Our purpose is to provide researchers, consultants, decision-makers, and other stakeholders with guidance to methods and metrics for investigating nocturnally active birds and bats in relation to utility-scale wind-energy development. The primary objectives of such studies are to 1) assess potential impacts on resident and migratory species, 2) quantify fatality rates on resident and migratory populations, 3) determine the causes of bird and bat fatalities, and 4) develop, assess, and implement methods for reducing risks to bird and bat populations and their habitats. We describe methods and tools and their uses, discuss limitations, assumptions, and data interpretation, present case studies and examples, and offer suggestions for improving studies on nocturnally active birds and bats in relation to wind-energy development. We suggest best practices for research and monitoring studies using selected methods and metrics, but this is not intended as cookbook. We caution that each proposed and execu...

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Assessing Impacts of Wind-Energy Development on Nocturnally Active Birds and Bats: A Guidance Document

Summary 1. Acoustic methods are used increasingly to survey and monitor bat populations. However, the use of acoustic methods at continental scales can be hampered by the lack of standardized and objective methods to identify all species recorded. This makes comparable continent-wide monitoring difficult, impeding progress towards developing biodiversity indicators, transboundary conservation programmes and monitoring species distribution changes. 2. Here we developed a continental-scale classifier for acoustic identification of bats, which can be used throughout Europe to ensure objective, consistent and comparable species identifications. We selected 1350 full-spectrum reference calls from a set of 15 858 calls of 34 European species, from EchoBank, a global echolocation call library. We assessed 24 call parameters to evaluate how well they distinguish between species and used the 12 most useful to train a hierarchy of ensembles of artificial neural networks to distinguish the echolocation calls of these bat species. 3. Calls are first classified to one of five call-type groups, with a median accuracy of 97·6%. The median species-level classification accuracy is 83·7%, providing robust classification for most European species, and an estimate of classification error for each species. 4. These classifiers were packaged into an online tool, iBatsID, which is freely available, enabling anyone to classify European calls in an objective and consistent way, allowing standardized acoustic identification across the continent. 5. Synthesis and applications. iBatsID is the first freely available and easily accessible continental- scale bat call classifier, providing the basis for standardized, continental acoustic bat monitoring in Europe. This method can provide key information to managers and conservation planners on distribution changes and changes in bat species activity through time.

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2664.2012.02182.x

A continental-scale tool for acoustic identification of European bats

Ecological constraints often shape the echolocation pulses emitted by bat species. Consequently some (but not all) bats emit species-specific echolocation pulses. Because echolocation pulses are often intense and emitted at high rates, they are potential targets for eavesdropping by other bats. Echolocation pulses can also vary within species according to sex, body size, age, social group and geographic location. Whether these features can be recognised by other bats can only be determined reliably by playback experiments, which have shown that echolocation pulses do provide sufficient information for the identification of sex and individual in one species. Playbacks also show that bats can locate conspecifics and heterospecifics at foraging and roost sites by eavesdropping on echolocation pulses. Guilds of echolocating bat species often partition their use of pulse frequencies. Ecology, allometric scaling and phylogeny play roles here, but are not sufficient to explain this partitioning. Evidence is accumulating to support the hypothesis that frequency partitioning evolved to facilitate intraspecific communication. Acoustic character displacement occurs in at least one instance. Future research can relate genetic population structure to regional variation in echolocation pulse features and elucidate those acoustic features that most contribute to discrimination of individuals.

The communicative potential of bat echolocation pulses.

Aims Because rhinolophids have been hypothesized to use echolocation call frequency to recognize conspecifics, sympatric species calling at similar frequencies should be subject to acoustic character displacement, i.e. a drift in frequency values to minimize the risk of misidentification of conspecifics. However, it has been proposed that insufficient geographical separation between populations in sympatry and allopatry may counter the establishment of frequency differences by character displacement. Here we tested the hypothesis that insular populations should exhibit acoustic divergence, and this should be revealed by comparing call frequencies with those observed in mainland, allopatric populations of conspecifics. We also tested whether the evolutionary pressure towards acoustic divergence should be especially strong at sites where rhinolophid species emitting similar call frequencies roost together in order to minimize interspecific frequency overlap.



Location  Sardinia and southern Italy (Campania, Lazio, Abruzzo).



Methods  Time-expanded echolocation calls and body size were recorded from Sardinian populations of Rhinolophus mehelyi Matschie, Rhinolophus hipposideros (Bechstein) and Rhinolophus euryale Blasius. Both call frequencies and forearm length of insular R. hipposideros and R. euryale were compared with those of populations from mainland areas of Italy where R. mehelyi is absent, to explore the hypothesis that the presence of the latter species (which calls at frequency values intermediate between the other two) may determine acoustic divergence in the other species. For Sardinian R. mehelyi and R. euryale, we also carried out intraspecific comparisons of call frequencies between bats from monospecific colonies and those from mixed colonies.



Results  As hypothesized, Sardinian R. hipposideros and R. euryale called at frequencies higher and lower, respectively, than in the peninsula. In this way, overlap with R. mehelyi is avoided. Body size showed no difference between insular and peninsular populations, i.e. frequency differences are not a by-product of difference in body size determined by insularity. Frequency values in Sardinian R. euryale from monospecific colonies did not differ from those of bats roosting together with R. mehelyi. However, R. mehelyi showed frequency values significantly higher when associated with R. euryale, possibly to minimize the risk of species misrecognition.



Main conclusions  At least under geographical isolation, character displacement may be a causal mechanism for shifts in call frequency of sympatric rhinolophids. Species recognition and facilitation of intraspecific communication (with possible implications for mate recognition) constitute the best candidate factors for the phenomenon we observed.

Divergent echolocation call frequencies in insular rhinolophids (Chiroptera): a case of character displacement?

The peak echolocation frequency of insectivorous bats generally declines as body size increases. However, there are notable exceptions to this rule, with some species, such as Rhinolophus clivosus, having a higher than expected peak frequency for their body size. Such deviations from allometry may be associated with partitioning of foraging habitat (the foraging habitat hypothesis) or insect prey (the prey detection hypothesis). Alternatively, the deviations may be associated with the partitioning of sonar frequency bands to allow effective communication in a social context (the acoustic communication hypothesis). We tested the predictions of these hypotheses through comparisons at the family, clade and species level, using species of rhinolophids in general and R. clivosus, a species with a wide distribution, as a specific test case. We compared the wing parameters, echolocation frequency and ecology of R. clivosus to those of the sympatric R. capensis. Rhinolophus clivosus has a much higher echolocation frequency than predicted from its wing loading or body mass. Furthermore, contrary to the predictions of the foraging habitat hypothesis, we found no difference in foraging habitat between R. clivosus and R. capensis. The size range of insect prey taken by the two species also overlapped almost completely, contrary to the prey detection hypothesis. On the other hand, the variation of echolocation frequencies around the allometric relationship for rhinolophids was smaller than that for Myotis spp., supporting the prediction of the acoustic communication hypothesis. We thus propose that the relatively high peak frequency of R. clivosus is the result of partitioning of sonar frequency bands to minimize the ambiguity of echolocation calls during social interactions.

The allometry of echolocation call frequencies of insectivorous bats: why do some species deviate from the pattern?

Horseshoe bats (Rhinolophus) use echolocation calls with a prominent part whose frequency is constant over time (CF) and matches the ‘acoustic fovea’ of the bats' hearing system. The present study on European Rhinolophus species investigates whether this CF component contains reliable information on species, sex, age class or quality (size and body condition) of the caller and could therefore have a communicative value. The resting frequencies (RF) were measured from stationary, handheld bats for the species Rhinolophus blasii, R. euryale, R. mehelyi and R. hipposideros (the latter with very low sample size) in Bulgaria, where they occur in sympatry. We recorded calls directly onto a laptop computer and used a specially designed analysis algorithm to achieve high and accurate frequency resolution. After silent periods, individuals ‘tuned in’ to their RFs always from lower frequencies, corroborating the recent finding that frequencies below RF might be used for auditory feedback control as well. R...

Is species identity, sex, age or individual quality conveyed by echolocation call frequency in European horseshoe bats?

We assessed effects of forearm bands on three species of horseshoe bats (Rhinolophus ferrumequinum, R. euryale and R. mehelyi) marked for studies on regional movements and colony structure in Northern Bulgaria. Overall, more than 85% of the 580 recaptured individuals showed no negative impact of the banding. We had to note, however, slight or severe injuries in 7.6 and 6.4% of the bats, respectively. Injury rates varied greatly according to species and ring sizes. The use of the smaller of two tested ring sizes caused major injury rates of more than 60% of the recaptured R. mehelyi. But even in R. ferrumequinum, for which we obtained the largest sample size, and for which the recommended ring size is well-established, carefully fitted forearm bands caused injuries in 9.3% of the recaptures, an injury rate that is much higher than in most vespertilionid bat species. The main reason for the sensitivity of the horseshoe bats to ringing was that the ring rubbed raw the bats' propatagium; the resultin...

http://centrostudinatura.it/public2/documenti/485-74364.pdf

Effects of forearm bands on horseshoe bats (Chiroptera: Rhinolophidae)

Since the first publications about the possibilities of a phonic discrimination of bats with bat detectors, it has been found that two types of specimens with different echolocation calls exist within the weU known European species Pipistrellus pipistrellus (Schreher, 1774) (Ahlen, 1981; Weid & V. Helversen, 1987). Later, it was detected that these types occur in sympatry and differ genetically (Barratt et al. 1993; 1995; 1997; Mayer & V. Helversen, 1999). These observations indicated that two sibling species occur in Europe (Jones & Parijs, 1993): P. pipistrellus (45-kHz form)^ and P. pygmaeus (55-kHz form). Finally, studies in Germany (Haussler et al., 2000) have shown that these sibling species can be distinguished on the basis of morphological differences in external characters, too: a) the 2"^ and the 3"* phalanges of the 3''' finger are of the same length in P. pygmaeus, while in P. pipistrellus the 3"* phalange is in most cases shorter than the 2°'' by more than 1 mm; b) the colour of the penis integument in adult P. pygmaeus is orange without a distinct median band in contrast to the greyish penis with a light median band in P. pipistrellus; c) P. pygmaeus has a longitudinal ridge-like structure, between the nostrils, that P. pipistrellus lacks.

Teodora Ivanova

Papers

Is species identity, sex, age or individual quality conveyed by echolocation call frequency in European horseshoe bats?

Effects of forearm bands on horseshoe bats (Chiroptera: Rhinolophidae)

First record of Pipistrellus pygmaeus (Leach, 1825) (Chiroptera: Vespertilionidae) for Bulgaria