Effects of tag mass on the physiology and behaviour of common noctule bats.

Background: External tags, such as transmitters and loggers, are often used to study bat movements. However, physiological and behavioural effects on bats carrying tags have rarely been investigated, and recommendations on the maximum acceptable tag mass are rather based on rules of thumb than on rigorous scientific assessment.

Methods: We conducted a comprehensive three-step assessment of the potential physiological and behavioural effects of tagging bats, using common noctules Nyctalus noctula as a model.

Differences in acute phase response to bacterial, fungal and viral antigens in greater mouse-eared bats (Myotis myotis).

The acute phase response (APR) is an evolutionarily well-conserved part of the innate immune defense against pathogens. However, recent studies in bats yielded surprisingly diverse results compared to previous APR studies on both vertebrate and invertebrate species. This is especially interesting due to the known role of bats as reservoirs for viruses and other intracellular pathogens, while being susceptible to extracellular microorganisms such as some bacteria and fungi.

Echolocation at high intensity imposes metabolic costs on flying bats.

Vocalizations are of pivotal importance for many animals, yet sound propagation in air is severely limited. To expand their vocalization range, animals can produce high-intensity sounds, which can come at high energetic costs. High-intensity echolocation is thought to have evolved in bats because the costs of calling are reported to be negligible during flight.

Nathusius' bats optimize long-distance migration by flying at maximum range speed.

Aerial migration is the fastest, yet most energetically demanding way of seasonal movement between habitats. However, for many taxa, and bats in particular, we lack a clear understanding of the energy requirements for migration. Here, we examined the energetic cost and flight speed of the long-distance migratory Nathusius' bat ().