Low intertidal communities of Oregon and Panama have many predator
and herbivore species. This diversity of consumers is important to the
organization of both communities because of qualitative differences
among the consumer species in their ability to circumvent specific prey
defenses. In Oregon, the red alga Iridaea cordata is protected...
Diet variation among individuals within populations is widespread. Often diet differences among individuals are attributable to obvious differences among individuals such as age, sex, or morphology. However, growing evidence suggests that individual diet variation is also common among seemingly identical individuals within populations. This phenomenon has been termed individual diet...
There is increasing awareness that human activities are altering the ways that natural systems operate and that local shifts in species composition and abundance can lead to abrupt and irreversible global change. Therefore, understanding the processes that buffer biological communities from critical shifts and how our actions affect natural stabilizing...
Rates of predation on artificial nests and nests of pen-reared
ring-necked pheasants (Phasianus colchicus), released in spring, were
compared between strip and block habitats at different densities of
nests. Nests in strips had rates of predation 4-7 times greater than
nests in blocks, regardless of nest density. Differences between
successful...
Understanding prey quality and prey selection by predators is critical for management efforts aimed at identification and protection of essential habitats and prey. Marine predators must make daily foraging choices in a heterogenous and dynamic environment in order to meet the high energetic demands of migration, reproduction and foraging. With...
Pleuronectid flatfish are generally thought to utilize stereotypical anti-predator behavior to reduce encounters with potential predators, including burial, maintaining a low profile on the bottom, cryptic coloration, and reduced activity. However, a series of laboratory experiments demonstrate significantly different predation rates on juvenile (Age-0) English sole (Parophrys vetulus), northern rock...
Many organisms with complex life cycles undergo transition periods associated with increased vulnerability to predation. Several evolutionary adaptations have been proposed as antipredator defenses for organisms during risky transition periods. These include: shortening of the transition period, parental care, cryptic coloration, and synchrony of risky transitions with large numbers of...
Diets and foraging strategies of Glaucous-winged Gulls were
studied in areas with and without sea otters in the western Aleutian
Islands, Alaska. Gulls foraged on invertebrates (e.g., sea urchins,
limpets, chitons, mussels, and others) in the rocky intertidal
community and on fish at sea; this study was conducted on gulls...
The body size (W) of animal species is one of the best predictors of
population density (D) when large assemblages are considered. It has been
shown that theoretically the D-W relationship can be the consequence of two
other distributions: the log-normal distribution of body sizes of the species and
of...