Quantifying lion (Panthera leo) demographic response following a three-year moratorium on trophy hunting

Abstract

Factors that limit African lion populations are manifold and well-recognized, but their relative demographic effects remain poorly understood, particularly trophy hunting near protected areas. We identified and monitored 386 individual lions within and around South Luangwa National Park, Zambia, for five years (2008–2012) with trophy hunting and for three additional years (2013–2015) during a hunting moratorium. We used these data with mark-resight models to estimate the effects of hunting on lion survival, recruitment, and abundance. The best survival models, accounting for imperfect detection, revealed strong positive effects of the moratorium, with survival increasing by 17.1 and 14.0 percentage points in subadult and adult males, respectively. Smaller effects on adult female survival and positive effects on cub survival were also detected. The sex-ratio of cubs shifted from unbiased during trophy-hunting to female-biased during the moratorium. Closed mark-recapture models revealed a large increase in lion abundance during the hunting moratorium, from 116 lions in 2012 immediately preceding the moratorium to 209 lions in the last year of the moratorium. More cubs were produced each year of the moratorium than in any year with trophy hunting. Lion demographics shifted from a male-depleted population consisting mostly of adult (≥4 years) females to a younger population with more (>29%) adult males. These data show that the three-year moratorium was effective at growing the Luangwa lion population and increasing the number of adult males. The results suggest that moratoria may be an effective tool for improving the sustainability of lion trophy hunting, particularly where systematic monitoring, conservative quotas, and age-based harvesting are difficult to enforce.

Do protection gradients explain patterns in herbivore densities? An example with ungulates in Zambia’s Luangwa Valley

“…We fit a single kernel utilization distribution to 7 785 lion locations collected over five years (2008–2012) from lions equipped with GPS radiocollars and direct observation of 18 lion prides and 14 male coalitions [20]. Though this spatial information overlaps only one year of this study, ongoing lion studies indicate little change in lion distribution [25]. We used sp , rgdal [38], and plyr [39] packages in R to estimate the distribution of daily distance moved from six lionesses equipped with GPS radiocollars (range: 0m - 17 300m) and used the 90th percentile (6 974m) as a smoothing parameter for the utilization distribution (UD) [40].…”

“…South Luangwa National Park (SLNP) is Zambia’s premier PA for wildlife-based photo-tourism and conserves regionally-important populations of several threatened and endangered species yet faces rapid human pressure from adjacent GMAs [19]. Recent studies of large carnivore demography and dynamics [20,22–25] and studies of bushmeat poaching patterns [21,26,27] suggest that the depletion of ungulate populations from bushmeat poaching may be affecting the ecological integrity of this protection gradient. Aerial surveys also suggest overall ungulate declines in the Luangwa Valley and lower ungulate density in GMAs compared to PAs [21], but these studies are generally inconclusive due to low precision of density estimates and no correction for variability in detection.…”

Assessing the performance of index calibration survey methods to monitor populations of wide‐ranging low‐density carnivores

“…However, unbiased population or density estimates with sufficient precision to reliably detect trends are difficult to obtain for low‐density, wide‐ranging, and cryptic species that often occur in remote areas. Unbiased and precise estimates are best acquired through long‐term intensive studies that are often time‐consuming, expensive, and labor‐intensive (Beukes, Radloff, & Ferreira, ; Loveridge, Valeix, Davidson, Mtare, & Macdonald, ; Mweetwa et al, ). Long‐term studies allow the use of capture–mark–recapture (CMR) or spatially explicit capture–recapture (SECR) techniques, with individuals being identified by direct observation (Beukes et al, ; Elliot & Gopalaswamy, ; Loveridge, Valeix, Elliot, & Macdonald, ; Mweetwa et al, ) or camera trapping (Borah et al, ; Karanth, ; Kelly et al, ; Rich et al, ; Silver et al, ; Tarugara, Clegg, Gandiwa, & Muposhi, ).…”

Spatially explicit density and its determinants for Asiatic lions in the Gir forests

“…The currently used total counts does not use individual identification of lions. 3) Traditional mark-recapture based on individual identifications of lions [19,[89][90][91]. This approach is superior to total counts as it gives a measure of precision by addressing detection probability.…”

“…Multiple observations on same individuals (recaptures) are used in a statistical framework to estimate detection probability, that is subsequently used to account for lions that may not be sampled in total counts. Traditional CMR method has been successfully demonstrated for both Asiatic [19,22] and African lions [90,91]. 4) Transect based distance sampling [92,93] and camera trap based distance sampling [94], have the potential of being used for estimating lion density.…”