Mechanisms of Habitat Selection by the Hispid Cotton Rat (Sigmodon hispidus)

Abstract

The Texas coastal prairie is composed of habitat patches characterized by monocots, dicots, or a mixture of both plant types. Radiotelemetry revealed that reproductive female hispid cotton rats (Sigmodon hispidus) preferred mixed habitats and avoided dicot habitats, whereas males did not show a preference. Such habitat selection can be attained by shorter distances moved or increased turning (i.e., area-restricted search). Reproductive females, but not males, moved shorter distances in mixed habitats. However, turns relative to straight-ahead movements for females, but not males, were fewer in mixed habitats than in monocot or dicot habitats suggesting directed foraging rather than area-restricted search. To obtain necessary amounts of nutrients, especially carbohydrates, protein, phosphorus, and calcium, reproductive females ingest both monocots and dicots. Directed movement may facilitate foraging for dicots because these food items occur in clumps in mixed habitats. Because their nutritional needs are less than those of females, males do not exhibit the same patterns of habitat selection. Differential patch occupancy was not explained by overhead plant cover, but more bare ground in dicot habitats may explain avoidance of these habitat types because of increased predation risk.

Sea turtles in the eastern margin of the North Atlantic: the northern Ibero-Moroccan Gulf as an important neritic area for sea turtles

“…If the confidence interval of the observed prevalence in a municipality overlapped the expected prevalence according to availability, then there was no significant difference between prevalence and availability. If the confidence interval was more than the availability of a municipality, strandings in that municipality were more than expected, whereas if the confidence interval was below availability, strandings in that municipality were less than expected (Byers et al, 1984;Cameron & Spencer, 2008;Bellido et al, 2010a).…”

“…Chi-squared test (χ 2 ), allows us to know if there are significant differences between areas or not. Therefore, in order to determine the differences in the distribution of Loggerhead strandings along the coast, a Bonferroni normal statistics test was developed testing by municipality (Byers et al, 1984;Cameron & Spencer, 2008). This test allows us to know the municipality in which strandings were significantly higher or lower than expected according to availability and was made by obtaining confidence intervals for the prevalence in each area using the formula:…”

Differential geographical trends for loggerhead turtles stranding dead or alive along the Andalusian coast, southern Spain

“…If the confidence interval of the observed prevalence in a zone overlapped the expected prevalence according to availability, then there was no significant difference between prevalence and availability. If the confidence interval was above availability of a zone, that zone was more prevalent than expected, whereas if the confidence interval was below availability, that zone was less prevalent than expected (Byers et al , 1984; Cameron & Spencer, 2008).…”

“…The identification of zones where strandings were significantly higher or lower than expected according to availability was made by using Bonferroni normal statistics to obtain confidence intervals for the prevalence in each zone (Byers et al , 1984; Cameron & Spencer, 2008): where is proportion of strandings by zone, α = 0.05, k is the number of zones tested, Z α/2 k is the upper standard normal table value corresponding to a probability tail area of α/2k, and n is the total number of strandings. The availability of each zone was calculated according to its coast length, so that the expected use was the proportion of the Andalusian coast corresponding to each zone.…”

Small Mammal Habitat Use within Restored Riparian Habitats Adjacent to Channelized Streams in Mississippi

“…Our results concur with these as we documented decreased cotton rat weights within small Type I habitats with reduced vegetative structure. We did not document differences in cotton rat abundance among restored riparian habitat types, but our results may have been obscured by gender differences as male and female cotton rats exhibit different habitat use patterns [49,50]. We also documented greater percent of juvenile cotton rats in Type I habitats than the other three habitat types during summer 1995.…”