Jaap van Schaik

An unexpected reaction to climate change: Daubenton's bats are hibernating for longer The days are getting shorter, the temperatures are dropping. Numerous animals are migrating south, others are seeking their hibernacula—including bats.

Daubenton's bats are now entering hibernation a month earlier than 13 years ago without increasing fat reserves, highlighting shifting survival challenges linked to climate change. doi.org/g955mn

This work highlights the power of long-term individualized monitoring! Frauke deserves immense credit for her perseverance and diligence in running this unique study site. 💪🫶

Bottom line: bat hibernation phenology can respond rapidly to climate change, but these shifts can’t continue forever. Now, more than ever, we need high-quality monitoring data to track bat population trends over the next decades. (Like:
batlas.info/en/trends/my...)

This may also come with risks, as sudden/early cold snaps may leave them with insufficient reserves. Such an event happened in the winter of 2010/11 in this population, resulting in ±60% winter mortality.

Finally, what about the Natterer’s? It's likely that they will become increasingly active in winter, only showing up at hibernacula during particularly cold periods (not unlike Barbastelle bats).

Whatever the reason, the current rate of shift is likely unsustainable long-term. Hibernation entry is already encroaching on the mating period, and the fat reserves these little fluffballs can accumulate is limited. What happens when limits are reached? Time will tell, but I fear it won’t be good

Weights of Daubenton's bats captured in August/September in 4 years. Weights of adult male and female bats increase steadily over the 2 month period, whereas juvenile weights remain similar throughout

Indeed, we observe almost no weight gain in juveniles throughout autumn capture season, which contrasts strongly with adults.

This scenario may be particularly problematic for juvenile Daubenton’s, as their entry into the hibernaculum has not shifted to the same degree as in adults. Having only been born a few months prior, they may simply need more time to fully develop and learn how to hunt effectively.

a man in a batman costume is standing on a bridge ALT: a man in a batman costume is standing on a bridge

Accumulating fat for winter is a tricky task for bats. The fatter they get, the more energetically costly it becomes to fly. So in order to keep ‘putting on the grams’, bats need progressively higher prey densities. With insect peaks shifting earlier, Daubs may have no choice but to shift along

In the most optimistic scenario, Daubenton’s bats are taking advantage of this shift, fattening up quickly, and diving into the safety of the hibernaculum as soon as they can. However, it could also be an attempt to make the best of a bad job...

Daubenton’s are specialists at scooping insects off water bodies (trawling). As water bodies have gotten warmer, peaks in insect emergence from these water bodies have advanced. As a result, the last big peak of prey availability for the Daubenton’s in late summer is getting earlier and earlier.

Plot of Daubenton's bat hibernation start date between 2010 and 2023. Adult male bats have advanced entry by 2 days/year, adult females by 1 day/year

Surprisingly, Daubenton’s bats (at the same site and over the same time-frame) have EXTENDED their hibernation duration, with adult bats entering the hibernaculum much earlier than they used to (males: 2 days/year, females 1 day/year). But why? We think in response to their prey…

Plot of Natterer's bat hibernation duration between 2010 and 2022; hibernation duration has shortened by nearly a month over this period

With temps rising, winters are getting milder and shorter, causing many organisms to extend their active periods in autumn and spring.
Natterer’s bats are doing this at an exceptional rate! Entering later, emerging earlier, reducing their hibernation period by nearly a month in just over a decade!

One Species Hibernates Shorter, the Other Longer: Rapid but Opposing Responses to Warming Climate in Two Sympatric Bat Species Hibernation timing is a crucial seasonal transition that directly influences the survival and reproduction of hibernating mammals. Climate change alters key drivers of hibernation phenology, includin...

Proud to present our latest 🦇 paper! Using 13 years of data, we show that hibernation timing has shifted dramatically in two bat species, but in opposite directions 😮

Huge congrats to Gabi, Frauke, and the whole team.

OA in @globalchangebio.bsky.social: dx.doi.org/10.1111/gcb....

Highlights in 🧵

Bats are underrated.

Whose poo?
New research shows bats are more likely to investigate new home if it smells of a friend's poo.
Hmm. Let's not try this at home humans!
🦇💩 #bats #nature #wildlife @batconservation.bsky.social
www.sciencedirect.com/science/arti...

Great opportunity!

We're looking for a PhD candidate who will characterise what echolocating agents do in groups using a multi-sensor rigs in the field. Wouldn't it be cool to finally figure out how bats manage their calling and flying - and even reconstruct what they may be hearing to make these decisions? 5/n

Nathusius' pipistrelle (Pipistrellus nathusii)

Systematic genetic monitoring of the species would be an incredibly valuable tool to track population dynamics, and we hope our work inspires the establishment of such a program! (6/6)
Big shoutout to the entire team that made this work possible! (none on Bsky unfortunately)

While the study only covered 4 years, we did observe a very subtle reduction in allelic richness (genetic diversity) over time, suggesting that the population may be declining. This fits to observations that it is amongst the most frequently observed bat fatalities at wind farms across Europe. (5/6)

More broadly, we found that the population is genetically very well-mixed and shows no signs of sub-structuring, suggesting the entire catchment area that passes through the Netherlands on their migration acts as a single genetic population. (4/6)

Image shows pairwise relatedness between adult female and juvenile Nathusius' pipistrelles captured together during migration. It shows that no mother-offspring pairs were detected amongst the bats captured at stopover sites together.

Turns out, this is not the case, as we found no mother-offspring pairs in any of the individuals sampled together, or even across the entire 4 year dataset. (3/6)

In autumn, male bats defend roosting sites along the migratory pathway, and try to attract females that are passing by to stopover and mate. We noticed that juveniles often stopped at these roosts together with the adult females. So we wondered whether mothers and their offspring migrate together?

Diverse but declining? Population genetic structure and genetic diversity of Nathusius’ pipistrelle along the Dutch coastline during the autumn migration period - Mammalian Biology Migratory bats are experiencing substantial increases in mortality risk from wind energy developments, but data on their migratory behavior and population dynamics are often lacking. Here, we develop ...

Nathusius’ pipistrelle 🦇 is quite a remarkable species, an 8g fluffball that can migrate over 2000km across Europe. In our new paper, we use population genetics to learn a bit more about this amazing creature. (🧵 1/6)
link.springer.com/article/10.1...

Just a few more days to apply for a PhD with me! Use new technologies to study movement and ecology of serotine bats in UK. Evidence can guide future rabies control strategies, helping bats and people. Click on project 'Understanding transmission..' here: www.surrey.ac.uk/bbsrc-wessex... #PhD #bats

looking for a good scientific read? This paper is out today and shows how much energy male bats can save by living in groups. Great for buffering environmental unexpectedness! Pic by Rene J doi.org/10.1242/jeb....
@mpi-animalbehav.bsky.social @jexpbiol.bsky.social @uni-konstanz.de

Hey 🦇 people / conservation geneticists: If a 3 (up to 6) year postdoc in a quiet college town on the Baltic coast is sounding pretty good right about now, the Kerth lab is looking for you!

(ad only in German unfortunately, but the group is int'l!) Happy to answer questions, deadline: Feb 10th!

Equally happy to share our new paper!
It turns out malaria's little brother is infecting Myotis bats 🦇 and bat flies 🪰 all over Europe. Definitely an under-appreciated pathogen that deserves some more study and attention.

Migrating bats surf warm winds to soar hundreds of kilometers Tiny transmitters reveal at least one bat species is surprisingly flexible in its migration timing and pathfinding

lovely write-up about our new paper in @science.org by @science.org 😍 @mpi-animalbehav.bsky.social @unikonstanz.bsky.social www.science.org/content/arti...

Come apply for my soon-to-be-former job! Advert unfortunately only in German, but the group is very international. Very happy to chat and answer any questions