Dominance is a behavioural mechanism that allows individuals to access and monopolize resources which should ultimately improve their fitness. Hierarchy strength should be strongest when resources are limited; however, this relationship is not consistent. We provided abundant food to assess whether hierarchy strength was consistent with resource abundance using 9 groups of captive female white-tailed deer (Odocoileus virginianus). We further assessed how body mass, age and testosterone levels were associated with rank position. Deer displayed a weak hierarchy with a mean linearity () of 0.39 (SD = 0.09) and a mean directional consistency index of 0.83 (SD = 0.06). Rank was related to body mass (, slope = 0.011), but not age or testosterone levels (). We demonstrate that hierarchy strength was weak in the presence of abundant food resources and suggest the possibility that dominance is a plastic behaviour that may vary with resource abundance.
Eric S. Michel, Stephen Demarais, Bronson K. Strickland, Jerrold L. Belant and Joshua J. Millspaugh
José F. González-Maya, Jerrold L. Belant, Sarah A. Wyatt, Jan Schipper, Josué Cardenal, Daniel Corrales, Iván Cruz-Lizano, Annelie Hoepker, Armando H. Escobedo-Galván, Fernando Castañeda and Addison Fischer
More than 90% of harlequin frog species (Atelopus spp.), endemic to the Americas, are currently threatened with extinction. We report the discovery of the only currently known breeding population of the Critically Endangered A. varius in Costa Rica. This population was located in 2008 on a private property in Las Tablas Protected Zone near San Vito, Coto Brus at 1300 m elevation. Previously, the only known remaining/remnant population of this species and genus was a single location near Manuel Antonio, Puntarenas, Costa Rica, where two individuals were documented in 2004. Subsequent searches at this location have yielded no additional sightings. Delineating the spatial limits of this population, quantifying demographics and resource use, and implementing conservation actions are necessary to ensure persistence of this population. Conducting additional surveys in this region to ascertain occurrence of additional populations is warranted.