Seasonal Variations in Diet and Foraging Behavior of <Emphasis Type="Italic">Ateles chamek</Emphasis> in a Southern Amazonian Tropical Forest

I present data regarding the diet and feeding ecology of a spider monkey community at Lago Caiman in northeastern Bolivia. The community was highly frugivorous, only consuming significant amounts of folivorous material during times of relative fruit resource scarcity. Spider monkeys fed on parts of 86 plant species, but the majority of the diet comprised a few dominant fleshy fruit species that were available at temporally distinct periods across the year. Accordingly, I identified candidate keystone resources for the region and discuss the results with reference to previous studies on Ateles and the importance of considering keystone fruit resources in the management of forestry concessions.     

斑块质量对大斑啄木鸟冬季觅食行为的影响

为了解大斑啄木鸟(Dendrocopos major)冬季对食物斑块的利用对策,2011年1月和2012年2～3月,在内蒙古乌拉特前旗的农田防护林中,采用目标动物取样法和全事件记录法,观察了大斑啄木鸟在食物斑块的觅食行为,利用主成分分析方法对斑块质量进行评价,通过比较不同质量斑块中大斑啄木鸟的觅食频次、停留时间、觅食成功频次及觅食成功率等指标,分析斑块质量对其觅食行为的影响。结果显示,在不同质量斑块中大斑啄木鸟的觅食频次、停留时间、觅食成功频次差异都极显著,但觅食成功率差异不显著;除停留时间外,不同性别间觅食差异不显著。大斑啄木鸟的觅食频次、停留时间、觅食成功频次与斑块质量呈显著正相关,觅食成功率与斑块质量相关性不显著。大斑啄木鸟倾向于在质量水平高的斑块觅食,表现为在这些斑块停留时间更长、往返次数更频繁;但觅食成功率不受斑块质量影响,这可能是大斑啄木鸟适应不同觅食环境的一种生存本能。     

Foraging Guppies and the Ideal Free Distribution: The Influence of Information on Patch Choice

10 male and 10 female guppies were each examined foraging for food at 2 separate feeders. The feeders provided food over a wide area so that individuals had equal access to the food. As the proportion of food at a feeder was altered, the proportion of fish using that feeder changed to match the availability of food. Thus, both groups of fish conformed to the predictions of the ideal free distribution (IFD) theory. However, the behaviour of the two groups differed. During these experiments, males continued to shuttle between these feeders whereas females tended to remain at a feeder. Also, the female group conformed less well to an IFD on the first trial of each day but conformed more closely to an IFD in successive exposures to the same food distribution. The male group exhibited no improvement with increasing experience. For both groups, the relative influence of the previous day's experience on foraging decisions declined with time. However, unlike the male group, the female group relied on experience for their initial foraging decisions. It is possible that sampling by males provides the additional benefit of increasing their probability of encountering receptive females. This may account for the difference in information use by the male and female group.     

Feeding Ecology of Guerezas in the Kakamega Forest,Kenya: The Importance of Moraceae Fruit in Their Diet

Eastern black-and-white colobus (Colobus guereza), or guerezas, have long been considered to be one of the most folivorous primates. I conducted a study of the feeding ecology of two guereza groups (T and O) over an annual cycle in the Kakamega Forest of western Kenya. I found that the annual diets of both groups comprised mostly of leaves (T: 48%, O: 57%) though fruit (T: 44%, O: 33%) also accounted for a substantial portion of the diet. In the six months when fruit was most abundant, fruit consumption constituted an average of 58% of T-group's monthly diet and 42% of O-group's monthly diet. In contrast to most previous studies of colobines, in which seeds were the primary fruit item consumed, almost all of the fruit eaten by guerezas at Kakamega consisted of whole fruits. At least 72% of the whole fruits consumed by T-and O-groups were whole fruits from trees in the Moraceae family, which dominates the tree family biomass at Kakamega. Unlike at sites where guerezas consumed fruit primarily when young leaves were scarce, at Kakamega guerezas ate fruit in accordance with its availability and irrespective of the availability of young leaves. My findings demonstrate that guerezas are more dietarily flexible than was previously known, which may help to explain why the species can survive in such a wide variety of forested habitats across equatorial Africa.     

Foraging Behavior and Patch Time Allocation by Fopius arisanus (Hymenoptera: Braconidae), an Egg-Larval Parasitoid of Tephritid Fruit Flies

This study quantitatively describes the host-searching behavior of Fopius arisanus (Sonan) (Hymenoptera: Braconidae), an important egg-larval parasitoid of tephritid fruit fly pests, on coffee berries infested with host eggs of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). We also investigate the parasitoid's response to local variation in host patch quality. The temporal pattern of behavioral organisation was examined by constructing an ethogram. The parasitoid spent over 90% of its foraging time in detecting and locating hosts after arriving on a host-infested fruit, and displayed a relatively fixed behavioral pattern leading to oviposition. Patch residence time increased in the presence of host-associated cues, following successful ovipositions, and with increasing size of host clutches per fruit, but decreased with each successive visit to the same host patch and with increasing availability of alternative host patches. The parasitoid females discriminated against previously parasitized hosts and spent significantly less time and searching effort on patches previously exploited by herself or by conspecific females. The effective host-searching behavior, perfect host discrimination ability, and success-motivated searching strategy shown by F. arisanus ensured a thorough exploitation of host resources by this parasitoid.     

Effects of Fruit Patch Availability on Feeding Subgroup Size and Spacing Patterns in Four Primate Species at Tinigua National Park, Colombia

We examined the effects of fruit patch size, density, and distribution on feeding subgroup size and feeding bout duration in four Neotropical primates—Lagothrix lagotricha, Ateles belzebuth, Cebus apella, and Alouatta seniculus—based on 2494 hr of focal animal sampling in Tinigua National Park, Colombia. All four species show positive correlations between patch size (tree diameter at breast height; DBH) and subgroup size (maximum number of individuals from the focal group feeding at the same time), but the determination coefficients are very low and this relationship does not seem to influence strongly the actual size of the groups. Ateles showed the weakest correlation between patch size and feeding party size, and their fission–fusion sociality is best explained as a mechanism to reduce intragroup competition rather than to adjust the subgroup size to the availability of patches. Feeding associations as well as proximal spacing patterns, in general, are more alike in species with similar ecological requirements.     

Diet of the Critically Endangered Brown Spider Monkey (Ateles hybridus) in an Inter‐Andean Lowland Rainforest in Colombia

Brown spider monkeys (Ateles hybridus) are one of the least known and more threatened primates in the Neotropics. Recognized as a species about a decade ago, field studies on these endangered primates have mainly focused on estimating local population densities. Since 2006, we habituated a group of wild brown spider monkeys at Serranía de Las Quinchas, Colombia, and studied their feeding ecology during 2.5 years using focal “subgroup” sampling, and conducted phenological surveys in order to estimate habitat‐wide fruit availability. Based on 847 hr of behavioral follows, brown spider monkeys spent approximately 25% of their time in feeding activities, and fed from fruits and leaves on at least 123 plant species. Ripe fruits were the most important item in the diet of A. hybridus at Las Quinchas comprising 92% of their feeding time. Probably due to the minor variation in the monthly proportion of fruits in brown spider monkey's diet throughout this study, there was no relation between habitat‐wide fruit availability and the proportion of fruit included in their monthly diet. The diet of brown spider monkeys at Las Quinchas is toward the high end of fruit intake, even within other wild spider monkeys’ populations, suggesting that these endangered primates might also be facing the challenges of being a large bodied fruit specialist under a regional scenario of habitat loss and fragmentation. Am. J. Primatol. 74:1097‐1105, 2012. © 2012 Wiley Periodicals, Inc.     

The Influence of Ants on the Foraging Behavior of Birds in an Agroforest1

Ants limit bird foraging success via interference or exploitative competition. We compared bird foraging (number and duration of visits, bird species visiting) on ant (Azteca instabilis)‐infested and ant‐free tropical trees (Inga micheliana and Alchornea latifolia). Ants did not affect the number of bird visits or the number of species visiting. Ant presence shortened visit duration (overall and for insectivores) only on A. latifolia where ant activity was higher. Ants may thus hinder bird foraging on some tropical trees potentially shaping how predators affect arthropod communities; yet ant effects depend on bird foraging guild and ant activity.     

The Influence of Previous Experience and Starvation on Aphid Feeding Behavior

It was hypothesized that (1) previous experience of aphids on a host plant leads to differences in their feeding behavior relative to aphids without previous experience on it and that (2) a change in the physiological state of the aphid modifies their experience-induced behavior. Using electronic recording, the feeding behavior of the aphid Sitobion fragariae (Walker) on wheat Triticum aestivum L. and oat Avena sativa L. was examined, comparing aphids with or without previous experience on a given host and with or without a period of starvation before assessing probing behavior. All comparisons were performed within a single aphid clone to minimize the effect of genetic variation. Feeding behavior on wheat was significantly affected by previous experience and starvation. The effect of previous experience interacted with the host plant where feeding behavior was tested. Aphids feeding on wheat following previous experience on wheat showed a longer time and a higher number of pathway activities and less time in waveform F (i.e., mechanical stylet work and penetration difficulties) than did aphids feeding on wheat after a previous experience on oat. No differences in the time from the beginning of the recording until the first salivation into the sieve elements were found. When aphids were subjected to a period of starvation, the time devoted to xylem ingestion increased compared with that of nonconstrained aphids. These results are discussed in terms of factors affecting foraging decisions.     

Influence of Seasonality on Activity Patterns, Feeding Behavior, Ranging, and Grouping Patterns in Taï Chimpanzees

Lowland rain forest chimpanzees (Pan troglodytes verus) of the Taï National Park, Ivory Coast, responded to the minor dry season (July and August) of 1988 in a predictable manner by spending more time feeding, feeding more frequently on lower quality food items, reducing day range and party size, and spending more time solitarily and less time in mixed groups than during the rainy season. These behaviors are consistent with a response to scarce resources. My findings do not support Boesch's (1991, 1996) hypothesis of bisexually bonded chimpanzees. Females spent 45% of time alone and associated with males in mixed parties only 18% of their time. This major discrepancy in our results probably stems from differences in the time of year when our studies were conducted, the year in which my study was conducted (potentially scarcer resources than on average), and methodological differences: focal animal sampling of males and females equally. Although Boesch (1991, 1996) and Steiner (1996) have demonstrated that Taï parties are usually larger and more mixed, Taï chimpanzee social structure—party size and composition—during this study closely resembles that found at other study sites.     

Crop Size and Fruit Neighborhood Effects on Bird Visitation to Fruiting Schefflera morototoni Trees in Puerto Rico1

Studies of zoochorous seed dispersal systems often consider crop size, yet seldom consider the kinds and amounts of fruits surrounding parent plants (the fruit neighborhood) when attempting to explain among‐plant variation in fruit removal. We studied avian frugivory at 24 Schefflera morototoni trees from February to May 1998 in central Puerto Rico. The number of fruits removed by avian seed dispersers per visit was similar among focal trees (typically 2–4). In contrast, visitation rate was highly variable (range: 0–71 visits per 4 h). We used multiple regression analyses to evaluate the relative roles of crop size (focal tree ripe fruit abundance) and fruit neighborhood variables (measured within 30 m of focal trees) in affecting visitation to focal trees by avian frugivores. Visitation rate was positively related to crop size (although this variable was only significant in one of four regression models considered) and negatively related to the presence or abundance of conspecific fruits, suggesting that trees competed intraspecifically for dispersers. Relationships between visitation and heterospecific fruits were mixed—some kinds of fruits appeared to enhance visitation to focal trees, while others seemed to reduce visitation. In most regression models, neighborhood variables had larger effects on visitation than focal tree fruit crop size. Our results highlight the important effects of local fruiting environments on the ability of individual plants to attract seed dispersers.     

The Influence of Temporal Changes in Fruit Availability on Diet Composition and Seed Handling in Blue Monkeys (Cercopithecus mitis doggetti)1

We investigated the relation between temporally varying resources, diet composition, and seed-handling behaviors in a group of blue monkeys (Cercopithecus mitis doggetti) in a tropical montane forest of Rwanda. Changes in diet composition were related to concurrent phenological studies of fruit-producing trees, and density and abundance of tree resources within the monkey's home range. Fruit composed nearly 50 percent of the diet. Over 50 percent of the fruits eaten had juicy fleshy pulp. Observations of seed handling behavior provided insights into the role of these animals as potential seed dispersal agents. The monkeys moved the seeds of 29 species out of parent canopies by defecating seeds intact and by potentially carrying seeds in cheek pouches and dropping them later. Seeds of 18 species were found intact in fecal piles. Our study showed community-level phenology patterns did not indicate a decrease in fruit availability during the study period, but an analysis of the preferred fruits consumed by the monkeys showed distinct periods of low fruit availability. The study period included two dry seasons; only one of these produced a period of fruit scarcity for the animals. The animals employed different strategies during times of preferred fruit scarcity. They increased consumption of leaves and other fleshy fruits, and diet diversity increased, or became mainly seed predators and diet diversity decreased. The variable responses of these monkeys to changes in food availability highlights their dietary plasticity and imposes significant variations in their role as potential seed dispersers.     

The Impact of Forest Disturbance on the Seasonal Foraging Ecology of a Critically Endangered African Primate

Forest loss and fragmentation threaten many primates globally, and often leads to a reduction in food resources. During a 22 ‐ mo period, the foraging ecology of the critically endangered kipunji Rungwecebus kipunji was studied in the heterogeneous Rungwe–Livingstone forests, southwest Tanzania, to identify periods of possible ecological stress, fallback foods used by the species, and the impact of forest disturbance on feeding resources. The studied group had a wide diet and was predominantly frugivorous. Fruit consumption was driven by fruit availability which peaked during the wet season, and dipped during the driest months. During this period, two fallback foods: mature leaves and pith were widely consumed, with Macaranga capensis an essential fallback species. α diversity and evenness of diet was remarkably similar across months, but there was high β diversity in diets at the cusp of wet and dry seasons, and during periods of low fruit availability. This suggests considerable dietary adaptability to fluctuating resources, which may act to buffer against further forest disturbance. Tree species associated with relatively undisturbed forest were significantly more important in the diet, especially in the dry season, than those of disturbed forests. Regeneration of key trees (determined through counting of seedlings and saplings in plots) appeared healthy except in two important Ficus species. Conservation management, while focusing on promoting old growth forest, should also consider populations of some important pioneer tree species such as Macaranga capensis both inside the forest and in any reforestation schemes outside the species’ current area of occupancy.     

浅斑近微蛛体形大小对交配行为的影响

理论和实验表明体形大小是许多动物择偶的重要信号。体形大小与产卵大小、最终产卵数量、后代适合度等都有着密切的关系,因此动物利用体形大小为信号来择偶可以获得高的生殖利益。目前研究交配行为和体形大小的关系的文献较少,特别在微蛛亚科。本文以浅斑近微蛛为实验材料,在室内研究了体形大小对交配行为的影响。测量了体重,体长,头胸甲与腹部的长和宽,以头胸甲的面积(头胸甲的长与宽的乘积)为变量来表示体形大小。以雄蛛的行为为依据,将其交配行为划分为4个时期:潜伏期、求偶期、插入期和纳精期,并记录了各个时期的持续时间。通过分析,发现了一种微蛛新的交配模式,即可将浅斑近微蛛的插入期分为三个阶段:首先是大约25min长插入期,接着是一个大约15min的中度插入期,最后是一个大约5min的短插入期。结果表明,在本试验条件下,浅斑近微蛛的体形大小对其交配行为的潜伏期、求偶期、插入期和纳精期的持续时间都没有影响,对插入期的3个阶段的长短也没有影响。     

The Effect of Patch Size and Persistence of Host Plants on the Development of Acaricide Resistance in the Two-spotted Spider Mite Tetranychus Urticae (Acari: Tetranychidae)

Spatial and temporal characteristics of host plants can influence the population biology of the herbivores feeding on them. In this study, I examined the effect of variation in host plant characteristics on the development of acaricide resistance in the two-spotted spider mite Tetranychus urticae, a widely distributed agricultural pest. This investigation examined the geographic variation in the degree of resistance to two new types of acaricide, pyridaben and fenpyroximate. From mortality tests at field-level concentrations of the acaricides, many populations collected from fruit trees and roses had a high frequency of resistant individuals for acaricides while almost all populations collected from herbaceous crops had low frequencies of resistant individuals. These results, combined with those from a previous allozyme study, indicate that patch size and persistence of host plants regulate the population structure of the mites including gene flow between populations and, by extension, the development of acaricide resistance.     

相关风险因子对高原鼠兔摄食行为的影响

研究了捕食风险环境中集和洞口距离对高原鼠兔摄食行为的影响。结果表明,集群数量的增加不仅降低了警觉行为,同时也减少了摄食行为,在高风险环境中,集群为1时的取食行为强度最大,低风险环境中,为0时最大,警觉行为主要出现在距洞口2m的范围内,其行为强度与洞口踪影职责负相关,当洞口距离大于3m时,风险处理区的高原鼠兔几乎无警觉行为出现,且该处理区的取食区域几乎压缩的洞口旁,研究结果表明,在捕食风险环境中,高原鼠兔摄食行为与集群和洞口距离之间具有复杂的关系,其行为决策反映了降低风险与摄取食物间的权衡,行为目标是在降低捕食风险的同时尽可能地取食食物。     

Foraging Efficacy of a Larval Parasitoid in a Cotton Patch: Influence of Chemical Cues and Learning

Plant-herbivore chemical signals and behavioral plasticity may enhance parasitoid host-foraging efficacy in the field; however, no studies have quantified the potential benefits from these factors under field-type conditions. The effect of plant-herbivore signals and learning on the foraging efficacy of Microplitis croceipes was quantified by directly observing and recording total and sequential duration of various foraging behaviors relative to 5 randomly placed herbivore-damaged and host-infested cotton plants and 20 undamaged and non-host-infested plants. Microplitis croceipes spent significantly more time searching (flying and antennation) on host infested versus uninfested plants. Antennation time was significantly and negatively correlated with successive host stings. Contrary to expectations of increased duration, flight time remained constant throughout the foraging bout, which may indicate that there was some learning associated with flight. These results suggest that plant-herbivore chemical signals and learning enhances the foraging efficacy of M. croceipes.     

Influence of pH on the Heat Inactivation of Staphylococcal Enterotoxin A as Determined by Monkey Feeding and Serological Assay

The effect of pH on the thermal inactivation of staphylococcal enterotoxin A was investigated. Analysis of heated toxin by immunodiffusion in gel indicated that enterotoxin A in beef bouillon was inactivated faster at pH 5.3 than at pH 6.2. The z values (slopes) for the heat inactivation curves at pH 6.2 and 5.3 were 49.5 and 55 F (about 27 and 30 C), respectively. Enterotoxin produced and heated in dialyzed Casamino Acids medium and assayed by monkey feeding was more easily inactivated by heat at pH 5.3 than at pH 7.8. Thermal inactivation curves for enterotoxin A in beef bouillon (5 mug/ml, pH 5.3) were determined by two methods, monkey feeding and serological assay. The z values for the curves obtained by these two methods were both 55 F, although loss of biological or toxic activity of the enterotoxin occurred before loss of serological activity.