barre_et_al_2017 farming_practices_bats

barre_et_al_2017 farming_practices_bat

Influence of light type on the activity of each bat species.

<p>Because the type of light is a categorical variable, the given estimate is the average estimate of bat activity for each type (white or orange) compared with the absence of light. Thus, the p-value provides information about the significance of the difference between an absence of light <i>vs.</i> the artificial light type (white or orange). Back-transformed estimate effects represent the average estimate of bat activity for each color type on the original scale.</p><p>Influence of light type on the activity of each bat species.</p

Observed species and their abundances.

<p>The percentages are calculated based on the number of stations at which at least one bat species call was recorded relative to the total number of sampling stations. The mean number of calls per minute was calculated only for the sampling stations at which at least one call was recorded. For <i>Myotis</i> and <i>Plecotus</i> spp., the counts are given at the genus level.</p><p>* <i>Myotis bechsteinii</i>, <i>Myotis daubentonii</i>, <i>Myotis myotis</i>, <i>Myotis mystacinus</i>, <i>Myotis nattereri</i>.</p><p>**<i>Plecotus austriacus</i> and <i>Plecotus auritus</i>.</p><p>Observed species and their abundances.</p

Effects of different factors on the light intensity at the sampling stations.

<p>Results of the GLM. SS is the sum of squares, F is the mean of squares for the factor/mean of squares for the error, and Pr is the probability value associated with the test (p-value of Anova).</p><p>Effects of different factors on the light intensity at the sampling stations.</p

Influence of light intensity on the activity of each bat species.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0103042#pone.0103042-Dietz1" target="_blank">[3]</a> Dietz C., Helversen O. von, Nill D.(2009) L'encyclopédie des chauves-souris d'Europe et d'Afrique du Nord: Biologie, caractéristiques, protection. Delachaux et Niestlé, Paris. 400 p.</p><p>Influence of light intensity on the activity of each bat species.</p

Comparison between models using light intensity or light type as explanatory variables.

<p>. AIC values are given for each model. (GLMP) indicates a Poisson distribution, (GLMNB) a negative binomial distribution, (ZAP) a zero inflated model with a Poisson distribution and (ZANB) Zero inflated model with negative binomial distribution. (*) indicates that as the best model did not converge for both effect (light intensity and light type), we compared the two models using a Poisson error distribution. The models retained based on the smallest AIC value are shown in bold <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0103042#pone.0103042-Burnham1" target="_blank">[45]</a>.</p><p>Comparison between models using light intensity or light type as explanatory variables.</p

Potential of bat pass duration measures for studies of bat activity

<p>Acoustic detectors have become increasingly used by bat workers to investigate bat ecology and assess the impacts of anthropogenic pressures. Within these studies, the metric used, ‘bat activity’, is based on the number of bat passes, without considering the bat pass duration (i.e. each event of a bat detected within the range of an ultrasonic detector). We expected that bat pass duration may contain information about site quality in terms of foraging potential. Because bats are expected to have a more sinuous trajectory and slower velocity when they exhibit foraging behaviour, as opposed to commuting behaviour, we hypothesize a longer bat pass duration in favourable habitats; during seasons with important energetic demands; or during night peak activity. We used datasets from a large-scale acoustic bat survey (<i>n</i> = 2890 sites), with a total of 24,597 bat pass measures from 6 taxa, and performed GLMM modelling. We detected a significant effect of habitat type on bat pass duration for five taxa. Shorter bat pass durations were detected at the beginning of the night. We detected longer pass durations during the lactation period or just before hibernating, while weather conditions or ageing and wear of the detector rarely influenced bat pass duration. Bat pass duration appears to be a simple and easy measure for position calls on a gradient between commuting vs. foraging behaviour. We suggest that the traditional measure of bat activity may be weighted by bat pass duration by giving more weight to events with potentially stronger links to foraging behaviour.</p