Provisioning in wild golden lion tamarins (Leontopithecus rosalia): benefits to omnivorous young

Provisioning may act to cushion weaned young from dietary insufficiencyand errors during the period in which they are mastering complexforaging techniques or learning to identify appropriate dietaryitems. That is, young mammals who receive food from others maygain nutritional and/or informational benefits. I conducteda longitudinal study of 13 wild golden lion tamarins 11–56weeks of age in six groups to evaluate hypotheses regardingthe functions of provisioning. All members belonging to thisprimate taxonomic family (the Callitrichidae) are cooperativebreeders and are known to provision their young more frequentlythan do other primate species, except humans. My results, togetherwith experimental findings, suggest that juveniles receive bothnutritional and informational benefits from being provisioned.My juvenile study subjects received animal prey (invertebratesand small vertebrates) from others more frequently than plantresources (fruits and hardened exudates). Apparently difficult-to-handlefruits were more likely to be transferred than readily processedfruits. These results support the nutritional benefits hypothesisbecause the young received items, particularly lipid- and protein-richprey, that they might not otherwise have acquired. That juvenilesfed independently on, and were provisioned with, the same fruitson the same day is counterevidence to the nutritional benefitshypothesis, however. The informational benefits hypothesis wassupported because juveniles received a large variety of foods(including more than 20% of fruit species eaten) and receiveduncommon fruits that were easily acquired. Adults emitted food-offeringcalls to encourage the transfer of prey to juveniles, particularlywhen the prey was whole and alive.     

雪豹两种人工育幼方式比较

北京动物园分别采用全人工和人工．狗乳交替哺育的方法,成功哺育6只雪豹幼崽。通过对育幼箱内外温、湿度的监测结果表明,幼崽呼吸频率随年龄增加而呈现周期性波动,9周后接近成年雪豹;幼崽体温0—87日龄呈逐渐下降趋势,50日龄后趋于稳定;排便和排尿量均随年龄增长呈增加趋势,70日龄增长量趋缓;幼崽体重直线增长。通过对两种哺育方式的卡方检验结果表明,两种哺育方式下雪豹幼崽体重生长存在显著差异。育幼箱内温度和幼崽自身体温对体重增长具有显著的影响;体温与幼崽呼吸频率和进食量具有显著的相关性。此外,还应注意饲料转换时机及微量元素对幼年雪豹生长发育的重要性。     

Offspring food allocation by parents and helpers in a cooperative mammal

In cooperatively breeding species, helpers and parents commonlyface two decisions when they find a food item: first, whetherto feed the item to a young group member or to eat it themselves;and second, which offspring to feed. Little is known aboutthe factors that influence these decisions in cooperative mammals,though optimal foraging theory provides a basis for a rangeof predictions. In this article we describe pup feeding behaviorby helpers and parents in a cooperative mongoose, the meerkat(Suricata suricatta). When meerkat pups begin accompanyingthe group, they beg food from older group members, who digup dispersed prey items. As predicted, the probability of aprey item being fed to a pup shows a positive relationship with prey size and a negative relationship with pup distance.Meerkats apparently follow a "feed the nearest pup rule" andare more likely to feed the nearest pup if it is hungry. Hungrierpups beg more and follow older group members more closely.Across all age categories, females feed pups more frequentlythan males, both in terms of the relative frequency of feeds,and the proportion of prey biomass found by each individualthat is fed to pups. Females also feed female pups significantlymore than male pups, while males feed pups of both sexes equally.These sex biases in feeding contributions may result from femalegroup members benefiting more than males from higher pup survival,and in particular higher female pup survival, because femalesare the philopatric sex.     

豚鹿的饲养管理与繁殖

本文报道成都动物园豚鹿的饲养管理、疾病预防和繁殖。适宜的饲养环境、宽敞的兽舍、高纤维含量和多样化的食物是豚鹿正常生长发育、繁殖的重要因素。     

Effects of Metarhizium anisopliae on searching,feeding and predation by Orius albidipennis (Hem., Anthocoridae) on Thrips tabaci (Thy., Thripidae) larvae

The generalist predator Orius albidipennis Reut. (Hem., Anthocoridae) and entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin (Ascomycota: Clavicipitaceae) are important biocontrol agents of Thrips tabaci Lindeman (Thys., Thripidae) in most greenhouses. In this study, we estimated searching time, feeding time and predation rate in O. albidipennis feeding on untreated and treated thrips larvae which had been inoculated with three concentrations of M. anisopliae V275 at four time intervals; 0, 24, 48 and 72 h after infestation. Applied concentrations were 1×10³, 2×10⁴ and 2×10⁵ conidia/mL which roughly correspond to the LC₂₅, LC₅₀ and LC₇₅ for second instar-larvae. O. albidipennis responded to the presence of the M. anisopliae on the treated hosts by increasing the searching time and decreasing feeding time and predation rate levels. It was also able to detect and avoid treated patches.     

Reproduction and survival of suricates (Suricata suricatta) in the southern Kalahari

In most respects, the demography of Kalahari suricates (Suricata suricatta) resembles that of other social mongooses. Average group size varies from four to nine, and groups typically include several mature females, of which one is responsible for the majority of breeding attempts. Breeding females show a postpartum oestrus; gestation is around 60 days; litter size is three to five pups at emergence and females rarely breed before the age of 24 months. In contrast, annual survival rates (0.20 for pups and 0.43 for animals over one year old) are lower than those recorded in other species. Breeding frequency is related to rainfall and breeding can cease altogether when rainfall is unusually low. In a year when this occurred, group size eroded rapidly and over 60% of groups became extinct. Total numbers were slow to recover during the following year because emigration by females was infrequent and new groups did not form in vacant ranges created by the extinction of groups. High rates of group extinction have been found in other cooperative breeders and may occur because breeding success and survival show inverse density dependence.     

Is foraging innovation lost following colonization of a less variable environment? A case study in surface‐ vs. cave‐dwelling Asellus aquaticus

Behavioral innovation is a key process for successful colonization of new habitat types. However, it is costly due to the necessary cognitive and neural demands and typically connected to ecological generalism. Therefore, loss of behavioral innovativeness is predicted following colonization of new, simple, and invariable environments. We tested this prediction by studying foraging innovativeness in the freshwater isopod Asellus aquaticus. We sampled its populations along the route of colonizing a thermokarstic water‐filled cave (simple, stable habitat with only bacterial mats as food) from surface habitats (variable environment, wide variety of food). The studied cave population separated from the surface populations at least 60,000 years ago. Animals were tested both with familiar and novel food types (cave food: bacterial mats; surface food: decaying leaves). Irrespective of food type, cave individuals were more likely to feed than surface individuals. Further, animals from all populations fed longer on leaves than on bacteria, even though leaves were novel for the cave animals. Our results support that cave A. aquaticus did not lose the ability to use the ancestral (surface) food type after adapting to a simple, stable, and highly specialized habitat.     

Predation, group size and mortality in a cooperative mongoose, Suricata suricatta

1. In social mammals where group members cooperate to detect predators and raise young, members of small groups commonly show higher mortality or lower breeding success than members of large ones. It is generally assumed that this is because large group size allows individuals to detect or repel predators more effectively but other benefits of group size may also be involved, including reduced costs of raising young and more effective competition for resources with neighbouring groups.
2. To investigate the extent to which predation rate affects survival, we compared mortality rates in two populations of suricates ( Suricata suricatta ), one living in an area of high predator density (Kalahari Gemsbok Park) and one living in an area of relatively low predator density (neighbouring ranchland). Most aspects of feeding ecology and growth (including time spent feeding, daily weight gain, growth, adult body weight, breeding frequency and neonatal mortality) were similar in the two populations. In contrast, mortality of animals over 3 months old was 1·7 times higher in the Park than on ranchland.
3. Mortality of juveniles between emergence from the natal burrow and 6 months of age was higher in small groups than large ones in the Park but significantly lower in small groups than large ones on ranchland. Adult mortality declined in larger groups in both areas.
4. The tendency for survival to be low in small groups had far-reaching consequences for the risk of group extinction. During a year of low rainfall in the Park, all groups of less than nine animals became extinct and population density declined to around a third of its initial level. We argue that high group extinction rates are to be expected in species where survival declines in small groups and mortality rates are high.     

Stress and the costs of extra-territorial movement in a social carnivore

Costs associated with extra-territorial movement are believed to have favoured the evolution of delayed dispersal and sociality across a range of social vertebrates, but remain surprisingly poorly understood. Here we reveal a novel mechanism that may contribute substantially to the costs of extra-territorial movement: physiological stress. We show that subordinate male meerkats, Suricata suricatta, exhibit markedly elevated faecal glucocorticoid metabolite levels (a non-invasive measure of hypothalamic–pituitary–adrenal axis activity) while conducting extra-territorial prospecting forays. While brief increases in glucocorticoid levels are unlikely to be costly, chronic elevations, arising from prolonged and/or frequent forays, are expected to compromise fitness through their diverse negative effects on health. Our findings strongly suggest that prolonged extra-territorial movements do result in chronic stress, as the high glucocorticoid levels of prospectors do not diminish on longer forays and are no lower among males with greater prospecting experience. A generalized ‘stress’ of extra-territorial movement may therefore have strengthened selection for delayed dispersal and sociality in this and other species, and favoured the conduct of brief forays over extended periods of floating. Our findings have implications too for understanding the rank-related distribution of physiological stress in animal societies, as extra-territorial movements are often conducted solely by subordinates.     

Group provisioning limits sharing conflict among nestlings in joint-nesting Taiwan yuhinas

Offspring often compete over limited available resources. Such sibling competition may be detrimental to parents both because it entails wasted expenditure and because it allows stronger offspring to obtain a disproportionate share of resources. We studied nestling conflict over food and its resolution in a joint-nesting species of bird, the Taiwan yuhina (Yuhina brunneiceps). We show that adult yuhinas coordinate their feeding visits, and that this coordination limits competition among nestlings, leading to a ‘fairer’ division of resources. Transponder identification and video-recording systems were used to observe adult feeding and nestling begging behaviours. We found that: (i) yuhinas feed nestlings more often in large parties than in small parties; (ii) feeding events occurred non-randomly in bouts of very short intervals; and (iii) food distribution among nestlings was more evenly distributed, and fewer nestlings begged, during large-party feeding bouts compared with small-party feeding bouts. To our knowledge, this is the first study in a cooperative breeding species showing that adults can influence food allocation and competition among nestlings by coordinating their feeding visits. Our results confirm the hypothesis that the monopolizability of food affects the intensity of sibling competition, and highlight the importance of understanding the temporal strategies of food delivery.     

Behavioral laterality in captive bonobos (Pan paniscus): Replication and extension

We report observational data on behavioral laterality in 10 captive bonobos (Pan paniscus)at the San Diego Zoo. The unimanual measures include carrying, leading limb in locomotion, self-touching, face-touching, reaching, and gestures. We also recorded bimanual feeding in these subjects. A significant population level left-hand bias exists for carrying. Right-hand biases occur for leading limb in locomotion and gestures. During bimanual feeding, the bonobos hold food items with the left hand while feeding with the right hand. Overall, bonobos exhibit behavioral asymmetries that are similar to previous findings in other pongid ape species. The asymmetries in gestures and bimanual feeding represent novel findings with theoretical implications for the origins of tool use and language.     

A test of the importance of direct and indirect fitness benefits for helping decisions in western bluebirds

In cooperative breeders, the extent to which helpers at thenest adjust their contributions in accordance with direct andindirect (kin-selected) fitness payoffs remains an open question.In a long-term study of the western bluebird, Sialia mexicana,helpers were exclusively male and helped at nests of both parents,a parent and stepparent, or a brother and unrelated female.This natural variation in the context of helping facilitatedcomparison of observational data on groups in which one typeof fitness benefit (current direct, future direct, or indirect)varied, whereas the other two were constant. Helpers reducedtheir share of provisioning as they got older, so comparisonswere restricted to groups with yearling helpers. When potentialdirect fitness benefits were identical, but relatedness wasreduced by half owing to the presence of a stepparent, yearlinghelpers failed to reduce their share of feeding trips to thenest. The potential for future direct fitness benefits via possiblemate and territory inheritance was low, and did not influencethe helper's share of provisioning in a comparison of groupswith similar relatedness and opportunities for current directfitness benefits. Even though cobreeding to gain current directfitness benefits was infrequent (17% of nests with brother-helpers),it was associated with an increase in the helper's share ofprovisioning, suggesting that a helper's feeding allocationresponds positively to increased opportunity for parentage inthe nest. The current study demonstrates a useful frameworkfor separating direct and indirect benefits with respect tohelping decisions, and indicates that western bluebird helpersadjust their feeding rates in response to the potential fordirect fitness benefits in the current nest, not indirect benefitsor future direct fitness payoffs. Although past studies of thispopulation showed that indirect benefits play a role in whetheror not helpers help, the current study indicates that they donot play a role in how frequently helpers feed at the nest.