Scientific Services, South African National Parks, Skukuza, South Africa.
Institute for Communities and Wildlife in Africa (iCWild), Department of Biological Sciences, University of Cape Town, Cape Town, South Africa.
PLoS One. 2019 Jan 16;14(1):e0209678. doi: 10.1371/journal.pone.0209678. eCollection 2019.
Unrelenting poaching to feed the illegal trafficking of rhinoceros (rhino) horn remains the principle threat to the persistence of south-central black and southern white rhino that live in the Kruger National Park (Kruger), South Africa. Other global environmental change drivers, such as unpredictable climatic conditions, impose additional uncertainties on the management and persistence of these species. The drought experienced in Kruger over the 2015/2016 rainy season may have affected rhino population growth and thus added an additional population pressure to the poaching pressure already occurring. Under drought conditions, reduced grass biomass predicts increased natural deaths and a subsequent decrease in birth rate for the grazing white rhino. Such variance in natural death and birth rates for the browsing black rhino are not expected under these conditions. We evaluated these predictions using rhino population survey data from 2013 to 2017. Comparisons of natural deaths and birth rates between pre- (2013/2014 and 2014/15), during- (2015/2016) and post-drought (2016/2017) periods in Kruger showed increased natural mortality and decreased births for white rhino, but no significant changes for black rhino, supporting our predictions. As a result, despite reduced poaching rates, the total mortality rate of white rhino remains significantly higher than the birth rate. Decreased poaching, decreased natural deaths and no apparent drought effects in black rhino resulted in a lower total mortality rate than the estimated birth rate in 2017. Active biological management and traditional anti-poaching initiatives together therefore represent the most likely way to buffer the impacts of decreased population growth through climate change and wildlife crime on the persistence of rhinos.
为满足犀牛角非法交易的需求，偷猎活动从未停止，这依然是生活在南非克鲁格国家公园（克鲁格）的中南黑犀牛和南部白犀牛生存面临的主要威胁。其他全球性环境变化驱动因素，如不可预测的气候条件，给这些物种的管理和生存带来了额外的不确定性。2015/2016 季降雨期间，克鲁格经历了干旱，这可能影响了犀牛种群的增长，从而给已经发生的偷猎压力增加了额外的种群压力。在干旱条件下，草生物量减少预计会导致自然死亡增加，随后食草白犀牛的出生率下降。在这种情况下，食草黑犀牛的自然死亡和出生率预计不会出现这种变化。我们使用 2013 年至 2017 年的犀牛种群调查数据来评估这些预测。在克鲁格，我们将干旱前（2013/2014 年和 2014/15 年）、干旱期间（2015/2016 年）和干旱后（2016/2017 年）期间的自然死亡率和出生率进行比较，结果显示白犀牛的自然死亡率增加，出生率下降，但黑犀牛没有明显变化，这支持了我们的预测。因此，尽管偷猎率有所下降，但白犀牛的总死亡率仍明显高于出生率。由于偷猎减少、自然死亡率降低，以及黑犀牛没有明显受到干旱的影响，2017 年的总死亡率低于估计的出生率。因此，积极的生物管理和传统的反偷猎措施共同代表了最有可能的方式，可以缓冲气候变化和野生动物犯罪对犀牛生存造成的种群增长下降的影响。
