We compiled all credible repeated lion surveys and present time series data for 47 lion (Panthera leo) populations. We used a Bayesian state space model to estimate growth rate-λ for each population and summed these into three regional sets to provide conservation-relevant estimates of trends since 1990. We found a striking geographical pattern: African lion populations are declining everywhere, except in four southern countries (Botswana, Namibia, South Africa, and Zimbabwe). Population models indicate a 67% chance that lions in West and Central Africa decline by one-half, while estimating a 37% chance that lions in East Africa also decline by one-half over two decades. We recommend separate regional assessments of the lion in the World Conservation Union (IUCN) Red List of Threatened Species: already recognized as critically endangered in West Africa, our analysis supports listing as regionally endangered in Central and East Africa and least concern in southern Africa. Almost all lion populations that historically exceeded ∼ 500 individuals are declining, but lion conservation is successful in southern Africa, in part because of the proliferation of reintroduced lions in small, fenced, intensively managed, and funded reserves. If management budgets for wild lands cannot keep pace with mounting levels of threat, the species may rely increasingly on these southern African areas and may no longer be a flagship species of the once vast natural ecosystems across the rest of the continent.

https://www.pnas.org/content/pnas/112/48/14894.full.pdf

Lion (Panthera leo) populations are declining rapidly across Africa, except in intensively managed areas

Trophy hunting is widely used in Africa to generate funding for wildlife areas. In 2015, a global media frenzy resulted from the illegal killing of a radio-collared lion, “Cecil,” by a trophy hunter in Zimbabwe. Trophy hunting is contentious and much of the media discourse is emotional and polarized, focusing on animal welfare and debating the value of hunting as a conservation tool. We use the Cecil incident to urge a change in the focus of discussion and make a call for global action. We highlight the dual challenge to African governments posed by the need to fund vast wildlife estates and provide incentives for conservation by communities in the context of growing human populations and competing priorities. With or without trophy hunting, Africa's wildlife areas require much more funding to prevent serious biodiversity loss. In light of this, we urge a shift away from perpetual debates over trophy hunting to the more pressing question of “How do we fund Africa's wildlife areas adequately?” We urge the international community to greatly increase funding and technical support for Africa's wildlife estate. Concurrently, we encourage African governments and hunters to take decisive steps to reform hunting industries and address challenges associated with that revenue generating option.

https://www.panthera.org/cms/sites/default/files/Lindsey_et_al-2016%20Life%20After%20Cecil%20Conservation_Letters.pdf

Life after Cecil: channelling global outrage into funding for conservation in Africa

The random encounter model (REM) is a novel method for estimating animal density from camera trap data without the need for individual recognition. It has never been used to estimate the density of large carnivore species, despite these being the focus of most camera trap studies worldwide. In this context, we applied the REM to estimate the density of female lions (Panthera leo) from camera traps implemented in Serengeti National Park, Tanzania, comparing estimates to reference values derived from pride census data. More specifically, we attempted to account for bias resulting from non-random camera placement at lion resting sites under isolated trees by comparing estimates derived from night versus day photographs, between dry and wet seasons, and between habitats that differ in their amount of tree cover. Overall, we recorded 169 and 163 independent photographic events of female lions from 7,608 and 12,137 camera trap days carried out in the dry season of 2010 and the wet season of 2011, respectively. Although all REM models considered over-estimated female lion density, models that considered only night-time events resulted in estimates that were much less biased relative to those based on all photographic events. We conclude that restricting REM estimation to periods and habitats in which animal movement is more likely to be random with respect to cameras can help reduce bias in estimates of density for female Serengeti lions. We highlight that accurate REM estimates will nonetheless be dependent on reliable measures of average speed of animal movement and camera detection zone dimensions. © 2015 The Authors. Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

https://wildlife.onlinelibrary.wiley.com/doi/pdf/10.1002/jwmg.902

Applying a random encounter model to estimate lion density from camera traps in Serengeti National Park, Tanzania

https://scholarworks.montana.edu/xmlui/bitstream/handle/1/8738/Creel_BioCons_2014POSTPRINT.pdf;sequence=1

Detecting declines of apex carnivores and evaluating their causes: An example with Zambian lions

While trophy hunting provides revenue for conservation, it must be carefully managed to avoid negative population impacts, particularly for long-lived species with low natural mortality rates. Trophy hunting has had negative effects on lion populations throughout Africa, and the species serves as an important case study to consider the balance of costs and benefits, and to consider the effectiveness of alternative strategies to conserve exploited species. Age-restricted harvesting is widely recommended to mitigate negative effects of lion hunting, but this recommendation was based on a population model parameterized with data from a well-protected and growing lion population. Here, we used demographic data from lions subject to more typical conditions, including source-sink dynamics between a protected National Park and adjacent hunting areas in Zambia's Luangwa Valley, to develop a stochastic population projection model and evaluate alternative harvest scenarios. Hunting resulted in population declines over a 25-year period for all continuous harvest strategies, with large declines for quotas greater than 1 lion/concession (~0.5 lion/1000 km2) and hunting of males younger than 7 years. A strategy that combined periods of recovery, an age limit of ≥ 7 years and a maximum quota of ~0.5 lions shot per 1000 km2 yielded a risk of extirpation < 10%. Our analysis incorporated the effects of human encroachment, poaching and prey depletion on survival, but assumed that these problems will not increase, which is unlikely. These results suggest conservative management of lion trophy hunting with a combination of regulations. To implement sustainable trophy hunting while maintaining revenue for conservation of hunting areas, our results suggest that hunting fees must increase as a consequence of diminished supply. These findings are broadly applicable to hunted lion populations throughout Africa, and to inform global efforts to conserve exploited carnivore populations.

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Assessing the sustainability of African lion trophy hunting, with recommendations for policy

The African lion Panthera leo is an iconic species but it has faced dramatic range reductions and possibly as few as 30,000 individuals remain in the wild. In the absence of detailed ground-based surveys, lion populations may be estimated using regression models based on prey biomass availability but these often overestimate lion densities as a result of a variety of compounding factors. Anthropogenic factors can be key drivers of lion population dynamics and in areas with high human impact lion numbers may be significantly lower than those predicted by prey biomass models. This was investigated in two protected areas in Zimbabwe, where lion population densities were found to be significantly lower than would have been predicted by prey-availability models. High hunting quotas either within or around the protected areas are the most likely cause of the low lion numbers, with quotas in some areas being as high as seven lions per 1,000 km2 in some years. Other factors, including persecution, poisoning and problem animal control, as well as disease and competition with spotted hyaenas Crocuta crocuta, are also discussed.

/pdf/surveys-of-lions-panthera-leo-in-protected-areas-in-zimbabwe-34b45u1c7q.pdf

Roseline Mandisodza

Papers

Surveys of lions Panthera leo in protected areas in Zimbabwe yield disturbing results: what is driving the population collapse?