of their regular migration route. For example, the effects of a large storm lead to a higher presence of the white-rumped sandpiper on the King George Islands.
Effects of Climate Warming
The warming of the climate has lead to changes in the number of individuals and the length of their stay in the South Shetland Islands. White-rumped sandpipers are now observed more frequently in this area as a result of both long and short term climate variations. The higher air temperatures, which occur as a result of the northern winds, bring warm moist air which creates more open habitats and better food resources that allow these birds to persist and survive. Migration routes as well as both winter and summer foraging grounds may also be altered.
One of the white-rumped sandpiper vocalizations consists of repeating “pip, pip, pip …” Another vocalization is the call. Their call has a distinctive note which makes them easily identifiable among a flock of small shorebirds. The call is a metallic “tzeep” and resembles the sound of two pebbles scraping against one another.
Their diet consists primarily of small invertebrates including: molluscs, crustaceans, annelids and both adult and larval insects. They are mainly reported to eat aquatic invertebrates. Although it was previously thought they only consumed invertebrates, it has been shown that seeds also make up a portion of the white-rumped sandpiper diet. This discovery lead to the idea that they might be opportunistic feeders depending on time, season and habitat. Stones and algae have also been found in their stomachs but these are most likely ingested by accident. The stones are of the same general shape and size as the seeds so it could be a case of mistaken identity. Algae could also be accidentally ingested through aquatic feeding.
While on mudflats the white-rumped sandpiper forages by probing in shallow waters and in mud but can also pick up some items from the surface. When they are in the tundra they must probe deeply in the moss and other vegetation.
The females build the nests which are a cup shaped depression in the ground. The nest is lined with pieces of lichen, leaves and moss which can occur naturally or can be added by the female. The nests are generally well hidden in a clump of moss or grass. Males defend the breeding territory by gliding and fluttering above it while making oinking and rattling sounds. When on the ground, the male stretches its wing out to the side and raises its tail into the air to display the white patch on its rump. He then walks and runs while repeating a call.
As with most shorebirds, the courtship behavior of the white-rumped sandpiper involves an aerial component. During courtship the male and the female fly upward side by side at an angle. At about 10m above the ground they stop about 0.5m apart and hover with shallow, rapidly vibrating wingbeats. The male remains above the female and repeatedly releases a series of “poing-zee” notes. They hover between 5 and 10 seconds before descending to the ground slowly and silently and land about 2m apart. During their downward glide their wings are held together in a “V” position above their backs. A few minutes later they initiate a second paired flight similar to the first one in every way. However, once they have landed on the ground the male begins to chase the female. The chase ends when the male does a wing raising display, this is common in many sandpiper species.
The females are small and nest in the high arctic which means these birds are more likely under a higher cold stress than birds nesting in temperate areas. Consequently, females spend an average of 82.5% of their time incubating their eggs. In total the females incubate the eggs for about 22 days. She generally lays 4 olive to green eggs; laying 3 eggs is a rare occurrence. These eggs can sometimes be blotched with brown, olive-brown or grey spots.
With the white-rumped sandpiper only the females incubate the eggs. Once the female has laid the eggs the male stops displaying and leaves the breeding grounds. This is unlike other members of the calidris genus where incubation is shared between males and females; therefore, the trait of male incubation has been independently lost in this species. There are only three documented species who have been known to do this. This development seems bizarre since experiments have shown that a decrease in the amount of male care is linked to a decrease in male fitness by lowering the amount of male descendants that survive. However, one explanation for this evolution is that a decrease in male care allows males to explore other breeding options. This hypothesis ties in with the fact that the white-rumped sandpiper is polygynous. This means that males will mate with several females but females will only mate with on male.
The young are covered in down feathers and leave the nest about a day after hatching. The female will tend to them by brooding them and keeping them warm, but they must find all their own food. Their first flight is at the age of about 16–17 days and soon after that they become independent.
- BirdLife International (2012). "Calidris fuscicollis". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Montalti1, Diego, Ana M. Arambarri2, Guillermo E. Soave1, Carlos A. Darrieu1, and Anibal R. Camperi1. "Seeds in the Diet of the White-Rumped Sandpiper in Argentina."Waterbirds. 26.2 (2003): 166-168. Web.Accessed 1 October 2015.
- Smithsonian Institution. “White-rumped Sandpiper.”Birds of DC. (2015)Web. Accessed 7 October 2015.
- McLaughlin K. A. & Wormington, A. (2000): "An apparent Dunlin × White-rumped Sandpiper hybrid". Ontario Birds 18(1): 8-12.
- "Calidris fuscicollis." ITIS Report. n.d. Web. Accessed 14 October 2015. <http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=176654>
- “White-rumped sandpiper - calidris fuscicollis”. USGS Patuxent Bird Identification InfoCenter. n.d. Web. Accessed 12 October 2015. <http://www.mbr-pwrc.usgs.gov/id/framlst/i2400id.html>
- Hannisian, Mike. “Shorebird ID Class.” San Antonio Audubon Society.(2005) Web. Accessed 7 October 2015.
- Bala, Luis Oscar and hernandez, M. “Prey Selection and Foraging patters of the White-rumped sandpiper (Calidris Fuscicollis) at Peninsula Valdes, Patagonia, Argentina.” ORNITOLOGIA NEOTROPICAL 18: 37-46, (2007). Web. Accessed 29 September 2015.
- Korczack-Abshire, Malgorzata et al. “Records of the white-rumped sandpiper (calidris fuscicollis) on the South-Shetland Islands.”Polar Record 47 (242): 262–267 (2011). Web. Accesses 28 September 2015.
- “White-Rumped Sandpiper.” The Cornell Lab of Ornithology. (2015) Web. Accessed 10 Oct 2015.
- National Audubon Society. "White-rumped Sandpiper Calidris fuscicollis."Guide to North American Birds. n.d. Web. Accessed 12 October 2015. <https://www.audubon.org/field-guide/bird/white-rumped-sandpiper>
- McCaffrey, Brian J. “Breeding Flight Display in the Female White-rumped sandpiper (Calidris fuscicollis).” Short Communications, Auk 100: 500-501. (1983). Web. Accessed 9 October 2015.
- Cantar, R. V. and R. D. Montgomerie . "The Influence of Weather On Incubation Scheduling of the White-Rumped Sandpiper (Calidris Fuscicollis): a Uniparental Incubator in a Cold Environment." Behaviour 95(3): 261-289.(1985) Web. Accessed 5 October 2015.
- Borowik, Oskana A. and McLennan, Deborah A. “Phylogenetic patterns of parental care in caldirine sandpipers.”The Auk 116(4):1007-1117, (1999). Web. Accessed 2 October 2015.
|Wikimedia Commons has media related to White-rumped sandpiper.|
|Wikispecies has information related to: Calidris fuscicollis|
- Ocean Wanderers: A putative hybrid white-rumped sandpiper × dunlin from the east coast of the USA. Retrieved 2006-Oct-11
- An online identification article covering this species and other small calidrids at surfbirds.com
- White-rumped sandpiper species account - Cornell Lab of Ornithology
- White-rumped sandpiper - Calidris fuscicollis - USGS Patuxent Bird Identification InfoCenter
- White-rumped sandpiper videos, photos, and sounds at the Internet Bird Collection
- White-rumped sandpiper photo gallery at VIREO (Drexel University)
- Interactive range map of Calidris fuscicollis at IUCN Red List maps