Feeding Roosts Research Articles

Conventional and genetic measures of seed dispersal for Dipteryx panamensis (Fabaceae) in continuous and fragmented Costa Rican rain forest

The effects of habitat fragmentation on seed dispersal can strongly influence the evolutionary potential of tropical forest plant communities. Few studies have combined traditional methods and molecular tools for the analysis of dispersal in fragmented landscapes. Here seed dispersal distances were documented for the tree Dipteryx panamensis in continuous forest and two forest fragments in Costa Rica, Central America. Distance matrices were calculated between adult trees (n = 283) and the locations of seeds (n = 3016) encountered along 100 × 4-m transects (n = 77). There was no significant difference in the density of seeds dispersed > 25 m from the nearest adult (n = 253) among sites. There was a strong correlation between the locations of dispersed seeds and the locations of overstorey palms favoured as bat feeding roosts in continuous forest and both fragments. Exact dispersal distances were determined for a subset of seeds (n = 14) from which maternal endocarp DNA could be extracted and matched to maternal trees using microsatellite analysis. Dispersal within fragments and from pasture trees into adjacent fragments was documented, at a maximum distance of 853 m. Results show no evidence of a fragmentation effect on D. panamensis seed dispersal in this landscape and strongly suggest bat-mediated dispersal at all sites.

Pollinators and pollen dispersal of Piper dilatatum (Piperaceae) on Barro Colorado Island, Panama

The genus Piper is an important component of tropical forests worldwide. Many Piper species have been reported as self-compatible (Figueiredo & Sazima 2000), and many have the ability to reproduce asexually, forming clonal aggregations (Grieg 1993). Furthermore, the main dispersers of Piper (bats) transport whole infructescences to feeding roosts (Fleming & Heithaus 1981), tending to disperse closely related seeds in clumps. These characteristics of Piper biology are likely to result in populations with strongly marked spatial genetic structure, and raise the potential for inbreeding depression through self-fertilization. A few studies using allozymes to evaluate spatial genetic structure in Piper spp. support this view. These studies indicate that populations separated by more than 1 km are genetically distinct (high FST values; Wright 1943) and that for some species inbreeding could be substantial (high values of FIS and FIT; Heywood & Fleming 1986, Mariot et al. 2002). However, the contributions of limited pollen and seed dispersal to generating spatial genetic structure remain unknown. Estimates of seed dispersal probabilities by Carollia perspicillata (Phyllostomidae) bats on Barro Colorado Island (BCI), Panama, and at Santa Rosa, Costa Rica, indicate that Piper dispersers move most seeds 50–300 m from the parent plant, with occasional long-distance events of > 1 km (Fleming 1981, Thies 1998). However, no studies have assessed how far Piper flower visitors move pollen. If seed dispersal is limited, and clonal reproduction is common, then long-distance pollen transfer may play a critical role in preventing inbreeding depression in Piper populations.

Seed Dispersal of Morus macroura (Moraceae) by Two Frugivorous Bats in Xishuangbanna, SW China

ABSTRACTThe dispersal of Morus macroura seeds by two species of frugivorous bats (Rousettus leschenaulti and Cynopterus sphinx) was studied in a forest at Xishuangbanna Tropical Botanical Garden in Southwest China from March to May 2005. Feeding roosts were identified within 500 m around parent trees and the types and number of seed loads under each roost were recorded. We found feeding roost density decreased with increasing distance from the parent, but found no correlation between distance and seed deposition. The effect of bat digestion on seed germination was investigated, and we found that germination percentage of all treatments involving ingestion by bats was significantly lower than control seeds and some germination parameters of seeds from different treatments changed.

Temporal and spatial patterns of seed dispersal of Musa acuminata by Cynopterus sphinx

The foraging behavior of greater short-nosed fruit bats (Cynopterus sphinx) on wild banana (Musa acuminata) and subsequent dispersal of seeds were studied in the Tropical Rainforest Conservation Area, Xishuangbanna Tropical Botanical Garden, Yunnan province, by direct observation of marked fruits, mist netting, and seed collection. The mean number (± SE) of individual C. sphinx captured by mist net were 2.2 ± 0.33/day and 1.4 ± 0.32/day in the rainy season (September to October) and dry season (November to December), respectively; the difference was not significant. The number of seed pellets expelled was 9.0 ± 1.12/day and 7.2 ± 1.37/day in the rainy and dry seasons respectively; again the difference was not significant. The removal curves for marked fruit were similar for 10 focal trees. Fruits were consumed heavily within two weeks after ripening and all the marked fruit were removed within one month. The difference in seed dispersal was significant between different feeding roosts indicating that patterns of seed dispersal may not be uniform. We found the seeds of M. acuminata can be dispersed by C. sphinx to a distance of about 200 m, and C. sphinx can be considered as an effective seed disperser of M. acuminata.

A note on the diet and foraging behavior of Artibeus lituratus (Chiroptera, Phyllostomidae) in an urban park in southeastern Brazil

Bats of the genus Artibeus are among the most important seed dispersers in early successional forests. We report observations on the foraging behavior of Artibeus lituratus in Pedra da Cebola Municipal Park, an urban park in the city of Vitória, Espírito Santo, southeastern Brazil. Observations were made during six consecutive days (April 1st to April 6th, 2006). Three mist-nets were opened each night close to a Maclura tinctoria tree (Moraceae), remaining open from 18:00 to 22:00, totaling four hours per night, and 24 hours of sampling effort. We observed two peaks of feeding activity at the tree, one between 18:20 and 19:30, and a second one at 21:00. This is the first observation of Artibeus lituratus feeding on M. tinctoria fruits, therefore adding a new item to the known diet of the species. M. tinctoria fruits have large seeds that are not swallowed by bats, they consume the fruit pulp and discard the seeds. A diet of fruits with large seeds may indicate an important resource not detected in dietary studies based on fecal samples, but better detected by direct observation or by studying feeding roosts. It is important to use different sampling techniques in dietary studies since they complement each other and, together, provide a better knowledge on the diet of bats.

Use of abandoned mines by a community of temperate bats in Durango, Mexico

ABSTRACT The Guanacevi region has been actively mined at least for the last 500 years. Mining activity has resulted in a large number of abandoned mines, which may represent important refuges for the chiropteran fauna of the region. I surveyed a sample of 25 abandoned mines during an annual cycle to determine which species use the mines, how they use it, and whether occupation is significantly related to a set of environmental variables measured from the mines. Simultaneously I carried out an inventory of the chiropteran fauna in the area, to determine what portion of the assemblage use the mines. I recorded 13 species for the region (12 vespertilionids and 1 molossid), out of 18 that are likely to occur. Five species were never found in mines; the remaining use them as feeding roosts, temporary roosts, or hibernacula, and only Corynorhinus mexicanus was found forming a maternity colony. Bats were significantly (P 50 m, and less than 3...

Spatial organization of the Dunlin Calidris alpina L. during winter – the existence of functional units

Capsule Dunlin use the same feeding grounds and roosts repeatedly and consistently over long periods of time, giving rise to functional units. Aims To examine the way in which wintering Dunlin organize and distribute themselves in a coastal lagoon. Methods Data collection was undertaken in the Mira Canal and in a salt-pan zone over five winters, mostly using counting, bird ringing and radiotracking. Results Birds restricted their activities to limited sectors of the lagoon, adopting behaviour which they maintained throughout winter. Conclusion The area of the Ria may, therefore, be divided into functional units, i.e. a group of feeding areas and high-tide roosts used by a group of birds, during a certain period of time, corresponding, for example, to winter. This type of spatial organization, already identified in ducks, has not previously been described in waders.

Diet variability of Micronycteris megalotis in pristine and disturbed habitats of Northwestern Ecuador

Feeding strategies in foliage-gleaning bats should be affected by insect availability and the constraints imposed by the environment. Under strong preferences for particular insect prey, habitat should not have an effect on the expected similarities in diet among conspecific bat colonies occupying different environments. We compared the diet of Micronycteris megalotis individuals in two colonies located at different sites in the Andean slopes of northwestern Ecuador, based on insect remains collected at feeding roosts. Our analysis revealed that lepidopterans were extremely abundant in the diet of bats that forage in grasslands (52% of all insect remains), whereas the diet of bats that roost in primary forest consists mostly of coleopterans (85%). Log-linear analyses suggested that Lepidoptera is an influential group determining differences in feeding habits between both colonies, and that there are temporal fluctuations in diet independent of the habitats that were sampled. Analyses of the families within Coleoptera exhibited a similar pattern of dietary variability. Our study is the first to determine differences not only through time, but also among habitats in the diet of M. megalotis. Although our analysis lacked the benefit of accurate data on prey availability (insect population density), the evidence suggests that, within the margin of potential preys, there was a level of diet plasticity related to differences in habitat.

Effect of location and season on the arthropod prey of Nycteris grandis (Chiroptera: Nycteridae)

Analysis of culled arthropod prey parts collected from beneath four feeding perches was used to assess prey taken by Nycteris grandis from November 1987 to May 1988. The perches were located along the Zambezi River in Mana Pools National Park in Zimbabwe.With the exception of an occasional solifugid, N. grandis ate mainly insects in addition to frogs and other small vertebrates. Three species of katydids and many species of moths were the most common prey. While bats using one feeding perch fed heavily on two species of cicadas at times, those at the other perches rarely did. There also were differences in the incidences of antlions, mantids and beetles in the diets of bats using different perches. Extensive samples from two feeding roosts about 2 km apart showed significant differences in prey composition. Smaller samples from two sites closer to one another showed similar patterns of the incidence of different prey.

Observations on the Role of Frugivorous Bats as Seed Dispersers in Costa Rican Secondary Humid Forests

The role of frugivorous bats as seed dispersers in humid neotropical tropical forests was evaluated between January and August 1995. Thirty germination trials were set up using seeds defecated by six bat species. Seeds of Piper multiplinervium and Ficus insipida, defecated by Carollia brevicauda and Artibeus jamaicensis, respectively, showed significantly higher germination percentages than seeds not ingested by bats. Of seven seed species regurgitated by bats, only Markea neurantha showed significant increases in percent germination compared to seeds not ingested by bats. Of 19 tents and three active feeding roosts found, 12 tents and three feeding roosts were in primary forest, while six tents were in abandoned plantations. For tent construction, four bat species used six plant species. Fifty-two percent of seeds found under tents and feeding roosts were from secondary forest species. Twenty-two percent of seed species in fecal samples from netted bats in three secondary forest types were primary forest species. Bats in our study dispersed seeds between different habitat types.

Novo registro de Micronycteris hirsuta (Peters) (Mammalia, Chiroptera, Phyllostomidae) na Mata Atlântica, Estado do Rio de Janeiro, Brasil

Duas novas ocorrências do morcego Phyllostomidae, Micronycteris hirsuta (Peters, 1869) são registradas na Mata Atlântica, ambas no Estado do Rio de Janeiro, sudeste do Brasil. Um casal foi capturado com rede ao entrar em um refúgio de alimentação em um oco de árvore, na Estação Ecológica Estadual Paraíso, Guapimirim. Uma outra fêmea foi capturada com redes de neblina em Paraíso do Tobias, Miracema, junto a um riacho, entre árvores frutíferas.

Aspectos sobre a biologia de Tonatia bidens (Spix) no estado do Rio de Janeiro, sudeste do Brasil (Mammalia, Chiroptera, Phyllostomidae)

A biologia de Tonatia bidens (Spix, 1823) foi estudada no Estado do Rio de Janeiro, sudeste do Brasil. Um total de 76 morcegos foi capturado usando redes de neblina e redes manuais para insetos em refúgios diurnos. Algumas observações dos morcegos em cativeiro foram incluídas. Machos compreenderam 47% das capturas. Fêmeas prenhas foram observadas em novembro e maio, e fêmeas lactantes em janeiro, abril e maio. Animais subadultos foram registrados em dezembro, fevereiro, maio e julho. Os restos de presas observadas em refúgios de alimentação demonstram a dieta insetívora e carnívora deste morcego. O comportamento alimentar é similar a de outras espécies carnívoras de morcegos Phyllostomidae.

On the density-dependence of seed predation in Dipteryx micrantha, a bat-dispersed rain forest tree.

We studied the effect of seed density on seed predation by following the fate of bat-dispersed Dipteryx micrantha (Leguminosae) seeds deposited under bat feeding roosts. The study was conducted in Cocha Cashu biological station, Amazonian Peru, during the fruiting period of Dipteryx. Predation of Dipteryx seeds in the area is mainly by large to medium-sized rodents. Seed deposits beneath bat feeding roosts were monitored for a 13-week period in an 18-ha study area. A total of 210 seed deposits were found, and on average, seed predators encountered 22% of them during any one week. About one-third of the seed deposits escaped predation, and those deposits that had relatively few seeds were more likely to go unnoticed by rodents than were deposits with many seeds. The mean seed destruction rate was 8% per week; deposits with many seeds tended to lose a smaller proportion of their seeds to seed predators than did deposits with few seeds. Regression tests for the weekly data showed that, at the beginning of the observation period, seed predation was not density-dependent. Later, when the total seed crop beneath roosts was high, the number of seeds predated per deposit was positively density-dependent, while the proportion of seeds predated was negatively density-dependent, indicating predator satiation. Seed deposits that had been visited by seed predators once had a higher probability of being revisited the week after, especially if they contained many seeds when first encountered. This indicates that the foraging behavior of rodents may be affected by their remembering the location of seed-rich patches.

Top-down and bottom-up factors in tidepool communities

Recent studies suggest that nutrient variation influences rocky intertidal community structure, however empirical evidence is rare. In the Gulf of Maine, tidepools that occur on seagull feeding roosts are potentially subjected to regular nutrient loading from seagull guano. The results of a survey conducted on Swan's Island, ME show that roost tidepools have very low macroinvertebrate and macroalgal diversity as well as very high phytoplankton biomass compared to non-roost tidepools. An experiment presented here tested basic food chain hypotheses in tidepool communities. These basic food chain models predict that in a tidepool with one trophic level (phytoplankton only), phytoplankton biomass will increase when nutrients are enriched. In contrast, these models predict that in two trophic level tidepools (phytoplankton and mussels) herbivory will prevent an increase in phytoplankton biomass when nutrients are enriched. A short term 2×2 factorially designed field experiment was used to test this basic conceptual model using herbivory by mussels and enrichment with nitrogen as the main effects. The results of this investigation are consistent with the predictions of basic food chain models, and indicate that over the short time interval of a few days, herbivory by mussels is sufficient to maintain low phytoplankton levels following enrichment with nitrogen. Experimental enrichment with phosphorus in this study had no effect on phytoplankton biomass. The results of this study suggest that periodic pulses of nitrogen into tidepools will have little effect on phytoplankton biomass when mussels are present and that longer-term chronic nitrogen influxes may be driving the patterns of community structure in tidepools occurring on roosts.

Food niche overlap among neotropical frugivorous bats in Costa Rica

Food habits of 15 species of frugivorous bats were studied at La Selva Biological Station, Costa Rica. Eight hundred and fifty-four (854) fecal samples and 169 samples from fruit parts and seeds discarded by bats beneath feeding roosts were analyzed. During eight months of study, 47 fruit species consumed by bats were identified. Five plant genera (Cecropia, Ficus, Piper Solanum, and Vismia) constituted 85% of all plants found in fecal samples. Feeding niche breadth differed significantly among the six most common species of frugivorous bats (Artibeus jamaicensis, Carollia sowelli, C. castanea, C. perspicillata, Dermanura sp., and Glossophaga commissarisi). All species, except for Dermanura sp., showed a diet dominated by one or two plant species. This suggests a pattern of resource partitioning at a generic level, in which Carollia consumed mainly Piper, Artibeus consumed Ficus and Cecropia, and Glossophaga consumed Vismia. Cluster analysis revealed higher values of food niche overlap in congeneric species than among species of different genera. Results show that if food is a limiting factor, mechanisms other than trophic selection must reduce interspecific interference or competition for food in this frugivorous bat guild.

TEMPORAL PATTERNS OF RESOURCE USE BY THE SHORT-NOSED FRUIT BAT,CYNOPTERUS SPHINX(MEGACHIROPTERA: PTEROPODIDAE)

The short-nosed fruit bat, Cynopterus sphinx (Megachiroptera: Pteropodidae), is a common plant-visiting bat that is widely distributed throughout the Indomalayan region. We quantified foraging behavior of C. sphinx as individuals fed on fruits of Annona squamosa, leaves of Cassia fistula and Mimusops elengi, and fruits and leaves of Coccinia indica. After making several circling flights and engaging in brief hovering bouts, bats typically land directly on a single fruit and remove all or part of it with the mouth. In contrast, individuals remove leaves from trees during flight, without landing or hovering. C. sphinx typically transports fruits and leaves to feeding roosts where it extracts soluble contents and expels fibrous spats beneath day and feeding roosts. This bat consumes mostly fruits upon emergence from day roosts and feeds on leaves later in the night. These temporal differences in nightly foraging behavior may reflect the higher water and carbohydrate (energy) contents of fruits, compared with leaves, and help sustain flight activity throughout the night.

Temporal patterns of individual and group foraging behaviour in the short-nosed fruit bat, Cynopterus sphinx, in south India

The short-nosed fruit bat, Cynopterus sphinx, begins to visit fruit-bearing trees about 30 min after sunset. Individual bats often hover near or land on fruits or on nearby branches to remove whole or parts of fruits with their mouth. These bats seldom remain in the fruit-bearing trees to feed, but instead carry fruits to feeding roosts, repeating this behaviour several times throughout the night. Analysis of the temporal distribution of feeding behaviour has revealed two peaks of activity, one in the pre-midnight hours when bats fed mostly on ‘steady state’ fruits, and another during the post-midnight hours when bats fed on ‘big-bang’ fruits. Only solitary bats visited and fed on species with steady state fruiting phenologies, whereas groups of bats regularly visited and fed on species with big-bang fruiting phenologies. Thus, plant species which produce large numbers of fruits appear to promote group foraging during the latter hours of the night. It is suggested that the temporal use of available fruits in south India made it possible for C. sphinx to successfully exploit them, and thereby reduced interference competition with conspecifics.

Food habits of Cynopterus brachyotis (Muller) (Chiroptera: Pteropodidau) in Peninsular Malaysia

Information on the feeding habits of the the lesser dog-faced friut bat, Cynopterus brachyotis, was obtained by the collection of food remains directly beneath daytime and feeding roosts. The bats were found to feed on the fruits of 54 plant species, the leaves of 14 species and the flower parts of four species. The seasonal phenological differences among congeneric plant species led to steady production of fruit throughout the year and the data suggets that Ficus spp. are a key component in the diet. Judging from its wide selection of fruits, C. brachyotis, is considered to be an important seed disperser. Folivory in C. brachyotis appears to be more common than previously thought. Of the leaves consumed by the bats, seven species belonged to the family Leguminosae, followed by Myrtaccae, Moraccae, Rhizophoacae and Euphorbiaccae. Friuts in general, provide an energy rich diet for phytophagous bats but most are low in protein. In contrast, leaves consumed by bats have a relatively high protein content. We suggest that folivory (by leaf fractionation) should be energetically more advantageous than the ingestion of large amounts of low protein friut or the active pursuit of mobile insects.

Moths Consumed by Corynorhinus townsendii virginianus in Eastern Kentucky

Abstract We collected culled forewings of moths from 26 feeding roosts to determine the species of moths consumed by the Virginia big-eared bat (Corynorhinus townsendii virginianus) in eastern Kentucky in June, July and August 1992. Feeding roosts were located in cliffs adjacent to two maternity and one bachelor roosts. A total of 45 species of moths were identified from 222 forewings collected, representing six families: Noctuidae (n = 139), Sphingidae (n = 41), Geometridae (n = 24), Notodontidae (n = 13), Thyatiridae (n = 3) and Lymantriidae (n = 2). Length of forewings collected ranged from 1.3–4.1 cm. The majority (77.8%) of species of moths eaten by C. t. virginianus develop from larvae dependent on forest plant species.

Behavioural and reproductive ecology of the dog-faced fruit bats, Cynopterus brachyotis and C. horsfieldi, in a Malaysian rainforest.

Roosting, foraging and reproductive aspects of two species of dog-faced fruit bats, Cynopterus brachyotis and C. horsfieldi, were examined in Ulu Gombak, Selangor, West Malaysia. The day roosts of C. horsfieldi were sparsely distributed and were found mainly in palms, whereas roosts of C. brachyotis were abundant, and mostly found in non-palm tree species. Males of both species frequently changed their roosts. The nocturnal activity patterns of the two species were different. The initial peak of flight activity of C. brachyotis was two hours sooner after sunset than that of C. horsfieldi, and its flight activity gradually declined during the night. In C. horsfieldi flight activity decreased around midnight then increased again three hours before sunrise. The home ranges of C. horsfieldi were larger than those of C. brachyotis, however these were non-exclusive ranges with individual home ranges of both species overlapping extensively. In association with their greater home range size, C. horsfieldi also tended to move further than C. brachyotis (when comparing means of greatest distances moved). The diets of the two species also differed, with C. brachyotis eating fruits, flowers and leaves, whereas C. horsfieldi ate Ficus fruits virtually throughout the year. The wet weight of figs carried by C. brachyotis per feeding bout averaged 7.9 g, while C. horsfieldi carried on average 17.8 g of figs. The average distances between feeding roost sites and fruiting Ficus variegata trees were 50-78 m. Cynopterus brachyotis probably produces two or three litters per year whereas C. horsfieldi has two litters.