Effects of Food Availability and Predation on Prairie Vole Demography: A Field Experiment

Abstract

Nutrition, spacing behavior, and predation have been proposed as major factors limiting the population density of microtine rodents (lemmings and voles). However, there is no general agreement as to the relative importance of these factors, nor have their interactions been carefully examined. This paper reports on a factorial experiment designed to test the general hypothesis that predation and the availability of high—quality food act simultaneously and additively to limit densities of microtine rodent populations. Our results showed that supplemental high—quality food significantly increased body growth rates, proportion of adults in the population, adult male body size, reproductive activity, recruitment, and density of prairie vole populations. Food availability had no effect on survival nor on sex ratio in any of the 3 yr of this study. Protection from predation significantly increased adult survival (somewhat sporadically), recruitment, and density, but it did not directly affect growth, population structure, or reproduction. Improved survival of young animals could not be detected, but increased recruitment suggested that it may have occurred, perhaps before the young reached trappable size. Food supplementation and protection from predation generally had additive and equal effects on density. The only significant food—predator interactions were for body growth rates and adult body size. The presence of predators appeared to inhibit the growth response to supplemental food, possibly because of more restricted movement and, therefore, less access to food.

Delayed density-dependent and rainfall effects on reproductive parameters of an irruptive rodent in semiarid Chile

“…Several experimental studies have been conducted to test the effects of density and food supplementation on reproductive traits of rodents (Andrzejewski 1975, Andrzejewski and Mazurkiewicz 1976, Cole and Batzli 1978, Ford and Pitelka 1984, Desy and Batzli 1989, Mihok and Boonstra 1992, Ostfeld and Canham 1995, Lofgren et al 1996. These studies have shown that the fraction of reproductive females is affected by density and food addition.…”

Food resources and intestinal parasites as limiting factors for boreal vole populations during winter

“…Although delayed density-dependent predation is often considered the principle driver of cyclic dynamics [6][7][8][9][10], regulatory processes are likely to be multifactorial and geographically variable [1,11]. Hence, consensus on causal factors behind cyclicity has not been reached despite several decades of research [1,[10][11][12][13][14].…”

Experimental manipulation of predation and food supply of arctic ground squirrels in the boreal forest

“…Predators frequently limit and sometimes regulate prey populations (Erlinge et al 1984;Kidd and Lewis 1987;Sinclair 1989), and food supplementation has dramatic effects on population densities, home-range size, recruitment, reproduction, and immigration in small-mammal populations (Gilbert and Krebs 1981;Taitt and Krebs 1981;Mares et al 1982;Boutin 1990;Klenner and Krebs 1991). In addition, recent theoretical research (McNamara and Houston 1987;Lima and Dill 1990;Abrams 1994Abrams , 1999 and empirical evidence (e.g., Desy and Batzli 1989;Desy et al 1990;Dickman 1992;Hughes and Ward 1993;Hughes et al 1994;Hik 1995;Krebs et al 1995) suggest that external factors, such as food and predation, interact to limit populations. Few studies, however, have attempted large-scale (i.e., several hectares) experimental manipulation of external limiting factors (Crawley 1992;Carpenter et al 1995).…”