Pampas deer (Ozotoceros bezoarticus) male–female agonistic behavior toward high and low social ranked females

Abstract

The pampas deer is an endangered species from the southern cone of South America. Although it is breed in confined groups, there is very scarce information on how their social relationships and aggressiveness are regulated in these groups. As we hypothesized that pampas deer males display different behaviors toward high or low social ranked females, we compared the number and pattern of agonistic behaviors used by pampas deer males to displace high- and low-ranked females. We performed focal observations recording all female–female agonistic interactions resulting in the displacement of an animal in six breeding groups (total = 6 males and 31 females), and calculated the success index for each hind. Then, we recorded all male–female agonistic interactions while animals received food, and compared the total number and the type of interactions used by males to displace high- and low-ranked individuals. Males displaced more frequently high-ranked than low-ranked females (P = 0.006), mainly by their presence (P = 0.0004); males tended to displace low-ranked females more frequently by kicking (P = 0.051). We designed a complementary study to determine if the male–female physical distances may explain that difference. We recorded male–female distances every 5 min for 30 min during 10 days while animals ate ration, and calculated an association index (AI) between each female with the male. Low-ranked females tended to have greater AI accumulated at 5 and 10-min scans (P = 0.071 and 0.077, respectively) than high-ranked females. The changes in the AI may indicate that high-ranked females were displaced during the period with more interactions. We concluded that (1) pampas deer males displayed more agonistic interactions toward high-ranked than low-ranked females; (2) this difference was mainly due to a greater number of displacements of females by mere presence; (3) high-ranked females moved far from males than low-ranked females, reflecting different relationships between them.