Brood success of sex-role-reversed pheasant-tailed jacanas: the effects of social polyandry, seasonality, and male mating order.

Multiple mating by avian females may increase hatching and overall brood success; however, reproductive effort and parental investment are costly, and females may be gradually depleted, with lowered outputs over time. Thus, males in social polyandry systems may differ greatly in their reproductive gains. In the present study, we investigated the reproductive outputs of social polyandrous and sex-role-reversed pheasant-tailed jacanas, Hydrophasianus chirurgus, to assess the effects of polyandry, seasonality, and male mating order on breeding success. Female jacanas produced multiple clutches, either by leaving two or more clutches with an individual male (22%), or by mating with two or more males (78%). The polyandrous females laid both the first and second clutches earlier and showed a breeding period more than twice as long as that of monandrous females. Both polyandry and seasonality affected the fate of a clutch, where clutches from polyandrous females and the early season had higher hatching and brood success rates, but the number of polyandrous females declined over the season. Polyandrous females not only laid more clutches and eggs, and gained more hatchlings and fledglings, but also achieved higher per-clutch outputs and hatching rates than monandrous females. In polyandry groups, males gained higher total hatchlings and fledglings, although not total clutches or eggs, than males in monandry or bi-andry groups. Moreover, males in polyandry groups achieved higher hatchlings and fledglings per clutch and higher hatching and brood success rates. In polyandry groups, the first-mating males obtained more clutches, eggs, and hatchlings; however, they did not have higher success rates, nor total fledglings and per-clutch outputs, than males who mated later. Overall, the results indicate a selective advantage of polyandry for the jacanas studied, particularly in the early breeding season. This advantage, however, differs both between the sexes and intra-sexually, suggesting strong connections with certain ecological/environmental conditions in addition to the jacanas' own quality.

Context-specific variation and repeatability in behavioral traits of bent-wing bats.

Animals may show consistent among-individual behavioral differences over time and in different contexts, and these tendencies may be correlated to one another and emerge as behavioral syndromes. The cross-context variation in these behavioral tendencies, however, is rarely explored with animals in contexts associated with different locomotion modes. This study assessed the variation and repeatability in behavioral traits of bent-wing bats Miniopterus fuliginosus in southern Taiwan, and the effects of contextual settings associated with locomotion mode. The bats were sampled in the dry winter season, and their behaviors were measured in hole-board box (HB) and tunnel box (TB) tests, both suited for quadrupedal movements of the bats, and flight-tent (FT) tests that allowed for flying behaviors. The bats in the FT tests showed more interindividual and between-trial behavioral variation than those in the HB and TB tests. Nearly all of the behaviors in the TB and FT tests, but only half of those in the HB tests, showed medium to high repeatability. These repeatable behaviors were grouped into distinct behavioral traits of boldness, activity, and exploration, which were correlated to one another across contexts. In addition, we observed a consistently higher correlation between behavioral categories across the HB and TB contexts than between either of these contexts and the FT context. The results indicate consistent among-individual behavioral differences across time and contexts in wildly caught bent-wing bats. The findings of behavioral repeatability and cross-context correlations also indicate context-dependent variation and suggest that test devices which allow for flight behaviors, such as flight tents or cages, may provide a more suitable setting for measuring the behaviors and animal personalities of bats, particularly for those species that display less or little quadrupedal movements.

Effects of host state and body condition on parasite infestation of bent-wing bats.

BACKGROUND: Ectoparasites inhabit the body surface or outgrowths of hosts and are usually detrimental to host health and wellbeing. Hosts, however, vary in quality and may lead ectoparasites to aggregate on preferred hosts, resulting in a heterogeneous distribution of parasite load among hosts. RESULTS: We set out to examine the effects of host individual state and body condition on the parasite load of multiple nycteribiid and streblid bat flies and Spinturnix wing mites on eastern bent-wing bats Miniopterus fuliginosus in a tropical forest in southern Taiwan. We detected a high parasite prevalence of 98.9% among the sampled bats, with nearly 75% of the bats harboring three or more species of parasites. The parasite abundance was higher in the wet season from mid spring to early fall, coinciding with the breeding period of female bats, than in the dry winter season. In both seasonal periods, the overall parasite abundance of adult females was higher than that of adult males. Among the bats, reproductive females, particularly lactating females, exhibited a higher body condition and were generally most infested. The Penicillidia jenynsii and Nycteribia parvula bat flies showed a consistent female-biased infection pattern. The N. allotopa and Ascodipteron speiserianum flies, however, showed a tendency towards bats of a moderate to higher body condition, particularly reproductive females and adult males. CONCLUSIONS: We found an overall positive correlation between parasite abundance and reproductive state and body condition of the host and female-biased parasitism for M. fuliginosus bats. However, the effects of body condition and female-biased infestation appear to be parasite species specific, and suggest that the mobility, life history, and potential inter-species interactions of the parasites may all play important roles.

Perch time allocation and feeding efficiency of flycatching Rhinolophus formosae: an optimal foraging behavior?

BACKGROUND: Flycatching bats are species-rare and comprise predominantly horseshoe bats (Rhinolophidae). Their hang-and-wait foraging mode and long constant-frequency echolocation calls offer advantages in energetics and prey detection, and may enable them apt to foraging optimally, yet not much is known about the foraging behavior of flycatching bats. Thus we assessed the perch use and foraging performance in the field by one of the largest horseshoe bats, Rhinolophus formosae, and offered insights on their perch time allocation. RESULTS: The perching-foraging behaviors of the bats did not differ significantly between forest settings, but the residence and giving-up time, mean attack, and attack rate were higher in the late spring-early summer, whereas the mean capture, capture rate, and attack efficiency were lower in the late summer when volant juveniles joined the nocturnal activity. The bats maintained flycatching and exhibited largely similar attack rates through the night with peak residence time around the midnight, but the capture rate and attack efficiency both reduced toward midnight and then increased toward the hours right before dawn. The attack rate was negatively correlated to the number of perches used and perch switch; by contrast, the capture rate was positively correlated with both factors. The total residence time at a site increased but mean residence time per perch decreased as the number of perches used and perch-switch increased. The giving-up time was inversely correlated to the attack rate and attack efficiency, and decreased with an increasing capture rate. CONCLUSIONS: The bats increased perch switch at lower attack rates in early spring, but switched less frequently in late spring and prime summer months when insect abundance is higher. By scanning through a broad angular range for prey detection, and switching more frequently among perches, R. formosae foraged with an increased capture rate, and were able to remain at the site longer by slightly reducing their mean residence time per perch. Our results concur with the predictions of optimal foraging theory for patch selection and offer implications for further exploration of the foraging behavior of flycatching horseshoe bats.

Neighborhood effects in mixed-species flocks affect foraging efficiency of intermediate and little egrets.

Birds aggregate for various survival needs, and ardeids form both conspecific and mixed-species flocks. However, it remains unclear whether and how ardeids' foraging while joining a flock is affected differently in conspecific versus mixed-species flocks. We studied egret flocks in southwestern Taiwan to assess the flock size and neighborhood effects on flock formation and foraging performance of egrets by examining landing tendencies and expelling behaviors of Little (Egretta garzetta) and Intermediate (E. intermedia) egrets, and assessing strike rates, strike efficiency, and intake rates of singles and egrets in conspecific and mixed-species flocks. We found no evidence of non-random landings to mixed-species flocks by either species, but egrets showed a trend of landing closer to conspecifics when conspecifics represented lower proportions in flocks. Intermediate Egrets displayed expelling behavior more frequently. Expelling by earlier arrived egrets interrupted subsequent flock formation on 45.2 % occasions, but was not affected by egrets' foraging performance. Solitary Little Egrets had higher strike and fish intake rates, but lower strike efficiency, than solitary Intermediate Egrets, whereas their biomass intake rates were similar. Strike and fish intake rates increased in flocks compared to singles in both species, but declined for Little Egrets as flocks increased from medium (11-30 birds) to large sizes (> 30). Intermediate Egrets had higher strike, fish intake, and biomass intake rates, but Little Egrets had lowered strike efficiency and fish- and biomass-intake rates, when near each other than when near conspecifics. Overall, Intermediate Egrets in mixed-species flocks improved foraging efficiency and food intakes by neighborhood effects at costs of reduced foraging efficiency to Little Egrets. The variation in landing tendency over flock compositions suggests potential interactions of the neighborhood effect with egrets' conspecific attraction.

Fruiting phenology and nutrient content variation among sympatric figs and the ecological correlates.

BACKGROUND: Figs are key resources for tropical frugivores and display unique fruiting patterns. While monoecious figs support both seeds and wasp rearing, dioecious plants perform the tasks separately and produce seeded figs in smaller asynchronous crops. Thus dioecious females, compared to monoecious figs, may afford to invest more efforts to maximize seediness, or increase fruit pulp, water content, and nutrient rewards to attract frugivores for better seed dispersal. Yet size variation among and within fig species in either breeding system may lead to complicated resource allocation. We assessed fruiting phenology, measured fig morphological traits, and analyzed fig nutrient contents of the monoecious Ficus caulocarpa and F. subpisocarpa and the dioecious F. ampelas and F. irisana in a sympatric tropical forest to investigate species differences and size effects on fig functional traits and their ecological correlates. RESULTS: All four species fruited nearly year-round. Monoecious figs' inter-tree asynchronous crops had high peak mature crop sizes over much shorter fruiting periods than dioecious figs. Among trees, F. subpisocarpa and F. irisana were greater in fig-size and size variation, F. caulocarpa and F. ampelas comparatively displayed large variation in fig compositions. As fig size increased, water contents gradually increased in large-fig species, but seediness with a decreasing trend in small-fig species. Dioecious figs had lower pulp-seed ratio but tended to have higher water contents than monoecious figs, particularly within a similar size range. Dioecious figs also had higher carbohydrates, whereas monoecious figs contained higher fiber and lipid contents. CONCLUSIONS: Our study revealed species differences in certain fig functional traits that were correlated with fig size or their breeding systems, with substantial inter-tree variation. This partially supported the predictions regarding their fruiting strategies of aiding seed dispersal by frugivores, yet suggests a fruiting plasticity of individual trees subject to environmental constraints and their biotic interactions.

Foraging dispersion of Ryukyu flying-foxes and relationships with fig abundance in East-Asian subtropical island forests.

BACKGROUND: Figs are widely distributed key resources to many tropical-subtropical animals, and flying-foxes are major consumers and seed dispersers of figs. Bat-fig interrelationships, however, may vary among species differing in fruiting traits, i.e., bat- versus bird-dispersed figs. We examined Ryukyu flying-fox foraging dispersion and the relationships with tree species composition and fig abundance in forests of Iriomote Island. RESULTS: Bat foraging dispersion showed no spatial patterns with respect to different areas of the island, and was not explained by heterogeneity, density, or basal area (BA) of total trees, nor by relative density or BA of fruiting trees or total fruiting figs among sites. Instead, bat densities were positively dependent on the relative density of total figs, and particularly the relative BA of bat-dispersed figs Ficus septica and F. variegata. Both species were dominant figs in forests, fruiting asynchronously with long crop seasons, and were used as predominant foods. Bats foraged mostly solitarily and the mean density was in a hump-shaped relationship with crop sizes of the dominant bat-figs. These two species and Ficus benguetensis are larger-sized bat-figs, all contained more seeds, higher dry-pulp mass and water mass, but not necessarily water content. By approximate estimation, higher proportions of seeds of these bat-figs would have been removed from fruits through the bat consumption, than that of small-sized bird-figs like F. virgata, F. superba, and F. microcarpa. CONCLUSIONS: The foraging dispersion of Ryukyu flying-foxes in forests depends on the availability of the most abundant bat-figs that serve as predominant foods. Intermediate levels of crop sizes of theses figs appear most fit with their solitary foraging. Our results suggest that as density and BA coverage of these dominant bat-figs are below a certain level, their effectiveness to attract bats may dwindle and so would their chance of dispersal by bats.

Energy state affects exploratory behavior of tree sparrows in a group context under differential food-patch distributions.

BACKGROUND: When facing a novel situation, animals can retreat or leave to avoid risks, but will miss potential resources and opportunities. Alternatively they may reduce environmental uncertainty by exploration, while risking no energy rewards and exposure to hazards, and use the information retrieved for subsequent decision making. When exploring, however, animals may adopt different tactics according to individual states. RESULTS: We tested that energy states will affect exploratory behavior by experimenting with wild-caught untrained Eurasian tree sparrows (Passer montanus) in fasted or fed states exploring in a novel space with hidden food supply in different patch distribution patterns. Our data revealed that fasted sparrows risked being earlier explorers more often, initiated more exploratory bouts before patches were found, and stayed longer on the ground under both patch patterns. Fasted sparrows discovered more patches and consumed more food than fed sparrows in dispersed, but not necessary so in clumped, patch patterns; whereas fed birds also increased patch finding to a certain level in dispersed patterns. Sparrows of both energy states, however, did not differ in feeding rates in either patch pattern. CONCLUSIONS: Exploratory behavior of tree sparrows is state-dependent, which supports our prediction that birds with an energy shortage will be risk-prone and explore more readily. Our study also indicates a game nature of tree sparrow exploratory behavior in a group context when explorers are in different energy states and are exposed to different patch distributions. Birds of lower energy state adopting an active exploring tactic may be favored by obtaining higher energy gains in dispersed patch patterns with lower patch richness. More satiated birds, however, achieved a similar feeding rate by lowered exposure time.

The noseleaf of Rhinolophus formosae focuses the Frequency Modulated (FM) component of the calls.

Bats of the family Rhinolophidae emit their echolocation calls through their nostrils and feature elaborate noseleaves shaping the directionality of the emissions. The calls of these bats consist of a long constant-frequency component preceded and/or followed by short frequency-modulated sweeps. While Rhinolophidae are known for their physiological specializations for processing the constant frequency part of the calls, previous evidence suggests that the noseleaves of these animals are tuned to the frequencies in the frequency modulated components of the calls. In this paper, we seek further support for this hypothesis by simulating the emission beam pattern of the bat Rhinolophus formosae. Filling the furrows of lancet and removing the basal lappets (i.e., two flaps on the noseleaf) we find that these conspicuous features of the noseleaf focus the emitted energy mostly for frequencies in the frequency-modulated components. Based on the assumption that this component of the call is used by the bats for ranging, we develop a qualitative model to assess the increase in performance due to the furrows and/or the lappets. The model confirms that both structures decrease the ambiguity in selecting relevant targets for ranging. The lappets and the furrows shape the emission beam for different spatial regions and frequency ranges. Therefore, we conclude that the presented evidence is in line with the hypothesis that different parts of the noseleaves of Rhinolophidae are tuned to different frequency ranges with at least some of the most conspicuous ones being tuned to the frequency modulated components of the calls-thus yielding strong evidence for the sensory importance of the component.

Ecomorphology, differentiated habitat use, and nocturnal activities of Rhinolophus and Hipposideros species in East Asian tropical forests.

We investigated the wing morphology and foraging distributions of sympatric Rhinolophus and Hipposideros species by acoustic sampling, measuring wing parameters, and observing bats in different settings of tropical East Asian forests, to evaluate their flexibility in habitat use and edge sensitivity. R. formosae and H. terasensis were more abundant at edges/in open habitats and shared the highest overlap, with R. formosae displaying the greatest breadth in habitat use, whereas R. monoceros had a higher abundance and feeding efficiency in forest interiors with a continuous canopy. H. terasensis was significantly larger and had higher wing loading and aspect ratio than R. formosae and R. monoceros, while R. formosae had higher wing loading but a lower aspect ratio than the smaller-sized R. monoceros. Shrubs and herbs were higher at sites where bats were captured than at those without bat captures, and R. monoceros and R. formosae were associated with greater canopy and ground coverage, respectively. R. monoceros always foraged while flying at lower heights close to the herb/shrub layers, while H. terasensis and R. formosae used perching to different extents, with R. formosae preferably using fly-catching techniques and appearing farther from the path in open forests rather than in forest interiors. Our results indicate that differences in wing parameters account for the different degrees of flexibility in habitat use, yet the deviations of call frequency from the expected values in R. formosae and H. terasensis suggest additional adaptations accounting for their flexibility in exploring habitats.

Spatiotemporal variation in avian diversity and the short-term effects of typhoons in tropical reef-karst forests on Taiwan.

The diversity and spatiotemporal variation of avifauna in different settings of tropical coral reef-karst forests on the Hengchun Peninsula, Taiwan, were examined. The short-term effects on bird assemblages following two typhoons that severely impacted Hengchun were investigated. Line-transect census recorded 46 species of birds, dominated by forest-associated gleaning insectivores or omnivores, and 13% of the endemics of Taiwan. Prior to the typhoons, the continuous-canopy forest was close to the open forest setting in species evenness, but the species heterogeneity was lower and more variable. The continuous-canopy and open forests differed in overall avian composition, whereas two continuous-canopy forest settings were similar in composition. Typhoons did not significantly lower the mean numbers of either species or birds, nor affect the pattern of their spatial distribution in the forest settings. However, they did increase similarities in the species composition between the open and continuous-canopy settings, and caused a decrease in the similarity between forest edges and interiors. Overall, typhoons affected species composition more in the continuous-canopy forests than in the open setting, and more in interiors than in forest edges. This pattern corresponded to an increase in the species heterogeneity and species evenness in the forest interiors, indicating movements of birds from the edge toward the interior. Among different functional groups, gleaning omnivores tended to retain a pattern of higher abundance in the open forest setting than in the continuous-canopy forests, whereas the abundances of gleaning insectivores and cavity-nesting frugivores tended to decline in the latter or both settings.

Composition, diversity, and spatial relationships of anurans following wetland restoration in a managed tropical forest.

We investigated the composition, diversity, and patterns of spatial use of an anuran community following a wetland restoration project in a managed tropical monsoon forest in southern Taiwan. Anurans comprising eight species in seven genera and four families reached a mean density of 0.025+/-0.004 anurans m(-2) within a year. The three most important species in terms of frequency of occurrence and relative abundance all had an early appearance; only the most abundant Fejervarya limnocharis (62.2% of total accounts), however, remained present throughout the entire year. The distribution of anurans observed among habitat zones was non-random, with most records occurring in densely planted (42.8%) and running-water (23.9%) zones, and the fewest in a buffer zone adjacent to a paved road. Mean numbers of anurans were correlated with the mean percent vegetation cover among individually divided small pools. Microhyla ornate, M. heymonsi, Polypedates megacephalus, and F. limnocharis appeared to be more heterogeneous in their use of space than Buergeria japonicus. Species differed in their most frequently used habitat zones within the wetland site, with the pairs F. limnocharis and P. megacephalus, and M. ornate and Bufo melanostictus, exhibiting similar respective distributions among zones. Our study demonstrates the value of even a small, isolated wetland in contributing to and maintaining regional amphibian diversity. Patterns of spatial relationships of this anuran community have important implications for the conservation of local populations across species.