Infanticide by Male Lions Hypothesis: A Fallacy Influencing Research into Human Behavior

Recently, familial abuse and killing of children have been correlated with infanticidal behavior by nonhuman male animals which is postulated to be genetic. However, infanticide by males as an evolutionary mechanism is unlikely to occur in primates, and is equally unlikely in lions. To investigate the sexual selection hypothesis of infanticide for lions, four questions should be considered: (1) because they all mate freely with lionesses, are male pride lions closely related? (often they are not), (2) do males kill the young cubs when they join a pride? (few such cases have been observed), (3) do the females then mate with the new males to produce offspring? (yes), and (4) do the males remain with the pride for over two years to protect this new generation? (often not). Field data indicate that in NO instance do we know that male lions killed cubs in a new pride, mated with their mother, and then remained with the pride to protect their own young. Rather, female lions may kill more cubs than males and certainly cause many more cub deaths by allowing them to starve, [ infanticide by male lions, infanticide hypothesis, faulty science]     

Translocating lions into an inbred lion population in the Hluhluwe-iMfolozi Park, South Africa

A fundamental problem in conservation biology is the risk of inbreeding in fragmented and declining populations. In the Hluhluwe-iMfolozi Park (HiP), a small, enclosed reserve in South Africa, a large lion Panthera leo population arose from a founder group of five individuals in the 1960s. The HiP lion population went through a persistent decline and showed indications of inbreeding depression. To restore the genetic variation of the inbred HiP lion population, new lions were translocated into the existing population. Translocated females formed stable associations and established enduring pride areas with other translocated lionesses, but did not bond into native female prides. The translocated male coalition was more successful in gaining and maintaining residence in a pride than the translocated lone male that split off on his own from the male coalition. Litter size and cub survival was about twice as high for pairings involving at least one translocated parent than for pairings of two native lions. It is therefore possible to infuse new genes rapidly and successfully into a small, isolated lion population. Such translocations may become an important adaptive management tool as lion populations become increasingly fragmented.     

High juvenile mortality in cheetahs (Acinonyx jubatus) and its consequences for maternal care

Juvenile mortality in cheetahs was found to be extremely high compared to other large mammals, with approximately 72.2% of litters dying before they emerged from the lair at eight weeks of age. An average of 83.3% of cubs alive at emergence died by adolescence at 14 months of age, thus cheetah cubs were estimated to have only a 4.8% chance of reaching independence at birth. The instantaneous rate of mortality was highest immediately after cubs emerged from the lair. Before emergence, lion predation was the major source of this mortality, although some cubs died from starvation after they were abandoned by their mothers, or as a result of grass fires and inclement weather. After emergence, predation again accounted for virtually all cub mortality, with lions and spotted hyaenas taking approximately the same proportion of cubs. Overall predation accounted for 73.2% of cheetah cub deaths in this study, with 78.2% of these being killed by lions. The extent of maternal care, in the form of vigilance and antipredator behaviour, mirrored cub susceptibility to mortality and, in the case of vigilance, possibly also starvation. The probability of a cheetah mother responding aggressively to a predator was found also to depend on the species of predator. This study highlights the importance of the influence of juvenile mortality on patterns of parental care.     

南非Hluhluwe-Umfolozi公园植被对非洲狮群大小的影响

非洲狮(Pantheraleo)群处于不断的分裂-聚合过程,其亚群大小与原狮群大小以及诸如狮群捕食成功度、协作幼仔保护及狮群领域防卫等社会性因素有关。我们分析了南非一个保护区(Hluhluwe-Umfolozi公园)15年间的狮群大小,其成年雌狮和成年雄狮群的大小在保护区内呈显著性变化。在开放生境中雌狮结大群,而茂密植被生境中则结小群。雄狮群大小与植被类型无关,但在大的雌狮群分布区域发现大雄狮群。令人惊奇的是,作为幼狮成活率指标的幼狮群大小和雌狮平均幼仔数在保护区内没有显著性差异。我们认为,雌狮群大小的不同是对植被结构的适应,即在开放生境中大群有利于协作狩猎、育幼、共同保护幼仔、应对高强度群间领域防卫竞争。相反,茂密植被中,群间竞争很低,高密度植被覆盖有利于狩猎成功及补偿小狮群对幼仔保护的不足。雌狮平均幼仔数在整个保护区内没有变化,我们认为是由于开放生境和茂密植被对狮群大小起到相似的调节作用     

Persistence and local extinction of lion prides in the Ngorongoro Crater, Tanzania

African lions (Panthera leo) live in social groups (prides) that exhibit group territorial behavior. Pride persistence is expected to depend on its ability to compete against neighboring prides as well as on average rates of reproduction and survival, thus providing a meaningful measure of intergenerational reproductive success. We used Akaike’s Information Criterion (AIC) to select the best approximating models explaining how demographic variables influenced pride persistence during a 30-year period in the Ngorongoro Crater, Tanzania, and identified landscape factors affecting those demographic variables. Pride persistence to 10 years depended on adult female density (pride size) and cub productivity (the ultimate source of new females). Average age of adult females had a weakly positive influence on pride persistence, while the effect of female mortality was weakly negative. Adult female mortality increased with disease epidemics and in territories with high human disturbance. Cub productivity was highest in territories closest to rivers and only slightly higher near swamps, and also high in areas of higher vegetative cover and high human use. No landscape variable significantly affected female density. The growth and population size of the Crater lions was closely linked to demographic performance of individual prides, while territorial behavior played a key role in mediating the interactive effects of landscape and demography.     

Demography of lions in relation to prey and habitat in the Maasai Mara National Reserve, Kenya

We studied lion demography in the Maasai Mara National Reserve between September 1990 and April 1992, with a special emphasis on the spatial and seasonal variation in demographic characteristics. Lion density (0.2–0.4 lions km^?2) and pride size (range 8–48) were high because of a high resident prey biomass (10 335 kg km^?2) augmented by migrant prey to 26 092 kg km^?2 in the dry season. Overall, their sex ratio was almost at parity and varied neither spatially nor seasonally. Sex ratio was even among subadults but skewed toward males and females among cubs and adults, respectively. This implies an increasing differential mortality of males with age through subadulthood. The age ratio varied seasonally because of a birth peak in March–June and an influx of subadults into the reserve during July–August, coincident with increases in migrant prey. The birth peak was apparently preceded by another peak in mating activity falling between November and May. Further research should investigate the precise causes of the biased cub sex ratio, low lion density in the Mara Triangle and the higher ratio of subadults in Musiara than in the Mara Triangle or Sekenani.     

Partitioning of space, habitat, and timing of activity by large felids in an enclosed South African system

Reintroductions of large carnivores into enclosed reserves that confine movements may fail due to intensive intra-guild interspecific conflict. To assess conflict potential, in winter 2006 we used direct observations aided by radio-tracking to focally monitor continuously one female cheetah with cub (Acinonyx jubatus), a female leopard (Panthera pardus), and a lion pride (Panthera leo) at Shamwari Private Game Reserve, South Africa. Home ranges of all individuals/social groups overlapped, whereas core areas had little overlap. The cheetah core area had no overlap with the lion core area, with lion avoidance also recorded for a radio-tracked single female cheetah and a male leopard. The female cheetah with cub selected thicket habitat which was avoided by lions, the latter preferring naturally revegetated areas that were also selected by the female leopard. Lions also selected low elevations, which were avoided by the smaller felids. Habitat preference differences occurred at study area and home range levels, suggesting a broad-scale feline avoidance strategy to minimize intra-guild conflict. In addition, the focally monitored cheetah and leopard were often stationary when the lions were active, especially during nocturnal lion hunts. These intra-guild mechanisms of reintroduced carnivore coexistence should be tested with longer-term studies across enclosed systems of different sizes, and hosting varying carnivore guilds.     

Ecological correlates of lion social organization (Panthers, leo)

Data on lion home range size, pride size, density, group size, cub survival, litter size and adult sex ratio were extracted from studies carried out in 10 habitats. The data were compared with five measures of food supply: mean prey biomass, prey biomass during the season of greatest abundance, prey biomass during the season of least abundance, biomass of middle-sized prey species (i.e. those with mean adult live-weights between 50 and 250 kg), and the mean size of carcasses fed on by lions. The results indicated that range size is inversely correlated with the abundance of prey during the period of least abundance, but not with overall prey abundance. Range size showed no consistent variation with pride size or with minimum metabolic requirements. Pride size (measured in terms of average number of animals per pride and average number of adult females) and cub survival strongly correlated with lean season food abundance. No relationship was found between group size or litter size and any of the measures of food supply Adult sex ratio did not vary consistently with food supply or lion density, although the data did suggest that prides inhabiting small, circumscribed reserves may experience less inter-male competition and this, in turn, may affect the adult sex ratio.     

OBSERVATIONS ON LIONS IN THE LAKE MANYARA NATIONAL PARK,TANZANIA

The lions of Lake Manyara National Park were observed for 1 1/4 years. About 0.4 lions/km² inhabited the park, a density nearly double that found in Nairobi National Park and Ngorongoro Crater. One group of lions occupied the southern half of the park; in the northern half, the range of two males included two distinct groups of lionesses each of which confined itself to its own area. The composition and changes in composition of each group are discussed. Buffalo were observed to kill a lion cub on three occasions, and elephant were seen to do so once. The lions' most important prey was buffalo, which comprised 62% of the kills, followed by zebra (18%) and impala (12%). Eighty-one per cent. of the buffalo killed were males. Lions were seen in trees on 2/3 of the occasions on which they were encountered. Possible reasons for tree-climbing are given.     

Changing vulnerability to predation related to season and sex in an African ungulate assemblage

The consequences of predation for prey population dynamics depend on the extent to which this mortality is predisposed by malnutrition or senescence, or additive in the sense that animals that would otherwise not have died at that time were killed. In places lacking effective predators, few adult ungulates die during the summer or wet season months when food is plentifully available. Hence the seasonal distribution of predator kills as well as the age and sex classes of the prey indicates the extent to which malnutrition contributes to mortality as well as other influences on vulnerability. Using records of animal deaths assembled over 35 years in South Africa's Kruger National Park, these patterns were investigated for 12 ungulate species forming the prey of lions, and for three other large predators with respect to one prey species. Buffalo, kudu and giraffe were more strongly represented in kills made during the late dry season, while wildebeest and zebra made relatively greater contributions during the wet season. Impala, waterbuck, warthog and rarer antelope species became more prominent in kills during transitional periods between seasons. Five prey species showed an elevation in representation of males in lion kills during the mating season, as well as impala for all predator species. Females were more prominently represented in kills during the time of late gestation and parturition for three prey species. Hence reproductive activities as well as changing vegetation cover and food resources affected vulnerability to predation. Shifts in susceptibility to predation over the seasonal cycle corresponded with rainfall‐related variation in the annual representation of these ungulate species in lion kills. The availability of vulnerable prey species, age and sex classes at different stages of the seasonal cycle helps maintain a high abundance of lions. These factors contribute to the strong additive impact that predation has had on the abundance of some of these ungulate populations.     

Urgent call for further breeding of the relic zoo population of the critically endangered Barbary lion (Panthera leo leo Linnaeus 1758)

The Barbary lion became extinct in the wild around 1942. Since the end of the 19th century, a last purebred captive breeding stock existed at the court of Morocco. The rest of these animals became the core exhibition of the new Rabat Zoo after passing through repeated bottlenecks and possibly some introgression events by foreign lions. This study uses mitochondrial DNA sequencing data to clarify the relationship among these lions and their sub-Saharan and Asian relatives. We analysed mitochondrial cytochrome b sequences obtained from a sample from a Barbary lion descended from a young female of the Barbary lion breeding group at the Rabat Zoo and various other members of the genus Panthera. In our cytochrome-b-based phylogenetic tree, the North African Barbary lion, represented by a biopsy sample from the Neuwied Zoo, joins the Asian lion clade, although it is slightly different from its Asian sister group. However, it is clearly distinct from sub-Saharan lions and can be considered as a genetically defined phylogeographic group of its own. Molecular dating of the extant sub-Saharan and Asian lion groups shows that the split between North African Barbary lions and Asian lions must be considerably more recent than 74–203 kilo years ago.     

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

After 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.     

Effects of social status, age, and season on androgen and cortisol levels in wild male golden lion tamarins (Leontopithecus rosalia)

This study examines factors affecting androgen and cortisol levels in wild, male golden lion tamarins (Leontopithecus rosalia). Golden lion tamarins are a cooperatively breeding species in which groups often contain two potentially breeding males. Brothers frequently emigrate together and develop a clear dominance hierarchy, but interactions between them are primarily affiliative. Duos in which the males are not related are less stable. In addition, reproductive skew theory predicts that dominant males will be less likely to share reproduction with related subordinates. As such, we predicted that both androgens and cortisol would be higher in subordinate males unrelated to the dominant male. We also predicted that androgens in breeding males would be higher during the mating season than the birth/infant care season, as per Wingfield's "challenge hypothesis" (1990). Fecal samples were collected from 24 males in 14 social groups and assayed by enzyme immunoassay. Androgen levels were higher in breeding males during the mating season, thus supporting the challenge hypothesis. However, while subordinate males unrelated to the dominant male had significantly lower androgens than any other group, cortisol levels were not correspondingly higher. These results suggest that unrelated subordinate males show measurable reproductive suppression and may use strategies such as infantilization to avert aggression from dominant males.     

Urinary volatile constituents of the lion, Panthera leo.

The volatile components of urine from lions were investigated using GC-MS headspace techniques. Fifty-five compounds were found in the urine samples. Seven potential species-identifying compounds were found. Male lion scent marks overlapped significantly more in compound composition with other males than they did with female marks. A similar relationship was not found for the females. Males had a significantly higher absolute content of 2-butanone in their urine than females, and females had a significantly higher relative content of acetone than males. Samples from 13/16 individual lions overlapped more within the individual than they did with samples from the other individuals, but only seven significantly so.     

Threat of rapid extermination of the lion (Panthera leo leo) in Waza National Park,Northern Cameroon

Lion populations in West and Central Africa are small and fragmented. In areas where park management is weak, threats will likely facilitate the extinction of the lion. Wildlife management requires knowledge of the population estimate. The population of lions in Waza National Park (Waza NP) was assessed by individual identification of members in the population. The population was assessed to comprise of 14–21 adult individual lions. The age structure was skewed towards adults; cubs comprised 22% of all lions identified while the sex ratio was 1 : 3. Two out of four collared lions were lost to illegal, retaliatory killings within 1 year; and probably two more males and one more female were also killed during this period. The lion population appears to have declined during the last 5 years with six lions dying per year, which is at a much higher rate than observed in the previous decades. Human‐livestock pressure has increased tremendously in this period, resulting to frequent human‐lion conflicts. To ensure the survival of the lion in Waza NP and in the entire region, management needs to intensify efforts to mitigate the pressure from humans and their livestock.     

Life history of Eulemur fulvus rufus from 1988-1998 in southeastern Madagascar

In this study, we compare the life-history patterns of male and female Eulemur fulvus rufus based on longitudinal data collected on individuals from two study groups from 1988-1998 in southeastern Madagascar. Mean group size was 9.5 individuals, and groups either contained more adult males than females or equal numbers of both sexes. Females reproduced for the first time between 2 and 4 years of age and reproduced each year, although the mean interbirth interval between surviving offspring was 2.1 years. An average of two adult females reproduced annually in each social group, and age and body weight may positively influence reproductive success. Females also appear to be philopatric but not female-bonded. Young natal males immigrated between 3 and 4.5 years of age and may join a new group within 612 months based on the age of emigrants. Once in a social group, they remained until old age, although a male's spatial position in the social group varied with age. Young nonnatal males were members of the social core and had the first opportunity to mate with all estrous females. Older males were peripheral to the social group and mated with females later in their cycle. We hypothesize that group size, the number of females in the group, and individual variation in reproductive success is influenced by several ecological conditions at this site: extreme variability in food availability during reproductive periods, the lack of large food patches, low plant species diversity, and small numbers of important aseasonal food sources such as Ficus species.     

Age-related and individual differences of reproductive success in male and female barbary macaques (Macaca sylvanus)

Age-related and individual differences in longterm reproductive success were analyzed in two social groups of free-ranging Barbary macaques. Maternity data were obtained from continuous birth records and paternity was determined with oligonucleotide-fingerprinting. The fathers of 246 of 286 investigated individuals could be identified. They were born during a 14-year period and represented 73 and 34% of all known offspring from the females of the study groups B/F and C, respectively. Only these infants were considered when comparing male reproductive success with that of females. The necessary adjustment of the female data resulted in small deviations from the true values in one group, but substantially increased individual differences in female fertility in the second group. Subadult males, 4.5 – 6.5 yrs old, had a much lower reproductive success than adult males (7.5 – 25 yrs old) and same-aged females. Reproductive success of adult males was not significantly affected by age, while females invariably ceased reproduction during the first half of the third decade of life. Males were more likely than females to leave no offspring, unless they survived 9 – 10 yrs of age. The number of years with breeding opportunities was important for male reproductive success but less significant than that for females. Reproductive success of several males during the 14-year study period was similar to or even exceeded that possible for a female in her whole lifetime. Variance of male reproductive success significantly exceeded that of females in both study groups.     

On the distinctiveness of the Cape lion (Panthera leo melanochaita Smith, 1842), and a possible new specimen from the Zoological Museum, Copenhagen

The Cape lion was a population of lions that probably inhabited the western part of the Cape Province of South Africa until their extermination by man in the mid-19th century. Only a few skeletal remains are known, making every specimen valuable. In this paper, I report on a possible new male specimen CN1570 from the Zoological Museum in Copenhagen. A multivariate discriminant analysis on 27 craniodental variables provided clear separation between four of the five lion subspecies (Panthera leo krugeri, nubica, persica, senegalensis) that were included, whereas P. l. bleyenberghi showed some overlap with P. l. senegalensis and P. l. krugeri. The only two undisputed Cape lion males grouped separately from all other lions. CN1570 also grouped separately from other lions, and towards the two Cape lions. The external morphology of the Cape lion is often cited as having been different from other sub-Saharan lions, but phenotypic plasticity argues for caution in placing emphasis on mane morphology as a distinguishing character among lion subspecies. Skull morphology, however, appears to clearly distinguish male Cape lions from other African lions.     

A molecular analysis of African lion (Panthera leo) mating structure and extra‐group paternity in Etosha National Park

The recent incorporation of molecular methods into analyses of social and mating systems has provided evidence that mating patterns often differ from those predicted by group social organization. Based on field studies and paternity analyses at a limited number of sites, African lions are predicted to exhibit a strict within‐pride mating system. Extra‐group paternity has not been previously reported in African lions; however, observations of extra‐group associations among lions inhabiting Etosha National Park in Namibia suggest deviation from the predicted within‐pride mating pattern. We analysed variation in 14 microsatellite loci in a population of 164 African lions in Etosha National Park. Genetic analysis was coupled with demographic and observational data to examine pride structure, relatedness and extra‐group paternity (EGP). EGP was found to occur in 57% of prides where paternity was analysed (n = 7), and the overall rate of EGP in this population was 41% (n = 34). Group sex ratio had a significant effect on the occurrence of EGP (P < 0.05), indicating that variation in pride‐level social structure may explain intergroup variation in EGP. Prides with a lower male‐to‐female ratio were significantly more likely to experience EGP in this population. The results of this study challenge the current models of African lion mating systems and provide evidence that social structure may not reflect breeding structure in some social mammals.     

High rates of pregnancy loss by subordinates leads to high reproductive skew in wild golden lion tamarins (Leontopithecus rosalia)

Across taxa, cooperative breeding has been associated with high reproductive skew. Cooperatively breeding golden lion tamarins (Leontopithecus rosalia) were long thought to have a monogynous mating system in which reproduction was limited to a single dominant female. Subordinates with few reproductive opportunities delayed dispersal and remained in the natal group to provide alloparental care to siblings, thus allowing dominant reproductive females to meet the energetic needs associated with high rates of reproduction and successful infant rearing. The goal of this study was to re-assess monogyny in wild golden lion tamarin groups based upon pregnancy diagnoses that used non-invasive enzyme immunoassay for progesterone and cortisol, combined with weekly data on individual weight gain, bi-annual physical examinations noting pregnancy and lactation status and daily behavioral observations. We established quantitative and qualitative criteria to detect and determine the timing of pregnancies that did not result in the birth of infants. Pregnancy polygyny occurred in 83% of golden lion tamarin groups studied. The loss of 64% of subordinate pregnancies compared to only 15% by dominant females limited reproductive success mainly to dominant females, thus maintaining high reproductive skew in female golden lion tamarins. Pregnancy loss by subordinate adults did not appear to result from dominant interference in subordinate hormonal mechanisms, but more likely resulted from subordinate abandonment of newborn infants to mitigate dominant aggression.