Food selection by the guanaco (Lama guanicoe) along an altitudinal gradient in the Southern Andean Precordillera (Argentina)

Wild ungulates like the guanaco are exposed to important changes in climate and plant diversity along altitudinal gradients in the Andes Mountains, such as in the Southern Andean Precordillera where three phytogeographic provinces are present in altitudinal belts. The guanaco’s diet and food availability were seasonally analyzed using microhistological analysis and point-quadrat transects at six sampling sites, representative of the phytogeographic belts along the altitudinal gradient. Plant cover and diversity decreased with growing altitude. Richness of plant species was poorer at the summit than in the lower altitudes, whereas the proportion of species eaten by guanacos increased with altitude. The diet included 77 species. Grasses were preferred and shrubs were avoided all year round. The grass Poa spp. occupied more than 50 % of the diet at all altitudes. Grasses were the main dietary item even at low altitudes, where shrubs constituted the main food available. Decreasing generalism with descending phytogeographic belts agrees with the prediction for altitudinal gradients. The increase of diversity in the diet during the winter decline of plant cover at high and middle altitudes follows that expected from the optimal foraging theory. The winter decline of vegetation and the dietary shift from grazing to browsing proved to be stronger as altitude increases and the climate become more rigorous. Plant species richness, food scarcity, and climate severity are relevant variables to explain altitudinal and seasonal changes in the diet of adaptive ungulates in mountain environments, such as the guanaco in the Southern Andean Precordillera.     

Group size, spatial segregation and activity of wild sympatric vicuñas Vicugna vicugna and guanacos Lama guanicöe

Group size, activity and spatial segregation of sympatric guanacos and vicuñas have been investigated in the wild in the Catamarca Andes, Argentina. A total of 65 groups of vicuñas and 32 of guanacos was sighted. The size of vicuña and guanaco groups (mean ± SD: 4.8 ± 4.5 individuals and 3.5 ± 3.6 individuals respectively) fell within the range reported by other studies. The occurrence of solitary guanacos was unusually high. Spatial overlap between vicuñas and guanacos was wide and occurred from 4000 to 4200 m altitude. Possibly, the two species attained segregation through the use of areas differing in slope gradient. Most guanacos and vicuñas were foraging when spotted. The proportions of individuals engaged in foraging, resting and walking were, however, different between the two species, the percentage of guanacos grazing (94%) being particularly high in comparison with vicuñas (69%). Vicuña activity pattern varied throughout the day. They were on the move mainly just after midday and rested mainly late in the afternoon. Guanaco group size and pattern of activity showed more variations from other studies than those of vicuña. These differences may be related to the high altitude. In such an area, which lies at the upper limit of their altitudinal range, guanacos may have problems in meeting their energy demands, which are higher than those of vicuñas. Competition between the two species may occur in sympatric areas.     

Ranging behaviour and habitat preference of a wild marmoset group, Callithrix humeralifer (Callitrichidae, Primates)

The ranging behaviour of a group of marmosets ( Callithrix humeralifer ) in seasonal Amazonian rain forest was studied during one year. Range sizes (monthly and daily), day range lengths and patterns of range use are examined for correlations with feeding behaviour and the distribution of three forest types within the marmoset's range. Seasonal differences in ranging are associated with changes in the abundance and distribution of plant food sources. The marmosets ranged more widely and used more sources of a greater diversity of plant food species, which were distributed over a wider area, in the wet season than in the dry season. In the dry season, they ranged over a smaller area and, although they used fewer sources of a reduced diversity of plant species overall, they exploited a larger number of sources of the five highest ranked plant species in the diet. Throughout the year, they showed a preference for disturbed primary forest, characterized by dense understoreys and abundant second growth patches. Reasons for this preference are discussed, taking into account their use of fruits of typical pioneer species (particularly in the dry season), insect prey abundance, sleeping site availability and defence against predators.     

Bayesian Inference on the Effect of Density Dependence and Weather on a Guanaco Population from Chile

Understanding the mechanisms that drive population dynamics is fundamental for management of wild populations. The guanaco (Lama guanicoe) is one of two wild camelid species in South America. We evaluated the effects of density dependence and weather variables on population regulation based on a time series of 36 years of population sampling of guanacos in Tierra del Fuego, Chile. The population density varied between 2.7 and 30.7 guanaco/km², with an apparent monotonic growth during the first 25 years; however, in the last 10 years the population has shown large fluctuations, suggesting that it might have reached its carrying capacity. We used a Bayesian state-space framework and model selection to determine the effect of density and environmental variables on guanaco population dynamics. Our results show that the population is under density dependent regulation and that it is currently fluctuating around an average carrying capacity of 45,000 guanacos. We also found a significant positive effect of previous winter temperature while sheep density has a strong negative effect on the guanaco population growth. We conclude that there are significant density dependent processes and that climate as well as competition with domestic species have important effects determining the population size of guanacos, with important implications for management and conservation.     

Seasonal and geographical influences on the feeding ecology of giraffes in the Luangwa Valley,Zambia: 1973–2014

Obtaining longitudinal data about the feeding ecology of long‐lived iteroparous mammals is rare, but enhances our understanding of how the environment influences niche breadth and dietary diversity within a species. We analysed forty years of feeding records obtained from a population of Thornicroft's giraffes (Giraffa camelopardalis thornicrofti) living in the Luangwa Valley, Zambia. Giraffes are browsers that have been reported to feed primarily upon Acacia leaves, but their feeding ecology in some locations conflict with this interpretation. Giraffes in the Luangwa Valley fed on 93 identified plant species, but only a few contributed to the bulk of the diet. Niche breadth was quite large (Shannon‐Weiner Diversity Index H′ = 3.699) and about 13% more diverse during the dry, than wet, season. Key species eaten during the dry season were very consistent across decades, with Kigelia africana and Capparis tomentosa prominent at this time. The evolutionary ecology of giraffes has probably benefitted from a foraging strategy that includes a variable and high‐quality diet during the hot, dry season, when feeding pressures are greatest. Giraffe feeding ecology has evolved in conjunction with their physiology, anatomy and morphology, resulting in an animal that is well adapted for survival in an arid environment.     

Seasonal and individual predictors of diet in a free‐ranging population of mandrills

Deciphering the dietary habits of a species is central to understanding its ecology, resource requirements, and the evolution of its life history traits. Detailed information on how primates use their environment to address their nutritional needs is available for many primate species. Such basic, but necessary data are, however, fragmented for secretive primates, especially regarding direct behavioral observations of individuals. In this study, we evaluated the impact of seasonality and demographic characteristics on diet and feeding habits in the only free‐ranging population of habituated mandrills (Mandrillus sphinx), a forest‐dwelling species inhabiting the dense humid forests of Central Africa. We collected fine‐grained quantitative data on feeding behavior of 57 individually‐recognized animals of both sexes and different age classes during a 17‐month period. We identified most consumed plant species and determined their abundance in the habitat of the studied mandrills. We showed that diet in this species was extremely diverse and included approximately 150 different plant species, but also mushrooms, invertebrates, and vertebrates. This omnivorous and highly diverse diet presented, however, a clear frugivorous tendency. While we identified three food items largely consumed throughout the year, we also found a strong seasonal signature on diet that was partly, but not only, related to food availability. Age and sex also influenced feeding habits with some feeding specializations according to the individual categories considered and their associated nutritional needs. Our quantitative data provide a basis for future studies examining the nutritional and mineral content of food items, which will further elucidate important aspects of the ecology of this little studied forest primate.     

Wet and dry season diets of the Endangered Lemur catta (ring‐tailed lemur) in two mountainous rocky outcrop forest fragments in south‐central Madagascar

Lemur catta's ability to consume a wide variety of plant foods is a key to this species' survival in a time of ecological crisis across its geographic range. We examined seasonal diet variability of L. catta groups inhabiting two rocky outcrop fragments in south‐central Madagascar: Anja Reserve and Tsaranoro Valley forest. Leaves and fruit of Melia azedarach were a keystone resource for Anja lemurs in wet and dry seasons. At Tsaranoro, L. catta relied on M. azedarach and Ficus spp. in dry season, but during the wet season, neither was a dominant food resource. Top food species at both sites differed markedly from those consumed by L. catta in other habitats. At Tsaranoro, a greater proportion of lemurs engaged in feeding during the dry season compared with wet season. We attribute this to resource scarcity during dry season, when greater feeding effort is needed to maintain energy requirements. Because M. azedarach is ubiquitous throughout Anja Reserve, producing fruit and leaves year‐round, Anja lemurs can meet energy requirements with little seasonal adjustment in feeding activity. L. catta's IUCN status has been upgraded to Endangered, thus, greater insight into its diet flexibility and ability to survive on introduced plant species, can inform conservation plans in remaining wild habitats and ex situ programs.     

Composition and seasonality of diet in wild Hamadryas baboons: preliminary findings from Filoha

Here we report the first year-round quantitative data on dietary composition and seasonality in wild hamadryas baboons. Study subjects were adult male members of band 3 at the Filoha field site in central lowland Ethiopia. Data collection consisted of 10-min focal samples during all-day follows 4-6 days per month over the course of 1 year. The two largest contributors to the diet were Hyphaene thebaica and Acacia senegal, and these were the only plant species found in the diet during every month of the year. Other relatively major contributors to the diet, such as Cyperus grandibulbosus, Seddera bagshawei, Tribulus cistoides and Typhalatifolia, showed a seasonal pattern. Fewer plant species were consumed during the dry months of the year compared to the wet months. During the hottest and driest months of the year, study subjects subsisted almost exclusively on H. thebaica, A. senegal, C. grandibulbosus and T.latifolia. Overall, these patterns suggest that this population of hamadryas baboons spends less time feeding and is able to subsist on a narrower array of plant foods compared to other baboons. This pattern may be driven by the presence at Filoha of the doum palm (H. thebaica), a high-quality food resource that is consumed year-round.     

Guanaco (Lama guanicoe) mortality by entanglement in wire fences

Wire fences are widely used in rangelands around the world and may have a negative impact on wildlife that varies among species and habitats. The guanaco (Lama guanicoe) is the largest Patagonian ungulate and though entanglement in wire fences is frequently reported, its impact on guanaco populations has not been previously evaluated. We estimated annual mortality rate of wild guanacos due to entanglement in wire fences and evaluated whether the frequency of entanglement was age-dependent in the two wire-fence designs traditionally used in Patagonian sheep ranches. We found that annual yearling mortality on fences (5.53%) was higher than adult mortality (0.84%) and was more frequent in ovine (93 cm high) than bovine (113 cm) fences. Most guanacos died entangled by their legs in the highest wire when trying to jump over the fence. Our results suggest that guanacos are more likely to die due to fence entanglement than ungulates studied in other regions. Indirect effects of wire fences should also be considered as they may act as semi-permeable barriers for guanaco populations. We suggest removal of unnecessary wire fences and replacement by guanaco-friendly fences, like high-tensile electric fences that may reduce mortality and barrier-effect on guanaco populations.     

Diet of <Emphasis Type="Italic">Pygathrix nigripes</Emphasis> in Southern Vietnam

Black-shanked douc langurs (Pygathrix nigripes) are Southeast Asian colobines about which primatologists know very little, but they are classed as endangered because of population decline due to habitat loss. Two preliminary studies have shown that this monkey is primarily folivorous, but there are few details of plant selection or seasonal changes in diet. We set out to observe douc langurs directly in the wild to quantify the diet during wet and dry seasons. We confirmed that the species relies on foliage throughout the year, but it includes significant proportions of fruit and flowers in its diet when those items are available. The douc langurs selected various parts from 152 species of plants in 2 national parks, but there did not appear to be favorite species that were heavily selected over others. In both the wet and dry seasons, the black-shanked douc langurs ate mostly leaves, but the diversity of plants consumed increased and the proportion of fruit eaten almost doubled in the wet season. There were diurnal shifts in food selection, but we found no evidence that the douc langurs were foraging strategically to maximize their protein or energy intake.     

Behavioural and physiological stress responses to handling in wild guanacos

Both ethology and physiology can provide insights about stress conditions in wild animals during handling. Lama guanicoe (guanaco) is the major large herbivore inhabiting arid zones in Argentina. Since 2005, the Payún Matrú Cooperative, a business established and run by native people, has captured and handled guanacos for shearing at Payunia Reserve, Mendoza Province, Argentina, to market the species’ fibre for clothing and other products. The aim of our study was to evaluate the behavioural and physiological stress responses to handling of wild guanacos during these shearing activities. We evaluated stress conditions in guanacos by monitoring the frequency of agonistic behaviour in the holding corrals, following capture, the rate of vocalisation and agonistic behaviour during handling, and by estimating cortisol levels in handled animals. Crowding increased agonistic behaviour; this appeared to be related to dominance conflicts between males in the corrals. Time of corralling increased rate of agonistic behaviour and vocalisations during handling. The rate of behavioural stress responses was negatively related to cortisol levels in males; which may be due to animal fatigue or because behavioural stress responses may help mitigate physiological stress responses. Incorporating our results into animal welfare practices could help reduce stress conditions in wild guanacos. Our results suggest that both behavioural and physiological responses are important measures of stress in handled animals, and that behavioural stress responses cannot be used as a simple surrogate for glucocorticoid levels.     

Cooperative vigilance: the guanaco's (Lama guanicoe) key antipredator mechanism

The concept of sociality has been associated with the effectiveness of antipredator mechanisms, like cooperative vigilance and the dilution effect. Lama guanicoe (guanaco) is a social native herbivore in South America and a social species. The objectives of this study were to evaluate the antipredator responses of different-sized groups of guanacos in areas with varying predation risks and to determine antipredator mechanisms in guanacos. For this, we measured different antipredator responses to a potential predator (human subjects). Detection of predator and flight distances from predator both increased with a greater number of guanacos per group and with greater distances among guanacos within the social group. Both buffer distance and flight time decreased with a greater number of guanacos per group, but increased with greater distances among guanacos inside the social group. Solitary adult males moved shorter distance and mixed groups moved greater distances. Flight distances were greater in areas with tall and dense vegetation than in areas with low vegetation. Buffer distance and flight time were shorter in undulating land than on flat lands, and groups were usually observed on hill slopes. Our results suggest that the benefit of social grouping in guanacos is the increased probability of avoiding predator with cooperative vigilance and not with the dilution effect. This means that a predator could be detected earlier when approaching a guanaco group than when approaching a solitary individuals and could thus be avoided.     

The food habits of wild ungulates in Uganda by analyses of stomach contents

Food eaten by six species of ungulates was studied by analysing stomach contents, using the method developed for faecal analyses. Frequency analyses showed that some herbivore species tend to be selective in their feeding. This suggested that availability and growth form of plants may be important in this respect. The observations agreed with those of other workers, which shows that feeding habits are consistent over large areas. In general, herbivores were classified in three groups with regard to preferences; namely pigs, certain antelope, and buffalo and waterbuck. Comparison of the proportions of epidermal fragments of particular grass species present in stomachs in wet and dry seasons showed that significant seasonal differences exist in the diet of most herbivores. Annuals and most members of the Andropogoneae were present in stomachs in larger proportions during the rains for reasons of availability and palatability. Chloris gayana and Sporobolus pyramidalis were usually present in greater proportions in dry seasons. Differences in the proportions of epidermal fragments of particular plant species present within wet or dry seasons were usually insignificant. A few herbivores, however, showed significant differences within seasons. This indicates that they are sensitive to small changes in plants and that they may have a feeding cycle involving a gradual and regular alternation of plant species. A comparison of the proportions of fragments of the same plant species in different herbivores showed that animal species usually avoided competition by their specialized food habits. There was greater separation in the longer dry season, but competition may have occurred when food supplies were reduced by large herbivores such as buffalo and hippopotamus.     

Odocoileus virginianus diet (Artiodactyla: Cervidae) in a temperate forest of Northern Oaxaca, Mexico

The Sierra Madre de Oaxaca region, located in the Northern state of Oaxaca, Mexico, is an area of forest ecosystems subject to high exploitation rates, although in some areas its temperate forests are conserved by indigenous community initiatives that live there. We analyzed the diet of white tailed-deer (Odocoileus virginianus) in the localities of Santa Catarina Lachatao and San Miguel Amatlán from June 1998 to August 1999. Sampling was done during both the wet and dry seasons, and included the observation of browsing traces (238 observations), microhistological analysis of deer feces (28 deer pellet-groups), and two stomach content analysis. The annual diet of white-tailed deer was composed of 42 species from 23 botanical families. The most represented families in the diet of this deer were Fagaceae, Asteraceae, Ericaceae and Fabaceae. There were significant differences in the alpha diversity of the diet during the wet and dry seasons (H'=2.957 and H'=1.832, respectively). The similarity percentage between seasons was 56%. Differences in plant species frequency were significantly higher during the wet season. Herbaceous plants made up the greatest percentage of all the species consumed. The preferred species throughout the year were Senecio sp. (shrub), Sedum dendroideum (herbaceous), Arctostaphylos pungens (shrub) and Satureja macrostema (shrub). Diet species richness was found to be lower than that observed in a tropical forest (Venezuela), tropical dry forest (Mexico) and temperate deciduous and mixed forest (Mexico), but similar to the diet species richness observed in a tropical dry forest (Costa Rica) and temperate coniferous and deciduous forests (USA).     

Environmental constraints on the foraging behaviour of a dwarf antelope (Madoqua kirkii)

Dik-diks (Madoqua sp.) inhabit semi-arid regions and experience very different conditions of food availability and quality between wet and dry seasons. By comparing the behaviour of dik-diks between these two seasons, we identified environmental constraints affecting their feeding strategies. In both seasons foraging time was limited by high mid day temperatures. In the wet season a high intake rate compensates for the loss in foraging time, but in the dry season water and protein become limiting. To meet minimum daily water requirements in the dry season dik-diks fed on plant species that they avoided during the wet season. Analysis at the plant species level showed higher species selectivity in the wet season than in the dry season. In a multiple regression analysis food species preferences were best explained by relative abundance and water content in the dry season, and by dry matter content in the wet season. In the wet season the daily dry-matter intake of dik-diks in the field was only about 10% higher than the theoretically predicted minimum for a ruminant of this body weight, while protein and water intake were about 3 times as high. This suggests that the most limiting dietary component in the wet season is energy. In the dry season the daily intake of all dietary components is lower than the theoretical minimum required, and also lower than the values suggested by laboratory studies of dik-diks. This dry season deficit is presumably met from body reserves. Dry season water intake was approximately 30% of the intake observed in laboratory studies indicating that dikdiks are even better adapted to arid conditions than suggested by physiological experiments.     

Ontogenetic diet shifts and resource partitioning among piscivorous fishes in the Venezuelan ilanos

Synopsis Resource utilization by nine abundant piscivores from a diverse tropical fish assemblage was examined over the course of a year. All nine species exhibited peak reproduction during the early wet season and a similar sequence of size-dependent shifts from a diet composed primarily of microcrustacea, to aquatic insects, and finally fishes. Three piranha species specialized on fish fins, particularly at subadult size classes (SL 30–80 mm). Gradual dessication of the floodplain during the transition season was associated with fish growth, increased fish density, and decreased aquatic primary productivity and availability of invertebrate prey. Based on 118 resource categories, average pairwise diet overlap was low during all three seasons: wet, transition, and dry. Of 72 species pairings, only one pair of fin-nipping piranhas exhibited high overlap simultaneously on three niche dimensions: food type, food size, and habitat. Adults of two species, a gymnotid knifefish and pimelodid catfish, were largely nocturnal. Patterns of habitat utilization indicate that piranhas may restrict diurnal use of the open-water region by other piscivores. Collective diet overlap of individual piscivore species with the other eight feeding guild members and collective overlaps with the entire fish community each revealed two basic seasonal trends. Four species that showed an early switch to piscivory also showed a high degree of diet separation with both the guild and community at large on a year-round basis. The five remaining species showed lowest collective diet overlaps during the transition season when availability of invertebrates was reduced and fish densities were maximal. Whereas predation may play a role in habitat separation, diffuse competition for food resources during the approximately four-month transition season probably is the principal factor yielding patterns of diet specialization.     

Feeding of tropical freshwater fishes: seasonality in resource availability and resource use

Summary Food resources in the environment and in the diets of small fish inhabiting two water bodies in a tropical savanna were studied during both wet and dry seasons. During the wet season (high water, abundant food) most fish species in both habitats fed predominantly on vegetation-dwelling invertebrates. Most fish species switched to alternative foods (algae and detritus) following the drastic decline in invertebrate food available towards the end of the dry season. In one habitat, this change in diet was accompanied by an increase in the volume of food intake. In the second habitat, only two larger species foraged intensively, while smaller species showed low food intake or almost ceased feeding. These differences may be explained by the high risk of predation for small fish in the second habitat. Dietary overlaps among fish species were high at the end of the dry season and moderate in the wet season. However, critical analysis of such factors as food abundance, the size and number of shared prey, and diet breadth showed that all significant overlaps were ecologically unimportant i.e. there was only weak competition for food.     

Diet selection in the green ringtail possum (Pseudochirops archeri): A specialist folivore in a diverse forest

Abstract This study investigated the feeding ecology of the green ringtail possum, Pseudochirops archeri (Pseudocheiridae) in a tropical rainforest with 94 plant species in the canopy. Over 50% of tree use was from only four tree species, Aleurites rockinghamensis, Ficus fraseri, Arytera divaricata and Ficus copiosa. These species were used significantly more frequently than would be expected if tree species were selected randomly in proportion to their relative abundance in the forest. Conversely, 88 other tree species present were used less frequently than expected. Possums also favoured particular individual trees within some of the preferred tree species. In 91% of feeding observations, possums consumed mature leaves only. The availability of young leaves, flowers and fruit varied throughout the year, with a peak in availability of these resources during the early wet season. By primarily selecting mature leaves, green ringtail possums reduce their dependence on seasonally variable resources. We suggest that green ringtail possums should be considered as specialist folivores, focusing on only a few of the tree species available, possibly due to advantages associated with limiting the number of plant secondary metabolites in their diet. Furthermore, they favour certain individual trees within species, perhaps due to intraspecific variation in plant secondary metabolites or nutrient content, behaviour that has been well established in eucalypt folivores. We conclude that green ringtail possums are highly specialized in their feeding ecology, limiting their diet to a small number of continuously available food items.     

Diets of the African Civet Civettictis civetta (Schreber, 1778) in selected coffee forest habitat,south‐western Ethiopia

Feeding ecology of the African civet, Civettictis civetta (Schreber, 1778), was studied in selected coffee forest habitat for two seasons between December 2012 and October 2013. The study was conducted in Limu Seka district, south‐west Ethiopia. Faecal analysis was employed to assess the diet spectrum, seasonal abundance and relative importance of food items. Over 55 different food items were identified from the analysis of 387 scat samples collected during the dry and wet seasons. In the coffee forest habitat, African civets showed omnivorous feeding habit with plant‐to‐animal diet biomass ratio of 1 : 1.36. A slight diet specialization was observed during the wet season (BA = 0.46) favouring animal prey. However, during the dry season, they showed generalist feeding habit (BA = 0.87) with more plant biomass in their diet. With over 64% occurrence and 14.4% biomass, coffee berries significantly contributed to the civets dry season plant diets. The excreted coffee beans, after civets ingested ripe coffee berries, are the tastiest product used by farmers for consumption and market. Seasonal collection of civet coffee from coffee forest floor economically supports the farmers while increasing the importance of civets in the habitat and hence contributing for its conservation.     

Baboon diet: a five-year study of stability and variability in the plant feeding and habitat of the yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania

The habitat and plant feeding of 64 well-habituated, individually identified adult male and female yellow baboons was studied for 5 years at Mikumi National Park, Tanzania. Variation across the years showed that a study of only one or two years would have been incomplete and misleading. The list of baboon food species obtained from Mikumi is considerably larger and more diverse than any previously reported. One to six plant parts were eaten from each of more than 180 species. The 25 most common tree genera all contained species used for food. Of the 50 most common grass, shrub and herb genera, 93% included plant foods. Using months in which a species was eaten during at least one year of the study, 21 staple species were eaten during a mean of 8.86 months and 7 were eaten in all 12 months. Although many foods were from commonly available plant species, 15 such species were only rarely eaten. The number of parts of a species eaten per month and an estimate of the amounts eaten per month both varied with temperature and rainfall, being lowest near the end of the cool, dry season. There were substantial differences from year to year in the timing and amount of food production of many species; nevertheless, the same broad feeding pattern was repeated in each of the 5 years of the study. Despite yearly variation in food availability, 14 or more staples and other common foods were eaten in any given month. If crops of many of these foods were to fail, a large number of less commonly eaten species could be substituted. Baboons are eclectic feeders that appear to be optimizing their diet by selective feeding from among a wide array of available foods in an ever-changing floristic environment.