| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Behavioral Ecology Vol. 12 No. 4: 467-474
© 2001 International Society for Behavioral Ecology
The foraging behavior of granivorous rodents and short-term apparent competition among seeds
Ecology, Evolution, and Conservation Biology Program, Department of Biology, University of Nevada, Reno, Reno, NV 89557, USA
Address correspondence to J.A. Veech, who is now at the Department of Zoology, Pearson Hall Room 212, Miami University, Oxford, OH 45056-1400. E-mail: veechja{at}muohio.edu .
The foraging behavior of a predator species is thought to be the cause of short-term apparent competition among those prey species that share the predator. Short-term apparent competition is the negative indirect effect that one prey species has on another prey species via its effects on predator foraging behavior. In theory, the density-dependent foraging behavior of granivorous rodents and their preference for certain seeds are capable of inducing short-term apparent competition among seed species. In this study, I examined the foraging behavior of two heteromyid rodent species (family Heteromyidae), Merriam's kangaroo rats (Dipodomys merriami) and little pocket mice (Perognathus longimembris). In one experiment I tested the preferences of both rodent species for the seeds of eight plant species. Both rodent species exhibited distinct but variable preferences for some seeds and avoidance of others. However, the differences in preference appeared to have only an occasional effect on the strength of the short-term apparent competition detected in a field experiment. In another experiment, I found that captive individuals of both rodent species had approximately equal foraging effort (i.e., time spent foraging) in patches that contained a highly preferred seed type (Oryzopsis hymenoides) regardless of seed density and the presence of a less preferred seed type (Astragalus cicer) in the patches. The rodents also harvested a large proportion of O. hymenoides seeds regardless of initial seed density; this precluded a negative indirect effect of A. cicer on O. hymenoides. But there was a negative indirect effect of O. hymenoides on A. cicer caused by rodents having a lower foraging effort in patches that only contained A. cicer seeds than in patches that contained A. cicer and O. hymenoides seeds. The indirect interaction between O. hymenoides and A. cicer thus represented a case of short-term apparent competition that was non-reciprocal. Most importantly, it was caused by the foraging behavior of the rodents.
Key words: density dependence, foraging behavior, heteromyid rodent, kangaroo rat, seed preference, short-term apparent competition.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. M. Fedriani and A. J. Manzaneda Pre- and postdispersal seed predation by rodents: balance of food and safety Behav. Ecol., November 1, 2005; 16(6): 1018 - 1024. [Abstract] [Full Text] [PDF]
|
|