Foraging activity of Rhinolophus hipposideros on the Island of Herrenchiemsee, Upper Bavaria

We studied the foraging behaviour of Rhinolophus hipposideros on the island “Herrenchiemsee” in Lake Chiemsee (Upper Bavaria) during summer 2001. The island offers extensively managed woodlands, highly structured open landscapes and a broad reed belt around the shore. On average the flight activity of the 6 radio tracked females outside the roost lasted 229 min per night. The home range size varied between 6.8 and 62.7 ha (mean 25.2 ha). The size of the activity centres varied between 2.8 and 8.2 ha (mean 5.3) and all except one were located almost exclusively in woodland. Within woodlands the bats did not select for specific spatial structures (different age classes of the stands or canopy densities). Only two bats regularly foraged in additional habitats outside woodlands. One of these bats used orchards and tree rows; the other foraged over artificial ponds and gardens adjoining to its woodland foraging area. We never found the bats foraging over the lake or the reed belt. Longer linear landscape elements as tree lines were used during commuting flights but there was no indication of a continuous foraging activity along these elements. Two females left the island to forage on the mainland in August after the fledging of juveniles. To reach the mainland shore, the bats had to fly at least 1.2 km across the lake.

Assuming that most foraging flights on the island occur in woodlands, a bat density in this habitat type of 0.7 bats/ha can be calculated.     

Stable isotopic niche predicts fitness of prey in a wolf–deer system

Interindividual variation in niche presents a potentially central object on which natural selection can act. This may have important evolutionary implications because habitat use governs a suite of selective forces encountered by foragers. In a free-living native black-tailed deer, Odocoileus hemionus , population from coastal British Columbia, we used stable isotope analysis to identify individual variation in foraging niche and investigated its relationship to fitness. Using an intragenerational comparison of surviving and nonsurviving O. hemionus over 2 years of predation by wolves, Canis lupus, we detected resource-specific fitness. Individuals with isotopic signatures that suggested they foraged primarily in cedar ( Thuja plicata )-dominated and low-elevation hemlock ( Tsuga heterophylla )-dominated forest stands were more likely to be killed by C. lupus . High-quality forage in T. plicata stands, as indexed by protein content, may be involved in maintaining this foraging phenotype. Moreover, nonsurvivors diverged more than survivors from median isotopic signatures, suggesting selection against foraging specialization. Stable isotope analysis provides a novel opportunity to integrate ecological and selective landscapes in order to identify underlying ecological mechanisms of selection and provide insight into the maintenance of variability.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 125–137.     

Multi-scale effects of resource patchiness on foraging behaviour and habitat use by longnose dace, Rhinichthys cataractae

1. We examined the response of a predatory benthic fish, the longnose dace ( Rhinichthys cataractae ), to patchiness in the distribution of benthic macroinvertebrates on cobbles at three hierarchical spatial scales during summer and autumn 1996, and spring 1997 in a southern Appalachian stream. 2. At the primary scale (four to five individual cobbles separated by <1 m), the intensity of foraging was not correlated with the biomass of benthic macroinvertebrates/cobble, regardless of season. 3. At the secondary scale (i.e. foraging patches <5 m in diameter) we found that benthic macroinvertebrates were patchily distributed in summer, but not in autumn or spring. Concomitantly, in summer, longnose dace foraged on cobbles with a significantly higher biomass of benthic macronvertebrates than nearby, randomly selected cobbles with similar physical conditions (i.e. longnose dace tended to avoid low-prey foraging patches). In contrast, when benthic macroinvertebrates were distributed homogeneously (spring and autumn), dace did not select patches with a significantly higher biomass of benthic macroinvertebrates than that available on randomly selected cobbles. 4. At the tertiary scale (i.e. stream reaches 11–19 m long), the biomass of benthic macroinvertebrates (per cobble per reach) was patchily distributed (i.e. differed significantly among reaches) in all seasons. Among reaches with physical characteristics preferred by longnose dace, (i.e. erosional reaches dominated by cobble/boulder substratum and high current velocity), we detected a significant, positive correlation between the biomass of benthic macroinvertebrates/cobble and longnose dace density in all seasons. 5. Our results demonstrated that both spatial and temporal patchiness in resource availability influenced significantly the use of both foraging patches and stream reaches by longnose dace.     

Sharing the same space: foraging behaviour of saproxylic beetles in relation to dietary components of morphologically similar larvae

1. Saproxylic beetles (Coleoptera) have particular requirements for dead wood. Little is known about their larval development, especially within intermediate and late stages of dead wood decay. 2. We studied the natural foraging behaviour of three saproxylic beetles with morphologically similar (i.e. convergent) larvae and similar habitat requirements –Cucujus cinnaberinus Scopoli (Cucujidae), Pyrochroa coccinea L., and Schizotus pectinicornis L. (Pyrochroidae) – examining dietary components using visual gut content analysis. 3. There were few significant differences in diet among the study species, but there were significant differences for the different dietary components in individual species. Guts of all three species included more plant and fungal material than animal. We also observed that with increasing body size larvae foraged significantly less on fungal material. We observed significant differences among species and selection with respect to body size during the overwintering period. Larvae swallowed more animal and less fungal material with increasing body size. 4. The study species seem to be opportunistic foragers, varying their foraging capability according to seasonality and age. They probably generally foraged woody material infested by filamentous fungi (i.e. xylomycetophagy), swallowing other material that is in their way while foraging, including animal parts and small arthropods. 5. We found that morphologically similar larvae do not differ much in their foraging behaviour even when sharing the same habitat. Larval size seems to be a useful predictor for foraging behaviour of saproxylic beetles within the same guild. The study species are probably occasional predators with less ability to forage on other animals than previously suggested.     

Foraging patterns of breeding Dolphin Gulls Larus scoresbii at Punta Tombo, Argentina

The Dolphin Gull Larus scoresbii is a little-known, rare species endemic to southern South America. Knowledge of its feeding ecology is essential for development of management and conservation strategies. To obtain information on their use of food resources and on the frequency and duration of their foraging trips, we followed seven individuals by radiotelemetry during the breeding season of 2002 at the Punta Tombo Reserve, Argentina. In 99% of mapped locations ( n  = 4069) the Gulls were within 2.4 km of their colony. Dolphin Gulls foraged mostly at the colonies of three other species, feeding on Magellanic Penguin Spheniscus magellanicus and Imperial Cormorant Phalacrocorax atriceps regurgitates and on Southern Sea Lion Otaria flavescens faeces. The sea lion colony was the most frequently visited foraging area, accounting for 64% of the total ( n  = 260 trips). A similar trend was observed during both the incubation (60%, n  = 38 trips) and the chick (64%, n  = 40 trips) stages. The mean number of trips per day was 3.8 (range = 3–5), with a mean duration of 123 min (sd = ±27). Trip duration differed between foraging areas, being significantly longer at the sea lion than at the penguin and cormorant colonies. The small foraging range given by its particular feeding strategy suggests that Dolphin Gulls, in contrast to most other seabirds that range over large expanses of ocean in search of food, may be effectively conserved within protected areas during the breeding season.     

Is food availability limiting African Penguins Spheniscus demersus at Boulders? A comparison of foraging effort at mainland and island colonies

The African Penguin Spheniscus demersus (Vulnerable) formed three new colonies during the 1980s, two on the South African mainland (Stony Point and Boulders) and one on Robben Island. One of the mainland colonies, at Boulders, Simon's Town, is in a suburban area, resulting in conflict with humans. Growth of the Boulders colony was initially rapid, largely through immigration, but has since slowed, possibly as a result of density‐dependent effects either on land (where there has been active management to limit the spread of the colony) or at sea. We test the latter hypothesis by comparing the foraging effort of Penguins feeding small chicks at island and mainland sites, and relate this to the foraging area available to birds. Three‐dimensional foraging paths of African Penguins were reconstructed using GPS and time–depth loggers. There were no intercolony differences in the rate at which birds dived during the day (33 dives/h), in diving depths (mean 17 m, max. 69 m) or in travelling speeds. The maximum speed recorded was 2.85 m/s, with birds travelling faster when commuting (average 1.18 m/s) than when foraging (0.93 m/s) or resting at sea (0.66 m/s during the day, 0.41 m/s at night). There were strong correlations between foraging trip duration, foraging range and total distance travelled. Foraging effort was correlated with chick age at Robben Island, but not at Boulders. Contrary to Ashmole's hypothesis, birds from Boulders (c. 1000 pairs) travelled further (46–53 km) and foraged for longer (13.2 h) than did birds from Robben Island (c. 7000 pairs) and Dassen Island (c. 21 000 pairs) (33 km, 10.3 h). The mean foraging range also differed significantly between mainland (18–20 km) and island colonies (9 km). The area available to central‐place‐foraging seabirds breeding on the mainland is typically less than that for seabirds breeding on islands, but the greater foraging range of Boulders birds results in an absolute foraging area roughly twice that of island colonies, and the area per pair is an order of magnitude greater for the relatively small Boulders colony. Ashmole's hypothesis assumes relatively uniform prey availability among colonies, but our results suggest this does not apply in this case. The greater foraging effort of Boulders birds probably reflects reduced prey availability in False Bay, and thus the recent slowing in growth at the colony may be the result of differential immigration rather than management actions to limit the spatial growth of the colony.     

The effects of foraging demand on social interactions in a laboratory group of Bonnet Macaques

The relationship between foraging demand and social behavior was experimentally studied in a laboratory group of bonnet macaques. Fourteen adult animals were housed in a large outdoor enclosure containing three shallow gravelfilled circular containers that served as the foraging sites. During the experimental foraging sessions raisins were placed in the containers and the social and foraging behaviors of the group were observed for 50 min following the distribution of raisins. Three types of foraging conditions were inter-spersed with one another on different test days: (1) surface load— raisins placed on top of the gravel; (2) buried load— raisins hidden underneath the gravel; and (3) sham load— no raisins placed at the foraging sites. Three basic foraging patterns, defined along a temporal dimension, were seen. One group of animals completed 50% of their total foraging by the end of the first 15 min. A second group foraged more steadily through the session. A third group foraged late, completing 50% of their foraging during the last half of the session. The foraging patterns were similar in the buried and surface condition, although the patterns were more compressed during the surface condition. More aggression and more avoidance of other animals occurred in the buried condition than in the surface condition. Very little foraging occurred during the sham condition. There was no clear relationship between the patterns of interaction during foraging and nonforaging observation sessions. The results suggest the value of manipulative laboratory studies in examining the relationship between ecological variables and social behavior in nonhuman primates.     

Individual foraging site fidelity in lactating New Zealand fur seals: Continental shelf vs. oceanic habitats

Wide‐ranging marine central place foragers often exhibit foraging site fidelity to oceanographic features over differing spatial scales (i.e., localized coastal upwellings and oceanic fronts). Few studies have tested how the degree of site fidelity to foraging areas varies in relation to the type of ocean features used. In order to determine how foraging site fidelity varied between continental shelf and oceanic foraging habitats, 31 lactating New Zealand fur seals (Arctocephalus australis forsteri 1 ) were satellite tracked over consecutive foraging trips (14–108 d). Thirty‐seven foraging trips were recorded from 11 females that foraged on the continental shelf, in a region associated with a coastal upwelling, while 65 foraging trips were recorded from 20 females that foraged in oceanic waters. There were no significant differences in the mean bearings (to maximum distance) of individual's consecutive foraging trips, suggesting individual fidelity to foraging areas. However, overlap in area and time spent in area varied considerably between continental shelf and oceanic foragers. Females that foraged on the continental shelf had significantly greater overlap in consecutive foraging trips when compared to females that foraged in oceanic waters (overlap in 5 × 5 km grid cells visited on consecutive trips 55.9%± 20.4% and 13.4%± 7.6%, respectively). Females that foraged on the continental shelf also spent significantly more time within the same grid cell than females that foraged in oceanic waters (maximum time spent in 5 × 5 km grid cells: 14%± 5% and 4%± 2%, respectively). This comparatively high foraging site fidelity may reflect the concentration of productivity associated with a coastal upwelling system, the Bonney Upwelling. Lower foraging site fidelity recorded by seals that foraged in oceanic waters implies a lower density/larger scale habitat, where prey are more dispersed or less predictable at fine scales, when compared to the continental shelf region.     

Foraging behavior of honeybees on white clover

Summary Measurements of several aspects of foraging behavior of honeybees on white clover and of factors that might influence it were made at one-to-two-week intervals during the season. Other measurements were made on intervening days. Individual blossoms yielded a mean of from 0.02 to 0.08 l of nectar containing 42 to 65% sugar during the season. On one day when the nectar averaged 65% sugar, bees with pollen on their corbiculae carried a mean of 5.2 mg of pollen and 37.3 mg of nectar; bees without pollen carried a mean of 37.9 mg of nectar. On 10 occasions each of 50 bees were timed while foraging a single blossom; the mean foraging speed differed significantly on the 10 occasions, and varied from 1.5 to 3.0 seconds per blossom. Each of 18 bees was timed during visits to 25 blossoms, and the total time required for the same bees to forage from the blossoms on 25 racemes was also measured. The mean foraging speed of these bees varied from 1.1 to 4.5 seconds per blossom; the differences were highly significant. These bees foraged 7.0 to 26.0 blossoms per minute, and there was a strong negative correlation between the mean seconds required for bees to forage blossoms and the mean number of blossoms foraged per minute. Fifty one bees observed for a total of 314.5 minutes foraged an average of 18.4 blossoms per minute and 3.4 blossoms per inflorescence. Sixty one per cent of the flights of foraging bees were made to inflorescences estimated to be less than 5 inches from the starting point.Published as Technical Contribution N^o 4244 from theTexas Agricultural Experiment Station.     

Foraging behaviour of individual coal tits,Parus ater,in relation to their age,sex and morphology

The aim of this study was to reveal the causes and consequences of individual differences in foraging behaviour of coal tits, Parus ater, on the island of Gotland in the Baltic. On Gotland the willow tit, P. montanus, and the crested tit, P. cristatus, are absent, while these larger species are abundant competitors on the mainland. The Gotland population of coal tits exploited parts of the foraging niches of their absent competitors. Gotland coal tits are bigger than those on the mainland; they have thus evolved towards the size of the missing competitors. Individual differences in niche use were related to their morphology. Large birds more often used the inner parts of trees whereas small individuals foraged more on needles in the outer parts of the trees. Also, individuals with wing shapes more suitable for hovering and slow flight foraged more on needles. It is argued that morphology affects the profitability of different foraging sites. However, for foraging site selection, age was more important than morphology. Older, and probably more dominant, individuals occupied the most profitable foraging sites.     

Influence of livestock grazing on meadow pipit foraging behaviour in upland grassland

Changes in grazing management are believed to be responsible for declines in populations of birds breeding in grassland over the last decades. The relationships between grazing management regimes, vegetation structure and composition and the availability of invertebrate food resources to passerine birds remain poorly understood. In this study, we investigated the foraging site selection of meadow pipits (Anthus pratensis L.) breeding in high intensity sheep-grazed plots or low intensity mixed (i.e. sheep and cattle)-grazed plots. We sampled above-ground invertebrates, measured vegetation height and density and conducted a vegetation survey in areas where meadow pipits were observed to forage and areas that were randomly selected. Birds foraged in areas with a lower vegetation height and density and in areas containing a lower proportion of the dominant, tussock-forming grass species Molinia caerulea. They did not forage in areas with a total higher invertebrate biomass but at areas with preferred vegetation characteristics invertebrate biomass tended to be higher in foraging sites than random sites. The foraging distance of meadow pipits was higher in the intensively grazed plots. Our findings support the hypothesis that resource-independent factors such as food accessibility and forager mobility may determine patch selection and are of more importance as selection criteria than food abundance per se. Food accessibility seems to become an even more important selection criterion under high grazing intensity, where prey abundance and size decrease. In our upland grazing system, a low intensity, mixed grazing regime seems to provide a more suitable combination of sward height, plant diversity, structural heterogeneity and food supply for meadow pipit foraging activity compared to a more intensive grazing regime dominated by sheep.     

Foraging habitat selection by Little Terns Sternula albifrons in an estuarine lagoon system of southern Portugal

We assessed the effects of environmental variables on the distribution and feeding behaviour of adult Little Terns Sternula albifrons in Ria Formosa Natural Park, Algarve, southern Portugal, in different foraging habitats (main lagoon, salinas and sea) during the breeding seasons, April–July, of 2003–05. Foraging density was higher in the lagoon than in the sea, and at low tide. The number of foraging individuals at sea was independent of tide. Individual Little Terns foraged further from the nearest breeding colony in April and May (courtship feeding and incubation) than in June and July (chick-rearing). During intermediate tidal phases, individuals foraged further from the nearest colony, and followed main lagoon channels, perhaps because stronger currents increased prey availability. Diving activity and foraging success were higher in 2003 than 2004 or 2005, perhaps because of greater availability of marine prey in 2003. Diving rate was higher in July (when independent juveniles began learning how to forage) but diving success was higher in June (chick-rearing) than in other months. The variables selected by the final logistic models reflected four basic needs for the selection of feeding habitats by Little Terns: (1) association between foraging individuals, (2) areas with abundant feeding resources, (3) entrance channels and main lagoon channels with strong currents, and (4) the proximity to areas with alternative feeding resources, the salinas. Areas subjected to strong human pressure were avoided by foraging Little Terns.     

Colony productivity and foundress behaviour of a native wasp versus an invasive social wasp

Abstract.  1. Colony productivity, prey utilisation, and foundress behaviour of a North American native wasp ( Polistes fuscatus ) versus an European invasive wasp ( Polistes dominulus ) were investigated in a controlled field experiment with optimal versus natural foraging conditions. Colonies with the optimal prey foraging conditions were provided with prey ad libitum within an enclosed area. The other colonies foraged in the adjacent field–woodland but had the same nest conditions as the other treatment.
2. When given prey ad libitum , both wasp species captured similar amounts of prey and the conversion to total offspring biomass was similar. But P. dominulus colonies produced 2.5 times the number of workers as P. fuscatus colonies, reflecting the smaller size of P. dominulus wasps.
3. Foundresses of P. dominulus were observed more often building or repairing the nest, thereby contributing to the production of colonies with twice as many cells as colonies of P. fuscatus . Foundresses of P. dominulus showed more acts of aggression toward workers than did P. fuscatus foundresses, which was not a function of adult density on the nest.
4. At the end of the experiment, P. dominulus colonies with optimal prey foraging conditions still had a high level of egg-laying and peaked in the number of pupae then, whereas egg-laying and the number of pupae per colony of the other treatments began to decline 2–3 weeks earlier. These results indicate that P. dominulus is more opportunistic than P. fuscatus , which may account in part for P. dominulus 's success as an introduced species in North America.     

Foraging and diet of the northern bat Eptesicus nilssoni in Sweden

Northern bats foraged predominantly in small individual and transient feeding sites usually in open places near trees and over water. Lakes were preferred as foraging habitat as compared to woodlands and farmlands. The pattern of habitat selection did not change drastically during the period of reproduction. The diet was probably unselective, consisting mainly of small dipterans and moths and also caddis flies, lacewings and mayflies (lake area) and dung beetles (farmland). Northern bats consumed insects of 3–30 mm body length, thus taking prey items of a broader size range than other bat species studied.     

Arthropod prey of imported fire ants (Hymenoptera: Formicidae) in Mississippi sweetpotato fields

The red imported fire ants, Solenopsis invicta (Buren), are generally considered pests. They have also been viewed as beneficial predators feeding on other insect pests of various agroecosystems. This study documents the foraging habits of fire ants in a sweetpotato field in Mississippi. Fire ant foraging trails connecting outside colonies to a sweetpotato field were exposed and foraging ants moving out of the field toward the direction of the colony were collected along with the solid food particles they were carrying. The food material was classified as arthropod or plant in origin. The arthropod particles were identified to orders. Fire ant foragers carried more arthropods than plant material. Coleoptera and Homoptera were the most abundant groups preyed upon. These insect orders contain various economically important pests of sweetpotato. Other major hexapod groups included the orders Hemiptera, Diptera and Collembola. The quantity of foraged material varied over the season. No damage to sweetpotato roots could be attributed to fire ant feeding. Imported fire ant foraging may reduce the number of insect pests in sweetpotato fields.     

TEMPORAL VARIATION IN FORAGING BEHAVIOUR OF PATELLA GRANULARIS (PATELLOGASTROPODA) AND SIPHONARIA CONCINNA (BASOMMATOPHORA) ON A SOUTH AFRICAN SHORE

Foraging activity of two mid- to low- shore species of limpet,Patella granulans (Prosobranchia) and Siphonaria concinna (Pulmonata)from an exposed shore on the Eastern Cape coast of South Africawas monitored. In both species, activity was compared duringspring and neap tides and, in P. granularis between summer andwinter. Rhythms of activity of the two species were similar,with foraging excursions being mainly associated with nocturnallow tide times, although some P. granularis foraged during daytimelow tides. It is suggested that foraging excursions in P. granularisare triggered by wave action. Both species foraged further onspring tides than on neap tides and this is suggested to bea result of the limited time limpets have to forage. P. granulariswas also found to forage further during summer when comparedto winter and the possibility that seasonal micro-algal productivityinfluences foraging distances in limpets is discussed. The foraging activity of both species could be divided into3 distinct phases, a relatively rapid outward phase, a muchslower foraging phase and a rapid homeward phase. Whether ornot these limpets graze throughout an excursion is not known.S. concinna was found to home to a fixed scar, although duringthe experiment some scar-swapping occurred. P. granularis didnot home to a fixed scar but possessed a ‘home range’(approx. 5 cm²) to which it returned after each excursion. Patella granularis was found to move randomly during foraging,whilst S. concinna foraged in a non-random direction -whichtook individuals upshore. No tidal-influence is thought to bepresent in this case and the possibility of a learning componentin the foraging behaviour of certain limpet species in relationto the return to optimal feeding patches is discussed. (Received 18 May 1996; accepted 2 September 1996)     

Morphology and foraging behaviour of Siberian Phylloscopus warblers

There are seven species of Phylloscopus warblers breeding sympatrically in Central Siberia. In general they are very similar in morphology and behaviour. Slight differences in morphology, however, are often interpreted as having arisen through adaptation to distinct foraging ecologies, thereby mediating species coexistence. We studied the morphology and foraging behaviour of these warblers, taking into account phylogenetic relationships using Felsenstein's method of independent contrasts. Striking correlations were found between morphology and foraging techniques, as well as between morphology and microhabitat selection. Species with large hind limbs and short wings foraged in dense vegetation near the ground using gleaning techniques. In contrast, species with long wings and large bills favoured open vegetation, and foraged using sallying manoeuvres. Independently of these trends, small species foraged at higher levels in the vegetation, and used hoverflight more often than did larger species. Foraging methods were highly correlated with vegetation structure. Coniferous trees were exploited using hoverflight when they had short needles and gleaning when needles were long. Sallying predominated in light deciduous vegetation whereas gleaning was used most in dense, deciduous bushes. After controlling for the effects of vegetation structure on foraging behaviour, species differences became less pronounced, but were still significant. It is therefore concluded that morphology may be regarded as having adapted to enable more efficient exploitation of certain microhabitats. A preference for these microhabitats then further increases the observed behavioural differences between species. Morphology may therefore partly determine a species' ability to colonise new habitats.     

Effects of size and sex on the courting success and foraging behaviour of Embiotoca jacksoni

To test life-history theory that body size and sex should influence how animals allocate time to foraging versus reproductive activities, we measured the effects of size and sex on courting success and foraging behaviour of black surfperch Embiotoca jacksoni off Santa Catalina Island, southern California. Observations of focal fish were made while snorkelling, during which the length of each fish (estimated to the nearest cm), total duration of courting encounters and foraging rates were recorded. We made observations during and outside the mating season. Courtship occurred only between pairs and its duration increased with the size of both the male and female. Although males would court females that were smaller or larger than themselves, pairs that were closely matched in size had long courting sessions, whereas those that differed considerably in size courted only briefly. Small fish foraged more than larger fish, both during and outside the mating season. Males and females foraged at similar rates outside of the mating season, but during the mating season males reduced their foraging rates to less than half that seen outside of the mating season, whereas females continued to forage at the same rate. This decrease in foraging rate of males during the mating season was seen in all sizes of males but was proportionally greatest in the largest males. These observations indicate that males trade off time spent on foraging for time spent courting during the mating season, whereas females do not.     

西双版纳野生亚洲象的觅食行为

以西双版纳勐养自然保护区的野象谷为基本监测点,通过定点摄像观察和跟踪观察,采用全事件取样、焦点动物取样和扫描取样相结合的方法,从2003 年8 月到2004 年7 月对三岔河地区野生亚洲象的觅食行为进行初步研究。发现野生亚洲象的雌性成体和未成年个体选择集群采食,而成年雄象一般单独采食,亚洲象在昼夜间的采食行为没有显著性差异,且有多种采食方式;采食农作物主要在夜间进行。亚洲象对主要采食地点采取循环利用的方式,这既提高了食物的数量和质量,又有利于热带雨林生态系统的更新与演化。     

Seed predation by birds and small mammals in semiarid Chile

We studied spatial and temporal patterns in foraging activity among diurnal birds and nocturnal mammals at a semiarid site in northern Chile using artificial foraging trays. Small mammals foraged more extensively under shrubs than in open microhabitats, but birds showed no such selection. Moreover, avian foraging was more extensive than that by small mammals in all seasons and both microhabitats. Avian foraging was highly seasonal, as many birds at our site migrate to the Andean prepuna or to Patagonia during the austral summer. Birds have tended to be overshadowed by small mammals and ants in studies of granivory, but this study suggests that their importance may be underestimated in some systems.