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Without regular maintenance bat boxes cannot operate effectively. Here a flat bat box has been colonised by hornets.
Source publication
If bat roosts in/on trees are to be removed during a project, they often have to be replaced by continuous ecological functionality measures (CEF). In many cases bat boxes are used to compensate for felling. Their effectiveness was reviewed
by the Bavarian Coordination Centre for Bat Protection by analysis of a survey on the use of bat boxes in for...
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Citations
... It is possible that Ochaechulla spinturniciformis is bat-associated rather than a free-living subcortical or saproxylic detriticole, for the following reasons: (1) the senior author has been observing and collecting the subcortical mesostigmatic mite fauna in Slovakia for many years and has not found any similar species so far; (2) the tree bark where the types were collected was loose at its edge, which creates a suitable place for bats to roost and hide [similar microhabitats were reported, for example, by Zahn and Hammer (2017), Dietz et al. (2018) and Apoznański et al. (2021)], and even the narrowest space between bark and cambium was relatively dry, as required for the occurrence of the common fauna of subcortical mites and wood-destroying insects; (3) the type locality is in close proximity to an extensive area of water with significant nocturnal flight activity of foraging bats; and (4) the external dorsal habitus of the species resembles ectoparasitic species from the genus Laelaps C. L. Koch, much more than free-living edaphic Hypoaspis-like species (or some strictly subcortical Dendrolaelaps-like species), although morphological features of the chelicerae in the new species do not clearly indicate a parasitic mode of life and active hematophagy. ...
We describe a new genus in the mite family Laelapidae from Slovakia, Ochaechulla gen. nov., to accommodate a new species, Ochaechulla spinturniciformis sp. nov., based on females collected from under loose tree bark that probably served as a bat roost. The new genus is characterized by a specific idiosomal setation with the loss of some setae on the dorsal shield and opisthogastric region, hypotrichy of the legs, an unusual arrangement of the ventral shields and legs on the idiosoma, and strongly shortened peritremes. Its thick dorsal setae, modified body shape, and strong reddish-brown sclerotization most closely resemble the ectoparasites of small mammals in the genus Laelaps C. L. Koch, although its unique combination of features clearly distinguishes it from them and any other dermanyssoids. The radial arrangement of the legs around the margin of the idiosoma is similar to the genus Spinturnix von Heyden.
... However, the effectiveness of bat boxes as conservation tools is controversial. On the one hand, because it is assumed they are rarely used by nursery groups and can be ecological traps, for example by increasing the risk of overheating (Crawford & O'Keefe, 2021), there is a general agreement that boxes cannot fully compensate for the loss of natural cavities (Chambers et al., 2002;Griffiths et al., 2017;Zahn & Hammer, 2017). On the other hand, it has been reported that boxes are a useful conservation tool (Flaquer et al., 2006). ...
... There is an indication that higher positioned natural roosts, and hence boxes with higher mounting height, are occupied more frequently (Ruczyński & Bogdanowicz, 2005), although few studies exist that statistically evaluated this for artificial roosts (Mering & Chambers, 2014;Rueegger, 2016). As bat boxes require time to become occupied, occupancy is assumed to be positively correlated with the age of a box (Chambers et al., 2002;Griffiths et al., 2017;Zahn & Hammer, 2017). Likewise, box occupancy is influenced by box density, that is the availability of nearby roosts (Mering & Chambers, 2014). ...
... Likewise, box occupancy is influenced by box density, that is the availability of nearby roosts (Mering & Chambers, 2014). Conservation practices recommend installing new boxes near pre-existing nursery groups to allow roost switching and social interactions between bat individuals (Fukui et al., 2010;Rueegger, 2017;Zahn & Hammer, 2017). Some studies reported high box occupancy in managed areas with few natural cavities (Ciechanowski, 2005;Flaquer et al., 2006), indicating that the environment in which boxes are installed plays an important role. ...
1. Bat populations are in steep decline and presently, 16% of all species are classified as 'threatened'. One main driver identified for this decline is the loss of natural roosting opportunities, caused by the removal of natural habitats. Installation of bat boxes is one solution to compensate for the lack of natural roosting opportunities. Current recommendations for box design emphasize low maintenance costs and are rarely based on empirical evidence.
2. We investigated occupancy of 13,634 bat boxes in northern Bavaria, Germany. In our study, boxes differed in type, age and mounting height, as well as in maximum community age, that is the length of time a group of boxes had been installed in a particular place, the size of box groups and the distance to the next box in the surrounding area, that is box isolation.
3. Our results showed that box occupancy depended on box type and bat species. As a case study, we analysed the two most common species found within the investigated boxes, Pipistrellus pipistrellus and Myotis nattereri, in more detail. Both species showed preference to a voluminous box that had a narrow entrance ('Gable box' 14 mm). For P. pipistrellus, only box type affected occupancy, whereas for M. nattereri, the relationship between box type and box age was important. Older boxes and boxes in areas with higher maximum community age of boxes showed higher box occupancy by bats. Box occupancy decreased with the distance between adjacent box groups ('box isolation'). High mounting height showed a tendency for increased box occupancy, but the effect was only weakly significant.
4. Because of the species-specific responses in our study, we suggest installing a combination of different box types, including at least one box type with a narrow entrance (14 mm). Boxes should be placed as box groups of three to four boxes, and there should be short distances between adjacent box groups. We also recommend installing new box groups close to areas of high maximum community age of boxes. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
... Bat boxes have also been used to attract displaced colonies to new areas (Neilson and Fenton, 1994;Brittingham and Williams, 2000;Ruffell et al., 2009), or to support local bat populations (Boyd and Stebbings, 1989;Flaquer et al., 2006;Long et al., 2006). In central Europe, artificial roosts have been used since the 1950s (Issel and Issel, 1955) and constitute a common practice to compensate for the destruction of roosts (Zahn and Hammer, 2017). ...
... The success of roost supplementation programs depends on the detection and occupancy of the newly placed boxes (Brittingham and Williams, 2000). There are several factors affecting box occupancy (reviewed by: Mering and Chambers, 2014) including time since installation (Agnelli et al., 2011;Bender, 2011), box design (Baranauskas, 2009Dodds and Bilston, 2013), microclimatic characteristics (Kerth et al., 2001), and the number and deployment of the boxes (Brittingham and Williams, 2000;Zahn and Hammer, 2017). ...
The availability of suitable roosts is an important factor affecting the viability of bat populations. In Europe and North-America, the installation of artificial roosts is a standard conservation measure to mitigate the loss of tree cavities or crevices at buildings. How quickly artificial roosts, such as bat boxes, are adopted, depends on how easily the bats can find them, and on their suitability for roosting. While there is some information about how the design of bat boxes influences their occupancy, it is unknown to what extent the use of bat boxes depends on their detectability. In this experimental field study, we studied the roost selection behavior of three forest-living bat species. We investigated whether attaching an external echo-reflector to bat boxes influenced the time until the bats discover a box or the total number of discovered boxes, which are proxies for detectability. We also assessed whether this modification improved the occupancy of newly placed boxes, as a proxy for their attractiveness. As a result of a previous study, all studied bat colonies were familiar with the echo-reflector as an indicator for the suitability of bat boxes as a day roost. For each species, we compared between boxes with and without an echo-reflector, the number of boxes discovered, the number of days elapsed until discovery, the number of subsequent visits, and the number of days that each box type was used as day roosts. Myotis bechsteinii and Myotis nattereri discovered, visited and used more unmodified boxes than boxes with echo-reflectors. Plecotus auritus did not show differences in behavior with regard to the box types. Our results show that attaching an echo-reflector to newly placed artificial roosts does not improve their discovery and subsequent occupation, even when bats are already familiar with this cue as an indicator of suitability. We discuss the implication of our findings for bat conservation.
... Die FH1500© wurden schneller und vonEinsatz seminatürlicher Fledermaushöhlen FH1500© als kurzfristig funktionale Interimslösung zum Ausgleich von BaumhöhlenverlustIm Rahmen der Eingriffsplanung sollte der Schutz von Baumhöhlen bzw. Quartierbäumen, unabhängig von einem vorliegenden Nutzungsnachweis, oberste Priorität haben(Zahn & Hammer 2017). Ersatzquartiere können das von Lokalpopulationen benötigte breite Spektrum der Eigenschaften natürlicher Baumhöhlen nicht vollständig abdecken. ...
Bei Eingriffen ist die Fällung von Höhlenbäumen regelmäßig unvermeidbar. Quartierverlust kann zur Beeinträchtigung lokaler Fledermauspopulationen führen. Durch vorgezogene Ausgleichsmaßnahmen (CEF-Maßnahmen) ist die ökologische Funktion der betroffenen Lebensstätte im räumlichen Zusammenhang zu erhalten (Runge et al. 2010), was durch Sicherung und Förderung natürlicher Baumhöhlen möglich ist. Bis die ökologische Funktion dieser langfristig wirksamen Maßnahmen vollständig erfüllt wird, sind kurzfristig funktionale CEF-Maßnahmen als Interimslösung erforderlich. Dafür werden oft Holzbetonkästen eingesetzt, die jedoch bei Neuinstallation häufig erst nach mehreren Jahren angenommen werden (Zahn & Hammer 2017). Ursächlich könnten Unterschiede zu Baumhöhlen hinsichtlich Aussehen, Material und Mikroklima sein. In vitale Baumstämme gefräste oder gesägte Kunsthöhlen bzw. –spalten ähneln in ihren Eigenschaften eher einer natürlichen Baumhöhle (Runge et al. 2010, Griffiths et al. 2018), können allerdings die Stabilität des Baumes beeinträchtigen und vor dem Hintergrund der Verkehrssicherungspflicht bei einem Baumversagen zur Verantwortlichkeit des Baumeigentümers führen (BGH 2012).
Somit stellt sich weiterhin die Frage nach einer kurzfristig funktionalen Interimslösung zum Ausgleich von Baumhöhlenverlust, die nicht die Verkehrssicherheit gefährdet. Als Lösungsansatz wurde eine seminatürliche Fledermaushöhle FH1500© (DPMA 2018) als Sommerersatzquartier entwickelt und durch ein 8-jähriges Monitoring hinsichtlich Mikroklima und Annahme vergleichend mit Holzbetonkästen überprüft.
Zusammenfassung
Der Ausbau der Windenergie findet zunehmend im Wald statt, da hier häufig windhöffige und damit ökonomisch attraktive Standorte zu finden sind. Allerdings ist hier der Konflikt mit dem Artenschutz im Allgemeinen und dem Fledermausschutz im Speziellen besonders hoch. In diesem Beitrag beleuchten wir vor dem Hintergrund des gesetzlich vorgegebenen normativen Rahmens den artenschutzrechtlichen Teil der Windkraftplanung im Wald mit Bezug auf Fledermäuse – von der Untersuchungsplanung über die eingesetzten Methoden bis zur Bewertung. Bezogen auf Fledermäuse stehen hier insbesondere die Vermeidung der direkten Tötung sowie die Verminderung der Beeinträchtigung ihres Lebensraums im Fokus der Betrachtung. Bundesland-spezifische Arbeitshilfen stecken den Untersuchungsumfang, die einzusetzenden Erfassungsmethoden und den räumlichen und zeitlichen Untersuchungsrahmen ab. Sie empfehlen zudem Maßnahmen zur Kompensation potenziell negativer Auswirkungen eines Eingriffs. Ihr Effekt auf die methodische Qualität der Fachbeiträge zu Fledermäusen ist jedoch gering. Meist kommen im Rahmen der speziellen artenschutzrechtlichen Prüfung zu Fledermäusen die Quartierbaumsuche, Netzfang, unterschiedliche Varianten des akustischen Monitorings (aktiv und passiv) sowie die Radiotelemetrie zum Einsatz. Insbesondere bei der bevorzugt empfohlenen akustischen Erfassung mindern zahlreiche methodische Probleme auf der technischen und der analytischen Ebene die Aussagekraft. Auch der Erfolg des Fangs von Fledermäusen mit Netzen hängt von zahlreichen Parametern ab. Die Quartierbaumerfassung lässt sich in ihrem Erfolg deutlich durch die Radiotelemetrie verbessern. Zur sinnvollen Quantifizierung des Lebensraumanspruchs einer Fledermauspopulation jedoch werden mittels Radiotelemetrie in der Regel zu wenige Tiere zu kurz untersucht. Die Bewertung der erhobenen Daten, hier gezeigt anhand akustisch ermittelter Aktivitätsdichten, erfolgt subjektiv, da Bewertungskriterien fehlen. Die am häufigsten empfohlenen und somit umgesetzten Methoden der Konfliktvermeidung und -minimierung sind CEF- (= Continued Ecological Function) und FCS-Maßnahmen (= Favourable Conservation Status) sowie das Gondelmonitoring und die selektive Abschaltung der WEA. Auch diese Maßnahmen entfalten z. T. Schwächen; die Bewahrung und Entwicklung von Waldstandorten als/zu ökologisch wertvollen Lebensräumen sowie die Verminderung der Schlagopferzahl durch spezielle Algorithmen (ProBat-Tool) sehen wir jedoch als sinnvoll an. Abschließend formulieren wir Anregungen zur Verbesserung und Objektivierung der Eingriffsplanung von WEA im Wald.
Summary
The development of wind energy is concentrating in forests, as windy and thus economically favourable sites can often be found here. However, the conflict with species conservation in general and bat conservation in particular is especially high in forests. We here examine the impact assessment on bats in the context of the legally prescribed normative framework in wind farm planning in the forest – from the study design to the methods used and the assessment itself. With regard to bats, the focus here is on avoiding direct killing and reducing the impairment of their habitat. Guidance documents for the German federal states define the extent of the surveys, the survey methods, and the spatial and temporal scope of a survey. They also recommend measures to compensate for potential negative impacts of wind energy plants (WEP). However, their effect on the quality of the expert reports on bats is low. In most cases, the search for roost trees, mist netting, different types of acoustic monitoring (active and passive) and radio tracking are used. In particular, numerous methodological problems at the technical and analytical levels reduce the validity of acoustic surveys. The success of mist netting bats also depends on numerous parameters. The success of roost tree surveys can be significantly improved by radio tracking. However, for a meaningful quantification of the habitat requirements of a bat population, radio tracking is usually used on too few animals for too short a time. The evaluation of the collected data, shown here on the basis of acoustically determined activity densities, is subjective because evaluation criteria are lacking. The most frequently recommended and thus implemented methods of conflict mitigation are CEF (= Continued Ecological Function and FCS (= Favourable Conservation Status) measures as well as nacelle monitoring and selective shut-down of wind turbines. These measures also show some weaknesses, but we consider the maintenance and development of forest sites as or into ecologically valuable habitats, as well as the reduction of the number of bat fatalities by means of specific algorithms (ProBat tool), to be sensible. Finally, we make suggestions for improving and objectifying the impact assessment of wind-energy facilities in forests.
Bäume mit Quartierstrukturen (Höhlen, Spalten) stellen Fortpflanzungs- und Ruhestätten für Fledermäuse dar. Werden durch Eingriffe solche Bäume beseitigt, müssen die Zugriffsverbote nach § 44 Abs. 1 Bundesnaturschutzgesetz (BNatSchG) beachtet werden. Mit dem Hinweisblatt der Koordinationsstellen für Fledermausschutz in Bayern „Vermeidungs-, CEF- und FCS-Maßnahmen für vorhabenbedingt zerstörte Fledermausbaumquartiere“ liegen nun konkrete Empfehlungen vor, welche Maßnahmenpakete geeignet sind, die Eingriffsfolgen zu vermeiden oder auszugleichen.
Download Positionspapier unter https://www.tierphys.nat.fau.de/fledermausschutz/
In Deutschland werden immer mehr Windenergieanlagen (WEA) an Waldstandorten errichtet. Für fast alle Fledermausarten stellen Wälder sensible Lebensräume dar, die sowohl als Quartier- als auch als Jagdgebiete genutzt werden. Neben dem Kollisionsrisiko sind an Waldstandorten auch erhebliche Lebensraumverluste zu erwarten. Um auch an Waldstandorten zu gewährleisten, dass der Ausbau der Windkraft nicht zu Lasten des Fledermausschutzes geschieht, müssen die Fledermausbestände mit spezifischen Methoden erfasst und muss auftretenden Konflikten mit angepassten Maßnahmen begegnet werden.
Wind turbines are currently being established on a large scale in forests in Germany. Numerous bat species are affected by the habitat loss and collisions associated with such constructions. In the BfN’s (German Federal Agency for Nature Conservation) research project “Investigations to minimize the impacts of wind turbines on bats, par-ticularly in forests” knowledge on the ecology and distribution of different bat species is built upon through several case studies. This knowledge allows specific recommen-dations for surveying and mitigation measures for the construction of wind turbines. Data on the distribution of bats has already been analysed in several meta-analyses (including nursery occurrence and acoustic data both close to the ground and at height). Investigations specifically into bat activity at height were carried out in roosting areas of the barbastelle bat (Barbastella barbastellus), common pipistrelle (Pipistrellus pipistrellus) and Leisler’s bat (Nyctalus leisleri) in addition to further investigations into phenology, roost use and spatial habitat use.
One important result of the investigations was that bat species which are relevant to planning should be expected to occur in practically all forest habitats. Pre-construction surveys (acoustic recordings, catching and radio-tracking) are therefore always crucial. To investigate collision risk acoustic monitoring must additionally be carried out after the construction of wind turbines, measurements should be taken at nacelle height and if necessary also in the area where the lower tips of the rotor blades pass. Forest habi-tats in which substantial habitat loss would be expected as a result of wind turbine construction are relatively easy to identify. Criteria exempting areas from the construc-tion of wind turbines are recommended, particularly for valuable habitats. Deciduous and mixed deciduous woodlands, semi-natural coniferous woodland with high roost potential and woodland areas within SACs (Special Areas of Conservation), which are important habitats for bats, should be covered by exemption criteria. Additionally, any loss of habitat should always be compensated for via several measures for the creation of new habitat or through improvement of the quality of existing habitat. Areas with a high collision risk are not easy to identify; shut down times are necessary for all wind turbines. At particular sites, e.g. close to roosts, the shut-down times should where necessary be increased depending on activity levels. Based on the biology of bats an increase in the risk of mortality almost certainly negatively effects population devel-opment, a cautious approach is therefore essential according to precautionary princi-ples.
