Adult Lions Research Articles

First systematic population survey of the desert‐adapted lions, Northwest Namibia

AbstractThe desert‐adapted lions (Panthera leo) of northwest Namibia inhabit arid and semi‐arid habitats, primarily within communal conservancy lands, which they share with semi‐nomadic pastoralists. Though of considerable conservation interest, no systematic population survey of these lions has previously been attempted. From 6 November 2022 to 6 January 2023, 45 trained surveyors covered approximately 40,000 km2 of conservancy and government‐managed lands, identifying individual lions by vibrissae (whisker‐spot) patterns and other demographic indicators. A systematic whole count, identifying every adult individual, was used to estimate population size. This approach drew upon the local ecological knowledge (LEK) of the Lion Rangers, community conservationists responsible for identifying and monitoring lions in their respective communal conservancies, as well as Regional Services staff of Namibia's Ministry of Environment, Forestry and Tourism (MEFT). The population is estimated between 57 and 60 individual adult lions and 14 cubs; this represents an inferred decrease of 46–60% over the past five years. At 0.11–0.12 lions/100 km2, this is the lowest recorded density for a free‐ranging, self‐sustaining lion population in Africa. Thirty‐six female and 21 male lions were found during the survey, yielding a sex ratio of 1 ♀: 0.58 ♂. While the population is considered stable and self‐sustaining despite recent declines, human‐lion conflict (HLC) remains the primary cause of lion mortality and recent drops in available prey are also concerning. Results serve as a baseline for future surveys, which will be an important part of monitoring this relatively small, widely dispersed population.

Fencing affects movement patterns of two large carnivores in Southern Africa

The erection of peripheral fences around protected areas has been shown to adversely affect the movement behavior, genetic connectivity and long-term viability of animal populations. However, fencing is also used extensively to reduce human encroachment, limit poaching activities, and mitigate human–wildlife conflicts. Limited information on the movement behavior of carnivores is available along the periphery of protected areas, particularly in semi-arid environments. To quantify the potential effects of the 824 km perimeter fence surrounding the Etosha National Park (Etosha, Namibia) on the movement and space use of carnivores, we collected GPS movement data from 36 lions (Panthera leo) and seven spotted hyenas (Crocuta crocuta) over a 14-year period. For these two apex carnivores, we measured the impact of the Etosha fence on their movements (step lengths and path straightness), calculated the likelihood of fence crossings, and evaluated the spatial–temporal characteristics of these crossings. Our results indicated that lions and hyenas moved faster (longer step lengths) when closer to the fence. Lions showed no variation in path straightness with respect to the fence but hyenas had straighter movement paths when closer to the fence. When moving within the vicinity of the fence, lions had a 9% likelihood of crossing the fence, while hyenas were much more likely (18%) to do so, which suggests that the Etosha fence was more permeable for hyenas than for lions. Fence crossings predominantly occurred at night for both species. Lions were more likely to cross the fence during the cold dry season (May–August) whereas hyenas crossed more often during the warm wet season (December–April). Female and adult lions had a higher probability of crossing the fence than males and subadults. These findings could be useful in the development of appropriate strategies to mitigate human–carnivore conflicts and thus promote the conservation of carnivores in multiple-use areas along the periphery of the park. Further research is needed to better elucidate the impact of perimeter fences on a broader suite of carnivores and other large mammals, including species-specific variation in the response to fences, as well as the economic benefits of fencing provided to local communities.

Movement and activity of endangered Asiatic lions in relation to land‐use, season and group characteristics

AbstractWe studied the activity patterns and movement characteristics of 19 Asiatic lions (Panthera leo leo) monitored through satellite radio‐collars equipped with activity sensors. We investigated the variations in the daily distance covered (movement) and the daily activity patterns from acceleration sensors (activity) in relation to season, group size, age and sex. We hypothesised that for the Asiatic lions: (1) the movement and activity should be variable in relation to demographic parameters (age, sex and social status) and (2) the land tenure characteristics, such as home range and daily distance moved, may be variable within and outside Gir PA (PA). Adult lions' mean daytime activity was 20.37 ± 11.15, while the daily distance moved was 5.1 ± 4.0 km. There was a significant difference in the mean daily distance between males and females, but none between adult and sub‐adult males. Females showed significantly less activity and movement compared to adult males. Adult males were significantly more active than sub‐adult males. Compared to within PA, the mean daily movement for adult males and females ranging outside PA was not different but more significant for sub‐adult males. At the same time, the home ranges are larger outside PA compared to within PA. The difference in space use outside PA was an artefact of long distance forays by adult and sub‐adult males and females on certain days. The foraying distances showed a characteristic pattern for sub‐adult males, adult males and females. We recommend incorporating such intra‐specific variation in movement behaviour due to age–sex and lions' life‐history requirements in conservation planning. We further recommend a detailed investigation of resource and habitat use considering demographic variability for implementing management action for conserving Asiatic lions in multi‐use landscapes.

Provocative tests with Kisspeptin-10 and GnRH set the scene for determining social status and environmental impacts on reproductive capacity in male African lions (Panthera leo)

Understanding the hypothalamic factors regulating reproduction facilitates maximising the reproductive success of breeding programmes and in the management and conservation of threatened species, including African lions. To provide insight into the physiology and pathophysiology of the hypothalamic-pituitary–gonadal reproductive axis in lions, we studied the luteinising hormone (LH) and steroid hormone responses to gonadotropin-releasing hormone (GnRH) and its upstream regulator, kisspeptin. Six young (13.3 ± 1.7 months, 56.2 ± 4.3 kg) and four adult (40.2 ± 1.4 months, 174 ± 6 kg) male lions (Ukutula Conservation Centre, South Africa) were used in this study. Lions were immobilised with a combination of medetomidine and ketamine and an intravenous catheter was placed in a jugular, cephalic or medial saphenous vein for blood sampling at 10-min intervals for 220 min. The ten-amino acid kisspeptin which has full intrinsic activity (KP-10, 1 µg/kg) and GnRH (1 µg/kg) were administered intravenously to study their effects on LH and steroid hormone plasma concentrations, measured subsequently by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. Basal LH levels were similarly low between the age groups, but testosterone and its precursor levels were higher in the adult animals. Adult lions showed a significant LH response to KP-10 (10-fold) and GnRH (11-fold) administration (p < 0.05 and P < 0.001, respectively) whereas in young lions LH increased significantly only in response to GnRH. In adults alone, testosterone and its precursors steadily increased in response to KP-10, with no significant further increase in response to GnRH. Plasma levels of glucocorticoids in response to KP-10 remained unchanged. We suggest that provocative testing of LH and steroid stimulation with kisspeptin provides a new and sensitive tool for determining reproductive status and possibly an index of exposure to stress, environmental insults such as disease, endocrine disruptors and nutritional status.272 words.

First Description of the Fur of Two Cubs of Fossil Cave Lion Panthera spelaea (Goldfuss, 1810) Found in Yakutia in 2017 and 2018.

The first description of well-preserved fur of one male and one female cubs of the fossil cave lion Panthera spelaea (finds of 2017-2018, Semyuelyakh River, Yakutia, Russia) is presented in comparison with the fur of two cubs (a male and a female) of the extant African lion P. leo and adult lions of both species: the color, differentiation, configuration, microstructure, and internal design of hair of different categories are considered. The coat of the cave lion is similar but not identical to that of the African lion, because it contains a high thick undercoat of spiral-shaped thick and airy down hair. This difference is most pronounced in the cave lion cubs, in which, however, the fur is not differentiated to the same extent as in the adult. The microstructure of hair is species-specific and subject to intraspecific age-related variability. Adaptive features of the hair structure in the cave lion are noted.

Battle of the sexes: a multi-male mating strategy helps lionesses win the gender war of fitness

Abstract In species exhibiting infanticide by males, females lose out with high stakes and should adopt preemptive mechanisms, pitching the genders in an evolutionary arms race for maximizing fitness. African lions remain a quintessential model of this gender war, with a coalition of males gaining temporary but exclusive breeding rights over a female group after killing all cubs of former males. However in Asiatic lions, now found as a single population in Gir forests, India, adults live in same-sex groups that interact primarily for mating. Intensive monitoring of 70 adult lions revealed that female groups (n = 9) used exclusive territories, whereas male ranges (n = 11 coalitions) overlapped at areas of intense female use. A social network of mating events (n = 76) indicated that lionesses mated with multiple rival coalitions before conceiving. These neighboring coalitions, although hostile to each other were tolerant toward the same litters, suggestive of confused paternity among them. Given a land-tenure system where lionesses encounter many males capable of killing unfamiliar cubs, multi-male mating buffers cub infanticide and likely diversifies paternal lineages in litters. Consequently, infanticide was observed only when “new” males invaded a female group’s territory. An age-based mate choice was observed in lionesses: maiden breeders chose males having highest range overlaps, whereas experienced females selected peripheral males. The intergender spacing patterns and resultant sexual strategies of lions differ in Asia and Africa probably because of contrasting resource availability, highlighting behavioral plasticity within species inhabiting diverse eco-regions. By mating with multiple males, lionesses safeguard their investments and outdo the males in the war of fitness.

Electrifying the fence or living with consequences? Problem animal control threatens the long‐term viability of a free‐ranging lion population

AbstractA fundamental problem in conserving large carnivores is habitat destruction, which results in patchy, isolated protected areas. In addition, human–wildlife conflict along reserve borders negatively affects carnivore populations throughout protected reserves. We present pride composition of nine lion prides and lion mortalities on bordering farmland over a 17‐year study in Etosha National Park, Namibia. Although Etosha National Park is fully fenced, lions can – due to poor maintenance of the fence – move freely onto bordering farmland. Conflict with humans caused 48% of mortalities among subadult and adult lions. Most animals killed by humans consisted of subadult males and adult females: 59% of subadult males and 27% of adult females were shot or poisoned along the border of Etosha National Park. The disproportional high killing of subadult males on farmland affected the tenure periods of resident male coalitions. Probably due to a lack of competition from maturing subadult males, adult males held tenure over prides for nearly 7 years, about three times longer compared to other ecosystems, which increases the risk of inbreeding in this population. Such unregulated and unplanned selective mortality may be more widespread, and managers should monitor for negative effects, especially in socially complex species.

Immobilization and Anaesthesia in Asiatic Lions (Panthera leo persica)

Asiatic lions (Panthera Leo Persica) and hybrid lions are often subjected to chemical immobilization and anaesthesia for various measures related to conservation and elective and emergency surgical procedures by veterinarians. Management of long term anaesthesia has been carried out under using injectable anaesthetics and ancillary drugs which pose problems due to change in depth of anaesthesia and alteration in homeostasis leading to stress and stress related complications. Significantly higher dose (p < 0.05) of xylazine and ketamine was required in sub-adult lions (1.08±0.10 and 2.70±0.26 mg/kg body weight) than adult lions (1.06±0.30 and 2.64±0.08 mg/kg body weight) for immobilization. Similarly lions required higher dose (p < 0.05) of xylazine and ketamine (1.08±0.07 and 2.71±0.16 mg/kg body weight) than lioness (1.04±0.40 and 2.61±0.10 mg/kg body weight) for immobilization irrespective of body weights. Ketamine and propofol (2 &1 mg/kg iv) could be used as induction agents. Propofol induction was safe for oral digital palpation of glottis and intubation. Isoflurane provided smooth maintenance. This work is useful for wildlife veterinarians.

Effect of portal access system and surgery type on surgery times during laparoscopic ovariectomy and salpingectomy in captive African lions and cheetahs

BackgroundA prospective randomized study was used to compare surgery times for laparoscopic ovariectomy and salpingectomy in female African lion (Panthera leo) (n = 14) and cheetah (Acinonyx jubatus) (n = 20) and to compare the use of a multiple portal access system (MPAS) and single portal access system (SPAS) between groups. Two different portal techniques were used, namely MPAS (three separate ports) in lions and SPAS (SILS™ port) in cheetahs, using standard straight laparoscopic instruments. Portal access system and first ovary was not randomized. Five different surgery times were compared for the two different procedures as well as evaluating the use and application of MPAS and SPAS. Carbon dioxide volumes for lions were recorded.ResultsIn adult lionesses operative time (OPT) (P = 0.016) and total surgical time (TST) (P = 0.032) were significantly shorter for salpingectomy compared to ovariectomy. Similarly in cheetahs OPT (P = 0.001) and TST (P = 0.005) were also shorter for salpingectomy compared to ovariectomy. In contrast, in lion cubs no difference was found in surgery times for ovariectomy and salpingectomy. Total unilateral procedure time was shorter than the respective bilateral time for both procedures (P = 0.019 and P = 0.001) respectively and unilateral salpingectomy was also faster than unilateral ovariectomy (P = 0.035) in cheetahs. Port placement time, suturing time and TST were significantly shorter for SPAS compared to MPAS (P = 0.008). There was, however, no difference in OPT between SPAS and MPAS. Instrument cluttering with SPAS was found to be negligible. There was no difference in mean volume CO2 required to complete ovariectomy in lions but the correlation between bodyweight and total volume of CO2 in lions was significant (rs = 0.867; P = 0.002).ConclusionsLaparoscopic salpingectomy was faster than ovariectomy in both adult lions and cheetahs. Using SPAS, both unilateral procedures were faster than bilateral procedures in cheetahs. Placement and suturing of SPAS in cheetahs was easier and faster compared to three separate ports in lions and lion cubs. The use of standard straight instruments during SPAS did not prolong surgery. Surgery was faster in cubs and CO2 required for laparoscopic sterilization in lions could be determined. Predictable surgery times and CO2 volumes will facilitate the accurate planning and execution of surgery in lions and cheetahs.

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Hematologic and serum chemistry reference intervals for free-ranging lions (Panthera leo)

Hematologic and serum chemistry values are used by veterinarians and wildlife researchers to assess health status and to identify abnormally high or low levels of a particular blood parameter in a target species. For free-ranging lions (Panthera leo) information about these values is scarce. In this study 7 hematologic and 11 serum biochemistry values were evaluated from 485 lions from the Kruger National Park, South Africa. Significant differences between sexes and sub-adult (⩽36months) and adult (>36months) lions were found for most of the blood parameters and separate reference intervals were made for those values. The obtained reference intervals include the means of the various blood parameter values measured in captive lions, except for alkaline phosphatase in the subadult group. These reference intervals can be utilized for free-ranging lions, and may likely also be used as reference intervals for captive lions.

CONGENITAL BILIARY TRACT MALFORMATION RESEMBLING BILIARY CYSTADENOMA IN A CAPTIVE JUVENILE AFRICAN LION (PANTHERA LEO)

A captive 3-mo-old white African lion (Panthera leo) presented with clinical signs of acute pain and a distended abdomen. Despite emergency treatment, the lion died a few hours after presentation. Postmortem examination revealed gross changes in the liver, spleen, and lungs and an anomalous cystic structure in the bile duct. Histologic examination identified severe generalized multifocal to coalescent necrotizing and neutrophilic hepatitis, neutrophilic splenitis, and mild interstitial pneumonia, consistent with bacterial septicemia. The abnormal biliary structures resembled biliary cystadenoma. However, due to the age of the animal, they were presumed to be congenital in origin. Biliary tract anomalies and cystadenomas have been reported previously in adult lions, and this case suggests that at least some of these examples may have a congenital basis. It is unclear whether the lesion was an underlying factor in the development of hepatitis.

FIV diversity: FIV Ple subtype composition may influence disease outcome in African lions

Feline immunodeficiency virus (FIV) infects domestic cats and at least 20 additional species of non-domestic felids throughout the world. Strains specific to domestic cat (FIV Fca ) produce AIDS-like disease progression, sequelae and pathology providing an informative model for HIV infection in humans. Less is known about the immunological and pathological influence of FIV in other felid species although multiple distinct strains of FIV circulate in natural populations. As in HIV-1 and HIV-2, multiple diverse cross-species infections may have occurred. In the Serengeti National Park, Tanzania, three divergent subtypes of lion FIV (FIV Ple ) are endemic, whereby 100% of adult lions are infected with one or more of these strains. Herein, the relative distribution of these subtypes in the population are surveyed and, combined with observed differences in lion mortality due to secondary infections based on FIV Ple subtypes, the data suggest that FIV Ple subtypes may have different patterns of pathogenicity and transmissibility among wild lion populations.

The effects of pastoralism and protection on lion behaviour, demography and space use in the Mara Region of Kenya

Contraction of their historic geographic ranges and conflicts with humans underpins declines in large carnivore populations worldwide. These declines, which characterize pastoral systems where carnivores, people and livestock live in close contact, may be paralleled by changes in carnivore behaviour. We investigated this by comparing the behaviour, demography and space-use of three lion (Panthera leo ) prides in the protected Masai Mara National Reserve and the adjoining Koyiaki pastoral ranch in southwestern Kenya during 2005–2006. The mean times lions were inactive was similar between the three prides except when the ranch lions were severely disturbed and became more nocturnal and inactive. The reserve lions ate their kills on open plains and returned to them often but the ranch lions did so only inside bushes and abandoned unfinished kills during a drought in 2005. The reserve lions spent most of their time on open plains while the ranch lions did so in bushes and woodlands. Activity budgets were similar between the prides regardless of land use. Adult lions altered not so much the type but the spatial location and timing of their behaviour on the pastoral ranches relative to the reserve.We discuss the implications of these findings for lion conservation on pastoral lands.

The Effects of Pastoralism and Protection on Lion Behaviour, Demography and Space use in the Mara Region of Kenya

Contraction of their historic geographic ranges and conflicts with humans underpins declines in large carnivore populations worldwide. These declines, which characterize pastoral systems where carnivores, people and livestock live in close contact, may be paralleled by changes in carnivore behaviour. We investigated this by comparing the behaviour, demography and space-use of three lion (Panthera leo ) prides in the protected Masai Mara National Reserve and the adjoining Koyiaki pastoral ranch in southwestern Kenya during 2005–2006. The mean times lions were inactive was similar between the three prides except when the ranch lions were severely disturbed and became more nocturnal and inactive. The reserve lions ate their kills on open plains and returned to them often but the ranch lions did so only inside bushes and abandoned unfinished kills during a drought in 2005. The reserve lions spent most of their time on open plains while the ranch lions did so in bushes and woodlands. Activity budgets were similar between the prides regardless of land use. Adult lions altered not so much the type but the spatial location and timing of their behaviour on the pastoral ranches relative to the reserve.We discuss the implications of these findings for lion conservation on pastoral lands.

Illness as a source of variation of laterality in lions (Panthera leo)

Brain asymmetry—i.e. the specialisation of each cerebral hemisphere for sensorimotor processing mechanisms and for specific cognitive functions—is widely distributed among vertebrates. Several factors, such as embryological manipulations, sex, age, and breeds, can influence the maintenance, strength, and direction of laterality within a certain vertebrate species. Brain lateralisation is a universal phenomenon characterising not only cerebral control of cognitive or emotion-related functions but also cerebral regulation of somatic processes, and its evolution is strongly influenced by social selection pressure. Diseases are well known to be a cost of sociality but their role in influencing behaviour has received very little attention. The present study investigates the influence of illness conditions as a source of variation on laterality in a social keystone vertebrate predator model, the lion. In a preliminary stage, the clinical conditions of 24 adult lions were assessed. The same animals were scored for forelimb preference when in the quadrupedal standing position. Lions show a marked forelimb preference with a population bias towards the use of the right forelimb. Illness conditions strongly influenced the strength of laterality bias, with a significant difference between clinically healthy and sick lions. According to these results, health conditions should be recognised as an important source of variation in brain lateralisation.

Inbreeding and density‐dependent population growth in a small, isolated lion population

AbstractIn South Africa, more than 30 small, enclosed game reserves have reintroduced lions over the last two decades, which now house more than 500 individuals. There is a high risk of inbreeding in these fragmented, fenced and isolated populations, which may be compounded by a lack of management guidelines. A population of 11 founder lions Panthera leo was reintroduced to Madikwe Game Reserve in 1995, and this population has in turn become a source for reestablishing other populations. Only four lineages were reintroduced, founder males were related to founder females, and since 1997, only one male lineage maintained tenure for &gt;9 years, resulting in breeding with direct relatives. Interventionist management to limit lion population growth and inbreeding in Madikwe has taken the form of translocating, trophy hunting and culling of mainly sub adult lions. Despite this management, inbreeding started 5 years after reintroduction. Reproductive performance and thus population growth in Madikwe were dependent on the overall lion population density. When lion density was low, females first gave birth at a significantly younger age and produced larger litters, resulting in a high population growth rate, which decreased significantly when lion density in the park reached carrying capacity, that is, 61 lions. This might have profound consequences for future reestablishment of lion populations when restocking new reserves: our study illustrates the need for founder populations of reintroduced endangered predator species to be as large and genetically diverse as possible, and thereafter new genetic material should be supplemented. The development of such management guidelines is becoming very important as large predator populations become increasingly fragmented and managed as metapopulations.

Changes in home range size of African lions in relation to pride size and prey biomass in a semi‐arid savanna

Within‐population studies are needed to investigate the extent of, and the factors underlying, intraspecific variation in home range size. We used data from 12 female and 8 male adult lions instrumented with GPS radio‐collars to describe the ranging behaviour of lions in a population from a dystrophic semi‐arid savanna, Hwange National Park, Zimbabwe. We measured prey availability at the home range scale in 2003, 2004, and 2005. For females, home range size increased as pride biomass increased, which is strongly suggestive of expansionism. Once controlled for pride biomass, home range size decreased as prey biomass increased. Pride ranges responded to changes in food abundance on an annual timescale rather than on a seasonal timescale. Female home range size was influenced by the abundance of kudu in the early dry season, whereas it was influenced by buffalo and young elephant abundance in the late dry season. This study shows that female home range size is mainly driven by the size of the pride, but also by prey abundance. Furthermore, female seasonal home range size may be determined, not only by prey abundance, but also by prey dispersion in the landscape. Home range size of males was driven by both prey biomass and the density of female prides.

Yohimbine antagonizes the anaesthetic effects of ketamine-xylazine in captive Indian wild felids

ObjectiveTo determine the effectiveness of yohimbine as an antagonist of ketamine-xylazine anaesthesia in captive Asiatic lions (Panthera leo persica), tigers (Panthera tigris) and leopards (Panthera pardus). Study designProspective clinical trial. AnimalsFifty-two healthy adult lions, 55 adult leopards and 16 adult male tigers. MethodsCaptive wild felids in Indian zoos were anaesthetized with a combination of ketamine (2.2-2.6 mg kg−1) and xylazine (1.1-1.3 mg kg−1) using a dart propelled from a blowpipe. Time to onset of anaesthesia, lateral recumbency and induction time were measured, and physiological variables (respiration, heart rate and rectal temperature) were recorded once after the onset of complete anaesthesia. Anaesthesia was antagonized at various time periods with an intravenous administration of either 0.1 or 0.15 mg kg−1 yohimbine. Onset of arousal and time to complete anaesthetic recovery were recorded. ResultsA total of 123 immobilizations were conducted between 2000 and 2005. Anaesthetic induction was achieved in 15-25 minutes in all animals. Incidents of sudden recovery or life-threatening effects associated with immobilizations were not observed. Yohimbine effectively antagonized anaesthesia in all animals within 10 minutes without any excitatory behaviour compared to control animals. No adverse reactions/side effects to yohimbine were recorded except that a few leopards exhibited seizure-like signs for a short period immediately after yohimbine administration. The duration of anaesthesia had no significant effect on the recovery time in any of the animals. Conclusion and clinical relevanceYohimbine antagonized the xylazine portion of ketamine-xylazine anaesthesia and thereby hastened recovery from anaesthesia in Asiatic lions, tigers and leopards.

Lens‐anomalies and other ophthalmic findings in a group of closely‐related angola lions (Panthera leo bleyenberghi)

AbstractAfter the diagnosis of bilateral, immature, nuclear, and posterior cortical cataracts in one Angola lioness, and because of the possible implications of the cataracts for a breeding program, complete ophthalmic examinations on a group of related adult Angola lions and their offspring were carried out. Five adult lions, ranging in age from 1.5–5.5 years, and five lion cubs were studied clinically. The examination included slit‐lamp biomicroscopy, indirect ophthalmoscopy, and photography. The eyes of three of the offspring were submitted for histopathologic examination and examined by light microscopy. The most significant findings were cataracts of various stages, which were observed in four adult lions and one male cub. Mild lenticular abnormalities were noted in the histopathologic examination of the lion cubs' eyes. Additional ophthalmic findings, of lesser clinical consequence, were also noted. This breeding program would benefit from further investigation by animal nutritionists and geneticists, and the animals in this group should undergo periodic ophthalmologic examinations. Zoo Biol 0:1–7, 2006. © 2006 Wiley‐Liss, Inc.