Migration patterns of Thomson's gazelles and cheetahs on the Serengeti Plains

Monthly changes in abundance of Thomson's gazelles at 142 locations on the Serengeti Plains are presented over a 3½ year period. Numbers of gazelles on the eastern plains were strongly correlated with rainfall, whereas numbers in the central and western plains appeared to be related to other variables. Movements of female cheetahs and non-resident male cheetahs corresponded closely to the movements of Thomson's gazelles but those of resident male cheetahs remained relatively independent of the gazelle migration.     

The functions of stotting in Thomson's gazelles: some tests of the predictions

Stotting in Thomson's gazelles (Gazella thomsoni) was found to have a negligible time cost in slow flights and it was normally shown in safe situations when prey were unlikely to be captured. Despite its probable energy cost and time cost during fast flights there was no evidence to show that, once a chase occurred, stotting gazelles were caught more or less often than gazelles that did not stott.Eleven hypotheses concerning the benefits of stotting were tested using a number of predictions about the stotting individual, its conspecifics and the predator (usually cheetahs), some of which were pertinent to several hypotheses. Although a number of hypotheses were supported by some of the predictions, most were refuted by one or more pieces of evidence. Only two were satisfactorily supported by all of them: stotting appears to inform the predator that it has been detected, but it does not invite or deter the predator from pursuing the gazelle. In neonate Thomson's gazelles, stotting probably has a different function, it informs the mother that the neonate has been disturbed and is in need of defence. In addition, mothers whose neonates escaped capture by cheetahs stotted significantly more during the attempt than mothers whose neonates were caught. Hypotheses concerning the prey signalling its health, startling or confusing the predator; group cohesion; anti-ambush behaviour; play in young animals; warning of conspecifics; and pursuit invitation or deterrence were dismissed by data presented here.     

Experimental transmission of gastro-intestinal nematodes between sheep (Ovis aries) and Thomson's gazelles (Gazella thomsonii).

Experimental cross-transmission of gastro-intestinal nematodes between Merino sheep (Ovis aries) and Thomson's gazelles (Gazella thomsonii) from similar but separate grazing habitats in Kenya was studied. Cross-transmission did occur with some species but the faecal egg counts of sheep were higher than the gazelles' following infection with larvae isolated from either sheep or gazelles. Of the 11 gastro-intestinal nematodes which became established in gazelles following infection with larvae cultured from nematodes in gazelles, only Haemonchus contortus, Trichostrongylus probolurus and Cooperia hungi were infective for sheep. Following infection with larvae of either sheep or gazelle origin, the H. contortus recovered from the sheep at necropsy were more numerous and had greater average weights, lengths and spicule lengths than those recovered from the gazelles. This would suggest that H. contortus is primarily a sheep parasite. It is concluded that Thomson's gazelles probably would not contribute significantly to the problem of haemonchosis in sheep in areas of shared grazing, unless efforts were being made to eradicate the parasite from sheep, in which case the gazelles would act as a continuing reservoir of infection.     

Exposure to FIV and FIPV in wild and captive cheetahs

Two RNA-containing viruses, feline infectious peritonitis virus (FIPV) and feline immunodeficiency virus (FIV), have been observed to infect cheetahs. Although both viruses cause lethal immunogenetic pathology in domestic cats, only FIPV has documented pathogenesis in cheetahs. We summarize and update here a worldwide survey of serum and plasma from cheetah and other nondomestic felids for antibodies to FIV and FIPV, based on Western blot and immunofluorescence assays. FIPV exposure shows an acute pattern with recognizable outbreaks in several zoological facilities, but is virtually nonexistent in sampled free-ranging populations of cheetahs. FIV is more endemic in certain natural cheetah populations, but infrequent in zoological collections. FIV exposure was also seen in lions, bobcats, leopards, snow leopards, and jaguars. FIV causes T-cell lymphocyte depletion and associated diseases in domestic cats, but there is little direct evidence for FIV pathology in exotic cats to date. Because of the parallels with a high incidence of simian immunodeficiency virus in free-ranging African primates without disease, the cat model may also reflect historic infections that have approached an evolutionary balance between the pathogen and immune defenses of their feline host species. Published 1993 Wiley-Liss, Inc.     

Early maternal behavior of wild cheetahs: Implications for captive husbandry

Against a background of poor breeding success and cub survival in captive cheetahs, a knowledge of the early maternal behavior in the wild may yield useful information for comparison with the captive situation. This paper documents the types of lair sites used by mothers to conceal their newborn cubs in the wild situation, and details patterns of maternal behavior observed during this period. Four kinds of lairs were used by cheetah mothers, and the amount of protection from the elements and predators was assessed for each. Lair type appeared to have little effect on cub survival. Cubs were concealed in lairs for 8.2 weeks on average, although larger litters tended to leave lairs earlier. During this period, cubs were moved to new lairs approximately every 5.6 days. Cubs were left for an average of 9.6 hours while their mothers went hunting, but mothers virtually always returned to them around nightfall, even if they failed to catch any prey. Maternal neglect and cub abandonment, which account for many cub deaths in captivity, are abnormal in the wild, except when prey is very scarce. Improved husbandry techniques, such as the provision of multiple, secluded nest boxes, and remote monitoring conditions should promote breeding success in captivity. In addition, noise and human disturbance should be minimized.     

Seasonal pattern in age, sex and body condition of Barn Owls Tyto alba killed on motorways

The Barn Owl Tyto alba was the most common owl killed on motorways in northeastern France. The possible causes of this mortality and the age, sex and body condition of the road-killed birds in 1991–1994 have been investigated. The number of birds killed on roads was highest in the period from early autumn to late winter, i.e. during the non-breeding period, and showed a pattern similar to that of the temporal difference between sunset, which varies with day length, and peak of traffic, the occurrence of which is constant throughout the year. An autumnal mortality peak, concomitant with the post-fledging dispersal, was mainly of immature birds, especially females. A second mortality peak in late winter was composed mainly of mature birds, with an equal proportion of males and females. From autumn to winter, there was no significant change in body mass in the different age and sex categories of birds killed on roads, except for mature males which had a significantly lower body mass in winter. From early autumn to late winter, the mean body mass of immature owls killed on motorways did not differ significantly from that of captive immatures fed ad libitum. This suggests that the immature birds were in good body condition. In contrast, the body mass of road-killed mature females was significantly lower than that of captive mature females over the same time periods. In mature males in late winter, a drop in body mass in both road-killed and captive birds suggests an endogenous seasonal phenomenon. Except for mature females, Barn Owls killed on roads in 1991–1994 were in good body condition. This does not support the idea that only birds in poor body condition were killed. We conclude that the mortality of Barn Owls on motorways in autumn and winter was probably related to the concomitance between the peak of traffic and the onset of hunting activity and the large number and dispersal of immature individuals during the same period.     

The decline of the Serengeti Thomson's gazelle population

Summary The population of Thomson's gazelles in the Serengeti National Park, Tanzania has declined by almost two thirds over a 13 year period. In the early 1970s, numbers stood at 0.66 million animals but had decreased to less than 0.25 million animals in 1985 as estimated by 5 different censuses using two different counting techniques. Predation, interspecific competition and disease are all factors that could have contributed to this decline, and at least one of these factors, predation, could now prevent the Thomson's gazelle population from increasing.     

Factors affecting life and death in Serengeti cheetahs: environment, age, and sociality

We examined environmental and social factors affecting reproductivesuccess across a 20-year data set of individually known cheetahson the Serengeti Plains of Tanzania. Because cheetahs are seeninfrequently and are not amenable to mark–recapture techniques,we devised a model to estimate time of death for individualsthat disappeared from our records. We found that males had markedlylower survival than females. Recruitment was negatively affectedby rainfall but positively affected by numbers of Thomson'sgazelles, the cheetahs' chief prey. There was a negative associationbetween recruitment and numbers of lions, demonstrating thatthe high rates of predation observed in previous studies haveimplications for the dynamics of cheetah populations. Recruitmentwas related to mother's age, peaking when she reached 6–7years. Sociality affected survival in two ways. First, adolescentsliving in temporary sibling groups had higher survival thansingletons, particularly males with sisters. Second, adult malesliving in coalitions had higher survival than singletons inperiods when other coalitions were numerous, yet they had lowersurvival when other coalitions were rare. These results corroborateobservations of enhanced prey capture by female adolescentsand antipredator benefits for adolescents in groups, as wellas competitive advantages for adult males in groups. Furthermore,our findings stress the importance of interactions between environmentaland social factors in affecting reproductive success in mammals.     

Case histories of wild birds killed intentionally with famphur in Georgia and West Virginia

Five incidences of bird mortality in Georgia and West Virginia (USA) involving migratory waterfowl, cranes, raptors, corvids and songbirds were investigated during the first 6 mo of 1988. Gross and histopathologic examinations revealed no evidence of infectious or other diseases. However, severe depression of cholinesterase activity was evident in brains of birds found dead, suggesting gross exposure to an organophosphorus (OP) or carbamate pesticide. All of the gastrointestinal tract contents chemically analyzed contained famphur, an OP insecticide used as a pour-on treatment against lice and grubs on livestock, ranging from 5 to 1,480 ppm (wet weight). Grain scattered at two of the mortality sites contained 4,240 and 8,500 ppm famphur. Gastrointestinal tracts of most of the dead birds contained mainly corn and some wheat. This is the first report to document the use of famphur as an intentional means of killing wildlife thought to be depredating crops.     

The influence of sex,sexual condition and age on the exploratory behaviour of wild wood mice (Apodemus Sylvaticus L.)

From April 1978 to April 1980 the exploratory behaviour of more than 1000 wild wood mice was studied in a modified open field test situation. The influence of sex, sexual condition and age on the exploratory activity was investigated. Sufficient data being available, the exploratory activity of both sexually active and sexually inactive adult males and adult females, of both sexually active and sexually inactive subadult males and subadult females and of both sexually inactive juvenile males and females was compared by means of a one way analysis of variance for each two-month period. In other analyses the influence of age of adult males and adult females on the exploratory behaviour was further examined. No differences could be found in the exploratory activity displayed by males or females and by sexually active or sexually inactive animals. Also a clear influence of age was absent. The interindividual variation was very large.     

Effect of guard dogs on the behavior and reproduction of gazelles in cattle enclosures on the Golan Heights

Cattle on the Golan Heights are kept in enclosures and some of these enclosures have guard dogs. We studied the effect of such dogs on the behavior and breeding success of mountain gazelles Gazella gazella living within enclosures. We found that guard dogs have both direct and indirect effects on gazelles. Gazelles living in enclosures with dogs spent more time in vigilance behavior and running, and less time resting and walking, in comparison with gazelles in dog-free enclosures. In the absence of dogs, gazelle female herds in enclosures tended to stay closer to the cattle, but shunned away from them in the presence of the dogs, which, in turn, remained near the cattle. The percentage of fawns per female was higher in enclosures without dogs in comparison with those with dogs, but the difference was not significant. However, the largest of the enclosures with dogs, which had the largest number of gazelles, had only an average number of dogs in it. Hence, the gazelles in this enclosure were better able to avoid the dogs in comparison with those in smaller enclosures. Removing this enclosure from the overall calculation revealed that guard dogs have a significant negative effect on gazelle reproductive success. In two of the four enclosures with dogs no fawn still survived 6 months after birth, while in each of the four enclosures without dogs some fawns did survive to that age and beyond, suggesting that the dogs themselves may predate the fawns.     

Comparative behaviour of sand and mountain gazelles

Behavioural observations of both captive and free-ranging sand and mountain gazelles revealed differences in group size and composition, territory size and agonistic behaviour. Sand gazelles are seasonal breeders and form large herds (maximum = 56) during rut and post-rut as compared to mountain gazelles, which breed throughout the year in smaller groups (maximum = 5). As a result, mountain gazelle males maintain their territories year round, whereas sand gazelle rams show marked morphological changes and defend a territory only during the rut. Mountain gazelle males exhibited threat displays rather than engaging in actual combat more often than did sand gazelles. Although subject to the same environmental conditions, sand gazelles are seasonal breeders and the young are born in March-April, whereas mountain gazelles give birth throughout the year.     

The importance of considering age when quantifying wild animals’ welfare

Wild animals experience different challenges and opportunities as they mature, and this variety of experiences can lead to different levels of welfare characterizing the day-to-day lives of individuals of different ages. At the same time, most wild animals who are born do not survive to adulthood. Individuals who die as juveniles do not simply experience a homogeneous fraction of the lifetimes of older members of their species; rather, their truncated lives may be characterized by very different levels of welfare. Here, I propose the concept of welfare expectancy as a framework for quantifying wild animal welfare at a population level, given individual-level data on average welfare with respect to age. This concept fits conveniently alongside methods of analysis already used in population ecology, such as demographic sensitivity analysis, and is applicable to evaluating the welfare consequences of human interventions and natural pressures that disproportionately affect individuals of different ages. In order to understand better and improve the state of wild animal welfare, more attention should be directed towards young animals and the particular challenges they face.     

Lifespan and age,but not residual reproductive value or condition,are related to behaviour in wild field crickets

Individuals frequently show long‐term consistency in behaviour over their lifetimes, referred to as “personality.” Various models, revolving around the use of resources and how they are valued by individuals, attempt to explain the maintenance of these different behavioural types within a population, and evaluating them is the key for understanding the evolution of behavioural variation. The pace‐of‐life syndrome hypothesis suggests that differences in personalities result from divergent life‐history strategies, with more active/risk‐taking individuals reproducing rapidly but dying young. However, studies of wild animals provide only limited support for key elements of this and related hypotheses, such as a negative relationship between residual reproductive value and activity. Furthermore, alternative models make divergent predictions regarding the relationship between risk‐taking behaviours and variables consistent in the short‐term, such as condition. To test these predictions, we regularly measured willingness to leave a shelter and the activity level of wild adult field crickets (Gryllus campestris) at both short and long intervals over their entire adult lives. We found some support for a pace‐of‐life syndrome influencing personality, as lifespan was negatively related to willingness to leave the shelter and activity. Crickets did not appear to protect their “assets” however, as estimates of residual reproductive value were not related to behaviour. Although there was considerable variance attributed to the short‐term consistency, neither trait was affected by phenotypic condition, failing to support either of the models we tested. Our study confirms that behaviours may covary with some life‐history traits and highlights the scales of temporal consistency that are more difficult to explain.     

Dispersal behaviour of African wild dogs in Kenya

Dispersal behaviour plays a key role in social organisation, demography and population genetics. We describe dispersal behaviour in a population of African wild dogs (Lycaon pictus) in Kenya. Almost all individuals, of both sexes, left their natal packs, with 45 of 46 reproductively active “alpha” individuals acquiring their status through dispersal. Dispersal age, group size and distance did not differ between males and females. However, only females embarked on secondary dispersal, probably reflecting stronger reproductive competition among females than males. When dispersing, GPS-collared wild dogs travelled further than when resident, both in daylight and by night, following routes an order of magnitude longer than the straight-line distance covered. Dispersers experienced a daily mortality risk three times that experienced by adults in resident packs. The detailed movement data provided by GPS-collars helped to reconcile differences between dispersal patterns reported previously from other wild dog populations. However, the dispersal patterns observed at this and other sites contrast with those assumed in published demographic models for this endangered species. Given the central role of dispersal in demography, models of wild dog population dynamics need to be updated to account for improved understanding of dispersal processes.     

Demographic and functional responses of wild dogs to poison baiting

Lethal control of wild dogs – that is Dingo (Canis lupus dingo) and Dingo/Dog (Canis lupus familiaris) hybrids – to reduce livestock predation in Australian rangelands is claimed to cause continental‐scale impacts on biodiversity. Although top predator populations may recover numerically after baiting, they are predicted to be functionally different and incapable of fulfilling critical ecological roles. This study reports the impact of baiting programmes on wild dog abundance, age structures and the prey of wild dogs during large‐scale manipulative experiments. Wild dog relative abundance almost always decreased after baiting, but reductions were variable and short‐lived unless the prior baiting programme was particularly effective or there were follow‐up baiting programmes within a few months. However, age structures of wild dogs in baited and nil‐treatment areas were demonstrably different, and prey populations did diverge relative to nil‐treatment areas. Re‐analysed observations of wild dogs preying on kangaroos from a separate study show that successful chases that result in attacks of kangaroos by wild dogs occurred when mean wild dog ages were higher and mean group size was larger. It is likely that the impact of lethal control on wild dog numbers, group sizes and age structures compromise their ability to handle large difficult‐to‐catch prey. Under certain circumstances, these changes sometimes lead to increased calf loss (Bos indicus/B. taurus genotypes) and kangaroo numbers. Rangeland beef producers could consider controlling wild dogs in high‐risk periods when predation is more likely and avoid baiting at other times.