It's easy to forget sometimes that London isn't just about cinemas, theatres, music, and other urban stuff. For people interested in wildlife there is plenty to observe. One interesting place to visit is Richmond Park, especially at this time of year because their large population of deer are in their mating season. During this period the strongest stags (male red deer) and bucks (male fallow deer) try to monopolise access to a large group of females. Occasionally, fighting takes place between the males, although this mainly seems to occur when the males are fairly equally matched. But for the most part, the younger, smaller, and less experienced males generally avoid overt conflict with their more dominant counterparts. Nonetheless, they still try to obtain access to the females, hanging around some distance from the group and waiting for a likely opportunity.
Having observed the red deer on various occasions, these opportunities seem to come about in various ways. For example, a dominant male may spot another male getting too close to the females and so move to chase him away. Whilst he is engaged in this activity, other males lurking nearby may try to move in and attempt to mate with a female. In the few observational trips I've made, with my colleague Tom Dickins (an evolutionary psychologist) I have never yet seen this result in a successful mating; either the dominant male returns or the younger stag does not find a receptive female. However, presumably matings do occasionally occur, otherwise such behaviours would not be worth the risk.
In the park environment, anything that disturbs a group of females, leading them to disperse somewhat, can lead younger/smaller stags to move in and try to round up a female. Such triggers could be people getting too close to the red deer, leading them to move, or even a group of fallow deer running towards the reds (as happened when we were observing during this past weekend). The following brief clips, taken on my mobile phone (hence the rather blurry quality), show (1) a dominant male trying to chase off challengers and round up his harem following such a disruptive event, and (2) the same male running back to join his harem
Although it cannot be seen in these clips, earlier in the day this male had sustained a wound just below his right eye and that side of his head was soaked with blood. Some students that were on this trip had observed this stag in combat with another, during which he sustained the wound although succeeded in driving the other stag away.
Following the disruption shown in the above clips, this stag and his harem moved to a more central area of open grassland, not far from another group of females with its own dominant stag. These two stags kept a wary eye on each other, occasionally moving towards each other but never getting involved in a fight. One moment of disruption occurred as a large number of fallow deer came running past, at which point a couple of nearby stags tried without success to round up a couple of females. The following clip shows some of this disruption, but doesn't capture the full scale of what was happening (many more animals were within view than could be captured in the brief camera shot):
After things settled down again, our dominant stag (nicknamed "Stallion" by the students) made a couple of unsuccessful attempts to mate with one of the hinds (female red deer), but eventually succeeding on a third attempt. After this had occurred, the stag seemed to become more confident, making early challenges to young males well before they had got close to the group. The clip below shows a generally quiet state of affairs among the group.
On this particular visit to the Park, we noticed that a couple of stags kept their harems in the ferns rather than in the open. These groups seemed to be smaller, but less susceptible to challenges from roaming stags. This led us to speculate that alpha stags have more than one strategy. The most dominant ones keep larger harems in the open grassland where the grazing is better, but where there is a greater risk of challenges. Other alphas, slightly less dominant, keep their smaller harems where the grazing is poorer but where disruptions are less likely to occur. However, whether or not this hypothesis is accurate will require further visits to assess.
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