Animal Food Caching Landscape Ecology

Hypothetical daily mass gain of hoarding and nonhoarding birds in winter. The nonhoarder has less predictable food availability and must hedge with larger body fat reserves. There are two cases for hoarders, baseline assumptions (dotted curve) and the three added assumptions described in the text (dashed curve). The most important difference is that under baseline assumptions, predation risk is mass-dependent at low levels of fat, whereas under the three added assumptions, predation...

The CS Pathway

In honeybees, odors activate chemoreceptors on each antenna, which relay signals to the antennal lobes, where odor characteristics are neurally encoded (Lachnit et al. 2004 Flanagan and Mercer 1989) (fig. 3.1). The projection neurons of the antennal lobe form three main tracts, one of which innervates the calyces ofthe mushroom bodies. This projection from the antennal lobe to the mushroom bodies serves as the CS pathway for conditioning ofthe proboscis extension response (PER). Menzel and...

Energy Storage and Expenditure

The snow creaks under our winter boots as we walk along the snow scooter track to our study site. The cold is overwhelming, and though we have been walking for an hour, we do not feel warm. The air is perfectly still, and the heavy snow on the branches of the surrounding conifers absorbs all sounds. When we arrive at the bait station, we spill some seeds onto the feeding tray and retire to the nearby trees. The seeds soon attract the attention of some willow tits. It is astonishing that these...

Topdown versus Bottomup Approaches Relating Individual Behavior to Population Dynamics

To understand phenomena such as the Arctic lynx-hare cycle discussed in the prologue, one needs population models. When abundances are great enough to be treated as continuous rather than discrete variables see box 11.1 , one uses differential equations see also chap. 13 , such as the predator half of a predator-prey model. The variables are P predator density, say, of lynx density is the number of individuals per unit area , R resource or prey density, say, of hares , and t time . The...

Time in patch

Patch use strategy of a predator that depresses patch quality by frightening its prey. Prey catchability is highest upon the entry of the predator into the area. The longerthe predator remains in the area, the less catchable the prey become as they become aware ofthe predator's presence. Once prey catchability declines to a threshold, the predator should abandon the area and seek another. The predator's threshold of acceptability should be higher in an environment rich in prey than...

Brief History of Optimal Foraging Theory

Interest by ecologists in foraging grew rapidly after the mid-1960s. Scientists in areas such as agricultural and range research already had long-standing interests in the subject see chap. 6 in this volume . Entomologists, wildlife biologists, naturalists, and others had long been describing animal diets. So what was new What generated the excitement and interest among ecologists We believe that the answer to this question is symbolized by a paper published by the economist Gordon Tullock in...

Optimal Behavior and Consumer Resource Models

Coexisting species often differ in body size, but such differences do not always lead to coexistence based on food size selection. Coexisting species ofgraniv-orous desert rodents often differ in body size e.g., Brown 1975 , yet may overlap almost completely in the sizes of the seeds that they consume e.g., Lemen 1978 . In contrast, coexisting species of Darwin's finches may show distinct differences in both their beak sizes and the seed sizes in their diets Grant 1986 see section 12.8 ....