Behavior

The Sharp-tailed Sandpiper is polygynous or, possibly, promiscuous (14 Pitelka, F. A. (1959). Numbers, breeding schedule, and territoriality in Pectoral Sandpipers of northern Alaska. Condor 61:233-264. Close , 15 Pitelka, F. A., R. T. Holmes and Jr. MacLean, S. F. (1974). Ecology and evolution of social organization in arctic sandpipers. American Zoologist 14 (1):185-204. Close , 16 Myers, J. P. (1982a). The promiscuous Pectoral Sandpiper. American Birds 36:119-122. Close , 17 Khlebosolov, E. I. (1985). The territorial behavior and its relation to the postnesting ecology in some tundra Limicolae. Zoologicheskij Zhurnal 64:1024–1035. Close ). Otherwise, its behavior is rather typical of a small shorebird.

Walks slowly, with head down, while foraging; stands upright, with neck extended when alert (SGM). Flight much like that of the Pectoral Sandpiper (Calidris melanotos)(SGM). Rarely, will swim (43 Higgins, P. J., and S. J. J. F. Davies, Editors (1996). Handbook of Australian, New Zealand and Antarctic Birds. Volume 3. Pratincoles to Pigeons. Oxford University Press, Melbourne, Australia. Close ).

No specific information.

Breeding Territory Maintenance

Sharp-tailed Sandpiper males maintain their breeding territory in part by flight displays, which can be broken into two portions as described by Flint and Tomkavich (61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close ), "demonstrative" and "reconnaissance." During the demonstrative portion, the male leaps into the air and flies steeply up to 30 or 40 meters. As it climbs, it utters a short cry – described as "piukhhh" – which is caused by air entering and inflating its throat sack (82 Flint, V. E. and P. S. Tomkovich. (1982). "Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper." In Ornithological Studies in the USSR, 241-261. Moscow: Nauka. Close , 59 Myers, J.P., Hildén O. and Tomkovich, P. (1982). Exotic Calidris species of the Siberian tundra. Ornis Fennica. 59: 175–182. Close ). As the bird reaches the apex of its "leap," its wings are held still, and at a marked upwards angle, as the bird begins to glide; at this point the bird issues a series of dry crackling warbles which stop at the mid-point of the descent (82 Flint, V. E. and P. S. Tomkovich. (1982). "Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper." In Ornithological Studies in the USSR, 241-261. Moscow: Nauka. Close ). When close to the ground, the bird either decides to land or enter the reconnaissance phase of its territorial flight; the reconnaissance phase is a circling of the territory at 30 to 50 meters above the ground, after which it lands at the same place it first leapt into the air (82 Flint, V. E. and P. S. Tomkovich. (1982). "Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper." In Ornithological Studies in the USSR, 241-261. Moscow: Nauka. Close ). The Sharp-tailed Sandpiper also has two types of territorial ground displays (82 Flint, V. E. and P. S. Tomkovich. (1982). "Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper." In Ornithological Studies in the USSR, 241-261. Moscow: Nauka. Close ). In the first, it is stationary, sitting horizontal at a high point in its territory, half-concealed by vegetation. In the second, it is active: The male stands with its legs straightened at an elevated point in its territory as it spreads its wings horizontally until half-bent while raising its slightly spread tail into the vertical position. Then the head is stretched forwards and upwards with the bill pointed slightly downwards. At that point the bird utters two sound, one a series of "khruk" syllables and the other a series click-like clear sounds, each resembling "pot." These two sounds are produced synchronously at a rate of 2/sec as the bird's body twitches and its head nods sharply with each utterance. This demonstration is relatively quiet, and cannot be heard more then 40 to 50 meters away.

Two males along a shared territorial boundary will sometimes fly parallel to each other for 100 meters or so, only one to two meters apart, while making a "chirring" sounds (83 Kistchinskii, A. A. (1974). [The biology and behavior of the Pectoral Sandpiper in the tundra of eastern Siberia]. Byull. Mosk. Obshch. Ispyt. Prir. (Otd. Biol.) 79:73-88. Close , 61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close ). This sometimes progresses into chase flights and posturing on the ground involving both upright postures and bowing that can, rarely, evolve into actual physical contact, with both birds jumping into the air and grappling each other with their feet (83 Kistchinskii, A. A. (1974). [The biology and behavior of the Pectoral Sandpiper in the tundra of eastern Siberia]. Byull. Mosk. Obshch. Ispyt. Prir. (Otd. Biol.) 79:73-88. Close , 61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close ). During the second half of June, male territories begin to disintegrate, at which time males perform coordinated flights in pairs or groups (84 Kistchinskii, A. A. (1973). Data on feeding of the Sharp-tailed Sandpiper in the tundra of northeastern Yakutiya. Fauna i ecologiya kulikov 1:46-48. Close , 83 Kistchinskii, A. A. (1974). [The biology and behavior of the Pectoral Sandpiper in the tundra of eastern Siberia]. Byull. Mosk. Obshch. Ispyt. Prir. (Otd. Biol.) 79:73-88. Close ).

Physical Interactions

In addition to those described above under Breeding Territory Maintenance, confrontations between Sharp-tailed Sandpiper are known to occur when feeding in close proximity, with such interactions seemingly more common between juveniles during southbound migration, but also occurring between birds on the wintering grounds (85 Coates, B. J. (1985). The birds of Papua New Guinea including the Bismarck Archipelago and Bougainville, Vol. 1: Non-passerines. Dove Publications, Alderley, Queensland, Australia. Close , 86 Starks, J. (1996). Intraspecific Aggression in the Sharp-Tailed Sandpiper Calidris acuminata. The Stilt 29:40. Close ). Coates (85 Coates, B. J. (1985). The birds of Papua New Guinea including the Bismarck Archipelago and Bougainville, Vol. 1: Non-passerines. Dove Publications, Alderley, Queensland, Australia. Close ) describes these interactions as occurring when an intruder enters the feeding area of another individual: the defender crouches with its head lowered and bill open while uttering threatening calls; if the intruder does not retreat, the defender often flies at the intruder, with the two birds often meeting in mid-air. This interaction may be repeated several times, typically with the intruder retreating at the end. Starks (86 Starks, J. (1996). Intraspecific Aggression in the Sharp-Tailed Sandpiper Calidris acuminata. The Stilt 29:40. Close ) described an interaction between an adult and juvenile on the wintering grounds as follows: "The adult bird was the aggressor and appeared intent on driving the juvenile away from a particular patch of mud. The two birds engaged each other with their bills and much flapping of wings, although the juvenile appeared to be defending itself rather than retaliating. The adult forced the juvenile into the water, then proceeded to jump on top of it, successfully pushing the juvenile completely underwater. The juvenile surfaced a second or two later and flew off."

Mating System and Sex Ratio

The Sharp-tailed Sandpiper is polygynous or, possibly, promiscuous (14 Pitelka, F. A. (1959). Numbers, breeding schedule, and territoriality in Pectoral Sandpipers of northern Alaska. Condor 61:233-264. Close , 15 Pitelka, F. A., R. T. Holmes and Jr. MacLean, S. F. (1974). Ecology and evolution of social organization in arctic sandpipers. American Zoologist 14 (1):185-204. Close , 16 Myers, J. P. (1982a). The promiscuous Pectoral Sandpiper. American Birds 36:119-122. Close , 17 Khlebosolov, E. I. (1985). The territorial behavior and its relation to the postnesting ecology in some tundra Limicolae. Zoologicheskij Zhurnal 64:1024–1035. Close ). Males arrive first on the breeding grounds, establish territories, and try to mate with any female that lands within its territory; females may then stay to nest within that territory, move to another male's territory, or nest at a location that is not within any male's realm (61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close ). Since males will attempt to mate with any female in its territory, and females may visit more than one territory, it is quite possible that females copulate with more than one male (15 Pitelka, F. A., R. T. Holmes and Jr. MacLean, S. F. (1974). Ecology and evolution of social organization in arctic sandpipers. American Zoologist 14 (1):185-204. Close ). The number of females at nesting areas exceeds that of males at a ratio that varies from at least 1.5:1 to 5:1 (61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close ). The skewed sex ratio may be due to males sampling multiple potential breeding sites perhaps allowing them to display and sire offspring at multiple locations during a single breeding season, much as is seen in the Pectoral Sandpiper (Calidris melanotos) (87 Kempenaers, B. and M. Valcu. (2017). Breeding site sampling across the Arctic by individual males of a polygynous shorebird. Nature 541 (7638):528-531. Close ). There have been several confirmed cases of a one-year-old female breeding (62 Handel, C. M., and R. E. Gill, Jr. (2010). Wayward Youth: Trans-Beringian Movement and Differential Southward Migration by Juvenile Sharp-tailed Sandpipers. Arctic 63:273-288. Close ).

Pair Bond

There is no evidence of pair bond formation longer than the time necessary for courtship and copulation (61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close , 17 Khlebosolov, E. I. (1985). The territorial behavior and its relation to the postnesting ecology in some tundra Limicolae. Zoologicheskij Zhurnal 64:1024–1035. Close ).

Extra-Pair Mating Behavior

Given that no true pair bond seems to exist, and given the species' seemingly promiscuous copulatory behavior, it is not clear that the term "extra-pair mating" is meaningful for the Sharp-tailed Sandpiper.

Nonpredatory Interspecific Interactions

Breeding territories of the Sharp-tailed Sandpiper and the similar Pectoral Sandpiper (Calidris melanotos) overlap extensively throughout its range, but agonistic interactions (which resemble territorial behavior) are rare; when they do happen, they are initiated by the Pectoral Sandpiper (61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close ). The minimum distance between nests of the Sharp-tailed Sandpiper and the Pectoral Sandpiper is 33 meters, even though Sharp-tailed Sandpipers will nest closer to other species of shorebirds (61 Flint, V.E. and Tomkovich, P.S. (1982). [Ecological and ethological isolation in the Pectoral Sandpiper and the Sharp-tailed Sandpiper]. Pp. 241–261 in: Gavrilov, V.M. & Potapov, R.L. eds. (1982). [Ornithological Studies of the USSR]. Vol. 2. Zoological Institute, USSR Academy of Sciences, Moscow. In Russian. Close ). Has been observed to be harassed by Red-necked Avocet (Recurvirostra novaehollandiae) when in proximity to the latter's nest (88 Bryant, C.E. (1948). More observations on nesting avocets. Emu. 48: 89–92. Close ).

Kinds of Predators

Predator attacks are considered rare at the western Alaskan staging areas of juveniles (62 Handel, C. M., and R. E. Gill, Jr. (2010). Wayward Youth: Trans-Beringian Movement and Differential Southward Migration by Juvenile Sharp-tailed Sandpipers. Arctic 63:273-288. Close , 3 Lindström, Å., Gill, R.E., Jamieson, S.E., McCaffery, B., Wennerberg, L., Wikelski, M. and Klaassen, M. (2011). A puzzling migratory detour: are fueling conditions in Alaska driving the movement of juvenile Sharp-tailed Sandpipers? Condor. 113(1): 129–139. Close ). Lindström et al studied staging juvenile Sharp-tailed Sandpiper at Alaska's Yukon-Kuskokwim delta during 2005 and 2006, and during their work they witnessed 61 interactions between avian predators and shorebirds, 45 of which involved Parasitic Jaeger (Stercorarius parasiticus), eight of which involved Northern Harrier (Circus hudsonius), and four of which involved Peregrine Falcon (Falco peregrinus), but they were unable to determine which shorebird species was involved in each interaction; in 2006, the resulting mortality rate was 0.02 deaths per hour, which equals roughly one shorebird killed every three days (3 Lindström, Å., Gill, R.E., Jamieson, S.E., McCaffery, B., Wennerberg, L., Wikelski, M. and Klaassen, M. (2011). A puzzling migratory detour: are fueling conditions in Alaska driving the movement of juvenile Sharp-tailed Sandpipers? Condor. 113(1): 129–139. Close ).

On the wintering grounds, the Little Raven (Corvus mellori) (89 Cardilini, A. P., K. B. Ekanayake, and M. A. Weston (2012). Little Ravens 'Corvus mellori' hunt, kill and eat individuals of two species of shorebird. The Victorian Naturalist 129:22–24. Close ), Black Falcon (Falco subniger) (90 Hobbs, J. N. (1961). The birds of south-west New South Wales. Emu 61(1):21–55. Close ), and Peregrine Falcon (91 Olsen J. and P. Olsen (1981). Australian Raptor Association News 2(3): 11-12. Close ) have been observed to predate Sharp-tailed Sandpiper.