The height of approaching humans does not affect flight-initiation distance

Capsule Responses of animals to anthropogenic disturbances are often quantified using flight-initiation distance, the distance at which an animal flees a stimulus such as a person. We showed that the height of 20 researchers, selected to represent a diversity of heights, did not affect estimates of flight-initiation distance of Black Swans Cygnus atratus, suggesting that the height of humans used to test hypotheses of flight-initiation distances is not a confounding variable

Time since urbanisation but not encephalisation is associated with increased tolerance of human proximity in birds

The examination of links between a high degree of encephalisation (i.e. large brain mass relative to body size) and the capacity of wildlife to inhabit anthropogenic habitats has formed the basis of several recent studies, although typically they have not uncovered any relationship. It, however, remains unclear whether encephalisation is directly related to a species’ capacity to develop tolerance to human proximity (i.e. a reduction in response to approaching humans). It is also unknown whether such a relationship is related to the size of specific areas of the brain. Using published data on flight-initiation distance (FID), the distance at which animals flee from an approaching human, we estimate the degree of tolerance of human proximity for 42 bird species by comparing FIDs in urban and rural areas, with relatively high and low exposure to humans, respectively. We used a phylogenetic, comparative approach to analyse the relationship of degree of tolerance, and of FID in urban and rural populations more directly, to relative sizes of whole brains (42 species) and brain components (25 species) for the species, and examine the effect of the year that the bird species was first recorded in an urban area (year of urbanisation). We demonstrate an interaction between bird habitat and year of urbanisation on FIDs. Urban populations of species that have a longer history of inhabiting urban areas have lower FIDs (i.e. birds that were urbanised earlier are more tolerant), which may suggest local selection for birds with reduced responsiveness to humans in urban areas. The pattern is not seen in rural populations of the same species, providing additional evidence that it is greater exposure to humans that has resulted in this tolerance. While we found that forebrain mass and optic lobe mass are influential, positive predictors of FID there was no indication that degree of tolerance itself was related to any brain size metric and hence no support for the idea that urban populations of species with larger brains are better able to habituate to human presence. This suggests that processes other than encephalisation explain the high degree of tolerance evident in urban-dwelling birds

Behavioral experiments in a wild passerine cause short-term reductions in parental provisioning and nestling mass Experimentos conductuales en un ave paserina silvestre causan reducciones de corto plazo en el cuidado parental y peso de pichones

Research on wild animals often involves the capture and temporary removal of individuals from their territory. Although the acute effects of such procedures are well understood in terms of stress hormone profiles, their effect on the behaviour of captured individuals after release is poorly known. Additionally, for socially-monogamous individuals captured whilst breeding, little is known regarding whether the remaining individual compensates for the temporary loss of its partner and whether offspring condition or survival ultimately decreases due to any reductions in parental provisioning. We investigated the influence of field-based experiments requiring temporary adult removal on adult provisioning behaviour and nestling mass in the thorn-tailed rayadito (Aphrastura spinicauda), a Chilean furnariid species with equal parental effort between sexes. During the absence of the removed individual, remaining individuals did not increase nestling provisioning rates while, upon their release, removed individuals did not return to nestling feeding for at least 38 minutes and typically much longer. This drastic reduction in combined parental provisioning negatively affected nestling mass, while average nestling mass increased during a control period, nestlings failed to gain weight during and subsequent to parental removal. Finally, our experiments did not affect fledging probability. Overall, our results indicate that the temporary removal of rayaditos from their territories can cause short-term reductions in parental provisioning and nestling weight, but is unlikely to lead to any long-term effects on nestling survival.Las investigaciones en animales silvestres frecuentemente requieren la captura y remoción de individuos de sus territorios. Si bien se conocen los efectos a nivel hormonal de tales métodos, sus efectos sobre la conducta de los individuos después de la liberación son escasamente conocidos. Además, para individuos de especies monógamas que son capturados durante la época reproductiva, se desconoce si el individuo restante compensa la pérdida temporal de su compañero ni si la condición o sobrevivencia de los pichones disminuye como consecuencia del cuidado parental reducido. Investigamos la influencia de experimentos de campo que remueven temporalmente un adulto sobre las visitas de aprovisionamiento y el peso de pichones en el rayadito (Aphrastura spinicauda), un furnárido con similar cuidado parental entre los sexos. Durante la ausencia de un adulto, los individuos restantes de cada pareja no aumentaron la frecuencia de aprovisionamiento. Después de su liberación, los individuos previamente ausentes no volvieron a alimentar a sus pichones por al menos 38 minutos. Esta acentuada reducción en cuidado parental por ambos adultos de la pareja afectó negativamente el peso de los pichones. Aunque el peso medio de los pichones aumentó durante el período control, los pichones no aumentaron su peso durante y después de la remoción parental. Nuestros experimentos no afectaron el éxito de los volantones. Globalmente, los experimentos causaron reducciones de corto plazo en cuidado parental y peso de pichones, pero es improbable que causen efectos de largo plazo en la sobrevivencia de los pichones

Sounds and courtship displays of the peruvian sheartail, chilean woodstar, oasis hummingbird, and a hybrid male peruvian sheartail × chilean woodstar

We describe the songs and courtship displays of three closely related hummingbirds, the Peruvian Sheartail (Thaumastura cora), Oasis Hummingbird (Rhodopis vesper), and the endangered Chilean Woodstar (Eulidia yarrellii). The Peruvian Sheartail and Oasis Hummingbird sing complex multisyllabic songs, while the Chilean Woodstar's song is monosyllabic and simple. Like North American "bee" hummingbirds (within the tribe Mellisugini), the Chilean Woodstar and Oasis Hummingbird perform stereotypical close-range shuttle displays and larger display dives. The Peruvian Sheartail also performs shuttle and dive displays but their kinematics are variable and they are less distinct from each other. The greatly elongated tail of the Peruvian Sheartail is split widely during display, such that the five rectrices (R1-R5), including R1 and R2 of each side of the tail, project laterally, apparently as a visual signal. Like most other "bee" hummingbirds, all three species produce sounds during their disp

Data from: Acoustic cues from within the egg do not heighten depredation risk to shorebird clutches

Egg predators use an array of olfactory and visual cues to locate eggs. Precocial avian embryos within eggs can produce vocalizations for a period prior to hatching, which may be audible to predators. Here, we investigated, under field conditions, the embryonic vocalizations emitted from eggs of a shorebird species, the Red-capped Plover Charadrius ruficapillus. We characterize the acoustic properties of the vocalizations and the circumstances under which they are emitted, then test whether such vocalizations are used as an acoustic cue by predators to locate eggs. Embryonic vocalizations typically occurred between 0 and 5 days before hatching (henceforth the “vocalization period”). Within the vocalization period, the maximum acoustic frequency (kHz) of vocalizations increased with egg age (perhaps as a consequence of embryonic development) and the minimum acoustic frequency (kHz) increased with ground temperature (perhaps as mode of communication with parents regarding thermal needs). An artificial nest experiment compared the survival of nests with and without acoustic cues (prerecorded embryonic vocalizations played continuously from the nest). Corvids were the major egg predator (accounting for 76% of cases of artificial nest predation). However, the presence of vocalizations did not affect the time taken for predators to locate and depredate eggs. Our results suggest that embryonic vocalizations are important signals that may aid in communication with parents but that they do not increase predation rates. Further research involving a greater diversity of predators (e.g., acoustic predators) is required to examine whether vocalizations from the egg incur costs under other predator regimes