Rarity in Neotropical Forest Mammals and Its Ecological Correlates

Abstract

Local density and size of distributional range have been used to characterize rarity, but conclusions are weakened by their possible lack of independence. The usefulness and validity of using these two variables were tested with data on distribution, local density, body size, and feeding habits for a set of 100 Neotropical forest mammals. In a bivariate plot of distributional range against local density, species clustered according to their trophic or taxonomic groups. This indicates that diet and phylogenetic history have an influence on rarity. A negative correlation was found between distribution and abundance. However this correlation was weaker within trophic or taxonomic groups, and vanished when body size was held constant. These results show that both distribution and abundance are valid and independent estimators of rarity when comparing species with similar sizes and ecological traits. Regression analysis showed that larger animals tend to have lower densities and wider distributional ranges. Rarity is clearly associated with body size. A dichotomous classification of rarity based on area of distribution and local density is suitable for Neotropical forest mammals. Species in each of four categories created by such a scheme require different conservation and management policies that are determined by the ecological characteristics of the species. Final conservation strategies must also be shaped by political and economic constraints.

Phylogenetic correlates of extinction risk in mammals: species in older lineages are not at greater risk

“…First, extinction probability might stochastically increase through time [4,16]. Second, specialization is known to correlate with extinction risk [17,18]. Older taxa might be more specialized through early occupation of fringe niches, phylogenetic constraint or by having more time to evolve a specialized ecology, behaviour or morphology [19,20].…”

Comunidad De Mamíferos No Voladores en Un Área Periurbana Andina, Cundinamarca, Colombia

“…Ahora bien, una especie rara es aquella que posee pequeñas densidades poblacionales locales y un hábitat y distribución restringidos (Arita et al, 1990). Sin embargo, se ha propuesto que para los mamíferos del Neotrópico, existen cuatro tipos de rareza (Arita et al, 1990).…”

“…Sin embargo, se ha propuesto que para los mamíferos del Neotrópico, existen cuatro tipos de rareza (Arita et al, 1990). En la reserva se encontraron especies con distribución restringida y densidad poblacional alta (tipo 1 de rareza sensu Arita et al, 1990) y especies con distribución amplia y densidad poblacional baja (tipo 4 sensu Arita et al, 1990). Las especies pequeñas, como M. minutus y N. bogotensis corresponden al primer tipo de rareza, mientras que L. tigrinus, C. taczanowskii y O. albicauda corresponden al tipo 4.…”

Population Density of the Helmeted Curassow (Pauxi pauxi) in Tamá National Park, Colombia

“…Habitat specialization is a dimension of rarity and an important factor of vulnerability (Arita et al 1990, Brooks 1998. Therefore, documenting spatial and temporal patterns of habitat use is critical for conserving cracid populations.…”