What you see is not what you get: the role of ultrasonic detectors in increasing inventory completeness in Neotropical bat assemblages

Abstract

Summary 1.Microchiropteran bats have the potential to be important biodiversity indicator species as they are distributed globally and are important in ecosystem functioning. Survey and monitoring protocols for bats are often ineffective as sampling techniques vary in their efficacy depending on the species involved and habitats surveyed. Acoustic sampling using bat detectors may prove an alternative or complementary technique to capture methods but is largely untested in the tropics. 2.To compare the efficacy of bat detectors and capture methods in surveys, we used ground mist nets, sub-canopy mist nets and harp traps to sample bats while simultaneously recording the echolocation calls of insectivorous bats in a diversity of habitats in the Yucatan, Mexico. We described echolocation calls, analysed call characteristics to identify species, and compared species inventories derived from traditional capture methods with those derived from acoustic sampling. 3. A total of 2819 bats representing 26 species and six families were captured; 83% were captured in ground nets, 13% in sub-canopy nets and 4% in harp traps. Fourteen species and five phonic types were identified based on five echolocation call characteristics. Discriminant function analysis showed a high level of correct classification of the calls (84·1%), indicating that identification of species by their echolocation calls is feasible. 4. In all habitats, acoustic sampling and capture methods sampled significantly more species each night than capture methods alone. Capture methods failed to sample 30% of the bat fauna, and aerial insectivores were sampled only by bat detectors. 5. Synthesis and applications . Given the importance of bats in ecosystem functioning, and their potential as indicator species, developing effective methodologies to survey and monitor bats is important for sustainable forest management and biodiversity conservation. Acoustic sampling should be used with capture methods to increase inventory completeness in bat assemblage studies, and could form part of a single standardized monitoring protocol that can be used globally in tropical forests, as this method detects aerial insectivores not sampled by capture methods.

Effects of tropical forest fragmentation on aerial insectivorous bats in a land-bridge island system

“…Kalko and Handley, 2001;Bernard, 2001;, it is acknowledged that richness and abundance of aerial insectivores was underestimated because these bats avoid mist nets effectively or fly above the canopy where sampling is unfeasible. With advancements made in monitoring aerial insectivores through the use of audio recording devices, we are now able to study this diverse group in more detail MacSwiney et al, 2008) and to complement the few studies on fragmentation effects of aerial insectivorous bats (Law et al, 1999;Estrada et al, 2004).…”

Lo que el viento se llevó: ¿conocemos el impacto que producir energía eólica causa sobre los vertebrados voladores de Costa Rica?

“…Por ejemplo, probar prototipos de turbinas éolicas amigables con las aves y murciélagos, utilizar grabadores ultrasónicos que permiten detectar especies de murciélagos que no se registran mediante otros métodos (p. ej. redes de niebla; MacSwiney, Clarke, & Racey, 2008), instalar dispositivos acústicos o electromagnéticos que repelen a los murciélagos de las turbinas (Nicholls & Racey, 2009;Johnson, Ford, Rodriguez, & Edwards, 2012), o usar radares para minimizar el impacto sobre especies de aves emblemáticas o migratorias. Como estas, existen muchas otras medidas complementarias de mitigación, cuya eficiencia se podría probar en nuestros ecosistemas (Soto, 2017).…”

Mobility explains the response of aerial insectivorous bats to anthropogenic habitat change in the Neotropics

“…While some AIB species disappear with urbanization (urban avoiders), others seem rather unaffected (urban adapters) or might even profit from human settlements, where they find high numbers of roosting sites (urban exploiters, Jung and Kalko, 2011). Most studies on AIB in the Neotropics, however, have focused on geographically restricted areas like national parks or cenotes (Delgado-Jaramillo et al, 2011;MacSwiney et al, 2008;Rydell et al, 2002) or the canal area in Panama (Estrada-Villegas et al, 2012;Jung andKalko, 2010, 2011). Working across broader geographical scales is important to reveal broad scale patterns and to test the validity of ecological hypotheses in multiple habitat contexts.…”