Panthera leo 

Note: This is an amended version of the assessment to replace the range map with a corrected version and to add some additional explanatory text to Table 3 in the Supplementary Information.

• 2016 – Vulnerable (VU)
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• 2015 – Vulnerable (VU)
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• 2015 – Vulnerable (VU)
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• 2012 – Vulnerable (VU)
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• 2008 – Vulnerable (VU)
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• 2004 – Vulnerable (VU)
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• 2002 – Vulnerable (VU)
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• 1996 – Vulnerable (VU)
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Population Trend
This assessment is based on a time trend analysis of census data from relatively well-studied Lion subpopulations (Packer et al. 2013, plus additional unpublished data provided by contributors). Census estimates were obtained by scientific research methods including total count, individual identifications, total or sample inventory using calling stations, radio telemetry, photo databases, spoor counts and density estimates based on direct observations corrected for patrol effort. These methods are rated as producing the most reliable type of Lion population estimates by background papers for the 2006 IUCN regional Lion workshops (Table 5 in Bauer et al. 2005a, b). We did not include population estimates for sites which were based on extrapolation of Lion densities obtained by research in other areas, or informed guesstimates by researchers. The minimum number of census surveys per site over the assessment time period is two, but some sites have been more regularly monitored (Table 3 - Data Points column, in Supplementary Material). In some cases census methodology varied between years, and for some surveys accuracy may have been low, but the complete data set shows an obvious trend that is unlikely to be an artefact of methodological insufficiencies.

IUCN Red List Criteria define three generations as the relevant time span for trend assessment. Lion Generation Length (GL) is based on the formulation of Pacifici et al. (2013):

       GL = R_span*z +AFR

Where AFR = Age of first reproduction = 3.5 yrs (Packer et al. 1998)

      R_span = 15.5 (the age when 95% of females are no longer reproductive) - AFR = 12 yrs (Packer et al. 1998)

      Z = 0.29 (a constant “depending on survivorship and relative fecundity of young vs. old individuals in the population” (IUCN 2014), calculated as the slope of the linear regression between GL and Rspan for 221 mammalian species (Pacifici et al. 2013)

Thus GL = 12*0.29 +3.5 = 6.98 yrs

To fill gaps between censuses conducted in non-consecutive years, we interpolated population sizes, assuming a linear change between years. For surveys conducted for only a few years between 1993 and 2014, we extrapolated to the beginning and end points based on an exponential rate of change taken from the observed growth rate for each respective subpopulation. However, all extrapolations are capped by the estimated carrying capacity for each reserve so that subpopulations that experienced dramatic population change were not assumed to have been at implausibly high totals in either 1993 or 2014. Subpopulations were first categorized according to whether or not the reserves were surrounded by a fence; unfenced subpopulations were further categorized according to geographical location with the exception of Niassa Reserve (Mozambique), treated as an outlier as discussed below.

In graph form (Figures 1-4 in the Supplementary Material) we summarize the repeated censuses of 46 different African Lion subpopulations using all available repeat-survey data. Figure 5 (in the Supplementary Material) addresses the 47th Lion subpopulation in our analysis, the only Asian subpopulation.

Outside parts of southern Africa, Lions in 23 unfenced reserves in 11 countries are estimated to have dropped by 62% between 1993 and 2014 (see Figure 1 in the Supplementary Material).  Although these totals only included about 4,600 Lions in the year 1993, several surveyed areas are restricted to the best-protected portions of much larger ecosystems (e.g., the phototourism areas of Selous and Serengeti).

In contrast, the total number of Lions in six unfenced reserves in Botswana, Namibia and Zimbabwe only declined by about 11% (Figure 2, Supplementary Material). Note that the overall stability in southern Africa masks considerable heterogeneity: between 1993 and 2014 the monitored Lion subpopulation in a portion of the Okavango ecosystem is estimated to have declined by 46%, whereas the much smaller subpopulations in Gonarezhou and Kunene have increased dramatically.

The striking contrast between these three countries in southern Africa and the rest of the continent is probably related to the equally striking differences in human population densities (Packer et al. 2013) in Namibia (2.5/km²), Botswana (3.4) and Zimbabwe (26) vs. Benin (78), Burkina Faso (57), Cameroon (40), Cote d’Ivoire (64), Ghana (102), Kenya (67), Nigeria (189), Rwanda (420), Senegal (68), Tanzania (48), Uganda (137) and Zambia (45).

The unfenced Niassa subpopulation is estimated to have increased by over 250% since 1993 (Figure 3, Supplementary Material); despite severe bushmeat poaching the Lions are still recovering from excessive prey depletion during civil war. In addition, on a shorter time scale, Lions have benefited from extensive ivory poaching, which has provided them with sizeable quantities of elephant meat (Colleen Begg pers. comm. 2014). Human population density in Mozambique is 74/km² with sizeable numbers of people living inside Niassa Reserve, so unless management is further strengthened, this unfenced Lion subpopulation may soon experience declining food supplies and increased human-lion conflicts. These arguments strongly suggest that the ‘boom’ in the Niassa Lion subpopulation has stopped and is unlikely to be repeated in the future. We therefore consider Niassa to be a special case and treat it as an outlier in our analyses, we believe that this offers a better understanding of trends, but we note that this does not alter the assessment (with Niassa included, the assessment would still be Vulnerable A2abcd).

The 16 fenced African subpopulations (10 in South Africa, and all but one in southern Africa) have grown by 29% since 1993, most having already reached their presumed carrying capacities by 2013 (Figure 4, Supplementary Material). Note that although these numbers now total over 3,226 lions, our data come from the great majority of fenced reserves in Africa and that little further growth can be expected in these subpopulations.

Asia is home to a single contiguous subpopulation in the Indian state of Gujarat (Figure 5, Supplementary Material). While the population has stabilized inside the Gir Reserve, the so-called “satellite” population in the surrounding countryside has expanded by ~400% in the past 21 years.

The 47 sample Lion subpopulations totalled an estimated 9,615 lions in 1993 (excluding Niassa, which is treated as an outlier as described above); that number shrank by 22% to 7,455 lions in 2014 (Table 2, Supplementary Material).  However, as described above, there are significant regional differences evident in population trend, and we use these to inform our inferences about population trend for the species as a whole. Table 2 (Supplementary Material) groups the sample subpopulations by region in Africa, following the IUCN (2006a, b) regional Lion conservation strategies, but combining West and Central Africa due to a small sample size for Central Africa.  In Southern Africa, the sample population grew by 8%, while in sharp contrast, sample populations declined by 59% in Eastern Africa and 66% in West and Central Africa.

Table 3 (Supplementary Material) shows the estimated Lion population size in 1993 and 2014 for each of the 47 sample subpopulations with percentage change, and it can be seen that most countries had a declining trend for sample Lion subpopulations, with only four countries (India, Namibia, South Africa and Zimbabwe) seeing a growth trend. Table 4 (Supplementary Material) groups these countries with Botswana, which had a relatively low average rate of decline for its sample populations; two out of three sample subpopulations increased; the decline documented in the Okavango subpopulation was restricted to only part of the protected area; and overall 2012 estimates for the national population suggest that it his increased since 2003 (C. Winterbach unpubl. data). Mozambique is not included in this group as the increasing trend in its Niassa subpopulation is treated as an outlier in this analysis. The sample Lion population in five countries (Botswana, India, Namibia, South Africa, Zimbabwe) grew by an estimated 12%, whereas the Lion population in the remaining African range countries declined by an estimated 61% (Table 4, Supplementary Material).

We infer population trend for the total Lion species population based on these two rates of change, as follows. In 2002, two separate country compilations of population estimates for Lions in Africa estimated the number of Lions in Botswana, Namibia, South Africa and Zimbabwe to comprise between 1/4 to 1/3 of the total African Lion population, as shown in Table 5 (Supplementary Material). We suspect that this proportion was somewhat lower in 1993, given that the number of Lions is inferred to have increased in these countries while decreasing in the remainder, and use a figure of 1/4 or 25% for our species population trend calculation. If 25% of the Lion population increased by 12%, and 75% decreased by 60%, this results in an inferred trend of (0.75*-60%) + (0.25*12%) = -43% between 1993 and 2014 (Table 6, Supplementary Material).

The main threats to Lions are indiscriminate killing (primarily as a result of retaliatory or pre-emptive killing to protect human life and livestock) and prey base depletion. Habitat loss and conversion has led to a number of subpopulations becoming small and isolated (Bauer et al. 2008). Furthermore, trophy hunting has a net positive impact in a some areas, but may have at times contributed to population declines in Botswana, Namibia, Tanzania, Zimbabwe (Packer et al. 2009, 2011, 2013), Cameroon (Croes et al. 2011) and Zambia (Rosenblatt et al. 2014).

Conflict
The economic impact of stock raiding can be significant: Patterson et al. (2004) estimated that each Lion costs ranchers in Kenya living alongside Tsavo East National Park US$290 per year in livestock losses. Likewise, annual losses of cattle to Lions in areas adjacent to Waza National Park in Cameroon comprised only about 3.1% of all livestock losses, but were estimated to represent more than 22% of financial losses amounting to about US$370 per owner (Bauer 2003). Consequently, Lions are persecuted intensely in livestock areas across Africa; their scavenging behaviour makes them particularly vulnerable to poisoned carcasses put out to eliminate predators. Little actual information exists on the number of Lions killed as problem animals by local people, even though this is considered the primary threat to their survival outside protected areas. Implementation of appropriate livestock management measures, coupled with problem animal control measures and mechanisms for compensating livestock losses, are some of the primary responses to resolving human-Lion conflict (Frank et al. 2006, Bauer et al. 2010, Hazzah et al. 2014).

Prey depletion
Lion population density across the species’ range is known to track the biomass of principle Lion prey species; large wild herbivores (Van Orsdol et al. 1985, Hayward et al. 2007). The latter are increasingly under threat from an unsustainable and increasingly commercialized bushmeat trade, leading to collapses in prey populations across large parts of savanna Africa (Lindsey et al. 2013a). Regional Lion population trends reported in this assessment, are closely mirrored by time series data on main Lion prey species from 78 herbivore populations monitored between 1970 and 2005 in West, Eastern and Southern Africa; while herbivore population sizes increased by 24% in Southern Africa, they declined by 52% in Eastern Africa and by 85% in West Africa (Craigie et al. 2010).

Use of Lion bones and body parts and derivatives for traditional medicine
Illegal trade in Lion body parts for medicinal purposes is considered a threat to African Lion subpopulations (according to the regional Lion conservation strategies, which call on countries to prohibit [IUCN 2006a] and control [IUCN 2006b] trade in Lion bone and other parts and products) as well as to the small subpopulation in India's Gir Forest (M. Ventraman pers. comm. 2014). In West and Central Africa, Sogbohossou (2006) found many reported uses for Lion skins and bone in Benin (with fat and bones being most commonly utilized: N'Diaye 2014), and a survey carried out around Nigeria's Yankari National Park found more than 22 Lion parts considered to be of medicinal value, with most of the over 200 interviewees saying they had used Lion parts in the past, and half within the past three years (Born Free Foundation 2008). The widespread prevalence of fakes in the traditional medicinal market is indicative of a continued demand. While fakes may replace items in the market that otherwise would be illegally sourced from the wild, they could perpetuate demand and poaching when consumers aspire to the genuine wild item rather than making a conscious choice of an (often cheaper) alternative (Nowell 2014).

There appears to be increasing interest in the use of African Lion bone in Asia. There is no history of Lion bone being used in traditional medicine there, but China has permitted the use of bones from captive Lions to make medicinal wines traditionally containing Tiger bone. South Africa has reported the export of large quantities of Lion bone sourced from captive animals to China, the Lao People's Democratic Republic and Viet Nam. Legal international trade in bone reported as from captive-bred Lions could serve as a cover for illegally wild-sourced Lion (and other big cat) parts (Nowell and Pevushina 2014). There is also concern that wild Lion parts from eastern and Southern Africa could be drawn into the large illegal wildlife trade to Asia centred around elephant ivory.

Trophy hunting
Trophy hunting is carried out in a number of sub-Saharan African countries and is considered an important management tool for conserving wild land providing financial resource for Lion conservation for both governments and local communities. However, there is concern that management regimes have not always been sufficient to deter unsustainable offtakes (Packer et al. 2006). A sustainable offtake level of one male lion per 2,000 km² has been recommended (Packer et al. 2011), but offtake has been higher in many areas, which suggests that it is potentially a threat (Lindsey et al. 2013b). Trophy hunting can thus be a tool for conservation but also a threat, depending on how it is regulated and managed (Whitman et al. 2004, Loveridge et al. 2007, Packer et al. 2011). Hunter et al. (2013) cautioned that regulatory measures which reduce the profitability of Lion trophy hunting could have widespread negative impacts for wildlife-based land use, anti-poaching and tolerance of Lion outside protected areas.

Other
Disease has also been a threat to Lion subpopulations (Munson et al. 2008, Trinkel et al. 2011). In parts of southeastern Tanzania there have been alarmingly high incidences of people killed by Lions, with up to 400 human Lion-related fatalities recorded from 1997-2007 (Ikanda and Packer 2007).