The Comparison of Usage and Availability Measurements for Evaluating Resource Preference

Abstract

Abst~act.Modem ~col.o_gical research often involves the comparison of the usage of habitat types or food Items to the availability of those resources to the animal. Widely used methods of determining preference from measureme~ts of usage and availability depend critically on the array of components that the researcher, often with a degree of arbitrariness, deems available to the animal. This paper proposes a new _metho~, base? on ranks of components by usage and by availability. A virtue of the rank procedure IS that .'t pro.vides co?II?arable results whether a questionable component is included or excluded from consideration. Statistical tests of significance are given for the method. . Th~ pape~ also offers a hierarchical ordering of selection processes. This hierarchy resolves certain mconsistencies among studies of selection and is compatible with the analytic technique offered in the paper.

The selection of breeding dens by the endangered Iberian lynx (Lynx pardinus): implications for its conservation

“…However, female lynx territories in the area under study are small (between 1.86 and 3.22 km 2 ) in comparison with those used by Iberian lynx females in the South of DonÄ ana (Ferreras et al, 1997). So, they do not need to walk a long way to reach the higher prey-density zones inside their territories, whereby any in¯uence of prey distribution on selection would be masked by high availability (Johnson, 1980). The tendency to place dens in the surroundings of activity centres has been interpreted as an e ort to optimise daily movements of the mother and to decrease the interaction with conspeci®c neighbouring territories (Ciucci and Mech, 1992).…”

“…We must point out that some habitat features which were not di erent in breeding dens and random sites within female lynx's home ranges, particularly prey availability, are probably in¯uencing habitat selection at lower orders of selection (Johnson, 1980).…”

Coastal fish farms are settlement sites for juvenile fish

“…Cage attached organisms (such as amphipods) were not used for calculations since it was virtually impossible to estimate their abundances from plankton tows. Prey that were absent from stomach contents were not included in calculations since their inclusion would have influenced the results for all other prey items (Johnson, 1980). were pooled using the same number of fish from each location.…”

Uso de áreas agrícolas por Mazama gouazoubira (Mammalia, Cervidae) no Estado de São Paulo

“…Para avaliar se houve uso desproporcional das classes pelo veado-catingueiro em relação à disponibilidade das mesmas, utilizou-se o teste do qui-quadrado de qualidade de ajustamento ("chisquare goodness-of-fit test") e posterior estimativa do intervalo simultâneo de confiança de Bonferroni (Byers et al, 1984). Considerou-se que houve seleção quando o uso foi desproporcional à disponibilidade (seleção de 3ª ordem, Johnson, 1980). Foi considerado haver preferência quando a proporção do uso foi maior que a disponibilidade e rejeição quando a proporção do uso foi menor.…”