AN INDIVIDUAL-BASED MODEL TO ESTIMATE THE DAILY ENERGETIC COST OF GREATER RHEAS AND ITS CONTRIBUTION ON POPULATION RECRUITMENT
Article first published online: 28 JAN 2013
Copyright ©2013 Wiley Periodicals, Inc.
Natural Resource Modeling
Volume 26, Issue 3, pages 435–454, August 2013
How to Cite
SIMOY, M. V., FERNÁNDEZ, G. J. and CANZIANI, G. A. (2013), AN INDIVIDUAL-BASED MODEL TO ESTIMATE THE DAILY ENERGETIC COST OF GREATER RHEAS AND ITS CONTRIBUTION ON POPULATION RECRUITMENT. Natural Resource Modeling, 26: 435–454. doi: 10.1111/nrm.12008
- Issue published online: 25 JUL 2013
- Article first published online: 28 JAN 2013
- Received by the editors on 2nd June 2012 and in revised form on 26th November 2012.
- Energetic costs;
- individual behavior;
- Rhea americana;
- reproductive costs
Abstract An individual-based model for estimating the energetic costs in Rhea americana was developed considering their sexual and seasonal differences in the behavioral activities. The model includes as variables the individual's characteristics, as well as corporal weight, the time spent on different activities, and the cost associated with each activity. We estimated the daily energetic demand of an adult rhea based on the activities individuals normally develop during postreproductive, nonreproductive, and reproductive seasons, differentiating between sexes. The time spent in each activity for one given animal was calculated from field observations of individuals and the estimations of energetic costs for each activity were obtained from specialized literature. The model built varied between sexes because males and females have different reproductive costs. Both models have the same general formulation but they differ in the cost associated with reproduction. In Greater Rheas, while males assume all of the incubation, the females only lay eggs communally in a single nest. Also the possibility that the individual reproduces or not was considered. The model does not allow to determine whether the energetic costs associated with the breeding are the reason why few individuals try to reproduce but it indicates that there is a clear difference in the daily energetic costs of individuals which reproduce and those which do not reproduce. Other activities associated with parental care posthatching, not taken into account here, would increase these differences, and would explain the low number of breeding attempts observed at wild.