نتایج جستجو برای: small birds
تعداد نتایج: 826161 فیلتر نتایج به سال:
We collected samples from apparently healthy geese in the Playa Lakes Region (USA) during the winters of 2000-01 and 2001-02 to determine whether carriers of Pasteurella multocida, the bacterium that causes avian cholera, were present in wild populations. With the use of methods developed in laboratory challenge trials (Samuel et al., 2003a) and a serotype-specific polymerase chain reaction met...
Many species of desert birds are relatively small (< 500 g), diurnally active ground dwellers that are naturally exposed to high ambient temperatures (T,) and low relative humidities (RH). Sandgrouse (Pteroclididae), being small birds (weighing between 200 and 400 g) having a relatively high standard metabolic rate (SMR), would have to possess an effective mechanism for dissipating heat. Spotte...
Habitat fragmentation exacerbates the problem of habitat loss for grassland and wetland birds. Remaining patches of grasslands and wetlands may be too small, too isolated, and too influenced by edge effects to maintain viable populations of some breeding birds. Knowledge of the effects of fragmentation on bird populations is critically important for decisions about reserve design, grassland and...
used in mobbing probably arose as a flight intention movement (Daanje 1950, Hinde 1954). A component of the evidence for its origin as a flight intention movement is the change in posture that accompanies the wing and tail movements; the movement is similar to the postural change that often precedes flight. This component of the flit (the change in posture) is missing from trogon mobbing tail f...
Birds are powerful indicator of an ecosystem because of their thin skull, feathers as dielectric receptor, high mobility and use of areas having high electromagnetic field. Among the total publications on the impact of electromagnetic radiation on living beings, only 3% are on birds. Both positive and negative results are reported regarding the biological responses of birds exposed to electroma...
Habitat fragmentation threatens biodiversity by disrupting dispersal. The mechanisms and consequences of this disruption are controversial, primarily because most organisms are difficult to track. We examined the effect of habitat corridors on long-distance dispersal of seeds by birds, and tested whether small-scale (<20 meters) movements of birds could be scaled up to predict dispersal of seed...
Approximately 3000 birds, mainly passerines, caught in mist nets in the northern provinces of South Africa, were examined for ticks. A total of 178 ticks, belonging to 14 species, were recovered from 83 birds of 43 different species. Hyalomma rufipes was the most numerous tick, with 26 larvae and 109 nymphs collected, followed by Amblyomma marmoreum, with 13 larvae and two nymphs. Despite the s...
In studies of forest fragmentation, birds of scrubby, early-successional habitats are considered edge specialists. Because these birds are assumed to thrive in fragmented, edge-dominated areas, their landscape ecology has received little attention from ecologists. With populations of shrubland birds declining throughout the eastern United States, the question of whether or not these birds reall...
During migration, passerine birds typically complete a series of multi-hour flights, each followed by a period of stopover. During flight, rates of respiratory water loss are high, yet these birds show no signs of dehydration after flights. During stopover, birds become hyperphagic to replenish fat reserves, often consuming food with high water content, such as fruit. Thus migratory birds seem ...
Navigation is an essential skill for many animals, and understanding how animal use environmental information, particularly visual information, to navigate has a long history in both ethology and psychology. In birds, the dominant approach for investigating navigation at small-scales comes from comparative psychology, which emphasizes the cognitive representations underpinning spatial memory. T...
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