喀斯特石山生境中熊猴的雨季食物组成

开展食物组成研究为人们了解灵长类对栖息地的反应提供了很好的途径,对深刻理解动物的行为可塑性及适应性具有重要意义。猕猴属(Macaca)为果食性灵长类,但是不同种类的食性差异很大;即使便同一物种,其不同地理种群也因其栖息环境不同,食物组成存在差异。一般说来,热带地区的种类比生活在较高纬度的种类采食更多的果实。于2012年7—9月,采用瞬时扫描法对广西弄岗自然保护区石山中的两群熊猴(Macaca assamensis)进行了跟踪和观察,对猴群的雨季食物组成及其日时段变化规律进行了研究。结果表明:研究期间熊猴共采食45种植物,其中乔木30种,灌木3种,藤本11种,草本1种。平均每月采食植物22.3种。嫩叶和果实是熊猴的主要食物,分别占食物组成的52.4%和46.1%(其中未成熟果实占21.3%,成熟果实占24.8%)。另外,花占食物组成的0.9%,成熟叶和其它部位分别占0.3%。石山特有植物芸香竹(Bonia saxatilis)的嫩叶提供了43.8%的食物。9种主要植物分别占食物组成的2%,共为猴群提供了85.5%的食物。分析还发现熊猴并不是严格按照环境中的植物生物量来选择食物。嫩叶在弄岗熊猴的食物中的比例高于其他地理种群,而果实低于其他地理种群,这可能与喀斯特石山中果实的丰富度和可利用性较低有关。熊猴一天中不同时间段的食物组成并不相同,主要表现在:熊猴上午时间段对成熟果实和总果实的采食比例高于下午时间段,而嫩叶的采食比例低于下午时间段。另外,不同时间段的食物组成受外界温度的影响,表现为温度与嫩叶的觅食比例成正比,与成熟果实和总果实的觅食比例成反比。这可能与猴群采取的能量平衡策略有关。对熊猴的食物组成的日时段变化规律进行首次报道,研究结果将有助于深入理解熊猴对喀斯特石山生境的适应策略。     

Variations in diet composition of sympatric Trachypithecus francoisi and Macaca assamensis in the limestone habitats of Nonggang,China

Comparative studies of sympatric species are essential for understanding behavioral and ecological adaptation as well as the mechanisms that can reduce resource competition to allow coexistence.Fran?ois' langurs(Trachypithecus francoisi) and Assamese macaques(Macaca assamensis) are sympatric primate species found in the limestone seasonal rainforests of Nonggang Nature Reserve,southwestern Guangxi, China. To explore their different adaptation strategies, we collected data on diet using scan sampling at 15-min intervals. Our results revealed that Fran?ois' langurs showed a more flexible diet composition than Assamese macaques.Fran?ois' langurs increased dietary diversity and mature leaf consumption in response to seasonal scarcity of preferred young leaves and fruits, whereas Assamese macaques relied heavily on young bamboo leaves(Indocalamus calcicolus) in most months.These variations reflect the differences in digestive physiology, morphology, and the temporal and spatial distribution of food resources.     

Non‐territorial Macaques Can Range Like Territorial Gibbons When Partially Provisioned With Food

Human food supplementation can affect components of animal socioecology by altering the abundance and distribution of available food. We studied the effect of food supplementation by comparing the ranging patterns and intergroup interactions of two groups of northern pigtailed macaques (Macaca leonina), a non‐territorial primate species. One group was partially reliant on food provisioning, whereas the other group foraged wild food. We also compared the macaques’ movement with that of a group of white‐handed gibbons (Hylobates lar), a territorial species inhabiting the same site. Home range, core area, and daily path lengths were significantly smaller for the semi‐provisioned group than for the wild‐feeding group. In contrast to wild‐feeding macaques, supplemented macaques showed higher fidelity to home range, core area, and particularly to the region where human food was most accessible and abundant. The relationship of daily path length and home range indicated a low defendability index for wild‐feeding macaques; the higher index for the semi‐provisioned group was consistent with the territorial pattern found in gibbons. Semi‐provisioned macaques showed further traits of territoriality with aggression during intergroup encounters. These findings indicate that human modification of food availability can significantly affect movement patterns and intergroup competition in macaques. The observed ranging dynamics related to food provisioning may decrease the efficiency of macaques as seed dispersers and increase predation on their home range, and thus have important consequences for plant regeneration and animal diversity.     

Niche separation of sympatric macaques, Macaca assamensis and M. mulatta, in limestone habitats of Nonggang, China

Comparative studies of sympatric species are essential in understanding those species’ behavioral and ecological adaptations as well as the mechanisms that can reduce resource competition enough to allow coexistence. We collected data on diet, activity budget and habitat use from two sympatric macaque species, the Assamese macaque (Macaca assamensis) and the rhesus macaque (M. mulatta), in a limestone seasonal rainforest of Nonggang Nature Reserve, southwestern Guangxi, China. Our results show that the two sympatric macaques differ in diet, activity budget, and habitat use: (1) out of the 131 plant species that were used by both macaque species as food over the year, only 15 plant species (11 %) were shared. Rhesus macaques used more plant species as major foods, and had higher dietary diversity and evenness indexes than Assamese macaques. (2) Assamese macaques fed predominantly on leaves, whereas rhesus macaques fed more selectively on fruits. The rhesus macaques’ diet varied according to season, and was significantly correlated to season fluctuation in fruit availability. (3) Assamese macaques devoted more time to resting, and less time to feeding than rhesus macaques (4) Assamese macaques were present mostly on the cliff, and tended to stay on the ground, whereas rhesus macaques were present mostly on the hillside, and showed preference to lower and middle canopy. The observed differences in diet and habitat use between the two macaque species represent behavioral patterns enabling their coexistence.     

The diet and feeding behavior of the silver leaf monkey (Trachypithecus auratus sondaicus) in Indonesia

I describe the diet and feeding behavior of silver leaf monkeys (Trachypithecus auratus sondaicus) in the Pangandaran Nature Reserve, West Java, Indonesia, and compare a group living in old secondary rain forest with a group living in mixed plantation/secondary forest to determine intraspecific variation in feeding behavior and the importance of the plantation species in the diet of the monkeys. Young leaves and leaf buds made up slightly less than half of their diets, with both groups showing a preference for a few species when seasonally available. Fruits and flowers of a few species were also preferentially selected when available. These included sweet, fleshy fruits, which most other colobines tend to avoid. Young leaf intake was greatest in months when fruit intake was low. Mature leaves were rarely eaten. Both groups spent approximately 20% of feeding time foraging on Moraceae species. Differences in the diet of the two groups were related largely to differences in vegetational composition and the availability and abundance of food items for the species common to both sites. Teak (Tectona grandis) was the top food species of the group living in mixed plantation/secondary forest, with the midribs of young leaves preferentially selected. Young leaves ofT. grandis, available throughout the study, provided a staple food and were eaten when preferred foods were scarce. More favored food items were available to the group living in old secondary forest, though none was a staple food.     

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.     

Food selection by the South Indian leaf-monkey,Presbytis johnii,in relation to leaf chemistry

Summary The leaf-monkey Presbytis johnii has been found to exhibit considerable selectivity in its dietary utilization of mature foliage in a rain-forest habitat. To investigate the basis of this selectivity and to examine the hypothesis that the observed selection is related to the digestibility and toxicity of the available foliage, chemical analyses have been made on 16 of the most important tree species in the monkey's habitat. It has been found that the most heavily used items, which form a staple part of the diet of P. johnii, are characterized by a low fibre content and a very low condensed tannin content. However, neither class of compound is an absolute feeding deterrent as minor, but still significant, mature leaf food items contain considerable amounts of both. It is suggested that the feeding deterrents in these minor items, which may be ingested to supply specific dietary requirements, can perhaps be tolerated because of their dilution in the gut by the dietary staples. An examination of the pepsin/cellulase digestibility of available mature foliage showed that the staple food items tended to be highly digestible. Little correlation has been found between alkaloid content and food selection and it is suggested that the colobine forestomach microflora has the ability to detoxify at least some alkaloids. Additional data on mature leaf petioles and young leaves suggest that the high ratio of cell-sap to cell-wall in these items, and their related high digestibility, explain the high relative abundance of these items in the P. johnii diet.     

Dietary generalists and nutritional specialists: Feeding strategies of adult female blue monkeys (Cercopithecus mitis) in the Kakamega Forest,Kenya

Generalist primates eat many food types and shift their diet with changes in food availability. Variation in foods eaten may not, however, match variation in nutrient intake. We examined dietary variation in a generalist‐feeder, the blue monkey (Cercopithecus mitis), to see how dietary food intake related to variation in available food and nutrient intake. We used 371 all‐day focal follows from 24 adult females (three groups) in a wild rainforest population to quantify daily diet over 9 months. We measured food availability using vegetation surveys and phenology monitoring. We analyzed >700 food and fecal samples for macronutrient content. Subjects included 445 food items (species‐specific plant parts and insect morphotypes) in their diet. Variation in fruit consumption (percentage of diet and total kcal) tracked variation in availability, suggesting fruit was a preferred food type. Fruits also constituted the majority of the diet (by calories) and some fruit species were eaten more than expected based on relative availability. In contrast, few species of young leaves were eaten more than expected. Also, subjects ate fewer young leaves (based on calories consumed) when fruit or young leaves were more available, suggesting that young leaves served as fallback foods. Despite the broad range of foods in the diet, group differences in fiber digestibility, and variation that reflected food availability, subjects and groups converged on similar nutrient intakes (grand mean ± SD: 637.1 ± 104.7 kcal overall energy intake, 293.3 ± 46.9 kcal nonstructural carbohydrate, 147.8 ± 72.4 kcal lipid, 107.8 ± 12.9 kcal available protein, and 88.1 ± 17.5 kcal structural carbohydrate; N = 24 subjects). Thus, blue monkeys appear to be food composition generalists and nutrient intake specialists, using flexible feeding strategies to regulate nutrient intake. Findings highlight the importance of simultaneously examining dietary composition at both levels of foods and nutrients to understand primate feeding ecology.     

The consequences of alternating diet on performance and food preferences of a specialist leaf beetle

The food quality of a given host plant tissue will influence the performance and may also affect the preference behavior of herbivorous animals. As nutrient contents and defense metabolite concentrations can vary significantly between different parts of a plant and change over time, herbivores are potentially confronted with diet differing in quality even when feeding on a single plant individual. Here we investigated to what extent feeding exclusively either on young or old, mature leaves of Brassica rapa or on a mixed diet of young and old leaves offered in alternating order affects the larval performance, food consumption, and the host preference behavior of adult mustard leaf beetles, Phaedon cochleariae. Analyzing different leaf quality traits, we found lower water contents, no changes in C:N ratio but more than threefold higher glucosinolate concentrations in young compared to old leaves. Individuals reared on mixed diet performed as well as animals reared on young leaves. Thus, compared to animals feeding exclusively on highly nutritious young leaves, diet-mixing individuals may balance the lower nutrient intake by a dilution of adverse secondary metabolites. Alternatively, they may integrate over the variation in their food, using a previously assimilated resource for growth at times of scarcity. Animals reared on old leaves grew less and had a prolonged larval developmental time, although they showed increased consumption indicating compensatory feeding. Additionally, we found that experience with a certain diet affected the preference behavior. Whereas individuals reared exclusively on young leaves preferred young over old leaves for feeding and oviposition, we did not find any preferences by animals reared exclusively on old leaves or by females reared on alternating diet. Thus, in contrast to positive feedbacks for animals reared on young leaves, an integrative growth of diet-mixing individuals potentially leads to a lack of feedback during development. Taken together, our results suggest that different diet regimes can lead to comparable performance of mustard leaf beetles but experienced feedbacks may differ and thus convey distinct diet preferences.     

Fallback Foods of Red Leaf Monkeys (Presbytis rubicunda) in Danum Valley, Borneo

Animals in Southeast Asia must cope with long periods of fruit scarcity of unpredictable duration between irregular mast fruiting events. Long-term data are necessary to examine the effect of mast fruiting on diet, and particularly on the selection of fallback foods during periods of fruit scarcity. No such data is available for colobine monkeys, which may consume substantial amounts of fruits and seeds when available. We studied the diet of red leaf monkeys (Presbytis rubicunda, Colobinae) in Danum Valley, Sabah, northern Borneo, using 25 mo of behavioral observation, phenology and vegetation surveys, and chemical analysis to compare leaves eaten with nonfood leaves. The monkeys spent 46% of their feeding time on young leaves, 38% on seeds, 12% on whole fruits, 2.0% on flowers, 1.0% on bark, and 1.2% on pith. They spent more time feeding on seeds and whole fruit when fruit availability was high and fed on young leaves of Spatholobus macropterus (liana, Leguminosae) as fallback foods. This species was by far the most important food, constituting 27.9% of the total feeding time, and the feeding time on this species negatively correlated with fruit availability. Consumed leaves contained more protein than nonconsumed leaves, and variation in time spent feeding on different leaves was explained by their abundance. These results suggest that red leaf monkeys show essentially the same response to the supra-annual increase in fruit availability as sympatric monogastric primates, increasing their seed and whole-fruit consumption. However, they depended more on young leaves, in particular Spatholobus macropterus, as fallback foods during fruit-scarce periods than did gibbons or orangutans. Their selection of fallback food appeared to be due to both nutrition and abundance.     

Differences in Activity Budgets and Diet Between Semiprovisioned and Wild‐Feeding Groups of the Endangered Barbary Macaque (Macaca sylvanus) in the Central High Atlas Mountains,Morocco

The Barbary macaque, Macaca sylvanus is a very adaptable primate species occupying a wide range of habitats in Morocco and Algeria. Several groups of this endangered macaque can be found in tourist sites, where they are affected by the presence of visitors providing food to them. We compare the activity budgets and the diet of semiprovisioned and wild‐feeding groups of Barbary macaques in the central High Atlas Mountains of Morocco from February to August 2008. We used instantaneous scan sampling at 15‐min intervals. The behaviors included in the activity budget were feeding, moving, foraging, resting, and aggressive display. Food items were grouped into seven categories. We found no differences between the two groups in the daily percentages of records attributed to feeding. The semiprovisioned group spent significantly more time engaged in resting and aggressive behavior, and foraged and moved significantly less than the wild‐feeding group. There was no significant difference between the two groups in time spent eating leaves, fruits, or roots and bark. The semiprovisioned group, however, spent significantly less time per day feeding on herbs, seeds, and acorns than the wild‐feeding group. Human food accounted for 26% of the daily feeding records for the semiprovisioned group and 1% for the wild‐feeding group. Our findings agree with previous studies and indicate that in the tourist site, where food is highly clumped, macaques decreased foraging time yet showed higher levels of contest competition. Our results support the common claim that the diet of the Barbary macaque is highly flexible, differing among its varied habitats. Conservation efforts for the Barbary macaques should take into account the changes in behavior that human‐modified environments may cause.     

Food selection by black colobus monkeys (Colobus satanas) in relation to plant chemistry*

Black colobus monkeys (Golobus salanas) in the Douala-Edea Reserve, a rain-forest on the coast of Cameroon, have been shown to avoid young and mature leaves of most of the common plants in their habitat and to feed disproportionately heavily on leaves of rare plants. The proportion of leaves in the diet was low compared to most colobines studied, and the monkeys spent over half their feeding time eating seeds. Patterns of food selection were analysed in relation to distribution of nutrients, digestion–inhibitors and toxins in the vegetation. Colobw satanas select food items that are rich in mineral nutrients and nitrogen and low in content of the general digestion-inhibitors, lignin and tannin. They achieve this in the following ways: (i) by feeding preferentially on young leaves, which have higher nutrient content and lower contents of digestion-inhibitors than mature leaves; (ii) by eating those mature leaves with highest nument content relative to content of digestion-inhibitors; and (iii) by eating seeds, which are sources of readily available energy and which, as an item class, are less rich in digestion-inhibitors. Seeds at Douala-Edea appear to contain Ins nitrogen than leaves and C. satanas selects those seeds with highest nitrogen content. It is suggested that seed-feeding may be facilitated by the ability of the forestomach flora of these ruminant-like monkeys to detoxify some of the secondary compounds contained in seeds. Avoidance of most unused young and mature leaf items is correlated with a low nutrienudigestion-inhibitor ratio; avoidance of most unused seeds could be accounted for by their low nitrogen contents. Most items whose avoidance could not be explained in terms of these major constraints on food selection possess secondary compounds likely to be toxic. It is proposed that relative importance of digestion-inhibitors, low nutrient content and toxins as constraints on food selection by generalist herbivores will vary greatly among forests with different nutrient and secondary chemistry profiles.     

Nutritional Ecology of <Emphasis Type="Italic">Ateles chamek</Emphasis> in lowland Bolivia: How Macronutrient Balancing Influences Food Choices

All free-living animals must make choices regarding which foods to eat, with the choices influencing their health and fitness. An important goal in nutritional ecology is therefore to understand what governs animals’ diet selection. Despite large variation in the availability of different food items, Peruvian spider monkeys (Ateles chamek) maintain a relatively stable daily protein intake, but allow total energy intake to vary as a function of the composition of available food items. This is referred to as protein-dominated macronutrient balancing. Here we assess the influence of this nutritional strategy on daily and seasonal nutritional intakes, estimate the nutritional value of different foods, and interpret unusual food choices. We conducted continuous all-day observations of focal spider monkeys inhabiting a semideciduous forest in Bolivia. We recorded feeding events, collected foods, and analyzed their nutrient content. By using the Geometric Framework for nutrition, we show that individuals reached their daily end-point in nutrient space —balance between protein and nonprotein energy intake— by consuming nutritionally balanced foods or by alternating between nutritionally complementary foods. The macronutritionally balanced figs of Ficus boliviana were their primary staple food and therefore dominated their overall nutritional intake. Our results also demonstrate that spider monkeys consumed a diverse array of ripe fruits to overcome periods of fig scarcity rather than vice versa; they could obtain sufficient protein on a diet of pure fruit; and unripe figs constituted a nutritionally rewarding and reliable food resource. We hope that the approaches taken and the conclusions reached in this study will catalyze further inquiries into the nutritional ecology of frugivorous primates.     

Selective herbivory by brushtail possums: Determining the age of ingested leaves using n‐alkanes

Abstract Leaves often decline in nutritional quality as they age, and selective feeding on young leaves may be nutritionally important for herbivores. Preference by mammalian herbivores for young leaves has rarely been measured in the field owing to technical difficulties. We measured preferences with respect to leaf age of an arboreal folivore, the brushtail possum (Trichosurus vulpecula Kerr), feeding on southern rata (Metrosideros umbellata Cav.; Myrtaceae) in a new application of the alkane technique. We characterized the cuticle waxes (n‐alkanes) of rata leaves that were less than 1 year old (‘1‐year’), between 1 and 2 years (‘2‐year’) and greater than 2 years old (‘>2‐year’). Simulations showed that the method accurately discriminated between 1‐year and other age groups but slightly overestimated the importance of rare components of the diet. This bias was larger when discriminating between 2‐year and >2‐year leaves apparently because they had more‐similar alkane profiles. Metrosideros umbellata leaf formed 20.8% of the diet of a population of possums from Rakiura, New Zealand, sampled in autumn 2002 (n = 33). Of the M. umbellata component, alkane analyses showed that 1‐year leaves formed 88.7 ± 3.9% of the diet despite making up only 39.5 ± 2.2% of the leaf biomass on rata trees (n = 14). The foliar concentrations of the macronutrients N, P and K all declined significantly with leaf age (P < 0.0001). Lignin content did not measurably increase with leaf age, suggesting that digestibility per se did not determine the preference of brushtail possums for young rata leaves. This study provides the first quantitative evidence that possums discriminate by leaf age and that the resulting diet is enriched in macronutrients.     

A preliminary study of food selection by the orangutan in relation to plant quality

We observed the foraging behavior of orangutans in Central Indonesian Borneo during October, November, and December 1980, and analyzed food and nonfood items for water content, neutral detergent fiber, crude protein, available crude protein, and protein:fiber ratio and the presence of alkaloids and tannins. The diet of the orangutan during this season was unusual because it consisted predominantly of seeds and unripe, rather than ripe, fruits. Also, the major diet item, the seeds ofIrvingia malayana, had been ignored in previous years when it had fruited. In leaves, protein content was more closely associated with food choice than either neutral detergent fiber or the protein:fiber ratio. Flowers had the highest protein content and protein:fiber ratio of any food item. Tannins were found in most food items, but the presence of alkaloids was found in only one.     

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.     

Folivory by a tropical tanager: species of plants used and the relationship between leaf consumption and fruit abundance

ABSTRACT Folivory, or eating leaves, is unusual for small passerines. Puerto Rican Spindalises (Spindalis portoricensis, Thraupidae), tanagers endemic to the island of Puerto Rico, are known to feed on leaves, but little is known about the possible importance of leaves in their diet. Our objectives were to determine the different species of leaves eaten, the percentage of their diet consisting of leaves, and the relationship between leaf consumption and fruit abundance. We used data from previous studies where the foraging activity of Puerto Rican Spindalises was systematically sampled, and from additional observations made throughout the island. We documented 160 records of folivory, with spindalises feeding on 44 plant species in 25 plant families, including monocots, dicots, gymnosperms, and pteridophytes. Spindalises fed on young leaves of 26 plant species, and mature leaves of 19 plant species. Spindalises were primarly frugivorous (83.9% of diet), but leaves were the second most frequent food item in their diets (8.9% of diet). We also found that leaf consumption was negatively correlated with the abundance of ripe fruit, suggesting that leaves were particularly important food items when less fruit was available. The frequency of folivory by spindalises in our study was less than reported for other folivorous passerines such as plantcutters (Phytotoma spp.) and saltators (Saltator spp.). Nonetheless, folivory may help spindalises cope with human‐dominated landscapes and other environmental changes on small islands.     

Temperature: Diet Interactions Affect Survival through Foraging Behavior in a Bromeliad‐Dwelling Predator

Temperature, food quantity and quality play important roles in insect growth and survival, influencing population dynamics as well as interactions with other community members. However, the interaction between temperature and diet and its ecological consequences have been poorly documented. Toxorhynchites are well‐known biocontrol agents for container‐inhabiting mosquito larvae. We found that Toxorhynchites haemorrhoidalis larvae (Diptera: Culicidae) inhabiting water‐filled rosettes of tank bromeliads catch and eat prey of both aquatic (mosquito larvae) and terrestrial origin (ants), using distinct predatory methods. They carried out frontal attacks on ants, but ambushed mosquito larvae. In choice tests, T. haemorrhoidalis favored terrestrial prey. Temperature had a significant effect on predator development and survival through its interaction with diet, but did not alter the preference for ants. T. haemorrhoidalis larvae emerged quickly when fed only mosquito larvae, whereas all individuals died before pupation when fed only ants. We conclude that behavioral factors (i.e., attraction to ants that disturb the surface of the water) overtake physiological factors (i.e., the adverse outcome of elevated temperature and an ant‐based diet) in determining a predator's response to temperature:diet interactions. Finally, because T. haemorrhoidalis larvae preferentially feed on terrestrial insects in tank bromeliads, mosquito larvae may indirectly benefit from predation release.     

Positive indirect effect of tadpoles on a detritivore through nutrient regeneration

In aquatic food webs consumers can affect other members of the web by releasing nutrients as a result of their feeding activity. There is increasing evidence of these positive effects on primary producers, but such nutrient regeneration can also affect detritivores, by favoring the activities of detritus-associated microbes. We examined the effects of nutrient regeneration by tadpoles on leaf-eating detritivores under laboratory conditions. We fed four species of tadpoles three different food items (leaf litter, algae, and sludgeworms). We then conditioned terrestrial dead leaves with water from reared tadpoles (treatments) or food items alone (controls), and compared the C:N ratios of the conditioned leaves and the growth of the isopod Asellus hilgendorfii fed on the conditioned leaves. Tadpole feeding activity reduced the C:N ratio of conditioned leaves, and the effect was greatest when tadpoles were fed algae. Isopod growth rates were often higher when they were fed the litter conditioned with water from reared tadpoles. Thus, nutrient regeneration by tadpoles had a positive indirect effect on detritivores by enhancing leaf quality. Tadpoles often occur in nutrient-limited habitats where leaf litter is the major energy source, and their facilitative effects on leaf-eating detritivores may be of great significance in food webs by enhancing litter decomposition.     

Seasonal changes in food resource distribution and feeding sites selected by Japanese macaques on Koshima Islet,Japan

Feeding sites of Japanese macaques (Macaca fuscata) change according to seasonal fluctuations in food resource distribution. To examine what characteristics of food items affect feeding site selection, I describe herein the seasonal changes in food items, feeding sites, and food resource distributions of this species. Feeding behavior of monkeys and their food resource distributions were investigated on Koshima Islet, southern Japan, for four study periods (i.e., seasons) in 2002. Monkeys showed large variations in their diet between seasons. To weigh the relative influence of the distribution and abundance of food items on feeding site selection in each season, multiple regression analyses were performed by 100 m × 100 m grid. In the analyses, feeding time was a dependent variable and the abundance of staple food items, for which feeding time was over 5% in each season, in each grid square was an independent variable. There was no correlation between the resource distribution of most food items and the distribution of feeding time by monkeys in each season. Monkeys spent more feeding time where multiple staple food items were available. Food items that affected feeding site selection by monkeys had the following three characteristics: (1) clumped distribution, (2) seasonal availability, and (3) fruit. This suggests that monkeys are likely to select feeding sites to consume food items whose availability is limited temporally and spatially, which may enable them to simultaneously use other widely distributed, abundant food items efficiently.