An Investigation of Assessment Games During Fallow Deer Fights

Abstract

An improved understanding of the decision rules used by competing animals can be achieved by examining both the temporal structure and display rate of competitors during a contest. Current models of animal competition make different predictions regarding the behaviour of competing animals and the present study evaluates the predictions of three such models, the energetic war of attrition (eWOA), the sequential assessment game (SAG) and the cumulative assessment model (CAM) by applying them to the fighting behaviour of male fallow deer (Dama dama L.). There was no difference in rate at which the jump clash and backward push were recorded over fight duration; therefore, in terms of the temporal distribution of behavioural acts within fights, the jump clash and backward push conformed to the predictions of the SAG. There was a difference between winners and losers of fights for the frequency that the jump clash and backward push were recorded consistent with both the SAG and CAM. Analysis of bout duration showed that there was a decrease in the duration of subsequent bouts of fighting; this is only permitted under eWOA. In so far as current assessment models permit interpretation of the data, our results meet only a limited number of predictions of any one model. Given the difficulty in interpreting our data within the context of current assessment models, recommendations for the development of more complex models are presented.

The role of skill in animal contests: a neglected component of fighting ability

“…However, injurious fighting is not restricted to massive animals and massive animals do not always use injurious tactics. For example, in large and powerful mammals such as red deer, Cervus elephas, and fallow deer, Dama dama, most fights are settled without injurious fighting (although serious injuries can occur in the most escalated contests) [28]. During the duels of Asian rhinoceros beetles, Trypoxylus dichotomus, on the other hand, males try to pinion their opponent on their head horn, which enables them to puncture the opponent's elytra using the sharp spikes of the thoracic horn [29].…”

Variation between Self- and Mutual Assessment in Animal Contests

“…Such studies suggest that assessment strategy is variable between and within species (e.g., Hsu et al 2008;Prenter et al 2008;Kasumovic et al 2010). Furthermore, the intensified scrutiny of recent studies has uncovered a variety of assessment modes that were not predicted by theory (Arnott and Elwood 2009), and there are multiple cases of inconclusive results concerning the assessment strategies being used within a population (Jennings et al 2005;Morrell et al 2005;Stuart-Fox 2006). Therefore, it is clear that a functional understanding of the basis of withdrawal decisions in contests is lacking.…”

Estimation of the probability of fighting in fallow deer (Dama dama) during the rut

“…Outlasting of the hierarchy from the pre-rut up to the rut and the tendency of adult fallow deer males to solve conflicts without antler contact contribute to a lower frequency of fights and decreased risk of serious injury [McElligott et al, 1998]. Vocalization (groaning), parallel walk and physical combat during the breeding season have been described by several authors [Apollonio et al, 1989;Festa-Bianchet et al, 1990;Jennings et al, 2002Jennings et al, , 2003Jennings et al, , 2004Jennings et al, , 2005Mattiangeli et al, 1998Mattiangeli et al, , 1999McElligott et al, 1998Reby et al, 1998]. These authors have examined various aspects of rutting combats, such as vocalization rates , fighting tactics and techniques and factors affecting the duration of fights [Jennings et al, 2004;Mattiangeli et al, 1998Mattiangeli et al, , 1999McElligott et al, 1998].…”