| hummingbird incubation: female attentiveness and egg temperature. | incubating hummingbirds adjust nest attentiveness patterns in different habitats to permit both regulation of egg temperatures for embryonic development and foraging of the adult for positive energy balance. anna's (calype anna) and black-chinned (archilochus alexandri) hummingbirds nesting in california chaparral left the nest six to nine times during each daylight hour. eggs usually cooled only 3-6°c during absences but sometimes cooled up to 20°c during long absences. one anna's hummingbird b ... | 1981 | 28310082 |
| hyperglycemia in hummingbirds and its consequences for hemoglobin glycation. | we measured levels of glucose and glycated hemoglobin in the blood of three of the world's smallest nectarivorous birds, the anna's (calypte anna), costa's (calypte costae), and ruby-throated hummingbirds (archilochus colubris). plasma glucose levels of hummingbirds that were fasted overnight (17 mm) were higher than those in any mammal and are among the highest ever measured in a fasting vertebrate. glucose levels in hummingbirds just after feeding were extreme, rising as high as 42 mm. the sur ... | 1998 | 9787825 |
| why do calypte hummingbirds "sing" with both their tail and their syrinx? an apparent example of sexual sensory bias. | courtship displays frequently include complex signals that females use to pick a mate. male costa's hummingbirds (calypte costae) generate two acoustic signals during courtship: a vocal song produced close to a female and a dive-sound produced during a courtship dive. the song and dive-sound sound similar, and both were assumed to be produced vocally by the syrinx. here, we show that they are not; whereas the song is produced by the syrinx, the dive-sound is produced by high-frequency fluttering ... | 2010 | 19916787 |
| humming hummingbirds, insect flight tones and a model of animal flight sound. | why do hummingbirds hum and insects whine when their wings flap in flight? gutin proposed that a spinning propeller produces tonal sound because the location of the center of aerodynamic pressure on each blade oscillates relative to an external receiver. animal wings also move, and in addition, aerodynamic force produced by animal wings fluctuates in magnitude and direction over the course of the wingbeat. here, we modeled animal wing tone as the equal, opposite reaction to aerodynamic forces on ... | 2020 | 32843364 |
| it's not just what you have, but how you use it: solar-positional and behavioural effects on hummingbird colour appearance during courtship. | animals exhibit a diversity of colours that can play key roles in mating interactions. however, we presently lack an understanding of the relative importance of the environment, behaviour and natural reflective properties of colourful ornaments in shaping an individual's colour appearance during mating displays. we investigated interactions among structurally based plumage, display environments and courtship shuttle displays of male costa's hummingbirds (calypte costae) to test how these element ... | 2018 | 30019524 |
| strategic acoustic control of a hummingbird courtship dive. | male hummingbirds court females with a high-speed dive in which they "sing" with their tail feathers. the male's choice of trajectory provides him strategic control over acoustic frequency and pressure levels heard by the female. unlike related species, male costa's hummingbirds (calypte costae) choose to place their dives to the side of females. here we show that this minimizes an audible doppler curve in their dive sound, thereby depriving females of an acoustic indicator that would otherwise ... | 2018 | 29657113 |