Population density estimates of spotted hyaena (Crocuta crocuta) in two KwaZulu-Natal protected areas

Despite increasing recognition of the important
ecological role large carnivores fulfil and their ability to generate income
for protected areas, they remain amongst the most threatened species on Earth.
Most large carnivore species have exhibited substantial population declines and
geographic range contractions during the past two centuries. Key to reversing
this trend is devising cost-effective monitoring methods that produce reliable
estimates of abundance or density over timeframes that allow for the success or
failure of conservation interventions to be measured. As both scavengers and
apex predators, spotted hyaenas (Crocuta crocuta) play extremely
important ecological roles, and it has been suggested that they are keystone
predators and key indicators of ecosystem health. Although the IUCN Red List of
Threatened Species lists spotted hyaenas as “Least Concern”, the overall
population trend is decreasing and regional declines have been observed in some
areas, such as the northern KwaZulu-Natal province of South Africa. Habitat
loss and direct persecution are causing spotted hyaenas to become increasingly
reliant on protected areas. In my study, I analysed hyaena by-catch data from
camera trap surveys that were conducted in 2019 to monitor leopards (Panthera
pardus) in two protected areas in northern KwaZulu-Natal, Mun-Ya-Wana
Conservancy and the uMkhuze section of iSimangaliso Wetland Park. I used
spatially explicit capture-recapture (SECR) models to estimate the population
density of spotted hyaenas in both protected areas. The density of spotted
hyaenas in Mun-Ya-Wana Conservancy was estimated to be 5.86 ± 1.12 individuals
per 100 km2, based on 30 identified individuals in a sample area of
3122 km2. The density of spotted hyaenas in the uMkhuze section of
iSimangaliso Wetland Park was estimated to be 2.97 ± 0.79 individuals per 100
km2, based on 26 identified individuals in a sample area of 2828 km2.
These results confirm both the importance of new protected areas (Mun-Ya-Wana
Conservancy) in reversing population declines while simultaneously showing that
long established protected areas (uMkhuze section of iSimangaliso Wetland Park)
may be failing to protect spotted hyaena and presumably other large carnivores.
Understanding the drivers of these differences between protected areas is
essential to provide regionally stable spotted hyaena populations. Routine
camera trap surveys combined with SECR models provide a cost-effective way to
monitor spotted hyaena populations and produce reliable estimates of population
density. Once more accurate, long-term data on the size and trends of spotted
hyaena subpopulations both within and outside protected areas have been
collected, the status of spotted hyaenas should be reassessed.

尽管大型食肉动物在维持生态平衡和为保护区创造收益方面的重要作用日益得到认可，但它们依然是地球上最为濒危的物种之一。在过去两个世纪中，大多数大型食肉动物物种均表现出显著的人口减少和地理分布范围的缩减。扭转这一趋势的关键在于制定经济高效的监测方法，以在允许衡量保护干预措施成败的时间框架内，提供关于种群丰富度或密度的可靠估计。作为食腐者和顶级捕食者，斑点鬣狗（Crocuta crocuta）在生态系统中扮演着极其重要的角色，并被认为是最关键的捕食者和生态系统健康的指标。尽管《濒危物种红色名录》将斑点鬣狗列为“最低关注”，但其总体种群趋势仍在下降，在某些地区，如南非北部的夸祖鲁-纳塔尔省，观察到区域性减少。栖息地丧失和直接捕杀导致斑点鬣狗越来越依赖保护区。在我的研究中，我分析了2019年在夸祖鲁-纳塔尔省北部两个保护区——蒙-亚-瓦纳保护区和iSimangaliso湿地公园的uMkhuze部分——进行的用于监测豹（Panthera pardus）的相机诱捕调查中捕获到的鬣狗数据。我利用空间显式的捕获-重捕（SECR）模型来估计这两个保护区中斑点鬣狗的种群密度。蒙-亚-瓦纳保护区内斑点鬣狗的密度估计为每100平方公里5.86 ± 1.12只，基于3122平方公里样本区域内识别出的30只个体。iSimangaliso湿地公园uMkhuze部分的斑点鬣狗密度估计为每100平方公里2.97 ± 0.79只，基于2828平方公里样本区域内识别出的26只个体。这些结果证实了新保护区域（蒙-亚-瓦纳保护区）在扭转种群减少趋势中的重要性，同时表明长期存在的保护区域（iSimangaliso湿地公园uMkhuze部分）可能未能有效保护斑点鬣狗以及其他大型食肉动物。理解这些保护区域之间差异的驱动因素对于提供区域稳定的斑点鬣狗种群至关重要。常规的相机诱捕调查与SECR模型的结合提供了一种成本效益高的监测斑点鬣狗种群并产生可靠种群密度估计的方法。一旦收集到关于斑点鬣狗亚种群大小和趋势的更准确、长期数据，无论是在保护区内外，都应该重新评估斑点鬣狗的状态。