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University of Arizona (1976)

Estimation of desert rodent populations by intensive removal

Olding, Ronald James

Titre : Estimation of desert rodent populations by intensive removal

Auteur : Olding, Ronald James

Université de soutenance : University of Arizona

Grade : Master of Science (MS) 1976

Six tests of the Standard Minimum Method for small mammal population estimation were conducted on two sites in southern Arizona to determine this method’s adequacy for sampling nocturnal desert rodent populations. The 256 station grids covered an area of 5.76 ha. and took a total of 1,626 small mammals in 19,968 trap nights. Al though four families and sixteen species of nocturnal small mammals were represented, 91.0% of all animals captured were in the family Heteromyidae. Hayne’s method of linear regression was used to calcu late population estimates, and from these, densities were calculated for total animals and for major species which displayed uniform capture probabilities. Densities for total animals ranged from 11.4 to 107.3 animals per hectare. Increased capture success in the outer trap belts was noted in all but one sample, however, tests for immi gration showed only minor movement onto the grid in two out of six samples. Heavy rainfall had a significantly negative effect on cap ture success twice during the testing. Minor species often displayed a non-uniform probability of capture, but for total animals and major species a five day trapping period preceded by two days of prebaiting gave a uniformly decreasing regression line and reliable population estimates.

Mots clés : Desert animals — Arizona. ; Rodents — Arizona. ; Rodent populations.


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