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Hervé Fritz - One of the best experts on this subject based on the ideXlab platform.
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Anti-predator behaviour of kudu and impala in response to mimicked African wild dog presence: do age and sex matter?
Behaviour, 2015Co-Authors: Hervé Fritz, Esther Van Der Meer, Olivier PaysAbstract:Predators not only prey upon certain prey species, but also on certain age–sex classes within species. Predation risk and an individual’s response to this risk might therefore vary with an individual’s characteristics. We examined the proportion of time different age–sex classes of kudu ( Tragelaphus strepsiceros) and impala ( Aepyceros melampus) spent high quality vigilant (costly vigilance that detracts from all other activities) in response to mimicked predation risk by African wild dogs ( Lycaon pictus). For both species predation risk was the main factor determining the investment in high quality vigilance behaviour. Age–sex class-specific responses were not related to age–sex class specific lethality risk presented by African wild dogs. For impala, regardless of predation risk, age seemed to have some effect on the investment in high quality vigilance with sub-adult impala spending more time high quality vigilant than adult impala, which is possibly why African wild dogs predominantly preyed upon adult impala.
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trophy hunting in africa long term trends in antelope horn size
Animal Conservation, 2013Co-Authors: Williamgeorges Crosmary, Andrew J Loveridge, Henry Ndaimani, S Lebel, V Booth, Steeve D Cote, Hervé FritzAbstract:Trophy hunting in ungulates may favour individuals with smaller horns. A decrease in horn/antler size may jeopardize the conservation potential of hunting areas, which would be a major concern in Africa where hunting zones represent over half of the total area of protected lands. We investigated horn length trends of harvested male impalas Aepyceros melampus, greater kudus Tragelaphus strepsiceros and sable antelopes Hippotragus niger, from 1974 to 2008 in Matetsi Safari Area, Zimbabwe. Horn length declined by 4% in impalas, partly because male harvest age decreased. In greater kudus, surprisingly, horn length increased by 14%, while mean age of harvested male greater kudus increased during the study period. Reduced hunting pressure on this species during the study may have allowed males to live longer and to grow longer horns before being harvested. Horn length declined by 6% in sable antelopes, independent of age, suggesting that trophy hunting selected male sable antelopes with smaller horns through time, provided that horn length is heritable. Hunting pressure and trophy value were higher for sable antelopes than for impalas and greater kudus. Accordingly, the decline of horn length in this species was more pronounced. More valuable trophy species, such as sable antelopes, require special attention because they may be exposed to higher hunting pressure, and are therefore more likely to experience a decrease in horn size. (Resume d'auteur)
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The Effect of Simulated African Wild Dog Presence on Anti-predator Behaviour of Kudu and Impala
Ethology, 2012Co-Authors: Esther Van Der Meer, Olivier Pays, Hervé FritzAbstract:In this study, we examined the behavioural, temporal and spatial effects of simulated African wild dog (Lycaon pictus) presence on its two main prey species: kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus). We spread African wild dog faeces around waterholes and played African wild dog sounds at different intervals to mimic immediate and non-immediate predation pressure. We looked at anti-predator behaviour at both a herd and individual level and distinguished between high-quality (detracts from all other activities), high-cost vigilance and low-quality (used to monitor the surrounding in spare time), low-cost vigilance to determine costs involved. We found that simulated African wild dog presence had little effect on anti-predator behaviour of their free-ranging prey. Only when immediate predation risk was mimicked did kudu invest in (additional) high-quality vigilance, whereas impala showed no response. Regardless of direct cues of African wild dog presence, behavioural adjustments to reduce predation risk were primarily based on environmental factors such as time of the day and broad-scale habitat structure. Predators have been shown to utilize waterholes to hunt, and prey species are therefore likely to maximize anti-predator behaviour in this high-risk environment based on environmental variables affecting predation risk, the main predator within the system, and water requirements, leaving little flexibility to respond to (simulated) African wild dog presence.
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Collective Vigilance in the Greater Kudu: Towards a Better Understanding of Synchronization Patterns
Ethology, 2011Co-Authors: Olivier Pays, Etienne Sirot, Hervé FritzAbstract:Collective detection of predators is one of the main advantages of living in groups in prey species. However, the mechanisms linking individual and collective vigilance remain largely unknown. Here, we investigated individual and collective vigilance in a natural population of greater kudu (Tragelaphus strepsiceros), a gregarious ruminant living under high predation risk. Controlling for environmental, individual and group factors, we show that the proportion of time during which at least one individual was vigilant increased with group size, whereas individual investment in vigilance decreased. We also show that individuals tended to synchronize both vigilance and feeding activities. More generally, and whatever the considered group size, we demonstrate how the independent scanning assumption underestimated both the proportion of time during which no individual was vigilant and the proportion of time during which all individuals were simultaneously vigilant, but overestimated the proportion of time during which one vigilant individual only was present. Our results thus contrast with the point of view that the alternative to independent vigilance is coordinated vigilance and plead for a better description of the processes whereby reciprocal influences between individuals shape collective patterns of vigilance.
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individual vigilance of african herbivores while drinking the role of immediate predation risk and context
Animal Behaviour, 2010Co-Authors: David W. Macdonald, Andrew J Loveridge, Stephanie Periquet, Marion Valeix, Hillary Madzikanda, Hervé FritzAbstract:Perceived risk of predation is considered to influence individual prey vigilance, but little is known about the extent to which the context (e.g. distance to cover, group size) and the immediate presence of predators determine individual prey vigilance. We combined behavioural data on individual vigilance of herbivores at waterholes with fine-scale spatiotemporal data from 27 African lions, Panthera leo, fitted with GPS radiocollars to test whether individual prey vigilance increases when predators are in the vicinity and whether this relationship is influenced by group size and presence of other herbivores. The study was conducted on giraffe, Giraffa camelopardalis, greater kudu, Tragelaphus strepsiceros, and plains zebra, Equus quagga, in Hwange National Park, Zimbabwe, between mid-September and mid-November 2008. Kudu was the only species to adjust its vigilance level significantly in the presence of lions, arguably owing to its higher contribution to lion diet in Hwange. Kudu devoted a significantly higher proportion of time to vigilance when lions were in the vicinity. Furthermore, the proportion of time spent on individual vigilance decreased as group size increased during the approach and drinking phases, particularly when lions were in the vicinity. Finally, the presence of other herbivores at the waterhole enabled kudu to spend less time vigilant while drinking. These adjustments involved changes in the length of vigilance bouts, but not in their frequency. Our study suggests that the interplay between the context (group size, presence of other prey) and the immediate presence of predators determines the level of vigilance in prey.
Olivier Pays - One of the best experts on this subject based on the ideXlab platform.
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Anti-predator behaviour of kudu and impala in response to mimicked African wild dog presence: do age and sex matter?
Behaviour, 2015Co-Authors: Hervé Fritz, Esther Van Der Meer, Olivier PaysAbstract:Predators not only prey upon certain prey species, but also on certain age–sex classes within species. Predation risk and an individual’s response to this risk might therefore vary with an individual’s characteristics. We examined the proportion of time different age–sex classes of kudu ( Tragelaphus strepsiceros) and impala ( Aepyceros melampus) spent high quality vigilant (costly vigilance that detracts from all other activities) in response to mimicked predation risk by African wild dogs ( Lycaon pictus). For both species predation risk was the main factor determining the investment in high quality vigilance behaviour. Age–sex class-specific responses were not related to age–sex class specific lethality risk presented by African wild dogs. For impala, regardless of predation risk, age seemed to have some effect on the investment in high quality vigilance with sub-adult impala spending more time high quality vigilant than adult impala, which is possibly why African wild dogs predominantly preyed upon adult impala.
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The Effect of Simulated African Wild Dog Presence on Anti-predator Behaviour of Kudu and Impala
Ethology, 2012Co-Authors: Esther Van Der Meer, Olivier Pays, Hervé FritzAbstract:In this study, we examined the behavioural, temporal and spatial effects of simulated African wild dog (Lycaon pictus) presence on its two main prey species: kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus). We spread African wild dog faeces around waterholes and played African wild dog sounds at different intervals to mimic immediate and non-immediate predation pressure. We looked at anti-predator behaviour at both a herd and individual level and distinguished between high-quality (detracts from all other activities), high-cost vigilance and low-quality (used to monitor the surrounding in spare time), low-cost vigilance to determine costs involved. We found that simulated African wild dog presence had little effect on anti-predator behaviour of their free-ranging prey. Only when immediate predation risk was mimicked did kudu invest in (additional) high-quality vigilance, whereas impala showed no response. Regardless of direct cues of African wild dog presence, behavioural adjustments to reduce predation risk were primarily based on environmental factors such as time of the day and broad-scale habitat structure. Predators have been shown to utilize waterholes to hunt, and prey species are therefore likely to maximize anti-predator behaviour in this high-risk environment based on environmental variables affecting predation risk, the main predator within the system, and water requirements, leaving little flexibility to respond to (simulated) African wild dog presence.
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Collective Vigilance in the Greater Kudu: Towards a Better Understanding of Synchronization Patterns
Ethology, 2011Co-Authors: Olivier Pays, Etienne Sirot, Hervé FritzAbstract:Collective detection of predators is one of the main advantages of living in groups in prey species. However, the mechanisms linking individual and collective vigilance remain largely unknown. Here, we investigated individual and collective vigilance in a natural population of greater kudu (Tragelaphus strepsiceros), a gregarious ruminant living under high predation risk. Controlling for environmental, individual and group factors, we show that the proportion of time during which at least one individual was vigilant increased with group size, whereas individual investment in vigilance decreased. We also show that individuals tended to synchronize both vigilance and feeding activities. More generally, and whatever the considered group size, we demonstrate how the independent scanning assumption underestimated both the proportion of time during which no individual was vigilant and the proportion of time during which all individuals were simultaneously vigilant, but overestimated the proportion of time during which one vigilant individual only was present. Our results thus contrast with the point of view that the alternative to independent vigilance is coordinated vigilance and plead for a better description of the processes whereby reciprocal influences between individuals shape collective patterns of vigilance.
Oliveira Bernardo - One of the best experts on this subject based on the ideXlab platform.
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Sobre uma população de ixodídeos colhida em troféus de caça nas províncias do Cabo e de Mpumalanga (República da África do Sul) e de Matabeleland South (Zimbabwé)
2010Co-Authors: Rosa Fernanda, Crespo, Maria Virgínia, Oliveira BernardoAbstract:Apresentação em PainelDurante os meses de Maio de 2008 e de 2009 e Março de 2010, foram observados treze troféus de caça obtidos em reservas de caça privadas nas províncias de “Eastern Cape” e Mpumalanga (República da África do Sul) e de Matabeleland South (Zimbabwé), tendo-se recolhido ixodídeos em vertebrados pertencentes à Classe Mammalia (Artiodactyla e Carnivora). A identificação baseou-se na chave adoptada por Travassos Dias (1989), nas descrições do género Rhipicephalus efectuadas por Walker et al. (2000) e na morfologia das genitálias. Dos 39 exemplares colhidos, 17 (89,74%) eram adultos e os restantes (10,26%), ninfas e larvas, com igual distribuição. Identificaram-se Ixodes sp. (12,82%) em Tragelaphus strepsiceros capensis e Oreotragus oreotragus; Haemaphysalis leachi (2,56%) em Caracal caracal e Haemaphysalis spp. (12,82%) em Tragelaphus scriptus silvaticus; Rhipicephalus evertsi evertsi (5,13%) em Taurotragus oryx; Rhipicephalus simus (5,13%) em Panthera leo; Rhipicephalus spp. (5,13%) em Damaliscus dorcas philipsi, Damaliscus dorcas; Hyalomma truncatum (7,69%) em Damaliscus dorcas, Rhapicerus melanotis e Cervus unicolor; Amblyomma hebraeum (46,15%) em Taurotragus oryx e Sincerus caffer; Boophilus sp. (2,56%) em Tragelaphus strepsiceros capensis. Relativamente a estudos anteriores, realizados na província de “Eastern Cape”, pelos mesmos autores, mas em épocas distintas, verificou-se um aumento da prevalência para a infecção por Ixodes sp. e Hyalomma truncatum. A espécie Amblyomma hebraeum evidenciou os valores de prevalência mais elevados, ou seja 30,77%, e a maior carga parasitária média, com 4,5 espécimes por hospedeiro parasitado. Com excepção do macho, salienta-se a presença de todas as formas de evolução no mesmo hospedeiro (Tragelaphus scriptus silvaticus) relativamente a Haemaphysalis sp. Predominaram as infecções simples (84,62%) e apenas ocorreram infecções duplas em três vertebrados (géneros: Ixodes e Boophilus, Rhipicephalus e Hyalomma). Salienta-se ainda que algumas das espécies identificadas poderão assegurar o ciclo de vida de alguns agentes patogénicos, nomeadamente de Ehrlichia ruminantium, Anaplasma spp., Theileria spp., entre outros, e consequentemente desempenhar um papel importante na transmissão destes às diversas populações silvestres e domésticas que coabitem os mesmos habitats.Escola Superior Agrária/Instituto Politécnico de Santarém e Instituto de Investigação Científica Tropical
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Sobre uma população de ixodídeos colhida em troféus de caça na província de “EASTERN CAPE” (República da África do Sul)
2008Co-Authors: Crespo, Maria Virgínia, Rosa Fernanda, Oliveira BernardoAbstract:Apresentação em painelDurante o mês de Maio de 2008 foram observados nove troféus de caça obtidos em reservas de caça privadas na Província de “Eastern Cape” (República da África do Sul), tendo-se recolhido ixodídeos em vertebrados pertencentes à Classe MAMMALIA (ARTIODACTYLA e CARNIVORA). A identificação baseou-se na chave adoptada por Travassos Dias (1989), nas descrições do género Rhipicephalus efectuadas por Walker et al. (2000) e na morfologia das genitálias. Dos 21 exemplares colhidos, 17 (80,96%) eram adultos e os restantes (18,04%), ninfas e larvas, com igual distribuição. Identificaram-se Ixodes sp. (23,81%) em Tragelaphus strepsiceros capensis e Oreotragus oreotragus; Haemaphysalis leachi (28,57%) em Caracal caracal e Haemaphysalis spp. em Tragelaphus scriptus silvaticus; Rhipecephelus evertsi evertsi (9,52%) em Damaliscus dorcas philipsi e Damaliscus dorcas; Hyalomma truncatum (19,05%) em Damaliscus dorcas, Rhapicerus melanotis e Cervus unicolor; Amblyomma hebraeum (14,29%) em Taurotragus oryx; Boophilus sp. (4,76%) em Tragelaphus strepsiceros capensis. Relativamente a estudos anteriores, realizados na mesma região, pelos mesmos autores, mas em épocas distintas, verificou-se um aumento da prevalência para a infecção por Ixodes sp. e Hyalomma truncatum. O género Haemaphysalis, para além de ter sido observado pela primeira vez, evidenciou os valores de prevalência mais elevados e a maior carga parasitária, salientando-se todas as formas de evolução no mesmo hospedeiro. Predominaram as infecções simples (66,67%) e apenas ocorreram infecções duplas em três vertebrados (géneros: Ixodes e Boophilus, Rhipicephalus e Hyalomma, Hyalomma e Amblyomma).Escola Superior Agrária do Instituto Politécnico de Santarém; Instituto de Investigação Científica Tropical/DE
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Acerca de alguns IXODIDAE de vertebrados silvestres do Sudeste Africano
2000Co-Authors: Oliveira Bernardo, Crespo, Maria Virgínia, Rosa FernandaAbstract:Apresentação em painelProcedeu-se à identificação de uma colecção de IXODIDAE do sudeste africano (Região de Tete, na República Democrática de Moçambique e da Região do Cabo, na República da África do Sul), recolhida em MAMMALIA (Artiodactyla, Perissodactyla e Carnivora) e AVES, capturados em coutadas privadas de caça. A identificação taxonómica baseou-se na chave de identificação adoptada por TRAVASSOS DIAS (1989) e na morfologia das genitálias. Em Moçambique, registou-se apenas uma espécie, Rhipicephalus sanguineus, em Aepyceros melampus (impala), Leptailurus serval (serval) e Gyps sp. (grifo). Na África do Sul, as espécies são: Ixodes pilosus (Connochaetus taurinus, gnú), Ixodes sp. (Damaliscus dorcas philipsi, damalisco), Amblyomma hebraeum (Oryx gazella gazella, orix), Boophilus florae (Damaliscus dorcas philipsi), Boophilus spp. (Connochaetus taurinus), Hyalomma truncatum (Alcelaphus buselaphus caama, caama e Tragelaphus strepsiceros, cudo) e Rhipicephalus sanguineus (Oryx gazella gazella e Equus burchellii antiquorum, zebra). Fazem-se considerações sobre a importância destes vectores e do papel que os hospedeiros vertebrados desempenham como reservatórios na transmissão de agentes patogénicos. Taxonomic studies were made in an IXODIDAE collection off MAMMALIA (Artiodactyla, Perissodactyla and Carnivora) and AVES, trapped in same private farms at Mozambique Democratic Republic (Tete Region) and South Africa Republic (Cape Region). Those studies were based on the TRAVASSOS DIAS (1989) identification keys and on genitalia morphology. In Mozambique, Rhipicephalus sanguineus was the only specie observed at Aepyceros melampus (impala), Leptailurus serval (serval) e Gyps sp. (white-backed volture). In South Africa farms, the ixodidae identified were Ixodes pilosus (Connochaetus taurinus, gnu), Ixodes sp. (Damaliscus dorcas philipsi, blesbok), Amblyomma hebraeum (Oryx gazella gazella, orix), Boophilus florae (Damaliscus dorcas philipsi), Boophilus spp. (Connochaetus taurinus), Hyalomma truncatum (Alcelaphus buselaphus caama, red hartebeest and Tragelaphus strepsiceros, cudo) and Rhipicephalus sanguineus (Oryx gazella gazella and Equus burchellii antiquorum, zebra). Some comments are made about their importance as vectors and about the importance of the vertebrate hosts as reservatoirs in the pathogens transmission
Mairi Macaskill - One of the best experts on this subject based on the ideXlab platform.
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Prey selection by African wild dogs ( Lycaon pictus ) in southern Zimbabwe
Journal of Zoology, 2004Co-Authors: Alistair Pole, Iain J. Gordon, Martyn L. Gorman, Mairi MacaskillAbstract:This study was an investigation of the diet and of prey selection by a population of African wild dogs Lycaon pictus in the Save Valley Conservancy (SVC) in the south-east lowveld of Zimbabwe. The diet of the dogs, based on the number of kills for each species located, consisted almost entirely of impala Aepyceras melampus (74%) and kudu Tragelaphus strepsiceros (22%), the two most abundant medium-sized antelope in the area. The level of selection for different prey classes killed by the wild dogs was investigated and it was found that the wild dogs: (1) exhibited strong selection for a number of prey classes on a seasonal basis; (2) selected kudu throughout the year but showed little selection between the other prey species; (3) selected the young of both impala and kudu and selected males at times of the rut. Bone marrow analysis showed that prey killed by the wild dogs on SVC were in poorer condition than unselectively culled individuals suggesting the selection of the weaker individuals in the prey populations.
Esther Van Der Meer - One of the best experts on this subject based on the ideXlab platform.
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Anti-predator behaviour of kudu and impala in response to mimicked African wild dog presence: do age and sex matter?
Behaviour, 2015Co-Authors: Hervé Fritz, Esther Van Der Meer, Olivier PaysAbstract:Predators not only prey upon certain prey species, but also on certain age–sex classes within species. Predation risk and an individual’s response to this risk might therefore vary with an individual’s characteristics. We examined the proportion of time different age–sex classes of kudu ( Tragelaphus strepsiceros) and impala ( Aepyceros melampus) spent high quality vigilant (costly vigilance that detracts from all other activities) in response to mimicked predation risk by African wild dogs ( Lycaon pictus). For both species predation risk was the main factor determining the investment in high quality vigilance behaviour. Age–sex class-specific responses were not related to age–sex class specific lethality risk presented by African wild dogs. For impala, regardless of predation risk, age seemed to have some effect on the investment in high quality vigilance with sub-adult impala spending more time high quality vigilant than adult impala, which is possibly why African wild dogs predominantly preyed upon adult impala.
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The Effect of Simulated African Wild Dog Presence on Anti-predator Behaviour of Kudu and Impala
Ethology, 2012Co-Authors: Esther Van Der Meer, Olivier Pays, Hervé FritzAbstract:In this study, we examined the behavioural, temporal and spatial effects of simulated African wild dog (Lycaon pictus) presence on its two main prey species: kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus). We spread African wild dog faeces around waterholes and played African wild dog sounds at different intervals to mimic immediate and non-immediate predation pressure. We looked at anti-predator behaviour at both a herd and individual level and distinguished between high-quality (detracts from all other activities), high-cost vigilance and low-quality (used to monitor the surrounding in spare time), low-cost vigilance to determine costs involved. We found that simulated African wild dog presence had little effect on anti-predator behaviour of their free-ranging prey. Only when immediate predation risk was mimicked did kudu invest in (additional) high-quality vigilance, whereas impala showed no response. Regardless of direct cues of African wild dog presence, behavioural adjustments to reduce predation risk were primarily based on environmental factors such as time of the day and broad-scale habitat structure. Predators have been shown to utilize waterholes to hunt, and prey species are therefore likely to maximize anti-predator behaviour in this high-risk environment based on environmental variables affecting predation risk, the main predator within the system, and water requirements, leaving little flexibility to respond to (simulated) African wild dog presence.