Daily activity pattern of reintroduced giant anteaters (Myrmecophaga tridactyla): effects of seasonality and experience

Abstract

We assessed the effect of seasonality and intrinsic conditions on daily activity pattern of giant anteaters reintroduced in the Iberá Reserve, Argentina. During 2007-2012 we gathered 159 24-h focal samples on 15 radio-marked individuals (11 captive-reared, four wild-reared; seven adults, eight juveniles), 216 records of beginning and end of activity bouts on 20 individuals, and 454 camera-traps records (3,345 trap-days). We estimated the daily hours of activity, the percentage of diurnal and nocturnal activity, and the daily activity range and time overlap using time as a circular variable in kernel density estimations. We assessed differences between seasons, sexes, age classes, and types of rearing. The average daily hours of activity was 8:43 h. Camera-traps and radio-telemetry showed similar results. Animals exhibited both diurnal (60-65%) and nocturnal (40-35%) activity. The higher probability for being active ranged within 09:00-03:00 h. Anteaters spent more hours active and were more nocturnal during summer. Activity was highly overlapped between sexes and wild reared individuals were more nocturnal than captive-reared ones. Seasonal shifts in daily activity highlights the importance of thermoregulation as a selective factor in this species. The giant anteater is a cathemeral species with flexibility to accommodate its activity pattern to local conditions or experience.