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 (Lldietfeces)· 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 marine environments. In a controlled experiment, the diet of two bat species (Myotis myotis, Rhinolophus fermmequinum) was altered to an isotopically distinct one. We measured stable nitrogen, carbon and the rarely used sulfur isotope in feces, and calculated Lldiet-Jeres values. RESULTS: The feces acquired the new dietary signature within 2-3 h from food ingestion; thus, they are suited for detecting recent and rapid dietary changes. The Lldietferes (L1) did not differ between species or diet {overall means± standard deviation (sd)): L1 The stable isotopes of animal tissue reflect the local dietary input over the time that the tissue was synthesized. Different tissues integrate diet over different time scales. Blood and muscle for example, which are commonly used for stable isotope analysis in mammals, 11 ,2 1 have turnover rates of some weeks to monthsP 1 However, when research questions require measurement of rapid changes in diet or trophic level, samples with a faster turnover rate such as exhaled breath or feces are required. Collection of both breath and feces is relatively easy, cost effective and non-invasive, but so far only a single element (carbon) can be measured in breath.1 4 1 Feces are a good candidate for stable isotope analysis with the aim of short-term diet investigation, because (i) they contain remains of the recent diet} 5 1 (ii) capturing of animals is not necessarily required as feces can be collected from below roosting sites; and (iii)

Many bats use aquatic habitats for foraging and for drinking water. Interactions between aquatic and terrestrial systems are important for understanding food web dynamics and for conserving species and ecosystems. Therefore, in this review, I examined the data available on bats’ use of aquatic habitats. The objectives of the present review were to evaluate the importance of aquatic resources for bats and to identify the effects that eutrophication, water pollution, and other anthropogenic impacts on water bodies have on bats. Most studies on bats and aquatic habitats have been conducted in Europe or in North America. They show, directly or indirectly, how bats use aquatic resources. Acoustic survey is the most common technique employed to assess habitat use by bats, although some researchers have used radio telemetry or other methods. Myotis daubentonii is the most commonly studied species. Within this topic, research does not tend to be focused more on threatened species. The effects of water pollution and eutrophication on bats remain unclear: different effects are reported for different species and in different areas. More studies are needed from Africa, South America, and Asia, regions for which few data are available, as well as from arid regions where fresh water is a limited resource.

Stable isotope and fatty acid signatures of biomaterials can provide important information about the dietary niche of animals. Stable isotope and fatty acid signatures differ between aquatic and terrestrial food webs, and therefore can be used to assess the aquatic and terrestrial contributions to the diets of species. We studied faecal samples of three co-occurring bat species with known differences in feeding preferences. The aim was to assess whether stable isotope and fatty acid signatures of faeces can be used to determine feeding preferences. We used bat faeces because they can be easily and non-invasively collected. We hypothesised that faeces stable isotope and fatty acid signatures will reveal the terrestrial, aquatic and mixed feeding niches of Myotis myotis, M. daubentonii, and M. mystacinus, respectively. As predicted, the faeces of M. myotis were characterized by higher δ 13C values and higher concentrations of linoleic acid and total ω6 polyunsaturated fatty acids (PUFAs), which are typically higher in terrestrial food webs. The faeces of M. daubentonii had higher δ 15Ν values and higher concentrations of docosahexaenoic acid and total ω3 PUFAs, characteristic features of aquatic systems. Myotis mystacinus faeces had intermediate δ 15Ν values and concentrations of both types of fatty acids. Our results show that analysing stable isotope and/or fatty acid signatures of faeces provides a promising, non-invasive tool to study the feeding ecology of bats and to assess aquatic-terrestrial interactions.

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.

No abstract

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.Electronic supplementary materialThe online version of this article (doi:10.1186/s40709-015-0029-0) contains supplementary material, which is available to authorized users.

As part of its policy, Mediterranean Marine Science started from 2014 to publish a new series of collective article with fisheriesrelated 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).

Food is an important factor for the survival of juvenile fish. Knowledge of the diet of co-existing species helps clarify their relationships with each other. A number of Mugilidae species are known to co-exist in estuarine systems, raising the question of whether they compete for food resources. The feeding behaviours of five juvenile Mugilidae species were studied in the estuaries of Strymonikos (North Aegean Sea) using stomach content analysis. It was found that the species Chelon labrosus, Liza saliens and Mugil cephalus presented high feeding activity during summer and autumn and L. ramada and L. aurata during winter and spring. The diet overlap between the species was generally moderate to low and the pair L. saliens – M. cephalus exhibited the highest overlap in Richios estuarine system. The species do not appear to compete for common resources, probably because there is not always a spatiotemporal overlap, enough food is available or they exploit different resources. Four out of the five species exhibited similar patterns of feeding strategies with varying levels of specialization at an individual level and a rather generalized pattern at the population level. This more generalized feeding strategy may permit them to co-exist. Only M. cephalus showed a more specialized feeding behaviour, with a strong preference for microalgae. The absence of a general pattern for the trophic levels according to seasons, sizes or locations, also imply the opportunistic character of the species. Both season and fish size influenced the variation in the diet composition.