Revista Chilena de Historia Natural 79 (2): 169-174, 2006
RESEARCH ARTICLE
Body mass variation in the Geoffroy’s cat (Oncifelis geoffroyi)
We report new data on the intersexual and geographical variation in body mass of the
Geoffroy’s cat (Oncifelis geoffroyi d’Orbigny and Gervais 1844), a little known small cat from South America, and combine
them with the existing information to compare alternative hypotheses for variation in body mass. Most data on the body mass of
O. geoffroyi have been obtained from previous research on this felid in four study areas of southern Brazil and central and
southern Argentina. These data were added to those reported for other three additional locations. Our results set the body mass of
O. geoffroyi to 4.26 ± 1.03 kg (mean ± SD, n = 56). We also show that males generally are heavier than females
throughout most of this species’ distributional range. Body mass dimorphism is 1.34 on average, but ranges from 1.19 and 1.21 in
Uruguay and southern Chile, respectively, to 1.76 in the northern Pampas of Argentina. When data from the best sampled areas are
considered (Torres del Paine, Lihué Calel, southern Pampas, Campos del Tuyú and southern Brazil), only male body mass varies with
geographic location. More intriguingly, no correlation was found between body mass and latitude. Our results suggest a smaller mean
weight of O. geoffroyi relative to what was previously published, but also suggest a wider variation. Our analysis do not
support Bergmann’s rule, according to which the largest individuals would occur in the southernmost regions of this cat’s geographic
distribution, while they seem supportive of a sexually-selected process affecting sexual size dimorphism in the Geoffroy’s
cat.
Key words:
carnivores, felids,
Oncifelis geoffroyi, South America, body mass
