An Analysis of Time-Budgeting By Roe Deer (Capreol Us Capreol Us) in an Agricultural Area

Abstract

AbstractAn analysis of time-budgeting by Capreolus capreolus in an agricultural area is presented in two sections: the first concerns resting behavior, the second, time-budgeting within the active state. Of primary interest were comparisons between age-/sex-classes over seasons. Data were collected by direct observation of a free-ranging roe deer population with ca 50% of the animals individually marked. The study site consisted of ca 200 ha of agricultural cropland with a small wooded area on one end and interspersed tree-rows. An ethogram was constructed to enable the recording of behavioral samples on tape; these were later transcribed onto computer cards and the data were analyzed by computer using non-parametric and parametric tests. Roe deer spent ca 55% of the day lying (and ruminating) during the Winter. Differences between age-/sex-classes over the year were related to differential behavior towards protective cover, rather than differential energy requirements. Therefore, age-/sex-differences in time-budgeting were sought within the active period. It was found that ca 90% of the time spent on foot was devoted to 4 non-overlapping ethogram elements - orienting, walking, moving (searching), and feeding - and one collective element - social behavior. These 5 elements were subjected to more detailed statistical analyses, and indeed, significant age-/sex-class, as well as seasonal differences were found. The differences elucidated were often in agreement with predictions made from models or theories based on energetic considerations. This does not reduce the importance of recently hypothesized nutrient-balancing tasks, but it did demonstrate that time-variable energy demands were still operative in herbivores. Several results indicated that females follow more conservative strategies than males: they tended to reduce costs when faced with higher energy demands, whereas males tended to increase energy intake.