In situ feeding tactics of short-nosed fruit bat (Cynopterus sphinx) on mango fruits: evidence of extractive foraging in a flying mammal

We report a sequence of behaviors exhibited by the short-nosed fruit bat Cynopterus sphinx while feeding on fruits of Mangifera indica. They peel off the outer skin to form a feeding area of about 3–6 cm diameter. Such food preparatory behaviors were more pronounced on larger mangoes. Bats competed among themselves to feed on the mangoes that had such feeding areas exposed. Individuals that spent a considerable amount of time on food preparatory behaviors actively secured the fruits. Altogether, these behaviors indicate that Cynopterus bats might have learnt, over evolutionary time, and developed behaviors that facilitate efficient processing and feeding of fruits such as mangoes. It appears that actions exhibited by C. sphinx in peeling off the outer skin of mangoes exemplify “extractive foraging”, a behavior that is prominently known in large-brained mammals. Thus, our findings will have implications on the distribution and evolution of extractive foraging and “technical intelligence” among mammalian lineages.     

Rapid shifting of foraging pattern by Yakushima macaques ( Macaca fuscata yakui ) in response to heavy fruiting of Myrica rubra

We describe short-term changes in foraging behavior by wild Yakushima macaques (Macaca fuscata yakui),which inhabit a warm-temperate broad—leaved forest on Yakushima Island (30°N, 131°E), Japan. Rapid changes of dietary composition, activity budget, and range use by the monkeys occurred from May to June, apparently associated with changes in the availability of the fruit of Myrica rubraBefore the fruit ripened, monkeys spent less time moving and more time feeding on many species of leaves, which accounted for 40% of feeding time. However, when M. rubrabegan to ripen, they fed intensively on the fruit, which accounted for three-fourths of feeding time,though the activity budget remained unaffected As fiuit of M. rubradecreased,the monkeys fed more on the fruit of other species and on insects, and spent more time moving at higher speeds. There marked shifts in foraging pattern occurred within only two months. In terms of moving cost and dietary quality,Yakushima macaques shifted their foraging pattern according to the availability of M. rubrafrom a “low-cost, low-yield” strategy to a “low-cost, high-yield” strategy, and then to a more costly strategy. The ability to make such rapid shifts in foraging pattern may allow the macaques to effectively use the highly variable food supply within their small range.     

Rank and age related feeding strategy observed through field experiments in the Koshima group of Japanese macaques

The feeding process of Japanese monkeys on soy beans which were scattered over a sandy beach on Koshima islet was studied. Younger monkeys were able to pick up more beans when 8 kg of beans were divided and given two times (“two times feeding”) than when the whole amount (8 kg) of beans was given at one time (“one time feeding”). The effect of saturation of the food intake capacity in younger monkeys at the first feeding in “two times feeding” did not appear at the second feeding one hour later. The minutely intake of soy beans (feeding speed) for each age class was analyzed. The decline of feeding speed in adult females after the peak in “one time feeding” was not related to the decline in density of beans on the ground, and this decline was caused by saturation of their food intake capacity. Adult females were divided into four classes according to their dominance rank order: high, lower-high, higher-low, and low classes. The total amount of intake in “one time feeding” was far larger in the high class than in any of the other classes. The total amount of feeding in the first feeding of “two times feeding” increased in accordance with rise in the dominance rank class, and there was no relation to rank and total feeding amount in the second feeding of “two times feeding.” Differences existed in the process of feeding between the rank classes. The feeding speed of the low class was as high as that of the high class on the curve of minutely intake, while the low class stopped feeding much earlier than the high class. The lower-high class displayed a low feeding speed, and stopped feeding the latest. The order of the duration to stay and to feed in the feeding area was lower-high > high > higher-low > low, and this order did not change under the three different feeding conditions, “one time feeding,” and the first and second feedings of “two times feeding.” Adolescent females tended to stay the longest duration in the feeding area among all age classes. Both the lower-high class females and adolescent females had an unstable social status in the Koshima group, and their social status affected their feeding behaviors. The feeding behaviors were similar in attitude depending on social status, and are considered to be maintained for a fairly long time. The feeding strategy of the lower-high class, in staying a longer duration in the artificial feeding area, and departing later, may be effective under the artificial feeding conditions, but it may be a bad strategy in a natural habitat where the food is not so clumped as in artificial feeding, and where choice of other food patches is possible. The above results agree well with previous reports for the Koshima group, indicating that the rank of the lower-high class females was unstable (Mori et al., 1989), and that their reproductive success was low (Watanabe et al., 1992).     

The role of foraging behaviour in the sexual segregation of the African elephant

Elephants (Loxodonta africana) exhibit pronounced sexual dimorphism, and in this study we test the prediction that the differences in body size and sociality are significant enough to drive divergent foraging strategies and ultimately sexual segregation. Body size influences the foraging behaviour of herbivores through the differential scaling coefficients of metabolism and gut size, with larger bodied individuals being able to tolerate greater quantities of low-quality, fibrous vegetation, whilst having lower mass-specific energy requirements. We test two distinct theories: the scramble competition hypothesis (SCH) and the forage selection hypothesis (FSH). Comprehensive behavioural data were collected from the Pongola Game Reserve and the Phinda Private Game Reserve in South Africa over a 2.5-year period. The data were analysed using sex as the independent variable. Adult females targeted a wider range of species, adopted a more selective foraging approach and exhibited greater bite rates as predicted by the body size hypothesis and the increased demands of reproductive investment (lactation and pregnancy). Males had longer feeding bouts, displayed significantly more destructive behaviour (31% of observations, 11% for females) and ingested greater quantities of forage during each feeding bout. The independent ranging behaviour of adult males enables them to have longer foraging bouts as they experience fewer social constraints than females. The SCH was rejected as a cause of sexual segregation due to the relative abundance of low quality forage, and the fact that feeding heights were similar for both males and females. However, we conclude that the differences in the foraging strategies of the sexes are sufficient to cause spatial segregation as postulated by the FSH. Sexual dimorphism and the associated behavioural differences have important implications for the management and conservation of elephant and other dimorphic species, with the sexes effectively acting as distinct “ecological species”.     

Ephedra sinica Stapf (Ephedraceae): The fleshy bracts of seed cones used in Mongolian food and its nutritional components

Ephedra sinica Stapf (commonly, Chinese ephedra) grows mainly in Mongolia, Inner Mongolia, and other regions of northern China. The stems of Chinese ephedra have been called the world’s oldest medicine; other uses remain to be reported. Among the Mongolian people, in addition to medical applications, the fleshy bracts of the seed cones (or “fruit”) are traditionally used as food, fresh or dried, in several ways; for example, the fruit is used as a refined sugar, a cheese condiment, and a tea substitute. In this paper, we analyze the fruit’s nutritional components: moisture, crude protein, crude fat, crude fiber, carbohydrate, ash, pectin, vitamins, fatty acids, mineral elements, and amino acids. Ethnobotanical and nutritional component information may indicate that the plant has potential for development as a special food plant     

Two types of using of space in the resident common shrews <Emphasis Type="Italic">Sorex araneus</Emphasis> L.

The home range of resident animals is considered as “familiar area” including a “foraging area.” It has been revealed that the activity of an average animal unit in the “foraging area” could be approximated by normal distribution. Estimation of activity distribution in the “familiar area” (beyond the “foraging area”) was impeded by means of marking since it might be difficult to record distant movements, and the method does not provide an essential body of data. In the case of the common shrew Sorex araneus, the “familiar area” was estimated using pitfall as animals evade them in the known areal. The “foraging area” radius of the average shrew was taken to be 30 m (95% of the animal unit activity), the radius of “familiar area” was within the range of 180–240 m. The “foraging area” was expected to provide the animal with vital resources, and the “familiar area” reflects its need for exploratory activity.     

The influence of host fruit morphology on parasitization rates in the Caribbean fruit fly,Anastrepha suspensa

Among the host fruits of the Caribbean fruit fly there are a variety of sizes and shapes. These morphological differences may influence the vulnerability of the larvae to parasites. In the laboratory, Caribbean fruit fly larvae placed in the smaller of 2 different sizes of artificial ‘fruit’ (cloth spheres filled with a diet material) were parasitized at a higher rate by the braconid,Diachasmimorpha longicaudata (Ashmead) when spheres were presented separately. However, when parasites were simultaneously presented with 6 different sizes of ‘fruit’ there was no significant relationship between size and parasitization rate. This may be due to the parasites preference to search for larvae in larger ‘fruit’. In field collections of different species of host fruit, a significant inverse correlation exists between fruit radius and rate of parasitization. However, host fruit size accounts for only about 5% of the variance in yearly parasitization rates.      

Flying bats use serial sampling to locate odour sources

Olfactory tracking generally sacrifices speed for sensitivity, but some fast-moving animals appear surprisingly efficient at foraging by smell. Here, we analysed the olfactory tracking strategies of flying bats foraging for fruit. Fruit- and nectar-feeding bats use odour cues to find food despite the sensory challenges derived from fast flight speeds and echolocation. We trained Jamaican fruit-eating bats (Artibeus jamaicensis) to locate an odour reward and reconstructed their flight paths in three-dimensional space. Results confirmed that bats relied upon olfactory cues to locate a reward. Flight paths revealed a combination of odour- and memory-guided search strategies. During ‘inspection flights’, bats significantly reduced flight speeds and flew within approximately 6 cm of possible targets to evaluate the presence or absence of the odour cue. This behaviour combined with echolocation explains how bats maximize foraging efficiency while compensating for trade-offs associated with olfactory detection and locomotion.     

Interpulse interval modulation by echolocating big brown bats (<Emphasis Type="Italic">Eptesicus fuscus</Emphasis>) in different densities of obstacle clutter

Big brown bats (Eptesicus fuscus) use biosonar to find insect prey in open areas, but they also find prey near vegetation and even fly through vegetation when in transit from roosts to feeding sites. To evaluate their reactions to dense, distributed clutter, bats were tested in an obstacle array consisting of rows of vertically hanging chains. Chains were removed from the array to create a curved corridor of three clutter densities (high, medium, low). Bats flew along this path to receive a food reward after landing on the far wall. Interpulse intervals (IPIs) varied across clutter densities to reflect different compromises between using short IPIs for gathering echoes rapidly enough to maneuver past the nearest chains and using longer IPIs so that all echoes from one sound can be received before the next sound is emitted. In high-clutter density, IPIs were uniformly shorter (20–65 ms) than in medium and low densities (40–100 ms) and arranged in “strobe groups,” with some overlap of echo streams from different broadcasts, causing pulse-echo ambiguity. As previously proposed, alternating short and long IPIs in strobe groups may allow bats to focus on large-scale pathfinding tasks as well as close-in obstacle avoidance.     

食物大小对棕果蝠和犬蝠取食行为的影响

按照最优化觅食理论,动物在取食时需在能量获取与捕食风险之间权衡。本文通过室内行为实验,研究两种旧大陆果蝠棕果蝠和犬蝠对食物大小的选择规律与取食策略。按体积由小到大将苹果分为Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型4 种类型的食物块,通过红外相机观察果蝠对不同大小食块的取食情况,并就其对各类型食块的取食率、取食次数和停留时间进行统计分析。结果表明:这两种果蝠对Ⅱ型和Ⅲ型食块的取食率显著高于Ⅰ型和Ⅳ型;对Ⅰ型食块的取食次数显著高于Ⅱ型和Ⅳ型;对Ⅳ型食块的停留时间显著高于Ⅰ型和Ⅱ型。它们在摄取体积较小的食块时,以取走后进食为主要取食方式,但摄取大体积食块时则主要在原地进食。取食过程中,果蝠优先选择大小适于搬运的食块,是捕食风险与能量收益权衡的结果。     

Long-Term Foraging Expeditions (Molongo) among the Baka Hunter-Gatherers in the Northwestern Congo Basin, with Special Reference to the “Wild Yam Question”

While “Pygmy” hunter-gatherers have generally been assumed to be the original inhabitants of the central African rainforest, recent studies dispute the viability of subsistence in tropical rainforests through foraging alone. There are, however, few studies that are based on sound data of actual long-term foraging. This paper examines the viability of “pure” foraging in tropical rainforests, based on data from participant observation of a long-term foraging expedition among the Baka in the northwestern Congo Basin. The group was observed to subsist solely on wild food resources, particularly wild yams, for two-and-half months. The study was carried out during the dry season when food resources are generally thought to be scarce in tropical rainforests.     

Sexes,species, and genomes: why males and females are not like humans and chimpanzees

This paper describes, analyzes, and critiques the construction of separate “male” and “female” genomes in current human genome research. Comparative genomic work on human sex differences conceives of the sexes as like different species, with different genomes. I argue that this construct is empirically unsound, distortive to research, and ethically questionable. I propose a conceptual model of biological sex that clarifies the distinction between species and sexes as genetic classes. The dynamic interdependence of the sexes makes them “dyadic kinds” that are not like species, which are “individual kinds.” The concept of sex as a “dyadic kind” may be fruitful as a remedy to the tendency to conceive of the sexes as distinct, binary classes in biological research on sex more generally.     

Complementarity effects through dietary mixing enhance the performance of a generalist insect herbivore

The ontogenetic niche concept predicts that resource use depends on an organism’s developmental stage. This concept has been investigated primarily in animals that show differing resource use strategies as juveniles and as adults, such as amphibians. We studied resource use and performance in the grasshopper Chorthippus parallelus (Orthoptera, Acrididae) provided with food plant mixtures of either one, three or eight plant species throughout their development. C. parallelus survival and fecundity was highest in the food plant mixture with eight plant species and lowest in the treatments where only one single plant species was offered as food. C. parallelus’ consumption throughout its ontogeny depended on sex, and feeding on different plant species was dependent on a grasshopper’s developmental stage. To depict grasshopper foraging in food plant mixtures compared to foraging on single plant species, we introduce the term “relative forage total” (RFT) based on an approach used in biodiversity research by Loreau and Hector (Nature 413:548–274, 2001). RFT of grasshoppers in food plant mixtures was always higher than what would have been expected from foraging in monocultures. The increase in food consumption was due to an overall increase in feeding on plant species in mixtures compared to consumption of the same species offered as a single diet. Thus we argue that grasshopper foraging exhibits complementarity effects. Our results reinforce the necessity to consider development-related changes in insect herbivore feeding. Thorough information on the feeding ontogeny of insect herbivores could not only elucidate their nutritional ecology but also help to shed light on their functional role in plant communities. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Flight is the key to postprandial blood glucose balance in the fruit bats Eonycteris spelaea and Cynopterus sphinx

Excessive sugar consumption could lead to high blood glucose levels that are harmful to mammalian health and life. Despite consuming large amounts of sugar‐rich food, fruit bats have a longer lifespan, raising the question of how these bats overcome potential hyperglycemia. We investigated the change of blood glucose level in nectar‐feeding bats (Eonycteris spelaea) and fruit‐eating bats (Cynopterus sphinx) via adjusting their sugar intake and time of flight. We found that the maximum blood glucose level of C. sphinx was higher than 24 mmol/L that is considered to be pathological in other mammals. After C. sphinx bats spent approximately 75% of their time to fly, their blood glucose levels dropped markedly, and the blood glucose of E. spelaea fell to the fast levels after they spent 70% time of fly. Thus, the level of blood glucose elevated with the quantity of sugar intake but declined with the time of flight. Our results indicate that high‐intensive flight is a key regulator for blood glucose homeostasis during foraging. High‐intensive flight may confer benefits to the fruit bats in foraging success and behavioral interactions and increases the efficiency of pollen and seed disposal mediated by bats.     

Simple rules result in the adaptive turning of food items to reduce drag during cooperative food transport in the ant <Emphasis Type="Italic">Pheidole oxyops</Emphasis>

Insect workers cooperate to carry out a variety of tasks. One example is cooperative transport of food items by two or more ant workers, which is important in foraging in many species. We predicted that natural selection would result in strategies that improve the performance of this task and tested this in Pheidole oxyops, a Neotropical ant in which ca. 70% of the biomass of dead insects brought back to the nest is transported cooperatively. We specifically tested the hypothesis that groups would re-orient food items to reduce drag, given that legs, wings, and other projections should affect the ease of dragging prey in different orientations. By presenting ants with artificial food items and dead cockroaches, both of which required approximately twice as much force to drag backwards as forwards, and a control which was equally easy to move in both orientations, we showed that natural groups of 3–20 food-transporting ants usually turned items that were facing backwards (72 and 83% of trials for artificial food items or cockroaches, respectively), the orientation requiring greater force, but not items facing forwards (10 and 12% of trials, respectively). Turning usually involved a single ‘steering’ ant. The key role of the ‘steering’ ant was shown by removing either the current steering ant or a randomly chosen ‘non-steering’ ant during turning. In 100% of the trials in which the steering ant was removed, turning stopped until another ant took its place. Conversely, turning stopped in only 17% of trials in which a ‘non-steering’ ant was removed. Turning is an emergent property of the system and may not have been directly selected for. Rather, turning seems to occur through a combination of pre-existing retrieval behaviour and the underlying physics of large loads. Points where the food item catches the ground can act as a fulcrum or pivot around which the item can rotate. Ants furthest from the fulcrum have more leverage and so are more likely to play a key role in turning. A simple rule relevant to individual transport of food items such as “grasp the food item and move towards the nest”, when used in the context of cooperative transport, has allowed the ants to solve a seemingly complicated problem requiring coordination.     

Echolocation behaviours of the Japanese pipistrelle batPipistrellus abramus during foraging flight

The acoustic structure of echolocation pulses emitted by Japanese pipistrellePipistrellus abramus (Temminck, 1840) bats during different phases of aerial hawking is described here for the first time. Behavioural observations of the foraging flight in conjunction with acoustical analysis of echolocation pulses indicated a flight path consisting of four distinct phases following the reconnaissance or search phase. Short (∼4.68 ms) and relatively broadband frequencymodulated (FM) pulses (∼23.55 kHz bandwidth) were emitted at a repetition rate of 15 Hz during presumed target approach. Presumed insect capture consisted of an early and a late buzz phase. Both buzz types were emitted at high repetition rates (111 Hz in early to 222 Hz in late) and consisted of very short, broadband FM pulses (1.26 ms in early to 0.3 ms in late). There was also a characteristically sharp drop in both the peak and terminal frequencies of each echolocation pulse during the transition from early to late buzz. No pulses were recorded during the final phase of foraging referred to as a “post-buzz pause”. Thus the foraging behaviour of this species consisted of five sequential phases involving four broad types of echolocation pulses.     

Feeding of <Emphasis Type="Italic">Ctenocalanus citer</Emphasis> in the eastern Weddell Sea: low in summer and spring,high in autumn and winter

The feeding activity and diet of the small dominant Antarctic copepod, Ctenocalanus citer, were studied throughout the seasonal cycle from samples taken during several “Polarstern” cruises to the eastern Weddell Sea. Two indices of feeding activity were used, percentage of copepods with food inside and length of the faecal pellets. C. citer guts contained food throughout the year thus confirming the year-round activity of this species without diapause. Both indices demonstrated a seasonal pattern of foraging, unusual for a predominantly herbivorous copepod: high-feeding activity in autumn–winter and low in spring–summer. Our results suggest that feeding is at least partially decoupled from the phytoplankton bloom. Diet of C. citer was assessed by analyzing the gut contents. The bulk of the recognizable food in the guts of all copepodite stages consisted of small-sized phytoplankton, and no evidence of switching to a more carnivorous diet at low-phytoplankton concentrations was obtained. Usage of ice-associated algae was proposed to explain high winter-feeding activity. This knowledge of seasonal feeding patterns fills in a gap in our understanding of the life-cycle strategy of C. citer.     

Seasonal intake responses in the nectar-feeding bat Glossophaga soricina

Food intake in nectar-feeding animals is affected by food quality, their energetic demands, and the environmental conditions they face. These animals increase their food intake in response to a decrease in food quality, a behavior named “intake response”. However, their capacity to achieve compensatory feeding, in which they maintain a constant flux of energy, could be constrained by physiological processes. Here we evaluated how both a seasonal change in environmental conditions and physiological constraints affected the food ingestion in the bat Glossophaga soricina. We measured food intake rate during both the wet/warm and dry/cool seasons at sucrose solutions ranging from 146 to 1,022 mmol L⁻¹. We expected that food intake and metabolic demands would be greater during the dry/cool season. Bats ingested ~20% more food in the dry/cool than in the wet/warm season. Regardless of season, bats were unable to achieve a constant flux of energy when facing the different sugar concentrations that we used in our experiments. This suggests that the rate of food intake is physiologically constrained in G. soricina. Using the digestive capacity of bats we modeled their food intake. The analytic model we used predicts that digestive limitations to ingest energy should have an important effect on the ecology of this species.     

Geophagy by the Indian short-nosed fruit bat, <Emphasis Type="Italic">Cynopterus sphinx</Emphasis> (Pteropodidae) while foraging on <Emphasis Type="Italic">Madhuca latifolia</Emphasis> (Sapotaceae) in Tamil Nadu,South India

Geophagy has been reported in many mammals and birds. However, in pteropodid bats, this behaviour has not been reported. Here, we document geophagy behaviour by the pteropodid bat, Cynopterus sphinx, during foraging in the fruiting trees of Madhuca latifolia (Sapotaceae). These bats removed single fruits from the foraging tree and carried it to the feeding roost for consumption. At around 1900 h, we observed three individuals of C. sphinx gleaning over the ground surface by circling flights. The bats landed with their wings spread apart and started licking the soil with head movements. Their ventral body surface rested completely on the ground while consuming the soil. A total of 91 feeding bouts of soil consumption were recorded within 1 h; however, thereafter, this behaviour was not observed. In order to understand the function of geophagy, we quantitatively analysed the composition of minerals in the soil, as well as in the M. latifolia fruits (partially ripe) along with its secondary metabolites from the study site. Our results revealed that the partially ripe fruits contained high levels of secondary metabolites (alkaloids, tannins, coumarins and saponins). The soil contained higher levels of Mg, Ca, Fe, Na and K minerals than the fruits. These findings suggest that bats may gain essential minerals that are low in their fruit diet by consuming soil. In addition, the observed minerals that play a role in detoxification of the secondary metabolites present in the partially ripe fruits that might be detrimental to the consuming bats. Frugivory, nectarivory and folivory are well understood in C. sphinx; however, geophagy behaviour has not been reported in this species so far. This may represent an ‘adaptive behavioural plasticity’ in the foraging behaviour of the observed C. sphinx population.     

Md-ACS1 and Md-ACO1 genotyping of apple (<Emphasis Type="Italic">Malus</Emphasis> x <Emphasis Type="Italic">domestica</Emphasis> Borkh.) breeding parents and suitability for marker-assisted selection

Fruit ethylene production genotypes for Md-ACS1 and Md-ACO1 were determined for 60 apple cultivars and 35 advanced breeding selections. Two alleles for each gene are commonly found in cultivated apple. Earlier studies showed that genotypes homozygous for the ACS1-2 allele produce less ethylene and have firmer fruit than ACS1-1/2 and ACS1-1/1 genotypes. ACO1 plays a minor role compared to ACS1, with homozygous ACO1-1 having lower ethylene production. In this study, ACS1-2 and ACO1-1 homozygotes had firmer fruit at harvest and after 60 days of 0–1°C cold storage compared to other genotypes. These genotypes, ACS1-2/2 and ACO1-1/1, were observed for the following 8 of 95 cultivars/selections: “Delblush”, “Fuji”, “Pacific Beauty”, “Sabina” and four breeding selections. Cultivars/selections that were homozygous ACS1-2 but not ACO1-1 were: “Ambrosia”, “Aurora Golden Gala”, “CrimsonCrisp”, “Gala”, “GoldRush”, “Huaguan”, “Pacific Rose, “Pacific Queen”, “Pinova”, “Sansa”, “Sonja”, “Sundance”, “Zestar”, and 17 breeding selections. Cultivars with the heterozygous ACS1-1/2 genotype were “Arlet”, “Braeburn”, “Cameo”, “Delicious”, “Delorgue”, “Empire”, “Enterprise”, “Ginger Gold”, “Golden Delicious”, “Granny Smith”, “Honeycrisp”, “Orin”, “Pink Lady”, “Silken”, “Suncrisp”, “Sundowner”, “Sunrise” and 11 breeding selections. No cultivars were detected homozygous for both ACS1-1 and ACO1-1, or for both ACS1-2 and ACO1-2. This study is the first large-scale allelic genotyping of both ethylene synthesis genes for a comprehensive set of apple breeding parents used in an ongoing breeding project. The data reported here are important for informative selection of parent combinations and marker-assisted selection of progeny for breeding low ethylene-producing apple cultivars for better storability and improved consumer acceptance.