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Male topi manipulate potential mates by threats to their offspring
Anita . Behar ., 1986, 34, 284-303
Short Communications Male Topi Manipulate Potential Mates by Threats to their Offspring Males can display to attract mates, gather resources that females need, win them fair and square by outcompeting rivals, or employ a variety of `dirty tricks' to secure matings . Dirty tricks rely on manipulating the behaviour of a rival or a potential mate . They range from male newts, Notopthalmus viridescens, deceiving rivals into dropping their spermatophores at the wrong moment during courtship (Verrell 1983) to an extreme situation where a male kills a female's offspring so that he can sire offspring conceived at the oestrus which follows (e .g . langurs, Presbrtis entellus : Hrdy 1974 ; lions, Panthera leo : Bertram 1975) . Here we report related behaviour in topi . Damiliscus korrigum, where males try to secure receptive females by behaving aggressively towards their calves, thus making females enter their territories to protect their offspring . Antelopes generally acquire mates either by following one or a group of females (e .g . greater kudu, Tragelaphus strepsiceros : Owen-Smith 1984) or by defending resources that females need so that they intercept their movements (e .g . impala, Aepvceros melampus : Jarman 1979 ; hartebeest, Alcelaphus buselaphus : Gosling 1974 ; these, and other, male antelope mating strategies are reviewed by Gosling, in press) . Topi have a flexible mating system (Duncan 1975 ; Montfort-Braham 1975) but probably most males defend territories which contain high protein grasses that attract females . The males whose behaviour we describe here were adopting this strategy . In resource defence territoriality, males rely on the resources in their territories to attract females and then on herding behaviour to prevent them from leaving . In herding, males attempt to intercept females that try to leave and threaten them, to drive them back into the territory (e .g . gazelles : Walther et al . 1983) . Herding is usually only effective over a short period and when females are determined to leave they eventually succeed . However, when a female is in oestrus, males herd more vigorously and sometimes manage to keep the female for a longer period (e .g . hartebeest: Gosling 1974) . Our observations were made at the northern edge of the Mara game reserve, Kenya in December 1984 . Topi are common in this area and were in the middle of their calving season, which lasts about 3-4 months (Duncan 1975) ; many females had calves of up to 6 weeks old and these females usually
joined groups of other females with calves . Large areas were covered by a mosaic of territories each defended by a single male . Territory size is difficult to estimate without long term observation because neighbouring males tend to clump (Gosling, in press) but nearest-neighbour distances (NNDs) give some impression : in a sample of 60 randomly selected males, NND ranged from 60 m to about 1250 in (excluding two males involved in an agonistic encounter at their common boundary) with 46 (77°) observations under 400 m . In the first observation a female was being courted by a territorial male (TM I ) . The female occasionally tried to escape but was herded by the male who headed her off as she tried to reach a boundary and drove her back into his territory (TI) . The intensity of courting and of herding, the latter sometimes at a gallop, suggested that the female was in, or close to, oestrus . The female had a young calf which, before we arrived, had become separated from its mother and was in the adjoining territory (T2) . The calf was in a group of four other females, all with young calves . As we watched, the calf walked towards its mother, some 250 m away . The resident territorial male (TM2) immediately ran to cut it off and herded it back into T2 with nodding horn threats . The call' ran back into T2 hut, despite this successful herding, TM2 continued to chase the calf and tried to butt it . The calf ran at top speed, twisting and turning as it tried to escape . The male pursued at a medium to fast canter . running awkwardly as it dipped its head low down towards the calf (Fig . 1) . We could not confirm that the male hit the calf but, if not, it came close and, as it did so, the calf uttered repeated loud `quacks', the characteristic distress call of young topi . Its mother, over 200 m away, looked intently towards it then started to trot towards the T I iT2 boundary . TM2 immediately stopped chasing the calf and ran towards the approaching female with nose raised in the characteristic posture of a male in pre-copulatory behaviour (Walther 1966 ; Montfort-Braham 1975) . But, before the female could reach the boundary she was cut off by TM I and herded back into T1 . TM2 stopped and watched TMI and the female, then turned and resumed chasing the calf, repeatedly trying to butt it and repeatedly eliciting the quack call . Each time the calf quacked its mother tried to approach it and was herded by TM I . This sequence of events was repeated five or six times in I h . The repeated chasing was eventually interrupted when a single adult spotted hyaena, Crocuta crocuta, walked towards the female group . 284
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species where females have previous offspring with them when they become receptive . However, to out knowledge, this is the only documented example of such 'devious' behaviour . *L . M . Gos>_iN , +M . PETRI $M . E . RAINY Figure 1 . A topi calf calling as a territorial male chases and attempts to butt it .
The calf saw the hyaena and immediately galloped towards its mother . TM2 was distracted by the hyaena and did not try to herd the calf . When the calf reached its mother the two ran in a large arc, moving at first obliquely away from T2 but then turning towards it, apparently to rejoin the other females and their calves. TM2 approached and the female ran away . closely pursued by TM2 for almost a kilometre . At this point they ran into another territory and TM2 returned to his territory after a brief agonistic encounter with the resident male . The main elements of this apparently manipulative male behaviour, including herding and chasing a separated calf were seen again in another area, a few days later . However, in this case, the mother entered the territory of the male that had chased its calf . The male approached and courted the female with raised muzzle, lowered ears and typical highstepping . prancing gait (Walther 1966 ; MontfortBraham 1975) . The female eventually ran from the territory before copulation could occur but this observation does suggest that males could gain coatings after females are attracted in this way . The occurrence of this behaviour would be partly dependent upon how often calves became separated from their mothers . This is surprisingly frequent, mainly because, while calves are dependent mainly on milk, they have a different pattern of activity to their mothers : calves often rest alone or in small groups as their mothers graze, sometimes at considerable distances away . We interpret this behaviour as a male manipulating a female's predictable response to a distressed calf, in order to secure matings . However, the case is based on only two observations and other explanations arc possible . Perhaps the male was trying to expel the calf from its territory or was trying to kill or injure it for some other reason . Against this interpretation are the observations that the male stopped chasing the calf immediately the female ran towards it, and that TM2 tried to prevent the calf from leaving its territory . Male manipulation of female protective behaviour could be potentially important in other
*Coypu Research Laboratory, M .A .F.F., Jupiter Road, Norwich, NR6 6SP, U .K . tAnimal Behaviour Research Group, Department of Biology, The Open University, Milton Keynes, MK7 6A A, U .K. Explore Mara Ltd, P.O . Box 45541, Nairobi, Kenya .
References Bertram, B .C.R . 1975 . Social factors influencing reproduction in wild lions . J . Zool . Lond ., 177, 463- 482 . Duncan, P. 1975. Topi and their food supply . Ph .D . thesis, University of Nairobi, Kenya . Gosling, L . M . 1974 . The social behaviour of Coke's hartebeest Alcelaphus huselaphus cokei . In : Ac Behaviour of Ungulates and its Relation to .Management (Ed . by V . Geist & F . R . Walther) . pp . 488--511 . Morges . Switzerland : International Union for the Conservation of Nature. Gosling, L . M . In press . The evolution of male mating strategies in antelopes . In : Ecological Aspects of Social Evolution (Ed . by D . I . Rubenstein & R . W . Wrangham) . Princeton : Princeton University Press . Flrdy, S . B . 1974 . Male-male competition and infanticide among the langurs (Preshytis entellus) of Abu, Rajastan . Folia primatol ., 22, 19-57 . Jarman, M . V . 1979 . Impala social behaviour: territory, hierarchy . mating and the defence of space . Adr . Ethol . . 21, 1--93 . Montfort-Braham, N . 1975 . Variations dons la structure sociale du topi, Damiliscus korrigunt Ogilby, au Pare National de l'Akagera, Rwanda . 7. . Tierps_rchoL . 39 . 332- 364 . Owen-Smith, N . 1984 . Spatial and temporal components of the mating systems of kudu bulls and red deer stags . Anim . Behar ., 32, 321-332 . Verrell, P . 1983 . The influence of the ambient sex ratio and intermale competition on the sexual behaviour of the red-spotted newt, Notaphthalmu .s riridcscens (Amphibia : Urodela : Salamandridae) . Behar . Ecol. Soctobiol ., 13, 307-313 . Walther, F . R . 1966 . Mit Horn and Hut . Berlin- Paul Pare) . Walther, F . R . . Mungall, E . C . & Grau . G . A . 1983 . Gazelles and their Relatives : a Study in Territorial Behavior . Park Ridges, New Jersey : Noyes Publications . (Received I April 1985 . revised 2 Juh , 1985 : MS, number: sc-247)
Short Communications Male Topi Manipulate Potential Mates by Threats to their Offspring Males can display to attract mates, gather resources that females need, win them fair and square by outcompeting rivals, or employ a variety of `dirty tricks' to secure matings . Dirty tricks rely on manipulating the behaviour of a rival or a potential mate . They range from male newts, Notopthalmus viridescens, deceiving rivals into dropping their spermatophores at the wrong moment during courtship (Verrell 1983) to an extreme situation where a male kills a female's offspring so that he can sire offspring conceived at the oestrus which follows (e .g . langurs, Presbrtis entellus : Hrdy 1974 ; lions, Panthera leo : Bertram 1975) . Here we report related behaviour in topi . Damiliscus korrigum, where males try to secure receptive females by behaving aggressively towards their calves, thus making females enter their territories to protect their offspring . Antelopes generally acquire mates either by following one or a group of females (e .g . greater kudu, Tragelaphus strepsiceros : Owen-Smith 1984) or by defending resources that females need so that they intercept their movements (e .g . impala, Aepvceros melampus : Jarman 1979 ; hartebeest, Alcelaphus buselaphus : Gosling 1974 ; these, and other, male antelope mating strategies are reviewed by Gosling, in press) . Topi have a flexible mating system (Duncan 1975 ; Montfort-Braham 1975) but probably most males defend territories which contain high protein grasses that attract females . The males whose behaviour we describe here were adopting this strategy . In resource defence territoriality, males rely on the resources in their territories to attract females and then on herding behaviour to prevent them from leaving . In herding, males attempt to intercept females that try to leave and threaten them, to drive them back into the territory (e .g . gazelles : Walther et al . 1983) . Herding is usually only effective over a short period and when females are determined to leave they eventually succeed . However, when a female is in oestrus, males herd more vigorously and sometimes manage to keep the female for a longer period (e .g . hartebeest: Gosling 1974) . Our observations were made at the northern edge of the Mara game reserve, Kenya in December 1984 . Topi are common in this area and were in the middle of their calving season, which lasts about 3-4 months (Duncan 1975) ; many females had calves of up to 6 weeks old and these females usually
joined groups of other females with calves . Large areas were covered by a mosaic of territories each defended by a single male . Territory size is difficult to estimate without long term observation because neighbouring males tend to clump (Gosling, in press) but nearest-neighbour distances (NNDs) give some impression : in a sample of 60 randomly selected males, NND ranged from 60 m to about 1250 in (excluding two males involved in an agonistic encounter at their common boundary) with 46 (77°) observations under 400 m . In the first observation a female was being courted by a territorial male (TM I ) . The female occasionally tried to escape but was herded by the male who headed her off as she tried to reach a boundary and drove her back into his territory (TI) . The intensity of courting and of herding, the latter sometimes at a gallop, suggested that the female was in, or close to, oestrus . The female had a young calf which, before we arrived, had become separated from its mother and was in the adjoining territory (T2) . The calf was in a group of four other females, all with young calves . As we watched, the calf walked towards its mother, some 250 m away . The resident territorial male (TM2) immediately ran to cut it off and herded it back into T2 with nodding horn threats . The call' ran back into T2 hut, despite this successful herding, TM2 continued to chase the calf and tried to butt it . The calf ran at top speed, twisting and turning as it tried to escape . The male pursued at a medium to fast canter . running awkwardly as it dipped its head low down towards the calf (Fig . 1) . We could not confirm that the male hit the calf but, if not, it came close and, as it did so, the calf uttered repeated loud `quacks', the characteristic distress call of young topi . Its mother, over 200 m away, looked intently towards it then started to trot towards the T I iT2 boundary . TM2 immediately stopped chasing the calf and ran towards the approaching female with nose raised in the characteristic posture of a male in pre-copulatory behaviour (Walther 1966 ; Montfort-Braham 1975) . But, before the female could reach the boundary she was cut off by TM I and herded back into T1 . TM2 stopped and watched TMI and the female, then turned and resumed chasing the calf, repeatedly trying to butt it and repeatedly eliciting the quack call . Each time the calf quacked its mother tried to approach it and was herded by TM I . This sequence of events was repeated five or six times in I h . The repeated chasing was eventually interrupted when a single adult spotted hyaena, Crocuta crocuta, walked towards the female group . 284
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species where females have previous offspring with them when they become receptive . However, to out knowledge, this is the only documented example of such 'devious' behaviour . *L . M . Gos>_iN , +M . PETRI $M . E . RAINY Figure 1 . A topi calf calling as a territorial male chases and attempts to butt it .
The calf saw the hyaena and immediately galloped towards its mother . TM2 was distracted by the hyaena and did not try to herd the calf . When the calf reached its mother the two ran in a large arc, moving at first obliquely away from T2 but then turning towards it, apparently to rejoin the other females and their calves. TM2 approached and the female ran away . closely pursued by TM2 for almost a kilometre . At this point they ran into another territory and TM2 returned to his territory after a brief agonistic encounter with the resident male . The main elements of this apparently manipulative male behaviour, including herding and chasing a separated calf were seen again in another area, a few days later . However, in this case, the mother entered the territory of the male that had chased its calf . The male approached and courted the female with raised muzzle, lowered ears and typical highstepping . prancing gait (Walther 1966 ; MontfortBraham 1975) . The female eventually ran from the territory before copulation could occur but this observation does suggest that males could gain coatings after females are attracted in this way . The occurrence of this behaviour would be partly dependent upon how often calves became separated from their mothers . This is surprisingly frequent, mainly because, while calves are dependent mainly on milk, they have a different pattern of activity to their mothers : calves often rest alone or in small groups as their mothers graze, sometimes at considerable distances away . We interpret this behaviour as a male manipulating a female's predictable response to a distressed calf, in order to secure matings . However, the case is based on only two observations and other explanations arc possible . Perhaps the male was trying to expel the calf from its territory or was trying to kill or injure it for some other reason . Against this interpretation are the observations that the male stopped chasing the calf immediately the female ran towards it, and that TM2 tried to prevent the calf from leaving its territory . Male manipulation of female protective behaviour could be potentially important in other
*Coypu Research Laboratory, M .A .F.F., Jupiter Road, Norwich, NR6 6SP, U .K . tAnimal Behaviour Research Group, Department of Biology, The Open University, Milton Keynes, MK7 6A A, U .K. Explore Mara Ltd, P.O . Box 45541, Nairobi, Kenya .
References Bertram, B .C.R . 1975 . Social factors influencing reproduction in wild lions . J . Zool . Lond ., 177, 463- 482 . Duncan, P. 1975. Topi and their food supply . Ph .D . thesis, University of Nairobi, Kenya . Gosling, L . M . 1974 . The social behaviour of Coke's hartebeest Alcelaphus huselaphus cokei . In : Ac Behaviour of Ungulates and its Relation to .Management (Ed . by V . Geist & F . R . Walther) . pp . 488--511 . Morges . Switzerland : International Union for the Conservation of Nature. Gosling, L . M . In press . The evolution of male mating strategies in antelopes . In : Ecological Aspects of Social Evolution (Ed . by D . I . Rubenstein & R . W . Wrangham) . Princeton : Princeton University Press . Flrdy, S . B . 1974 . Male-male competition and infanticide among the langurs (Preshytis entellus) of Abu, Rajastan . Folia primatol ., 22, 19-57 . Jarman, M . V . 1979 . Impala social behaviour: territory, hierarchy . mating and the defence of space . Adr . Ethol . . 21, 1--93 . Montfort-Braham, N . 1975 . Variations dons la structure sociale du topi, Damiliscus korrigunt Ogilby, au Pare National de l'Akagera, Rwanda . 7. . Tierps_rchoL . 39 . 332- 364 . Owen-Smith, N . 1984 . Spatial and temporal components of the mating systems of kudu bulls and red deer stags . Anim . Behar ., 32, 321-332 . Verrell, P . 1983 . The influence of the ambient sex ratio and intermale competition on the sexual behaviour of the red-spotted newt, Notaphthalmu .s riridcscens (Amphibia : Urodela : Salamandridae) . Behar . Ecol. Soctobiol ., 13, 307-313 . Walther, F . R . 1966 . Mit Horn and Hut . Berlin- Paul Pare) . Walther, F . R . . Mungall, E . C . & Grau . G . A . 1983 . Gazelles and their Relatives : a Study in Territorial Behavior . Park Ridges, New Jersey : Noyes Publications . (Received I April 1985 . revised 2 Juh , 1985 : MS, number: sc-247)