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Peruvian Sheartail Thaumastura cora

  • Order: Caprimulgiformes
  • Family: Trochilidae
  • Monotypic
  • Authors: Clark, Christopher J.
Sections

Behavior

Behavior

Peruvian Sheartail is utterly reliant on flight for locomotion, like all hummingbirds. Uses feet for perching and preening. It is versatile: Peruvian Sheartail can hover with ease, as well as fly at high speeds. Males have a hovering wingbeat frequency of 49 ± 4.6 Hz (n = 9; Clark et al. 2013), females a hovering wingbeat frequency of 42 ± 2.7 Hz (n = 5, Clark et al. 2013). Male wingbeat frequency is substantially higher during courtship displays (see Sexual Behavior).

Peruvian Sheartail has recently colonized the Vitor Valley, an island of habitat surrounded by the inhospitable Atacama desert. To do so, individuals must have flown roughly 40 km, a distance that similar sized hummingbirds can fly in less than an hour (Clark and Dudley 2010).

Foraging

Little direct information. Like all hummingbirds, takes nectar from flowers, often flying continuously during a feeding bout, but may also cling to flower to feed. Will visit hummingbird feeders, although does not find them as readily as Oasis Hummingbird (Rhodopis vesper) (personal observation). Unknown if it adopts feeding territoriality during the non-breeding season. Co-occurs with few other species of hummingbird, and so is likely a generalist. Visits small 'insect syndrome' flowers as well as larger 'bird syndrome' flowers.


Self-maintenance

The Peruvian Sheartail preens and stretches as other hummingbirds do. The bill is used to straighten and preen feathers and apply preen oil; the feet are used to scratch areas the bill can’t reach such as the head.

Agonistic behavior

Agonistic is the default behavioral state of hummingbirds. Peruvian Sheartail is fairly aggressive, although it is behaviorally subordinate to Chilean Woodstar (Eulidia yarrellii) (van Dongen et al. 2013, contra Schuchmann 1999), likely on account of its longer wings (Clark et al 2013). Males chase and harass other male sheartails in long chases accompanied with extended bouts of singing (or calling), and such skirmishes can include three or four birds from neighboring territories (personal observations). M. E. Deville wrote: "it is seen in small troops composed of six or eight couples, which are constantly pursing one another, and uttering a slight cry. It is very airy in its flight, and rarely permits any other humming-bird to remain in its neighborhood, but wages a continual and terrible war with them" (as translated by Gould 1861). Not known to be social other than when female tends to young, and when the male courts the female.

Territoriality

It is unknown whether individual Peruvian Sheartails defend feeding territories in the nonbreeding season.

During the breeding season, male Peruvian Sheartail hold courtship territories that are approximately 40 × 40 m, in open, sparse habitat, such as the wash of the river Azapa (Clark et al. 2013, van Dongen et al. 2013). On their territory, they spend most of the day perched on prominent locations such as twigs at the tops of bushes, or telephone wires, 2-5 (occasionally 10) m in height. They sing undirected song from these perches, and shift perches often. Male Peruvian Sheartails were chased by and subordinate to male Chilean Woodstars (Eulidia yarrellii) (van Dongen et al. 2013), and there was no overlap of territories of these two species (Clark et al. 2013; van Dongen et al. 2013). By contrast, male Oasis Hummingbird (Rhodopis vesper) territories sometimes overlapped with male Peruvian Sheartail territories, to the point that one male of each species used the exact same territorial perch (at different times). In other locations, Oasis Hummingbirds evicted sheartails from their territories.

Territories held by males during the breeding season are ambiguous as to whether flowers are being guarded, and by extension, whether the mating system is closer to resource defense polygyny vs a dispersed lek. Most males found guarding territories in Azapa, September 2010 had copious food on their territories (in the form of Tecoma fulva), and predominantly fed on their territories (van Dongen et al. 2013). But, elsewhere males were only observed holding territories in open areas, and many were observed visiting dense stands of Leonotis sp. in a dense, mostly closed orchard, in an area apparently lacking territories; this suggests habitat openness plays a role in determining territory suitability.

Territorial males flew at and chased other sheartails that entered their territory. In one instance, a male in immature plumage repeatedly intruded on an adult male’s territory, and was repeatedly attacked and chased by the resident male; no displays to this individual were observed.

One distinctive behavior males frequently perform on their territories was termed 'floating' by Clark et al. (2013), who describe this behavior as follows:
"[the male] would rapidly fly over to a bush or other vegetation on or near his territory, and then hover, stationary, 1 to 10 m above it. With bill pointed down they would turn their head from side to side, hovering in place for up to a couple of minutes. The apparent function is to search for a visiting female or intruder in the vegetation below. Many related species also perform this behavior (CJC pers obvs), and it is normally terminated with either the male locating and interacting with the bird it was apparently looking for, or seemingly failing to locate the other bird, and returning to a perch. In other species the male may descend while hovering, but remains above the canopy. This behavior was unique in the Peruvian Sheartail in that, while scanning, males would slowly descend down through the canopy of a bush, sometimes down to within a few decimeters of the ground, giving the impression that the male was searching for the target hummingbird deep inside the bush. Both times a male was observed naturally displaying to a female, the female was perched deep inside the bush, close to the ground. The wingbeat frequency (wbf) during this display was 69 ± 5.5 Hz (n = 3 videos)".

Sexual Behavior

Clark et al (2013) rarely saw females on male territories; females were mostly observed in areas with greater vegetation cover. As in all hummingbirds, there is no indication that males help the female raise the offspring.

Females observed on male territories during Clark et al.'s (2013) study were perched deep in thick bushes, with the male frenetically flying around and into the bush during display. Clark et al. (2013) elicited displays by placing a caged female on male territories. The displays that ensued were largely of two types, 'shuttles' and 'dives'. The next several paragraphs are from the description in Clark et al. (2013) of these two types of displays (figures are in Clark et al. 2013):

"Many male Peruvian Sheartails responded frenetically to the stimulus of a female in a cage placed in a bush. Sometimes when they seemed unaware of the female’s exact location, they would perform the 'floating' behavior in the bush near the cage, or even underneath the cage (i.e., looking for the female below where she was). Some males would perform bouts of displays to the female over a long period of time (occasionally for > 30 min). Some eventually ignored the female in the cage, but others ended their displays only after one or more additional males began to repeatedly intrude onto the focal male’s territory to look at or also display to the female in the cage. When this occurred the focal male would spend most of the time evicting (chasing) the other male(s), and few additional displays occurred.

Dives and shuttles. Courtship displays typically began with the male hovering above the female with an elevated wingbeat frequency, singing. After a bout of song the male would then transition to a series of repeated flights back and forth over or past the female. As a part of these displays, the male would spread the gorget, apparently maximizing the surface area directed towards the recipient, and hold the tail spread widely.

These back-and-forth flight displays of the Peruvian Sheartail were far less stereotyped than the distinct shuttle and dive displays in other related 'bee' hummingbirds. In general the display flights seemed bimodal, with most individuals performing both relatively large display dives (Fig. 2A-D) and relatively small shuttle displays (Fig. 2E-G). However, unlike all other bee species studied, there was overlap in the kinematics (particularly in the amplitude of the flights) between the two displays, and some displays were of ambiguous type. It appeared that males always sang vigorously during the smaller displays (shuttles), and did not sing during the larger displays (dives), so we have divided the behavior into these two categories based on the presence or absence of song.

Males often performed the shuttle display for a period, then shifted to dives, or vice versa. Individual males varied greatly in their propensity to shuttle or dive, with some individuals primarily performing shuttles, some primarily performing dives, although most or all individuals performed both types of displays. Examples of the dives and shuttles are presented in a supplemental online video (www.youtube.com/watch?v=M8DeiswDB8k).

'Dives' were back-and-forth flights performed by the male that were usually larger in amplitude than the shuttle. These were especially non-stereotyped. They ranged in horizontal amplitude from 1 to 15 m. The male would ascend vertically 0 to 10 m, then turn and swoop past the female at speed, describing a shallow J (Fig. 2A-C). Occasionally the male did not ascend, so there was not an actual dive in which the male descended with the aid of gravity; these ‘dives’ were simply fast horizontal flights past the female. Dives usually passed within 1 m of the female.

The wings were typically flapped throughout the dive at 75 ± 3.5 Hz (high-speed videos from 8 males), but occasionally the male briefly glided when approaching or passing over the female. The tail was kept widely spread at ~180º throughout the dive, and the tips of R2 visibly fluttered in aerodynamic response to each wing beat. Occasionally the males would undulate the forward trajectory of the dive just after passing over the female (Fig. 2A-B). High-speed video suggested that these undulations were produced by the male rolling to one side...”

"Males often performed bouts of dives, with subsequent dives either in the opposite direction as the previous dive, or at a 90º angle (azimuth) from the previous dive. In the latter case, at the end of a dive the male would loop around to the right or left and then dive again, so that the two subsequent dives would trace out a figure 8 in the horizontal plane, with the female near the intersection (Fig. 2D). This may have been associated with the male avoiding obstacles such as a bush or recordist.

"Shuttles consisted of a series of back and forth flights past the female along a curving or straight line that tended to be short, as compared to dives. They ranged in amplitude from 0.5 to 2 m (Fig. 2E-G). Each short flight we term a 'shuttle segment'. At the end of a shuttle segment males would change direction and begin a new shuttle segment. Often the male would reverse direction and fly back the way he had come, thus causing the male to return to his initial position after two shuttle segments (Fig. 2G). Occasionally the male would fly in a new direction in a subsequent shuttle segment, causing the orientation of the display to shift, e.g. from one face of the cage holding the female, to another (Fig. 2G). The males rotated their bodies as they passed by the female in order to remain facing her. During this display the wingbeat frequency was 73 ± 8.3 Hz (n = 7 males), and shuttle segments were performed at a frequency of 1.8 ± 0.3Hz (n = 5 males). Males sang as they flew shuttle segments and would also pause between segments to hover and sing.

"The tail was spread 180º throughout this display; high speed videos and photos clearly indicated that even the R1s were widely spread, such that they projected laterally out to either side of the bird, rather than posteriorily (Fig. 2F). Many individuals had R2s were broken, missing, or the white areas of the feather were worn away. In birds with intact R2s, the combination of the black R5 R4 and R3 contrasted with the white on the R2, gave a striking impression of a black on white stripe protruding laterally from each side of the bird (Fig. 2F).

"During most dives and occasionally during shuttle segments, a tonal sound [the dive-sound, see above] was produced. This sound was only produced when the tail was spread widely, and it was accentuated during the undulating portion of the trajectory of the dive. Because the sound was produced during some shuttle displays and not all dives, it was not diagnostic of either behavior." (Clark et al. 2013).

Social and interspecific behavior

See Behavior: agonistic behavior.

Predation

Not known for the Peruvian Sheartail specifically, but likely falls prey to a wide range of opportunistic predators such as flycatchers, hawks, house cats, etc.

Parasites

No parasites specifically reported for the Peruvian Sheartail.

Recommended Citation

Clark, Christopher J. 2013. Peruvian Sheartail (Thaumastura cora), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, editor). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/nb.pershe2.01