Fighting between males is a frequent component of the rutting behavior of Cervidae. Frequent conflicts are exhausting; fighting may be risky and can lead to serious injuries or even death. We focused on the process of assessment of the opponent's fighting ability and escalation of the combat, estimating the probability of fighting based on the encounter components such as groaning and parallel walk. In this study, we observed the agonistic behavior of fallow deer bucks (Dama dama) during the rut over four seasons. During this time, we recorded 205 encounters between bucks. Non-contact display, which allows contestants to assess their opponents fighting ability, occurred in 83% of the encounters. The highest predicted probability of a fight was found when both of the males vocalized and turned into the parallel walk. The chance of a clear outcome decreased when the males were fighting in comparison to when they did not fight. The initiator of the competitive encounter won 41% of the cases, while the attacked buck won 23% of the encounters. If the contestants avoided fighting, however, the initiator won 78% of encounters. Therefore, the initiator was more successful when no fight occurred compared to when the encounters escalated into fighting. In most cases where ritualized behavior occurred, one of the opponents left after vocalization or parallel walk occurred. Thus, vocalization and parallel walk increased the probability for a clear outcome. The probability of a fight was lowest in situations where the males displayed asymmetric behavior. Increased symmetry of the contestants' behavior was strongly correlated with a higher probability of a fight. Thus, these results indicate that fallow deer bucks use efficient tactic during the rut, which, in turn, minimizes the chance of injury while fighting during the breeding season. Aggr. Behav. 33:7-13, 2007. r

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The opening of the preorbital gland of red deer (Cervus elaphus) calves has been previously associated with feeding and satiety. However, it has been suggested to be most likely affected by some other factor or factors, possibly by excitement of the calf. If so, a calf should open its preorbital gland while being exposed to any stressful procedure. The hypothesis was tested that the preorbital gland is closed in a relaxed calf, whereas it is opened in a stressed calf. Preorbital opening was observed in 41 newborn red deer farm calves during a regular daily routine consisting of a search for newborn calves, their inspection, weighing, and painful marking with an ear tag. The openness of the preorbital gland (preorbital gland closed or opened) was recorded just before manipulation of a lying calf (i.e., in a calm calf) and then during the manipulation (i.e., in a distressed calf). Before manipulation, in all but 3 calves (7.3%, all of which were males), the preorbital gland was closed. All calves observed (100%) opened their preorbital gland during their manipulation, at least by the time the ear was punctured by the ear tag. The proportion of individuals with an open gland was lower (P < 0.001) before than during manipulation (7.3 vs. 100%, respectively). Hence, openness of the preorbital gland in newborn red deer calves was associated with a stressful manipulation by the humans, which suggests that it may be a simple and easily recognized indicator of calf stress.