Few tracking studies consider seasonal changes in ability to re-sight wildlife, despite potential for biases in sightability to mislead our interpretation of models of movement and abundance. We developed seasonal sightability models based on visual observations of radio-collared elk (Cervus elaphus) in Manitoba, Canada, through 6 seasons. We located 377 elk 8,862 times using aerial telemetry f...

—Nest placement of open-nesting bird species may affect risk of nest predation, nest microclimate, and reproductive success. In populations that breed in multiple habitat types and over long seasons, nest placement should vary seasonally and by habitat to compensate for seasonally changing and habitat specific environmental conditions that might affect the relationship between nest placement an...

– The Toco Toucan (Ramphastos toco) is a large canopy frugivore common in the seasonal areas of the interior of Brazil. In this study, I evaluated fruit production and analyzed the toucan’s feeding habits in two types of dry forests, one deciduous, although rich in figs, and another semi-deciduous, both in the western Brazil. Both areas exhibited marked fruiting patterns, which peaks overlapped...

The spatial and temporal structure of spider communities was studied in the clay semi-desert of the north-western Caspian Lowland, western Kazakhstan (49°23' N, 46°47' E). The soils and vegetation are complex, being composed of a mosaic of desert and steppe plant communities. Besides the native associations, there are plantations of different tree species. The ground-dwelling spider assemblages...

The reduction in extent of riparian forests in the southwestern United States has been a topic of recent concern. The effect of dams on downstream river flow and the consequent modification of the riparian habitat was studied along the lower Salt River in central Arizona. Dams were found to change the magnitude of river flows and change the seasonal timing of flows in such a way that the habita...

Masai (Giraffa tippelskirchi), Reticulated (G. reticulata) and Rothschild's (G. camelopardalis) giraffe lineages in East Africa are morphologically and genetically distinct, yet in Kenya their ranges abut. This raises the question of how divergence is maintained among populations of a large mammal capable of long-distance travel, and which readily hybridize in zoos. Here we test four hypotheses...

The activity of animals is defined mostly by internal genetic mechanisms, but physical factors, such as temperature, soil Ph, light duration, and humidity, play a role in the regulation of this biological process. For centipedes, for example, humidity is one of the key environmental factors that determines their distribution and activity. However, abiotic and biotic factors such as soil pH, tem...

Along the west coast of North America, the invasive mussel Mytilus galloprovincialis and a native congener M. trossulus overlap in range and compete for habitat in an extensive hybrid zone along central California. The two species have been shown to exhibit diVerential abiotic tolerances in laboratory studies, yet little is known about how such tolerances aVect spatial and temporal patterns of ...

A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct p...

1. Organisms are adapted to particular habitats; consequently, community composition changes across environmental gradients, enhancing regional diversity. In Panama, a rainfall gradient correlates with the spatial turnover of tree species. While strong evidence suggests that tree species common in the wetter forests are excluded from the drier forests by seasonal drought, the factor(s) excludin...