Selective Predation on Utah Prairie Dogs

Abstract

Predation always affects demography and population dynamics, but removal of certain types of individuals is especially consequential. Predators strike quickly and commonly avoid areas with human observers, however, and thereby make it difficult to document patterns of predation under natural conditions. At a colony of marked Utah prairie dogs (Cynomys parvidens), a high frequency of predation in 2005 provided an unusual opportunity to examine susceptibility of five types of individuals to predation by red foxes (Vulpes vulpes) and northern goshawks (Accipiter gentilis). Juveniles were more vulnerable than adults to predation by northern goshawks. Adults at the edge of the colony were more vulnerable than central adults to predation by both red foxes and northern goshawks. Recent immigrants, who were not yet familiar with the best routes for escape, were more likely than longtime residents to be captured by northern goshawks. Adult males, preoccupied with finding, impregnating, and guarding estrous females during the 17-day mating season, were easy targets for red foxes and northern goshawks. Pregnant females, who could not run quickly, were especially prone to predation by red foxes.

Disappearance and Mortality Causes in Thirteen-lined Ground Squirrel (Ictidomys tridecemlineatus) Juveniles

“…The period shortly after weaning is a critical time for many young, although few studies document the exact time juveniles disappear from the population (but see Dunford, 1977a;Doolan and MacDonald, 1997;Hoogland et al, 2006;Meijer et al, 2011). In the first few weeks, juveniles learn to forage efficiently on their own, explore beyond the natal burrow, and are exposed to above ground predators.…”

“…We were surprised that females were less vigilant than males, but believe this difference arose because females spent more time foraging with their head down than did males. Juveniles may also differ in their level of vigilance while in different activities (e.g., Play, Social, Foraging; Harcourt, 1991;Stuart-Smith and Boutin, 1995;Blumstein, 1998;Hoogland et al, 2006) and predators (especially aerial ones) can strike unexpectedly and quickly.…”

Polyandry Promotes Enhanced Offspring Survival in Decorated Crickets

“…This lower survivorship probably resulted because polyandrous females paid higher costs of reproduction (Olsson and Madsen 2001;Johnson and Brockmann 2010;Madsen 2011) than monandrous females. Specifically, polyandrous females were more likely to conceive and to wean larger litters, and therefore were more likely to pay the costs of pregnancy and lactation (Sherman and Morton 1984;Clutton-Brock et al 1989;Hoogland 1995), including increased susceptibility to predation (Hoogland et al 2006;Madsen 2011). Other factors that might have contributed to the lower survivorship of polyandrous versus monandrous females include significantly less time for foraging on the day of estrus, and tendencies for polyandrous females to engage in more hostile interactions, from which they tended to incur more wounds and injuries.…”

Reproductive state affects reliance on public information in sticklebacks

“…To date, however, little attention has been paid to the role that reproductive state might play in affecting the relative use of social information. Reproductive state directly influences fitness by determining immediate and future reproductive potential, while the development of eggs and conspicuous breeding ornamentation require the sequestration of energy and resources that can increase conspicuousness to predators [16,17], lead to preferential targeting by predators [18] and reduce the capacity for escape [16,[19][20][21].…”