We have developed a model that reconciles information-sharing and producer-scrounger models of group foraging. Our includes producers, scroungers, an opportunistic forager can both produce scrounge but with reduced efficiency. show these three strategies coexist only in the unlikely case opportunist's loss searching ability is exactly equal to its gain scrounging ability. However, all pairs coexist. Three parameters control proportions coexisting strategists: degree compatibility between...

Bird community response to both landscape-scale and local (forest types) changes in forest cover was studied three boreal mixed-wood landscapes modified by different types of disturbances: (1) a pre-industrial landscape where human settlement, agriculture, logging activities date back the early 1930s, (2) an industrial timber managed forest, (3) dominated natural disturbances. Birds were sampled at 459 sampling stations distributed among landscapes. Local habitat characteristics context...

We measured the activity of Peromyscus maniculatus, Clethrionomys gapperi, and Napaeozapus insignis using a sand transect in forest Quebec. Activity on each 651 summer nights over 8 years was compared to weather night. All three rodents were most active rainy warm nights. C. gapperi N. showed increased cloudy moonless when rain had not fallen for several also with humidity. Variation due slight more likely associated predator avoidance than physiological restrictions.

Annual censuses of duck populations from two localities differing in environmental variability were used to test the effectiveness six tests density dependence. The magnitude Type I error for each was estimated simulated density—independent data having same mean and variance as observed censuses. actual census evaluate ability detect Only autoregression had desired level type error, but this ineffective when grew or declined. standard major axis effective latter cases did not grow decline....

L'entassement (exemple pris chez des Peromyscus) a avantages energetiques toutes les fois que la temperature ambiante et du nid sont bien au-dessous de zone neutre thermiquement

Summary We examined mechanisms of coexistence between two congeneric species frugivorous primates, the blue monkey ( Cercopithecus mitis ) and red‐tailed C. ascanius ). used giving‐up densities (the amount food which animals leave in a patch) fruit trees to measure foraging efficiency evaluate possible coexistence. Animals with higher are less likely persist company those lower because former not able exploit patches previously by latter. climbed estimate counting primates left behind....

The integration of behavioral and population ecology is necessary when behavior both feeds into demographic parameters depends on parameters. We show that scrounging behavior, the exploitation others’ resources, can affect dynamics, including stability interactions with prey. Scrounging a common tactic its pay‐offs exhibit density‐ frequency‐dependence. demonstrate act as regulator through effects individuals’ reproductive rate mortality. also explore predator‐prey dynamics presence...

Activity of three rodent species was measured on tracking stations in 10 different sampling areas within a northeastern deciduous forest throughout the summer 1974. Total activity as number crossings (903 Peromyscus maniculatus, 186 Clethrionomys gapperi and 9996 Napaeozapus insignis) compared with measures habitat structure. Habitat separation between rodents detected by discriminant function analysis. use differed among rodents. insignis used coniferous heavy ground cover. little cover...

The effect of weather on the daily activity Sorex cinereus has been observed during eight consecutive summers. greatly increases when rain falls at night. Maximum occurs about 1 cm falls. Afternoon rainfall may also result in increased if S. have relatively inactive previous nights and night remains cloudy. When does not fall, moderately with temperature, but this response is evident afternoon or evening. Weather explains least 27% variation activity.Total summer influenced by temperature...

We constructed a model of territoriality relating the probability starvation in nonstationary, variable environment to costs and benefits feeding, defense, exploration their variances. The suggests that survival territory increases with increasing food abundance decreasing defense costs. Territoriality, risk-averse behavior, is favored when an animal's net expected energy balance positive (see also Stephens 1981). When negative, risk-prone abandoning become marginal or floater, appropriate....

We developed an innovative method for estimating human impacts on animal species by measuring changes in feeding behaviour. illustrate our approach with a study of the effect vegetation control power-line right-of-way (ROW) passing through essential winter habitat white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)) at northern limit their range. used giving-up densitiy (GUD; i.e., amount food left behind when stops foraging patch) to evaluate, one yard, if loss forest shelter...

In arid environments, population dynamics of many organisms follow resource pulses in time and space. This heterogeneity accessibility is due to irregular local rainfalls. drought periods, the density small mammals such as rodents falls so that animals seem absent across landscape. How can they avoid extinction persist space at low densities during droughts? We hypothesize a fraction may survive refugia—less patches—and recolonize landscape after drought‐breaking rains. When precipitation...