Scintillant Hummingbird Selasphorus scintilla
Version: 1.0 — Published February 10, 2011
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Utterly reliant on flight for locomotion, like all hummingbirds. Uses feet for perching and preening. It is versatile: the Scintillant Hummingbird can hover with ease, as well as fly at high speeds. Males have a hovering wingbeat frequency of 68.9 ± 7.6 Hz (n=2; Clark et al. 2011).
Tends to visit small flowers yielding little nectar individually, making up for quality with quantity. During the non-breeding season, likely holds feeding territories when possible, although a weak interspecific competitor with other (larger) hummingbirds due to its small size. Uses small size to ‘sneak’ onto larger hummingbird’s territories without notice; retreats into foliage when discovered, persistently returns (Fogden and Fogden 2006: 52).
The Scintillant Hummingbird preens and stretches as other hummingbirds do. The bill is used to straighten 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. The Scintillant Hummingbird is quite aggressive; will chase other hummingbirds, especially other Scintillant and Volcano (Selasphorus flammula) hummingbirds. Not known to be social other than when female tends to young, and when the male courts the female.
Likely holds feeding territories in the non-breeding season, when resource distributions favor territoriality (i.e., clumped flowers not defended by a superior competitor).
Males on breeding territory spend the majority of time sitting on exposed perches such as the very top branches of a short tree or bush or on telephone wires; only occasionally perch in less exposed locations. Female Scintillant Hummingbirds released on territory were immediately pursued and displayed to, while female Volcano Hummingbirds (Selasphorus flammula) released on same territory were ignored (Clark et al. 2011). May pursue or chase male Scintillant and both sexes of Volcano hummingbirds.
Territories held by males during the breeding season are ambiguous as to whether flowers are being guarded (and by extension, mating system: resource defense polygyny vs exploded lek). Of six territories observed by Clark et al. (2011), all contained flowers and were defended against Volcano Hummingbirds (nectar competitors), similar to the interspecific territoriality of breeding Allen’s (Selasphorus sasin) and Anna’s (Calypte anna) hummingbirds. This suggests that the presence of food was necessary for breeding territoriality, and that by extension, the mating system could be some form of resource defense polygyny. But, all six territories were in open areas; abundant resources in closed areas were used (fed from) but not defended. Clark et al. (2011) speculate that males seen feeding from undefended Fuchsia in closed habitat had territories elsewhere (i.e. in open habitat). Moreover, males of related species (Calliope [Stellula calliope] and Anna’s hummingbirds) are known to forage away from their breeding territory when food on their territory is insufficient. These latter observations give indirect support to the suggestion that breeding territories by males may be for courtship (e.g. exploded lek) rather than foraging potential (Clark et al. 2011).
Only females have been observed making nests and rearing offspring. Two nests observed by Clark et al. (2011) were away from known male territories. There is no evidence that males provide any care for offspring, although it is possible they allow females to feed from their territories. Copulation has not been observed.
During the breeding season, males hold territories (see Territoriality). A female was seen visiting a territory and feeding from it for a few minutes; the male chased, scolded, and displayed to the female. Males perform two types of displays to females that visit, shuttle displays and dive displays.
Shuttle display.-- During the shuttle display, the male elevates his wingbeat frequency to 98 ± 2.64 Hz (n=4 displays) and undergoes periodic motions termed ‘shuttle motions’ or ‘shuttle segments’. During each segment the wings are flapped with bilaterally asymmetic motions, and the tail is swept around. The gorget is flared (held out away from the body) apparently to maximize the reflected color seen by the recipient. Males perform this display in two contexts, 1) following (chasing) a female on their territory, termed by Clark et al. (2011) as a ‘traveling’ shuttle, in which lateral (side-to-side) motion is minimal, and 2) when flying back and forth laterally in front of a (perched) recipient, termed by Clark et al. (2011) as a ‘stationary’ shuttle. The sounds produced during the two variants are similar; the main difference is forward flight versus lateral flight. During the lateral flight, the amplitude of each shuttle segment is roughly 20-40 cm. Sounds are produced by the wings during the shuttle display (see Nonvocal Sounds). Listen to a shuttle display plus chipping from the female on xeno-canto: XC70112.
The Scintillant’s shuttle display is very similar to the shuttle displays performed by the Allen’s (Selasphorus sasin) and Rufus (Selasphorus rufus) hummingbirds (CJC unpublished).
Display dive.-- The male performs 1 to 6 dives to a perched female on his territory, usually preceded by a bout of shuttle display. To dive, the male first ascends at a steep angle, following a slightly undulating trajectory that is similar to the traveling shuttle (see figure). After rising roughly 25 m above the female he swoops, tracing out a giant U. Subsequent dives are in the same plane as the previous dive but from the opposite direction. Four high-speed videos of dives suggested the following kinematic stages of the dive. 1 the male begins the dive by descending at a steep angle, flapping his wings to increase speed. 2. The males sometimes glide as they approach the bottom of the dive, resulting in a momentary pause in the wing trill. 3. They resume flapping and periodically spread and shutting the tail 2-4 times, matching the timing of the sound pulses produced by the tail at the bottom of the dive. Rectrix 2 flutters to produce the sound pulses (Clark et al. 2011). Listen to a dive on xeno-canto XC70113.
Shuttle displays and dives seemed to be primarily directed to female Scintillant Hummingbirds; female Volcano Hummingbirds (Selasphorus flammula) released on a Scintillant’s territory were ignored whereas males always responded to female Scintillant with chases and displays (Clark et al. 2011). Nevertheless it is likely that ‘indiscriminate’ males perform both types of displays to other males or to other species, as indiscriminate males have been observed in several other species within the ‘bee’ clade. It is possible that these displays serve multiple functions.
Social and interspecific behavior
See agonistic behavior.
Not known for the Scintillant Hummingbird specifically, but hummingbirds generally fall prey to a wide range of opportunistic predators such as flycatchers, frogs, spiders, hawks, house cats, etc.
No parasites specifically reported for the Scintillant Hummingbird.