Social development of bonnet macaques from six months to three years of age: A longitudinal study

Observations of age-sex class associations of three young female and five young male bonnet macaques born in the spring, 1975, were taken semiannually over three years beginning in the fall, 1975. Analysis reveals several patterns: (1) both males and females show continuous decline in association with age mates; (2) solitary time of females peaks at 1.5 years after which they begin to associate with adult females; (3) solitary time of males peaks at 2.5 years after which they associate predominantly with sub-adult males; (4) both males and females showed higher association with juveniles of the same sex than of opposite sex; and (5) both males and females showed annual cycles of association with some age-sex classes. These results are best understood with reference to the natural breeding cycle of the animals and the different life histories of male and female macaques in the wild.     

Spatial organization of female groups in red deer (Cervus elaphus L.)

The spatial organization of female groups in red deer was studied in the periods before and after the rut, in a study area located in the central Sierra Morena (Córdoba, Spain). The study was carried out in terms of age-sex classes, and was based on direct observation and video recording.Movement order proved to be linear, and highlighted the role of the mature hind as group leader and potential group protector. Two tendencies were found in the calf: to place itself behind the adult female, and to take up a central position in the group. With regard to relationships of spatial proximity, the mature hind and the calf tended to keep separate from the rest of the group both in the period before and after the rut. The yearling male became progressively independent of the matriarchal group, tending in the second period of study to associate with individuals from its own age-sex class.     

Modification of aggression through socialization and the special case of adult and adolescent male rhesus monkeys (Macaca mulatta)

Significant differences exist in the frequencies with which age-sex classes of rhesus macaques engage in agonistic interactions with other age-sex classes. In the study reported here, individuals engaged in significantly more agonistic interactions within their own age-sex classes, but, adult females also showed significantly more aggression toward infants and young females whereas adult males directed significantly more aggression toward adolescent males. Infants directed aggression toward infants of both sexes, but adults showed significantly less aggression toward adults of the opposite sex. These findings are hypothesized to reflect (1) competitive conflict among those individuals in the group most similar to each other (members of the same age-sex class); (2) the protection and socialization of offspring by adult females; and (3) the modification of adolescent male aggressive expression by the selective interference of adult males. As a consequence of adult response to the agonistic behavior of adolescent males, maturing males (1) selectively target other older males, avoid aggression against females and immatures; (2) form alliances with other males; and (3) become progressively isolated from their matrilines.     

Geometry for a selfish foraging group: a genetic algorithm approach

The advantages of group living are not shared equally among all group members and these advantages may depend on the spatial position occupied by a forager within the group. For instance, it is thought that socially dominant individuals prefer the predator-safe central position of groups forcing subordinates to the periphery. Uneven spread of benefits among group members can occur when some animals (the scroungers) parasitically exploit the food findings of other foragers (the producers). Here we focus on how playing producer or scrounger affects an individual''s spatial position within a group. We model the movement of foraging animals playing scrounger or producer using a spatially explicit simulation and use a genetic algorithm to establish movement rules. We find that groups containing producers and scroungers are more compact compared to an equivalent group of producers only. Furthermore, the position occupied by strategies varies: scroungers are mainly found in central positions, while producers in the periphery, suggesting that the best position for strategies differs. Dominants, therefore, should prefer movement rules which lead to central positions because of the positional benefits provided to the scrounger strategy they use. Moreover, position within a group will introduce an asymmetry among otherwise phenotypically symmetric individuals.     

Demographic study of a large-sized unit-group of chimpanzees in the mahale mountains,Tanzania: A preliminary report

Long-term demographic observations on a large-sized unit-group of chimpanzees in the Mahale Mountains, Tanzania, are summarized. The unit-group, the M group, contains over 100 individuals, which makes it the largest unit-group ever reported. The age-sex composition, natality, mortality and transfers of the M group are analyzed. An attempt is made to illustrate an age-sex pyramid of the group by estimating the ages of all the individuals in the group. The results reveal that: (1) the mortality rate of the male infants within 1 year almost doubled that of female infant; (2) adult male to adult female ratio of the M group is considerably higher than any other unit-groups elsewhere; and (3) the M group contains a relatively large number of old animals over 40 years of age, suggesting that the longevity of wild chimpanzees might be greater than estimated so far.     

The influence of daily variation in foraging cost on the activity of small carnivores

The daily activity of some predators is correlated with the activity pattern of their prey. If capture efficiency varies as a function of prey activity, a predator that synchronizes its foraging activity with the time of day that prey are most vulnerable should capture more prey, and at lower cost, than a predator that initiates foraging at random. Mink, Mustela vison, and weasels, M. erminea and M. nivalis, were presented with an opportunity to maximize their intake in similar circumstances in the laboratory. An animal's ability to synchronize its foraging activity with the time of day when food was most available was tested. Energy costs (wheel revolutions) were varied to encourage an animal to redistribute its activity from a preferred 12-h phase of the light-dark cycle to the other phase, and then back again. The degree to which activity changed to coincide with the most economical phase was analysed for each individual, and weasels were compared to mink. The activity of six (of seven) animals shifted in response to modified foraging costs, but only two animals (both mink) approached the 180° redistribution of activity expected of an energy-maximizing forager. In general, all animals were active during a favoured phase (usually dark) of the light-dark cycle and relatively large variations in foraging cost during this cycle had only modest effects on activity.     

When food fights back: Cebid primate strategies of larval paper wasp predation and the high-energy yield of high-risk foraging

Optimal foraging theory predicts that well-defended potential foods should be exploited only when energy pay-offs are great. Although stinging hymenopteran nests are both well-defended and predated by primates, their larvae's energy yields rarely have been calculated, and predation-linked foraging behaviours by primates infrequently documented. Based on 58 opportunistic observations of primates raiding wasp nests for larvae, we calculated energetic yields of low- and high-risk wasp nest predation for Cebus albifrons, Saimiri collinsi, S. sciureus and Sapajus apella, and tested predictions derived from optimal foraging theory. We recorded how nests were processed and by which age-sex classes, eaten nest fragment sizes, number of occupied and empty cells, and nest occupancy patterns (percent larvae/pupae, eggs, empty cells). Basal metabolic rate (BMR) calculations showed energetic yields from 15 min foraging on low-risk nests (Polybia quadricincta) would meet energy needed to sustain adult female and male C. albifrons BMR for 4.9 and 4.5 h, respectively; yields from high-risk (Chartergus artifex) nests for 6.5 and 6.2 h; Mischocyttarus sp. nest yields (low risk, but mimetically resembling other wasps) would meet S. collinsi BMR for 2.9 h (female) and 2.3 h (male), and 2.6 and 2.1 h, for the slightly larger S. sciureus, respectively. The Chartergus energetic-yield value is nearly 20% of a 36 g chocolate bar (741 kJ). Our data provide quantitative support for the common assertion that wasp larvae and pupae are high-yield foods for primates. As predicted by optimal foraging, energetic yield is sufficient to offset the risk and pain of being stung.     

湖北石首麋鹿昼间活动时间分配

为探讨性别、年龄和季节对麋鹿(Elaphurus davidianus)行为的影响,2006年9月-2007年10月,作者采用焦点取样法和瞬时记录法,将麋鹿昼间活动归为采食、饮水、运动、休息、警觉、其他行为等六大类型,每月6-8 d对湖北石首麋鹿国家级自然保护区麋鹿种群的昼间活动时间分配进行了跟踪观察.结果表明:麋鹿有晨、昏两个采食高峰和一个午间休息期,各种行为类型所占比例依次是:休息53.40％(±5.59％)、采食22.36(±8.34％)、运动11.23％(±0.63％)、警觉5.03％(±1.76％)、其他行为4.42％(±2.06％),饮水2.65％(±0.74％).不同季节,时间分配变化明显.非参数Kruskal Wallis H检验结果显示(n=120),季节、年龄和性别显著影响麋鹿的活动时间分配.除运动行为(x2=16.856,df=3,P＞0.05)和饮水行为(x2=7.667,df=3,P＞0.05)无显著差异外,采食(x2=15.657,df=3,P＜0.01)、休息(x2=13.173,df=3,P＜0.01)、警觉(x2 =13.887,df=3,P＜0.01)和其他行为(x2=16.317,df=3,P＜0.01)在不同季节所占时间百分比均有极显著差异.对不同性别年龄组的活动时间分配采用两个独立样本的Mann-Whitney U检验,各性别-年龄组间的运动行为所占时间比例有极显著差异(P＜0.01),雄鹿与雌鹿之间的警觉行为有极显著差异(P＜0.01),雄鹿花较多时间用于警觉.幼鹿与成年鹿及亚成年鹿之间的采食行为时间有极显著差异(P＜0.01).不同性别、年龄组在不同季节的昼间活动时间分配的差异采用方差(ANOVA)分析后发现:所有年龄组,夏季与冬季饮水、春季与夏季警觉均存在显著性差异(P＜0.01);成体和亚成体麋鹿,春季与冬季警觉、夏季与冬季运动均存在显著性差异(P＜0.01).     

Balancing predation risk,social interference,and foraging opportunities in backswimmers,<Emphasis Type="Italic"> Notonecta maculata</Emphasis>

Loss of foraging opportunities and intraspecific competition for prey may be important costs of using refuges, because a hiding animal is unable to use or defend its foraging area from conspecific intrusions. Thus, animals should balance antipredator demands with other requirements in deciding when to come out from a refuge after a predators unsuccessful attack. Observations on foraging and social interactions of backswimmers Notonecta maculata suggest that foraging may be costly in terms of intraspecific agonistic interactions. When prey density is low, increasing the probability of finding a prey may require active exploration of a larger area, but this also increases the probability of encountering a competitor. After simulated exposure to predators, unfed bugs resumed feeding positions after a significantly shorter hiding period than recently fed bugs. We hypothesized that hiding time may also be reduced by recent interactions with conspecific competitors, due to an increased perceived need to defend feeding opportunities. Thus, when a predator attack occurred immediately after an agonistic conspecific interaction, backswimmers resumed feeding positions more quickly, and closer to the original position from which they were disturbed, suggesting short-term defense of particular positions. We conclude that when foraging, backswimmers balance the benefits of finding prey with the costs of predation risk and social interference in deciding their foraging strategy.Communicated by P.K. McGregor     

Social Affiliations within Sperm Whale (Physeter macrocephalus) Groups

We examined patterns of affiliation within groups of sperm whales ( Physeter macrocephalus ), particularly concentrating on how short-term spatio–temporal associations reflect long-term relationships. Female and immature sperm whales live in stable, and partially matrilineal, social units. Two or more social units may move together for periods of several days, forming a cohesive group of about 20 animals. We observed that sperm whales in the eastern tropical Pacific quite consistently associated with members of their own social unit more than they did with other animals in their group with whom they did not share a long-term relationship. There was little evidence for preferred, or avoided, affiliations within social units, except in two large and relatively unstable units. In two well-studied groups, individuals did not show consistently favoured positions in the foraging rank relative to other members of their social unit. These results indicate the importance of long-term relationships to female and immature sperm whales, but suggest that relationships are quite homogeneous within social units.     

Niche expansion, body size, and survival in Galápagos marine iguanas

Foraging theory predicts that dietary niche breadth should expand as resource availability decreases. However, Galápagos marine iguanas often die during algae shortages (El Niños) although land plants abound where they rest and reproduce. On Seymour Norte island, a subpopulation of iguanas exhibited unique foraging behavior: they consistently included the succulent beach plant B. maritima in their diet. We investigated the consequences of land-plant feeding for body size and survival. Batis-eaters supplemented their algae diet both before and after intertidal zone foraging, and more Batis was eaten during tides unfavorable for intertidal zone foraging (dawn and dusk). Larger, energy-constrained iguanas fed more on land than did smaller animals. Compared to intertidal zone algae, Batis was 39% lower in caloric content (1.6 vs. 2.6 kcal g^–1 dry mass), 56% lower in protein (8.3 vs. 18.9% dry mass) and 57% lower in nitrogen (1.3 vs. 3.0% dry mass). In spite of its lower nutrient value, iguanas that supplemented their diet with this plant were able to attain nearly twice the body size of other iguanas on the island. Age estimates indicate that many Batis-eaters survived repeated El Niño episodes during which animals of their relative size-class experienced high mortality on other islands. The larger animals were, however, completely dependent upon this supplementary source of food to maintain condition, and all perished in the 1997–1998 El Niño when high tides inundated and killed Batis on Seymour Norte Island. We hypothesize that Batis feeding developed as a local foraging tradition, and that dietary conservatism and strong foraging site fidelity explain why the inclusion of land plants in the diet has been observed in only a single population. Ultimately, a unique algae-adapted hindgut morphology and physiology may limit a switch from marine to terrestrial diet.     

Ontogeny of Foraging Competence in Capuchin Monkeys (Cebus capucinus) for Easy versus Difficult to Acquire Fruits: A Test of the Needing to Learn Hypothesis

Which factors select for long juvenile periods in some species is not well understood. One potential reason to delay the onset of reproduction is slow food acquisition rates, either due to competition (part of the ecological risk avoidance hypothesis), or due to a decreased foraging efficiency (a version of the needing to learn hypothesis). Capuchins provide a useful genus to test the needing to learn hypothesis because they are known for having long juvenile periods and a difficult-to-acquire diet. Generalized, linear, mixed models with data from 609 fruit forage focal follows on 49, habituated, wild Cebus capucinus were used to test two predictions from the needing-to-learn hypothesis as it applies to fruit foraging skills: 1) capuchin monkeys do not achieve adult foraging return rates for difficult-to-acquire fruits before late in the juvenile period; and 2) variance in return rates for these fruits is at least partially associated with differences in foraging skill. In support of the first prediction, adults, compared with all younger age classes, had significantly higher foraging return rates when foraging for fruits that were ranked as difficult-to-acquire (return rates relative to adults: 0.30–0.41, p-value range 0.008–0.016), indicating that the individuals in the group who have the most foraging experience also achieve the highest return rates. In contrast, and in support of the second prediction, there were no significant differences between age classes for fruits that were ranked as easy to acquire (return rates relative to adults: 0.97–1.42, p-value range 0.086–0.896), indicating that strength and/or skill are likely to affect return rates. In addition, fruits that were difficult to acquire were foraged at nearly identical rates by adult males and significantly smaller (and presumably weaker) adult females (males relative to females: 1.01, p = 0.978), while subadult females had much lower foraging efficiency than the similarly-sized but more experienced adult females (subadults relative to adults: 0.34, p = 0.052), indicating that skill, specifically, is likely to have an effect on return rates. These results are consistent with the needing to learn hypothesis and indicate that long juvenile periods in capuchins may be the result of selection for more time to learn foraging skills for difficult-to-acquire fruits.     

The effect of ambient humidity on the foraging behavior of the hawkmoth Manduca sexta

The foraging decisions of flower-visiting animals are contingent upon the need of an individual to meet both energetic and osmotic demands. Insects can alter their food preferences to prioritize one need over the other, depending on environmental conditions. In this study, preferences in nectar sugar concentrations (0, 12, 24 %) were tested in the hawkmoth Manduca sexta, in response to different levels of ambient humidity (20, 40, 60, and 80 % RH). Moths altered their foraging behavior when placed in low humidity environments by increasing the volume of nectar imbibed and by consuming more dilute nectar. When placed in high humidity environments the total volume imbibed decreased, because moths consumed less from dilute nectars (water and 12 % sucrose). Survivorship was higher with higher humidity. Daily foraging patterns changed with relative humidity (RH): moths maximized their nectar consumption earlier, at lower humidities. Although ambient humidity had an impact on foraging activity, activity levels and nectar preferences, total energy intake was not affected. These results show that foraging decisions made by M. sexta kept under different ambient RH levels allow individuals to meet their osmotic demands while maintaining a constant energy input.     

秦岭川金丝猴冬季和春季在自然栖息地的空间利用

2000年9月到2003年3月共计197天的时间里,我们采用目标动物取样法(Focalanimalsampling)和行为的全事件记录法(Alloccurrencesampling)对一群生活在秦岭北坡周至保护区内的秦岭金丝猴(Rhinopithecusroxellana)在自然栖息地内空间利用的进行了研究。当猴群在离开人工投食区进行自由活动时我们开始收集数据。结果表明:秦岭川金丝猴在不同年龄性别组的个体对植被的空间利用明显不同,它们花费每天活动的14%的时间在地面上活动,53%时间在树叉处活动,33%的时间在树冠中间活动。与其它年龄性别个体相比,成年雄性有27%的观察时间在地上活动,并且20%的取食时间或29%的休息时间是在地上的,明显地高于其它年龄性别组的个体。群体迁移时,成年雄性有53%的时间在地上移动,而只有13%的时间是在树冠层移动的。在通过不同树冠的时候,成年雄性经常会同时抓住两边再把身体摆过去。它们也经常下到地上迁移而回避在树间跳跃。相比之下,亚成年雌性和青少年猴更加经常地在低植被层和树冠层中找食和休息。它们明显地比成年猴更加频繁地在树冠中移动,却很少下地。它们还经常使用跳跃的方式通过树冠间的空隙。从观察到摔下树的事例分析,青少年猴从树上摔下来的风险比成年猴大。本文进而讨论了影响秦岭金丝猴空间分布和移动的因素,比如说身体的重量等.     

Predation risk, gender and the group size effect: does elk vigilance depend upon the behaviour of conspecifics?

Many animals benefit from the presence of conspecifics by reducing their rate of scanning for predators while increasing their time spent foraging. This group size effect could arise from a decreased perception of individual risk (dilution hypothesis) and/or an increased ability to detect predators (detection hypothesis). We compared individual and group vigilance of Rocky Mountain elk, Cervus elaphus, in three regions of Yellowstone National Park, Wyoming, U.S.A. that varied in their encounter frequency with coyote, Canis latrans, grizzly bear, Ursus arctos, and grey wolf,Canis lupus , predators. Adult females without calves increased scanning and decreased foraging with high encounter risk and small herd size. Adult females with calves increased scanning and decreased foraging with high encounter risk, but showed no decrease in scanning with large herd size. Yearlings increased scanning and decreased feeding with small herd size, but not with high encounter risk. Adult males were least vigilant, fed most and were not influenced by encounter risk or herd size. These age-sex class differences led to significant differences in group vigilance depending on the composition of the herd. Herds with a majority of mothers were significantly more vigilant than herds with a majority of adult males. However, these differences in group vigilance had no influence on the individual scanning of females without calves. Thus, the decrease in individual scanning with herd size may depend more on changes in individual risk than on cooperative detection of predators. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.      

Inter-population differences in the time budgets of bonnet monkeys (Macaca radiata)

Time budgets for five major activities viz., Passive Sitting, Locomotion, Foraging, Social Behaviour, and Self-directed Behaviours were recorded for bonnet monkeys inhabiting forest, urban, and rural habitats. The time budgets were further classified into those of various age-sex classes. Significant inter-population differences were found in group size, social behaviour, foraging, and locomotion, which are discussed in relation to the habitat features.     

The expression of aggression in old world monkeys

The expression of agonistic behavior in adult and juvenile members of both sexes was studied in groups of from 23 to 93 animals representing Macaca mulatta, M. arctoides, M. nemestrina, M. nigra, and Cercocebus atys. Data were collected using focal animal techniques over a period of 1 year for each group. Adult male biting was notably infrequent in all cases, and adult male participation in agonistic encounters was less frequent than for any other age-sex class, especially in the groups with the highest agonistic rates. Adult male agonistic behavior was often expressed as aggression but seldom involved contact forms of aggression, and biting constituted the smallest proportion of contact aggression for all age-sex classes. Adult males were also seldom the targets of aggression and had the highest rates for shaking of objects and bouncing displays. A tendency for the most severe forms of aggressive expression to be most frequent in those animals least capable of inflicting injury was noted in all groups, along with a tendency for aggression to be directed toward immature animals. Sex differences in aggressive expression and responses to aggression were noted, but the frequency of receipt of aggression was not directly reflected in the wounding noted. Different means to achieve the same consequence, infrequent adult male damaging attacks, are suggested to operate in the several groups studied.     

Nuisance Ecology: Do Scavenging Condors Exact Foraging Costs on Pumas in Patagonia?

Predation risk describes the energetic cost an animal suffers when making a trade off between maximizing energy intake and minimizing threats to its survival. We tested whether Andean condors (Vultur gryphus) influenced the foraging behaviors of a top predator in Patagonia, the puma (Puma concolor), in ways comparable to direct risks of predation for prey to address three questions: 1) Do condors exact a foraging cost on pumas?; 2) If so, do pumas exhibit behaviors indicative of these risks?; and 3) Do pumas display predictable behaviors associated with prey species foraging in risky environments? Using GPS location data, we located 433 kill sites of 9 pumas and quantified their kill rates. Based upon time pumas spent at a carcass, we quantified handling time. Pumas abandoned >10% of edible meat at 133 of 266 large carcasses after a single night, and did so most often in open grasslands where their carcasses were easily detected by condors. Our data suggested that condors exacted foraging costs on pumas by significantly decreasing puma handling times at carcasses, and that pumas increased their kill rates by 50% relative to those reported for North America to compensate for these losses. Finally, we determined that the relative risks of detection and associated harassment by condors, rather than prey densities, explained puma “giving up times” (GUTs) across structurally variable risk classes in the study area, and that, like many prey species, pumas disproportionately hunted in high-risk, high-resource reward areas.     

Opening mechanism of the mouth of the hematophagous hemipteran, Triatoma infestans

A morphological study of the tips of the stylets in an haematophagous hemipteran has been performed with a scanning microscope in order to determine both the relative positions of the mouthparts during a meal, and the means by which the ‘functional mouth’ can open. If the stylets of Triatoma are examined following severance of the labium, differences in the morphology and relative position of the two maxillary tips are observed. When, prior to a meal, the insect explores the medium with its mouthparts, the tips of its maxillary stylet are united. By contrast, when the bug is pumping food the left stylet is retracted relative to the right stylet and its tip is bent outwards.We have studied the mechanics of the system which allows the tip of the left maxillary to rock, resulting in the opening of the alimentary canal. Finally, we have re-examined the stylet movements of dissected animals in the light of these new morphological findings.     

Foraging Ecology Predicts Learning Performance in Insectivorous Bats

Bats are unusual among mammals in showing great ecological diversity even among closely related species and are thus well suited for studies of adaptation to the ecological background. Here we investigate whether behavioral flexibility and simple- and complex-rule learning performance can be predicted by foraging ecology. We predict faster learning and higher flexibility in animals hunting in more complex, variable environments than in animals hunting in more simple, stable environments. To test this hypothesis, we studied three closely related insectivorous European bat species of the genus Myotis that belong to three different functional groups based on foraging habitats: M. capaccinii, an open water forager, M. myotis, a passive listening gleaner, and M. emarginatus, a clutter specialist. We predicted that M. capaccinii would show the least flexibility and slowest learning reflecting its relatively unstructured foraging habitat and the stereotypy of its natural foraging behavior, while the other two species would show greater flexibility and more rapid learning reflecting the complexity of their natural foraging tasks. We used a purposefully unnatural and thus species-fair crawling maze to test simple- and complex-rule learning, flexibility and re-learning performance. We found that M. capaccinii learned a simple rule as fast as the other species, but was slower in complex rule learning and was less flexible in response to changes in reward location. We found no differences in re-learning ability among species. Our results corroborate the hypothesis that animals’ cognitive skills reflect the demands of their ecological niche.