Malemale interactions during musth

The anecdotal observations that male elephants become more aggressive during musth have been quantified at Amboseli by Joyce Poole. She found that the median frequency of agonistic interactions by musth bulls was 7.5/ hour compared to 3.5/hour by nonmusth, sexually active bulls. Just as dominance rank in nonmusth bulls is decided by body size, the larger bulls also won most of the agonistic interactions of a pair of musth bulls. Of 75 pairs of such contests observed between musth bulls, the larger bull emerged dominant in 93% of cases. However, in aggressive contests between a musth bull and a nonmusth bull, the winner was determined not by body size, but by musth. Thus, in 49

Figure 3.5

The relationship among age, musth, and reproductive success in African bull elephants at Amboseli: (top) age versus cumulative mating success from 1980 through 1987; (bottom) age versus average annual duration of musth during 19801981. (From Poole 1989a. Reproduced from Animal Behaviour with the permission of Elsevier Science.)

Figure 3.5

The relationship among age, musth, and reproductive success in African bull elephants at Amboseli: (top) age versus cumulative mating success from 1980 through 1987; (bottom) age versus average annual duration of musth during 19801981. (From Poole 1989a. Reproduced from Animal Behaviour with the permission of Elsevier Science.)

Figure 3.6

The relationship between average monthly rainfall and percentage conceptions by cows and bulls (>20 years old) in musth in two South African elephant populations: (A) Kruger National Park, 19821986; (B) Addo National Park, 1976-1986. (From Hall-Martin 1987. Reproduced with permission of the South African Journal of Science, National Research Foundation, South Africa.)

Figure 3.6

The relationship between average monthly rainfall and percentage conceptions by cows and bulls (>20 years old) in musth in two South African elephant populations: (A) Kruger National Park, 19821986; (B) Addo National Park, 1976-1986. (From Hall-Martin 1987. Reproduced with permission of the South African Journal of Science, National Research Foundation, South Africa.)

such contests observed, when the musth male was smaller in body size, the smaller male emerged victorious in 86% of interactions.

Joyce Poole also observed that, when a large, high-ranking musth bull chased a smaller, lower-ranking musth bull, the latter often stopped showing signs of musth (urine dribbling, temporal gland secretion, and behavioral postures). On the other hand, two high-ranking musth bulls did not cease musth, but tried to avoid each other's company by using different areas if their musth periods overlapped. The musth periods of many large males, of course, were also spaced out during the year to avoid overlap.

The aggressive contests described above are confined to threat displays, chasing, and minor combat using tusks. Escalation of contests into serious fights is rare, even when bulls are in musth. Observations on retreat distances by males of different sizes seem to suggest strongly that male elephants not only believe that musth in an opponent announces aggression, but also enables them to assess the chances that a contest may escalate into a serious one. In 14 years of field observations, Joyce Poole observed only 31 escalated fights between bulls, of which 20 were between pairs of musth bulls; two such contests resulted in the deaths of one contestant. During 1981-1982, I recorded three such elephant deaths in male-male combat in southern India. Since then, I have heard of few such instances, but this could be a reflection of the overall paucity of large males in southern India as a consequence of ivory poaching. Anthony Hall-Martin recorded seven adult bulls killed in fights during 19761986 in South Africa's Kruger National Park. Interestingly, all seven victors were bulls in musth, while four of the bulls killed were themselves in musth.

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