New publication: Acoustic exploration is a repeatable behavioral response in migratory bats

On the 14th of April, my first bat paper came online in the journal Scientific Reports. In this paper, led by the talented Theresa Schabacker, we studied how bats explore novel roost-like environments using a newly developed maze-type testing arena. We here show that individuals differ in how they use echolocation to explore, with some bats consistently under-sampling a novel environment while others over sample.

Through exploration animals gain vital information about the availability of resources, the distribution of conspecifics, and the presence of predators. It also helps them to pick up changes in the environment quicker. Studies on how animals explore novel environments are usually conducted by measuring spatial movements. Yet, when exploring, not only where an animal goes is relevant, but also, or even especially, the information it acquires. Birds get new information primarily by using vision, which is challenging to measure. Bats, on the other hand, primarily use echolocation, which we can measure!

Schematic drawing of the maze used during behavioral assay. A) Opaque start tube where bats were placed at the start of each assay B) Barriers closing entrance to maze C) Gates connecting single chambers D) Position of microphone. ©Rebecca Scheibke

We developed a maze-like test arena in which tree-roosting bats could explore small chambers that were connected through ports. This arena is designed so it can easily be brought to the field, in this case the Pape Ornithological Station in Latvia, and so the bats do not need to be transported away from their habitat. Using a night-vision camera and a sensitive microphone we recorded the spatial and acoustic behavior of migratory Nathusius’ pipistrelles (Pipistrellus nathusii) for two minutes after they voluntarily entered the maze (some never entered). We did this twice for over 50 individual bats and discovered that not only the echolocation behavior and the number of chambers they visited was strongly correlated (more chambers meant more echo calls), individuals also consistently differed in how many calls they made per chamber. Some were just more thorough in sampling these new chambers than others. This sampling behavior was also correlated to another seemingly explorative behavior: the number of times they took peeks (but did not enter) other chambers.

Nathusius pipistrelle. Photo credit: Evgeniy Yakhontov, Creative Commons Attribution-Share Alike 3.0 Unported
Nathusius pipistrelle. These little guys are excellent climbers and crawlers, which helps them in finding suitable new roosts, often in trees and bat boxes. Photo credit: Evgeniy Yakhontov, Creative Commons Attribution-Share Alike 3.0 Unported

These bats remind me of how people differ when going through a museum. Some go and look at every painting in a room while others are satisfied with just a few highlights. Bats are not so different as it turns out. Of course, this raises tons of new questions, like: do more thorough exploring bats indeed detect changes in their environment sooner? Does this bring them a fitness-benefit? Or is it actually very costly to echo-locate this much? And does a quickly changing environment select for more thoroughly exploring bats?

Still so much to explore!

Experimental set-up of maze-type arena for testing exploration behavior in tree-roosting bats. Photo credit: Lysanne Snijders


Schabacker T, Lindecke O, Rizzi S, Marggraf L, Pētersons G, Voigt CC, Snijders L (2021). In situ novel environment assay reveals acoustic exploration as a repeatable behavioral response in migratory bats. Scientific Reports: Online.


New publication: Repeatability of signalling traits in the avian dawn chorus

Our newest open access paper on repeatability of avian signalling (song)  traits just came online in the journal Frontiers in Zoology.

Repeatability, consistent individual differences, in signalling behaviour is interesting because it means that those receiving the signal (i.e. listening to the song) could reliably learn something about how the individual singer compares to other singers/competitors.

We repeatedly recorded the dawn song of great tit males throughout the breeding season and show that start time of dawn song and repertoire size are individually repeatable both before and during the egg-laying stage of the mate (when she is fertile). Surprisingly the time a male started singing appeared to be more repeatable (consistent) than repertoire size, despite that the start time was also influenced by variable overnight temperatures. Start time was also more repeatable before than during egg-laying and we suggest that this is related to the behaviour of the (assumingly) intended receivers of the song, the females.

For a subset of the singers, we also explored a potential link between the absolute song trait values, the repeatability of these values and personality. We did not find a link but follow-up studies with a larger sample size, and including additional song traits, will be needed to confirm the true absence of such a link.

Naguib M, Diehl J, van Oers K, Snijders L (2019). Repeatability of signalling traits in the avian dawn chorus. Frontiers in Zoology 16: 1-11. 


A new project! Personality and migration strategies in bats

This month, I officially started with my two-year postdoc fellowship at the Leibniz Institute for Zoo and Wildlife Research (IZW), granted by the Alexander von Humboldt-Stiftung. As of now, I am part of the Evolutionary Ecology Department, or more specifically: the Batlab, and I will study the role of personality and social associations in the movement behaviour of partially migratory noctule bats, Nyctalus noctula. In Germany they are called Abendsegler, meaning something like ‘Evening sailor’. Beautiful isn’t it? I am very much looking forward to my work at IZW and I hope to learn many new things, meet many passionate wildlife researchers and contribute some fascinating new insights into noctule bat behaviour.


Abstract of my awesome bat project:

Migratory animals vitally connect distant ecosystems worldwide, impacting key ecological processes by transporting nutrients, seeds, parasites and pathogens. As the only flying mammals, bats represent a unique and widespread group of migratory animals, serving important ecosystem functions as pollinators and pest controllers. Bats comprise one fifth of all mammal species, but little is known about their migration strategies. Yet understanding animal migration strategies provides important insights into ecosystem connectivity. Therefore, I aim to gain a better understanding of the key mechanisms that drive variation in bat migration strategies.

A single bat population can contain resident as well as migrating individuals. Such populations offer an excellent opportunity to study individual differences in migration strategies within populations. Hitherto, research on migration has mostly focused on birds, yet novel tools have recently become available to study partial migration in bats. Migration poses a trade-off: migration can lead individuals to more favourable habitats, but is also risky and energetically costly. Individuals have to balance these costs and benefits of migration and are likely to differ in how they do so. Bats fundamentally differ from many migrating bird species in key life-history traits that profoundly impact migration decisions. Knowledge about bat migration strategies, may thus lead to crucial insights into the maintenance of animal migration over evolutionary timescales.

New and improved techniques, such as non-invasive isotopic geolocation, allow for novel insights into the migration strategies of this poorly understood migratory taxon. Using this novel technique in combination with bat personality assays, social network analyses and bat banding, I will test whether individual bats consistently or plastically differ in their migration strategies and investigate the key social, physiological and behavioural factors underlying these differences.