Science

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

Reference

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.

Communication, Science

New publication: Causal evidence for the adaptive benefits of social foraging in the wild

On 20-01-2021 the latest fruit of our Trinidadian guppy research project came online in the Open Access journal Communications Biology. With this experimental field study, we provide rare causal evidence for the adaptive benefits of social foraging in the wild. For both sexes!

For the complete story, check out the paper here.
For the popular science summary, check below (Dutch version here)

Guppies with friends eat more

Guppies that socialise with more conspecifics get more food. This applies to both males and females, despite the common assumption that males are not very social. This is revealed through a unique field study conducted by Wageningen University & Research in Trinidad in collaboration with Leibniz-Institute of Freshwater Ecology and Inland Fisheries.

‘Much research has already been done under lab conditions on the impact of group size on animals’, says Lysanne Snijders. ‘Still, you never know whether the results such studies show, apply equally in nature’. Moreover, in the wild, other factors such as predators’ presence also influence animals’ social behaviour.

Three female Trinidadian guppies

Benefits of social behaviour

As far as we know, this is the first time a causal relationship was found between the number of animals of the same vertebrate species and it’s benefits to individuals. In Trinidad, Snijders and her colleagues were able to get a close look at the influence of size and composition of groups under natural circumstances by distributing the guppies over different pools. The behaviour of the fish in different group sizes was extensively analysed and recorded.

Snijders and her team showed that guppies living in larger groups were often more successful at obtaining food. From an evolutionary perspective this is interesting: apparently, an increased food intake is a direct benefit of being social in the wild (as is protection from predators), and may thus partly explain why we often see guppies engage in social associations.

Our fieldwork site in the Trinidad rainforest

Males

Moreover, the study, published in Communication Biology, shows that males and females alike benefit from larger groups. This is remarkable, as females are generally perceived as more social.

Snijders: ‘In the vast majority of guppy research, the study is limited to females because males are thought to be predominantly occupied with mating opportunities. This study, under natural circumstances, clearly shows that males also benefit from social behaviour and that this advantage is not solely restricted to them obtaining females. Assumptions about a lower level of sociability do thus not necessarily translate into fewer social benefits.’

Guppies eating a berry they just found

Reference

Snijders, L., Krause, S., Tump, A.N. et al. Causal evidence for the adaptive benefits of social foraging in the wild. Commun Biol 4, 94 (2021). https://doi.org/10.1038/s42003-020-01597-7

Communication, Conservation

Exploring Conservation Conflicts: New format

For our Exploring Conservation Conflicts blog, we are trying out a new format: personal contributions. We already got two wonderful personal stories tackling very different but important questions in conservation. Check them out!

Climate change is one of the greatest challenges humans have ever faced. This exploration is a personal account of the role that climate change plays in the daily life of researcher Dr Yann Gager. Yann explains to us what individual researchers can (and should?) do to help the fight against climate change. Read more

flatten the curveIn conservation, often a choice has to be made for the lesser of two evils. How can conservationists cope with such situations of seemingly inevitable loss? Here, we share a personal contribution from Dr Chelsea Batavia, in which she takes us along in the background story of her recent publication The moral residue of conservation, addressing exactly this issue. Read more

Science

New publication: Don’t forget about your friends

Remember those friends you never see anymore after they got hitched? Not in geese!

In our recently published paper, we show that barnacle geese keep hanging out with there favourite early-life social companions also after they pair up. Females show a break during the breeding season but display their social preferences again in the following winter. Males keep their prefered companions throughout the breeding and wintering season and these companionships were predicted by familiarity and genetic relatedness.

We also show that especially males were aggressive during the breeding season towards both males and females and this possibly hampered their female partners to hang out with their own ‘friends’ during breeding but not winter.

In summary, our study reveals the robustness of social preferences formed early in life, carrying over across pair formation, even after extended temporal disruptions. Our findings thus highlight how the early-life social environment can have life-long consequences on individuals’ social life, even in monogamous species.

Reference
RHJM Kurvers, L Prox, DR Farine, C Jongeling, L Snijders (2019)
Animal Behaviour 164: 25-37
Also as a preprint on BioRxiv