Isotopic evidence for dietary niche overlap between barking deer and four-horned antelope in Nepal

BackgroundMorphologically similar sympatric species may have a high degree of niche overlap. Barking deer Muntiacus vaginalis and four-horned antelope Tetracerus quadricornis are solitary ungulates of the Indian sub-continent. Limited information is available regarding their trophic ecology, particularly of the endemic four-horned antelope. We present stable carbon (δ13C), nitrogen (δ15N), and sulphur (δ34S) isotopic values, and nitrogen content (%N) of faeces from barking deer and four-horned antelope living in lowland Nepal to assess trophic niche differentiation of these herbivores along the browser-grazer continuum. We also describe trophic differences between those two species in ecological niches and seasonal effects on their diets.ResultsWe found that the barking deer and four-horned antelope consumed C3 plant sources exclusively. The niche partitioning in their diet was reflected by δ34S values. Some seasonal effects observed were: δ13C and δ15N were significantly lower in the dry season diet of four-horned antelope than that of barking deer, while δ34S values were significantly higher in the winter diet; monsoon diet was similar for both species. Faecal N levels for barking deer and four-horned antelope were similar throughout all the seasons, indicating that both species adapted their feeding behaviour so as to maximize protein intake, in accordance with season and environment.ConclusionsBarking deer and four-horned antelope both are browsers; their dietary sources overlapped during monsoon but differed during the dry season. Conservation actions focused on resource management during the dry season to reduce food scarcity and competition over limited resources is likely to be the most effective

Seasonal bat activity related to insect emergence at three temperate lakes

Knowledge of aquatic food resources entering terrestrial systems is important for food web studies and conservation planning. Bats, among other terrestrial consumers, often profit from aquatic insect emergence and their activity might be closely related to such events. However, there is a lack of studies which monitor bat activity simultaneously with aquatic insect emergence, especially from lakes. Thus, our aim was to understand the relationship between insect emergence and bat activity, and investigate whether there is a general spatial or seasonal pattern at lakeshores. We assessed whole-night bat activity using acoustic monitoring and caught emerging and aerial flying insects at three different lakes through three seasons. We predicted that insect availability and seasonality explain the variation in bat activity, independent of the lake size and characteristics. Spatial (between lakes) differences of bat activity were stronger than temporal (seasonal) differences. Bat activity did not always correlate to insect emergence, probably because other factors, such as habitat characteristics, or bats’ energy requirements, play an important role as well. Aerial flying insects explained bat activity better than the emerged aquatic insects in the lake with lowest insect emergence. Bats were active throughout the night with some activity peaks, and the pattern of their activity also differed among lakes and seasons. Lakes are important habitats for bats, as they support diverse bat communities and activity throughout the night and the year when bats are active. Our study highlights that there are spatial and temporal differences in bat activity and its hourly nocturnal pattern, that should be considered when investigating aquatic–terrestrial interactions or designing conservation and monitoring plans.publishe

Advantages of using fecal samples for stable isotope analysis in bats: Evidence from a triple isotopic experiment

RATIONALE: Stable isotope analysis in ecological studies is usually conducted on biomaterials, e.g. muscle and blood,that require catching the animals. Feces are rarely used for stable isotope analysis, despite the possibility of non-invasive sampling and short-term responsiveness to dietary changes. This promising method is neglected due to a lack of calibration experiments and unknown diet-feces isotopic difference (Δdiet-feces.METHODS: To fill this gap, we simulated trophic changes occurring in nature when animals switch feeding habitats, e.g.by moving from freshwater to terrestrial systems, from cultivated areas to forests or changing distance from marineenvironments. In a controlled experiment, the diet of two bat species (Myotis myotis, Rhinolophus ferrumequinum) wasaltered to an isotopically distinct one. We measured stable nitrogen, carbon and the rarely used sulfur isotope in feces,and calculated Δdiet-feces values.RESULTS: The feces acquired the new dietary signature within 2–3 h from food ingestion; thus, they are suited fordetecting recent and rapid dietary changes. The Δdiet-feces (Δ) did not differ between species or diet (overall means ± standard deviation (sd)): Δ15N: 1.47 ± 1.51‰, Δ13C: –0.11 ± 0.80‰, Δ34S: 0.74 ± 1.10‰. Only Δ15N for M. myotis wassignificantly different from zero and only Δ13C differed among the days of the experiment.CONCLUSIONS: Fecal stable isotopes can be now further applied in mammalian ecology. This includes a range ofapplications, such as studying changes in trophic level, resource or habitat use, on a short time-scale. Such informationis gaining importance for monitoring rapidly changing ecosystems under anthropogenic influence. Copyright © 2013John Wiley & Sons, Ltd

New Fisheries-Related Data From The Mediterranean Sea (April, 2014)

As part of its policy, Mediterranean Marine Science started from 2014 to publish a new series of collective article with fisheries-related data from the Mediterranean Sea. In this first collective article we present length frequencies and weight-length relationships for the northern brown shrimp Farfantepenaeus aztecus in the Eastern Mediterranean, weight-length relationships for 10 fish species in the North Aegean Sea, the feeding habits for 11 sparid fishes in the North Aegean Sea, a review of the existing literature on the feeding and reproduction of common carp Cyprinus carpio in Anatolia (Turkey) and mouth dimensions and the relationships between mouth area and length for seven freshwater fishes from Lake Volvi (Northern Greece).Wo