Sounds

Development

No information.

Vocal Array

No distinction has been made between songs and calls in this species, so vocalizations will be considered calls because of their simple structure (SMH pers. obs. unless noted otherwise). Ten different call types have been described for adults and three for chicks (Sung 1999). Many calls could be considered songs because they are transmitted over long distances or are part of ritualistic courtship displays and thus presumably under hormonal control. (See Behavior for behaviors associated with these calls.)

Courtship calls. The aerial display call and nest-scraping call are two common vocalization types used during courtship. From the beginning of the breeding season until mid-July males perform elaborate flights over territories to advertise ownership to neighboring males and prospective mates. In flight they utter a continuous series of high-pitched pipe-pipe-pipe-pipe-pipe- (Fig. 4A). This call is a series of complex notes that usually contains three parts: a very brief introductory tonal click, a harmonic second part, and a pulsed ending. On average, call note duration is approximately 0.16 s (s = 0.012, n = 65, range = 0.13–0.18; SMH unpubl. data); repetition rate is 4.1 call notes/s (s = 0.67, n = 39, range = 3.0–5.0); intercall interval lasts approximately 0.06 s long (s = 0.025, n = 26, range = 0.04–0.14). Individuals may be identified by the frequency pattern in the central part of this call, which is relatively consistent within individuals over time (Sung 1999). This portion of the call varies between individuals but generally shows an initial increase in frequency (1.5-2.3 kHz), levels off, then decreases abruptly. Bout duration difficult to estimate owing to length of time birds spend calling; often lasts hundreds of rhythmic call repetitions. May continue from several minutes to several hours (Sung 1999) and well into the night (SMH). In some cases, males stop only for brief rest periods on the ground or if another bird enters the territory. However, after beginning to court (if the new bird is female) or threaten (if male), intensity of calling may increase. Males in adjacent territories often display simultaneously. This call sometimes precedes aggressive interactions with neighboring males and may precede nest-scraping (Sung 1999). Cairns (1982) indicated females may display with males, but this was not observed during 2,900 h of observation in Manitoba (SMH), nor was it recorded during vocalization research in Newfoundland and Prince Edward Island (Sung 1999). Between bouts of the aerial display flight, a male may creep toward a nest site (or potential nest site) and begin to dig a scrape in the sand. While digging, he utters the nest-scraping call. This call is a series of high-pitched pipe-pipe-pipe’s more rapid and higher in frequency than aerial call (Fig. 4B), but structurally very similar. Mean duration 0.05 s (s = 0.011, n = 42, range = 0.03–0.08); intercall interval of 0.09 s (s = 0.010, n = 38, range = 0.08–0.12); repetition rate of 7.3 notes/s (s = 0.25, n = 12, range = 7.0–8.0; SHM unpubl. data). After digging, the male may sit in the scrape and make a sound similar to the brief contact call and nest-scraping call, consisting of a few slower, lower-pitched pi-ipe, pi-ipe, pi-ipe’s . See also Behavior: sexual behavior.

Contact Calls A group of sometimes variable calls given between mates during courtship, incubation and brood rearing; adults also use calls to make contact with chicks (Sung 1999). One common call used thoughout the breeding season is quiet, brief, and variable in duration and frequency (Sung 1999). It is shorter and softer than the aerial display call but during courtship, this call is often intergraded into the aerial display call. Female may respond to aerial display calls and nest-scraping calls with the common contact call. This brief contact call can also used when an incubating or brooding bird calls for its mate to relieve it. A second, long, declining call is used in addition to the common call to make contact with chicks (Sung 1999). The long call includes a strong second harmonic, appears to elicit a greater response from chicks than the common contact call, and is sometimes used in conjunction with alarm calls. A third contact call is a variable, two part, peep-lo sound that is given in a variety of contexts (Sung 1999). It is mainly used to make contact with chicks, but sometimes used in conjunction with alarm calls. When used with the common contact call during pre-nesting, the peep-lo may be used by unmated males to attract females. The peep-lo call may also be used between premigratory birds in small flocks (Sung 1999).

Territorial threat calls. In addition to the aerial display call described above, two calls commonly used during territorial interactions are the head-bobbing call and the horizontal threat call. The head-bobbing call is a series of brief, repeating, high-frequency calls (Sung 1999). Commonly used during the pre-nesting period when territory boundaries are established. When boundary-line is challenged by a conspecific, territory holder often flies to intruder uttering this call and continues calling after landing, while maintaining erect posture and bobbing head. The horizontal threat display often follows the head-bobbing call, and is used by males and females to keep intruders out of territories (Cairns 1982, SMH). Associated with the horizontal threat display, this call involves a broadband “series of low, rattling bec, bec, bec ’s….. which become increasingly rapid and take on a whirring, throaty undertone as the display progresses” (Cairns 1982, p. 534). The call and accompanying display are usually directed toward conspecifics, but sometimes are directed at shorebird species of similar size (Sung 1999, SMH). See also Behavior: agonistic behavior.

Alarm calls . Three previously described calls are sometimes used as warning calls to chicks when predators are nearby: the long declining contact call, the peep-lo contact call, and a long variation of the head-bobbing call. Three additional calls are also elicited by nearby predators. One is a long, drawn out, plaintive, woo-up, woo-up (SMH). May be used to warn mate or chicks of predators, and after the horizontal threat display during intense interactions with conspecifics, but also used during copulation (Sung 1999). If a perceived predator (e.g., human, dog, falcon, etc.) enters the area, many individuals may utter this alarm call simultaneously (SMH). A second call, consisting of a loud, brief, kee-ah kee-ah, is used during intense interactions with aerial and ground predators (Sung 1999). This call may function as a warning to chicks but its volume gains the attention of predators and is therefore used in aggressive encounters and distraction displays. A third, sharp, high-frequency, whistle call is used in response to aerial predators (Sung 1999). This call also may function as a warning to chicks, and is sometimes used during aerial chases of low-flying predators.

Chick calls . Three call types have been described for chicks (Sung 1999). A common call heard throughout brood rearing is a brief descending note. This call is used by chicks during foraging and often to make contact with parents after chicks wander off. Parents may respond to this call with a brief contact call, the long descending contact call, or the long, woo-up woo-up alarm call (Sung 1999). A second call used by chicks while walking toward parents after hatching is a very soft gently rising whistle. This call is difficult to localize and can only be detected at close range, so it is unknown whether older chicks continue to make this call (Sung 1999). A third call uttered by chicks in hand, during banding, is a quick, high-frequency, trill (Sung 1999).

Phenology

See Vocalizations: vocal array. No information about calls during nonbreeding season.

Not known to produce these.