Provisioning

A honeybee (Apis mellifera) colony contains thousands of foragers that collect large amounts ofnectar, pollen, propolis, and water and deliver them to the hive. The colony's activities and, ultimately, reproduction depend on these resources. Millions ofyears ofhoneybee evolution and thousands of years of domestication have selected for proficient resource provisioning. Bees divide the labor ofresource acquisition and provisioning. Scout bees specialize in finding ephemeral resources and...

Houston And Mcnamara 1999

Where m is a deterioration factor (e.g., decay) andpN is the probability that a food item that was not stored will remain available. If a hoarder stores food in a location where any member of the group is equally likely to find it, the hoarder will be at a disadvantage. If stored supplies are communal property, the individuals that refrain from assuming the costs of hoarding will gain the same benefit from the stored supplies as others. Even if population size is decreasing due to a lack of...

Info

At least one stomach-produced signal has the opposite effect. Ghrelin is a hormone secreted from gastric cells just prior to the onset of an anticipated meal, and its levels fall precipitously once eating is initiated. Exoge-nously administered ghrelin stimulates eating, even in individuals that have recently eaten (Cummings et al. 2001). Hence, ghrelin is unique among the signals that have been described that arise in the gastrointestinal tract and influence food intake, since all of the...

Examples Offoraging Behavior In Animals

Results of a grazing study examining how sheep trade off diet preference against intake rate. In this experiment, replicate flocks of sheep were stocked on replicate paddocks in which one-half of the paddock contained white clover and the other half contained perennial ryegrass. Different paddocks were managed to achieve different contrasts in sward surface height (SSH) 6 cm clovervs. 6 cm grass, 3 cm clovervs. 6 cm grass, or 3 cm clovervs. 9 cm grass. The investigators estimated...

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

Agrp Satiety Center

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...

Predicting Group Size

Stable Group Size Often Exceeds Rate-Maximizing Group Size Many animals find themselves in a so-called aggregation economy, in which individuals in groups experience higher foraging payoffs than solitary individuals e.g., Baird and Dill 1996 review by Beauchamp 1998 . Peaked fitness functions are the hallmark of such economies fig. 10.1 Clark and Mangel 1986 Giraldeau and Caraco 2000 . By contrast, animals in a dispersion economy experience maximal foraging payoffs when solitary and strictly...

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 ....