![]() ![]() The Center is working to secure this habitat. Such twisted reasoning continues to hold sway currently, the Pacific pocket mouse still doesn't have its much-needed critical habitat. The agency maintained that determining to do so would not be “prudent” because a critical habitat designation would only further threaten the species by identifying and publishing the location of the sole remaining Pacific pocket mouse population. But when the Service listed the Pacific pocket mouse, the agency declined to designate any critical habitat. Fish and Wildlife Service, then was fully protected under the Endangered Species Act in 1994. It initially received an emergency listing from the U.S. Pacific pocket mice were feared extinct for nearly 20 years before the species was “rediscovered” in 1993. Without sufficient habitat, the Pacific pocket mouse is left with nowhere to hide during the hard winters. Currently, habitat destruction due to urban expansion, road construction and agriculture poses the greatest threat to this critically imperiled mouse. But if adequate food supplies are available, the mouse will remain active during winter. longimembris are expected to be able to persist without ongoing management of competitor species.In winter, if environmental factors are unfavorable, the Pacific pocket mouse may hibernate underground until spring brings better conditions. However, during the later growth and regulation phases of a reintroduction, P. Collectively, this research suggests that during the initial phases of reintroduction when Pacific pocket mice are establishing their burrows and foraging areas, they will benefit from a reduction of heterospecific competitors, who may displace them from optimal sites. Species differed in the microhabitat they utilized, and although it is not clear if patterns of spatial niche partitioning are due to interspecific interactions or differences in habitat preferences, this study provided clear guidance for habitat management and release site selection for P. A year-long trapping study showed that species utilize spatial niche partitioning, but aggregate the timing of their activity, in areas with high levels of rodent activity. In a field experiment with dyed seeds I found that cache pilfering occurred infrequently, and a field-enclosure experiment revealed that none of the species use heterospecific scent to find (or avoid) seed caches. longimembris, if pocket mice pilfer from the other species' seed caches more frequently than the other species pilfer from their caches. However, the presence of other members of the seed-foraging guild could have a net benefit for P. As such, temporarily reducing the density of competing species might be an advisable reintroduction strategy, in combination with other interventions, such as predator exclusion. Repeated aggressive interactions from resident heterospecifics could lower the chances of reintroduced pocket mice establishing burrows during the critical settlement period. Body size asymmetries strongly predicted dominance, regardless of phylogenetic relatedness or residency status. longimembris and four sympatric species, and determined that pocket mice, the smallest species, are subordinate to all larger species. I conducted simulated territory intrusion experiments between P. The species in this foraging guild compete for seeds both exploitatively and through direct interference interactions. The endangered Pacific pocket mouse (Perognathus longimembris pacificus) is being reintroduced to parts of its former range where multiple species of native rodents have overlapping diets. Reintroduction programs for endangered species rarely take competitive interactions between species into account. ![]()
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