Rodent Societies: An Ecological & Evolutionary Perspective

tions such as territoriality, interference competition, and
group vigilance. We discuss the implications of the cost of
predation for (1) foraging in terms of space use and habitat
selection, (2) timing and /or suppression of breeding, (3) so-
cial foraging in terms of vigilance, alarm calls, and various

forms of safety in numbers, and (4) ecological implications

in terms of population dynamics and seasonality.

Boreal Voles and Desert Rodents: Why?

Boreal voles and desert rodents have been traditional sub-

jects for studies on foraging ecology, breeding ecology, and

predator-prey interactions. The “vole cycle” (the periodic

fluctuations of boreal vole populations) has inspired strong

debate ever since Elton’s (1924) pioneering analysis. Cur-

rent evidence implies a strong role for predation risk in

affecting the nature of the fluctuations (e.g., Hanski and

Henttonen 1996; Korpimäki and Krebs 1996; but see also

Graham and Lambin 2002). In addition to detecting strong

lethal effects of predators on boreal voles, research has iden-

tified potentially important effects of predators on foraging

behaviors, space use, and reproduction (e.g., Ylönen 1994;

L. Oksanen and Lundberg 1995; Norrdahl and Korpimäki

2000).

Deserts and semi-arid environments support unusually

diverse assemblages of rodents. An assemblage often in-

cludes nocturnal granivores whose members include fami-

lies with striking adaptations for hot, arid conditions (Het-

eromyidae and subfamilies of Muridae and Dipodidae),

omnivores that consume plant material and insects (such

genera as Peromyscusand Onychomys), nocturnal and di-

urnal herbivores /granivores (Sciuridae, Dipodidae, Octo-

dontidae), and herbivores that live in groups (Cynomys,

some Spermophilus, Octodon, Mastomys). These rodent

communities often provide geographical replicates and nat-

ural experiments of coevolution and community structure.

Desert rodent communities have taught us aspects of spe-

cies interactions, competition, and resource use, and espe-

cially how these respond to habitat properties and resource

renewal (e.g., Rosenzweig and Winakur 1969; Price 1978;

Mitchell et al. 1990; Ovadia et al. 2001).

Both the lethal (Webster and Webster 1971) and non-

lethal effects (Kotler 1984) of predators have obvious and

important impacts on desert rodents — affecting foraging,

habitat selection in time and space, and species coexistence

(Brown et al. 1988; Longland and Price 1991; Kotler et al.

1992; Abramsky et al. 1996). The openness of desert habi-

tats leaves rodents more exposed than habitats with denser

vegetation cover, such as those occupied by voles. Yet re-

search starting in the 1990s suggests major roles for pred-

ators and predation risk in voles as well (Jedrzejewski and

Jedrzejewska 1990; Dickman 1992; Ylönen et al. 1992;

Korpimäki et al. 1994; Bolbroe et al. 2000). During recent

years, research approaches to desert rodents and to boreal

voles have converged. A synergy emerges from studies of

these two model systems.

Fear and the Foraging, Breeding, and Sociality of Rodents 329

Figure 28.1 The field vole (Microtus agrestis,top), bank vole (Clethrionomys
glareolus,middle), and sand gerbil (Gerbillus pyramidum,bottom) are model
species in many studies on predator-prey interactions and antipredatory behav-
ior in boreal, temperate, and desert rodent communities, respectively. Field vole
photo by X. Lambin, bank vole by Ines Klemme, and gerbil by J. Brown.