Rainfall and the decline of a rare antelope, the tsessebe (Damaliscus lunatus lunatus), in Kruger National Park, South Africa

Dunham, Kevin M.; Robertson, E.; Grant, C.C.

doi:10.1016/s0006-3207(03)00267-2

Cited by 34 publications

(30 citation statements)

References 23 publications

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“…Other studies have suggested that dry season rainfall influences the survival of large herbivores across Africa (e.g. Mduma et al 1999;Ogutu and Owen-Smith 2003;Dunham et al 2004). In contrast, in this analysis dry season rainfall did not affect elephant survival.…”

Section: Discussioncontrasting

confidence: 85%

“…To explore whether accumulative rainfall during this critical period could affect elephant survival, we incorporated mean rainfall during first 2, and 3 years of life. Dry season rainfall can be critical to herbivore survival (Ogutu and Owen-Smith 2003;Dunham et al 2004). If there is a long rainy season, high quality green vegetation is available to herbivores late into the short dry season (Mduma et al 1999).…”

Section: Study Areamentioning

confidence: 99%

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Elephant survival, rainfall and the confounding effects of water provision and fences

2010

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Elephant are increasing across some areas of Africa leading to concerns that they may reduce woodlands through their feeding. Droughts may help limit elephant numbers, but they are generally both episodic and local. To explore more general impacts of rainfall, we examine how its annual variation influences elephant survival across ten sites. These sites span an almost coast-to-coast transect of southern Africa that holds the majority of the *500,000 remaining savanna elephants. Elephants born in high rainfall years survive better than elephants born in low rainfall years. The relationship is generally weak, except at the two fenced sites, where rainfall greatly influenced juvenile survival. In these two sites, there are also extensive networks of artificial water. Rainfall likely affects elephant survival through its influence on food. The provision of artificial water opens new areas for elephants in the dry season, while fencing restricts their movements in the wet season. We conclude that the combination of these factors makes elephant survival more susceptible to reductions in rainfall. As a result, elephants living in enclosed reserves may be the first populations to feel the impacts of global warming which will decrease average rainfall and increase the frequency of droughts. A way to prevent these elephants from damaging the vegetation within these enclosed parks is for managers to reduce artificial water sources or, whenever practical, to remove fences.

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Section: Discussioncontrasting

confidence: 85%

Section: Study Areamentioning

confidence: 99%

Elephant survival, rainfall and the confounding effects of water provision and fences

2010

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“…Rainfall has been reported to drive population dynamics of most tropical large herbivores studied so far (Owen-Smith 1990 on greater kudu (Tragelaphus strepsiceros (Pallas, 1766)); Mduma et al 1999 on blue wildebeest (Connochaetes taurinus (Burchell, 1823)); Georgiadis et al 2003 on Burchell's zebra (Equus burchelli (Gray, 1824)); Ogutu and Owen-Smith 2003 on ungulate species of Kruger Park; Dunham et al 2004 on tsessebe (Damaliscus lunatus (Burchell, 1823)). Dry years are generally associated with resource limitation leading to a decline in ungulate population performance (e.g., Sinclair et al 1985).…”

Section: Introductionmentioning

confidence: 99%

Density-dependent body condition and recruitment in a tropical ungulate

Gaidet

Gaillard

2008

Can. J. Zool.

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In tropical areas, annual rainfall and predation have been reported to drive population dynamics of most species of large herbivores studied so far, with little direct empirical evidence for density-dependent responses of life-history traits. We here investigated in a game ranch in Zimbabwe density-dependent responses of body condition and recruitment in an impala (Aepyceros melampus (Lichtenstein, 1812)) population that underwent an experimental drastic reduction of density within 2 years under similar rainfall and predation pressure. Body condition of all sex and age classes was lower during the high-density year than during the low-density year, suggesting increased competition for restricted resources at high density. In addition, we observed a significant increase in population recruitment (from 0.47 to 0.80 juveniles/female) as population density declined. Our study provides a rare example of a direct density-dependent response of body condition at the individual level in a tropical ungulate species, and indicates that food resource variation controls population dynamics of impala under constant and moderate predation pressure as is commonly reported in temperate populations of large herbivores. Résumé :Dans les régions tropicales, on a montré que les précipitations annuelles et la prédation sont les facteurs qui contrôlent la dynamique de population de la plupart des espèces de grands herbivores étudiées à ce jour; en revanche, il y a peu de données empiriques sur des réactions dépendantes de la densité dans les caractéristiques démographiques. Nous étudions ici dans un ranch de gibier du Zimbabwe les réactions dépendantes de la densité de la condition corporelle et du recrutement dans une population d'impalas (Aepyceros melampus (Lichtenstein, 1812)) qui a subi une réduction expéri-mentale considérable de sa densité au cours de 2 années pendant lesquelles les précipitations et la pression de prédation sont restées constantes. La condition corporelle chez toutes les classes d'âge et de sexe était plus basse durant l'année de forte densité que durant l'année de faible densité, ce qui laisse croire à une compétition accrue pour les ressources limitées à la forte densité. De plus, nous avons observé une augmentation significative du recrutement de la population (de 0,47 à 0,80 jeunes/femelle) au cours du déclin de la population. Notre étude fournit un rare exemple d'une réaction directe dé-pendante de la densité de la condition corporelle à l'échelle individuelle chez une espèce tropicale d'ongulés; elle indique ainsi que la variation des ressources alimentaires contrôle la dynamique de population des impalas dans les conditions de pression de prédation constantes et modérées comme on observe souvent dans les populations tempérées de grands herbivores.[Traduit par la Rédaction]

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“…(Damaliscus lunatus) (Harrington et al 1999;Dunham et al 2004;Ogutu et al 2011). The most thorough assessment of antelope declines comes from analysis of monitoring data for Kruger National Park (hereafter Kruger) spanning the years -1996(Owen-Smith and Mills 2006.…”

Section: Introductionmentioning

confidence: 99%

Drivers of population dynamics in sable antelope: forage, habitat or competition?

Marshal

Rankin

Nel³

et al. 2016

Eur J Wildl Res

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Similar to declines in antelope species across African conservation areas, sable (Hippotragus niger) at Kgaswane Mountain Reserve, South Africa, has exhibited a negative trend in abundance since 2000. To investigate the cause of decline, we assessed three hypotheses: seasonal forage abundance, habitat conditions and interspecific competition. We considered the evidence for each hypothesis by analysing reserve survey data, rainfall records and historical burn data with hierarchical models that incorporated potential density-dependent effects and environmental covariates. After accounting for the effects of sable abundance, we found that sable population growth was most strongly related to the interspecific competition covariates and to waterbuck (Kobus ellipsiprymnus) count in particular. Also, the strength of the relationship was shaped by the trend in sable numbers and whether the population was before or after peak abundance: the strongest indication of interspecific competition occurred after sable had reached peak abundance. The interaction between abundance of sable and that of potentially competing species emphasizes the importance of accounting for densitydependent processes, and in particular longer-term phases in abundance, when judging the roles of other factors that affect species abundance.

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Rainfall and the decline of a rare antelope, the tsessebe (Damaliscus lunatus lunatus), in Kruger National Park, South Africa

Cited by 34 publications

References 23 publications

Elephant survival, rainfall and the confounding effects of water provision and fences

Elephant survival, rainfall and the confounding effects of water provision and fences

Density-dependent body condition and recruitment in a tropical ungulate

Drivers of population dynamics in sable antelope: forage, habitat or competition?

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