نتایج جستجو برای: small birds
تعداد نتایج: 826161 فیلتر نتایج به سال:
Despite a wealth of fossils of Mesozoic birds revealing evidence of plumage and other soft-tissue structures, the epidermal and dermal anatomy of their wing's patagia remain largely unknown. We describe a distal forelimb of an enantiornithine bird from the Lower Cretaceous limestones of Las Hoyas, Spain, which reveals the overall morphology of the integument of the wing and other connective str...
Mangaia (Cook Islands) consists of a weathered volcanic interior encircled by limestones known as the makatea. Excavations at Tangatatau Rockshelter (site MAN-44), located on the inner cliff of the makatea, produced a stratified sequence of Polynesian artifacts and faunal remains ranging from A.D. 1000-1100 to A.D. 1500-1600. Resident species of birds represented at MAN-44 include nine seabirds...
Vocal learning, a key behavior in human speech development, occurs only in a small number of animal taxa. Ontogeny of vocal behavior in humans and songbirds involves acquisition of an acoustic model, which guides the development of self-generated vocalizations (sensorimotor period). How vocal development proceeds in the absence of an acoustic model is largely unknown and cannot be studied direc...
We recorded the distribution and abundance of marine birds in the northern Barents Sea from 27 February to 8 March 1987 and from 20 to 31 May 1988. Birds were more abundant in waters associated with pack ice than in open water away from pack ice. Within the pack ice, thick-billed murres (Uria lomvia) were the most commonly encountered birds in both periods. Murre densities in the pack ice north...
Long-distance dispersal (LDD) promotes the colonization of isolated and remote habitats, and thus it has been proposed as a mechanism for explaining the distributions of many species. Birds are key LDD vectors for many sessile organisms such as plants, yet LDD beyond local and regional scales has never been directly observed nor quantified. By sampling birds caught while in migratory flight by ...
Predator detection is improved when individuals join groups. Theory assumes that the transfer of social information about predators among individuals is immediate and accurate. However, animals in groups space themselves at different distances. Little is known about the shape of the social information transfer function over distance, which can affect group cohesion and ultimately the costs and ...
Despite extensive work-on mammals there is a shortage of accurate data on the anaesthesia of birds. Those publications which exist frequently fail to supply information on the methods used to assess the depth of anaesthesia, as was emphasized by Jordan, Sanford and Wright (1960). Birds have a high metabolic rate and a specialized respiratory system and hence frequently react poorly or adversely...
Domestic fowl in small groups are assumed to establish hierarchical systems based on individual recognition. Conversely, interactions in large groups are modulated by badges of status. Previous studies suggested that birds differing in phenotypic appearance (PA) became targets for aggression, possibly mistaking altered PA for badges of status. We evaluated the impact of altering PA on 0, 30, 50...
Small populations of endangered species can be impacted by genetic processes such as drift and inbreeding that reduce population viability. As such, conservation genetic analyses that assess population levels of genetic variation and levels of gene flow can provide important information for managing threatened species. The São Paulo Marsh Antwren (Formicivora paludicola) is a recently-described...
The importance of wild birds as potential vectors of disease has received recent renewed empirical interest, especially regarding human health. Understanding the spread of bacterial pathogens in wild birds may serve as a useful model for examining the spread of other disease organisms, both amongst birds, and from birds to other taxa. Information regarding the normal gastrointestinal bacterial ...
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