Male fallow deer are highly competitive during the rutting season; successful mating depends mainly on body size and dominance rank.
Many factors can determine the seasonal reproductive success of an individual male fallow deer; these factors include body size, which can affect reproduction and survival.
The amount of time spent in a lek can be an important factor in determining male reproductive success; energy can play an important role for the duration of competitive leks.
Among ungulates, fallow deer exhibit one of the most outstanding examples of sexual dimorphism, as males are much larger than females.
For sexual selection to lead to the evolution of sexual dimorphism, where males are bigger than females, there must be advantages: (1) advantages during combat, (2) endurance rivalry advantage, (3) female preference for larger males and (4) advantages during sperm competition.
Sexual selection has chosen bigger males over an evolutionary time scale and conferred advantages during competition of mates by a variety of mechanisms, which are intrasexual competition, access to females, and resource accessibility, which effects female attractiveness.

Body size is important during male-male agonistic interactions and endurance rivalry, while females tend to have a preference for larger males.
Dominance rank is a good indicator of body size and body mass, however, age was not an important factor.
In a study done by McElligott et al. (
2001), it was found that mating success was related to body size, pre-rut and rut rank.
Similarly, in another study, researchers found that age, weight, and display effort were all significant factors in determining mating success; in both studies, mating success was measured by the frequency of copulations, which means that a variety of factors in different fallow deer populations can affect the overall energy allocation which will ultimately affect mating success.
Maternal investment early in life can be critical to the development of body size, since it can be quite variable at that stage depending on resources and habitat type.
Mature male body size can be a better indicator of overall male quality rather than body mass, since body mass depends on a variety of resources each year and is not a static trait; body mass can be a complex trait to measure.
Male fallow deer are highly competitive during the rutting season; successful mating depends mainly on body size and dominance rank. Many factors can determine the seasonal reproductive success of an individual male fallow deer; these factors include body size, which can affect reproduction and survival. The amount of time spent in a lek can be an important factor in determining male reproductive success; energy can play an important role for the duration of competitive leks. Among ungulates, fallow deer exhibit one of the most outstanding examples of sexual dimorphism, as males are much larger than females. For sexual selection to lead to the evolution of sexual dimorphism, where males are bigger than females, there must be advantages: (1) advantages during combat, (2) endurance rivalry advantage, (3) female preference for larger males and (4) advantages during sperm competition. Sexual selection has chosen bigger males over an evolutionary time scale and conferred advantages during competition of mates by a variety of mechanisms, which are intrasexual competition, access to females, and resource accessibility, which effects female attractiveness.
Body size is important during male-male agonistic interactions and endurance rivalry, while females tend to have a preference for larger males. Dominance rank is a good indicator of body size and body mass, however, age was not an important factor. In a study done by McElligott et al. (2001), it was found that mating success was related to body size, pre-rut and rut rank. Similarly, in another study, researchers found that age, weight, and display effort were all significant factors in determining mating success; in both studies, mating success was measured by the frequency of copulations, which means that a variety of factors in different fallow deer populations can affect the overall energy allocation which will ultimately affect mating success. Maternal investment early in life can be critical to the development of body size, since it can be quite variable at that stage depending on resources and habitat type. Mature male body size can be a better indicator of overall male quality rather than body mass, since body mass depends on a variety of resources each year and is not a static trait; body mass can be a complex trait to measure.
Fallow deer