Relative age determination of Rattus tiomanicus using allometric measurements

Aude Verwilghen (1, 2) , Marie-Agnès Rabillard , Yannick Chaval (3) , Dominique Rieffel (1) , Martua Hasiholan Sinaga (4) , Mohd Naim (5) , Jean-Pierre Caliman (5, 2) , Patrick Giraudoux (1, 6) , Francis Raoul (1)

1 LCE - Laboratoire Chrono-environnement (UMR 6249)
2 UPR Système de pérennes - Performance des systèmes de culture des plantes pérennes
3 UMR CBGP - Centre de Biologie pour la Gestion des Populations
4 Indonesian Institute of Sciences (LIPI) & Museum Bogoriense
5 SMARTRI - Smart Research Institute [Indonésie]
6 IUF - Institut universitaire de France

For sustainable oil palm production, barn owl (Tyto alba) predation should be enhanced and monitored to better understand its impact on rodent population dynamics, notably for selective predation based on age or size. Our aim was to assess the best combination of osteometric variables that predict eye lens weight and thus the relative age of an individual Rattus tiomanicus based on pellet remains. We captured 161 individuals in an oil palm plantation in Indonesia and measured 15 osteometric variables for the jaw, skull, and femur. We investigated the variables’ correlations with eye lens weight and estimated the measurement errors. In addition, 120 pellets were collected to assess the frequency of different types of bones. Predictive modelling was then used. We suggest that the model using the femur length would be more appropriate, even if it is slightly less precise than the models that consider the skull and jaw variables. The femur was well represented in the pellet sample, its length highly correlated with the eye lens weight, with a low measurement error. Our study demonstrates the utility of femur length for age prediction in prey from macroremains in oil palm plantations, wherein most pellets are headless and R. tiomanicus is the dominant prey.

Mots clés: rodent prey; owl tyto-alba; eye-lens weight; allometry; barn owl pellet; eye lens weight; rodent; long term; sex class; barn owl; differential predation; prey selection

Mots clés: oil palm plantation; oil-palm-plantation; population-structure

Domaines: Ecologie, Environnement

Aude Verwilghen, Marie-Agnès Rabillard, Yannick Chaval, Dominique Rieffel, Martua Hasiholan Sinaga, et al.. Relative age determination of Rattus tiomanicus using allometric measurements. Mammalia, 2015, 79 (1), pp.81-90. ⟨10.1515/mammalia-2013-0113⟩. ⟨hal-01114386⟩