Conservation, Science

New publication: Conditioned taste aversion in human-wildlife conflicts

On the 13th of October, our review on an animal behaviour-based conservation intervention appeared online in Frontiers in Conservation Science. In this review, we visually, quantitatively and narratively synthesize the existing (English) evidence-base on the effectiveness of conditioned taste aversion (CTA) in human-wildlife conflict contexts. By evaluating this literature in the view of learning principles we were able to compose a decision-support table to guide future applications of this technique. Working with all coauthors for the first time, this project has taught me a lot about learning theory and the state-of-the-art application of it in conservation.

Modern wildlife management has dual mandates to reduce human-wildlife conflict (HWC) for burgeoning populations of people while supporting conservation of biodiversity and the ecosystem functions it affords. These opposing goals can sometimes be achieved with non-lethal intervention tools that promote coexistence between people and wildlife.

CTA has been applied to a wide range of animal taxa (57 (sub)species, 26 families and 11 orders)

One such tool is conditioned taste aversion (CTA), the application of an evolutionary relevant learning paradigm in which an animal associates a transitory illness to the taste, odor or other characteristic of a particular food item, resulting in a long-term change in its perception of palatability. Despite extensive support for the power of CTA in laboratory studies, field studies have exhibited mixed results, which erodes manager confidence in using this tool.

Application of CTA in various human-wildlife conflict categories across time

In this paper, we review the literature on CTA in the context of wildlife conservation and management and discuss how success could be increased with more use of learning theory related to CTA, particularly selective association, stimulus salience, stimulus generalization, and extinction of behavior. We apply learning theory to the chronological stages of CTA application in the field and illustrate them by synthesizing and reviewing past applications of CTA in HWC situations. Specifically, we discuss (1) when CTA is suitable, (2) how aversion can be most effectively (and safely) established, (3) how generalization of aversion from treated to untreated food can be stimulated and (4) how extinction of aversion can be avoided.

For each question, we offer specific implementation suggestions and methods for achieving them, which we summarize in a decision-support table that might be used by managers to guide their use of CTA across a range of contexts. Additionally, we highlight promising ideas that may further improve the effectiveness of CTA field applications in the future. With this review, we aspire to demonstrate the diverse past applications of CTA as a non-lethal tool in wildlife management and conservation and facilitate greater application and efficacy in the future.

Snijders, L., Thierij, N. M., Appleby, R., St Clair, C. C., & Tobajas, J. (2021) Conditioned taste aversion as a tool for mitigating human-wildlife conflicts. Frontiers in Conservation Science, 72: 744704


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.

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



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. 


New publication: Supporting ape rights: a comment on the role of science

Autumn 2018, friend and colleague Edwin van Leeuwen asked me an intriguing question: if I was interested in co-authoring a comment on an essay about Nonhuman rights? This was a topic we had talked about before and I find very fascinating, timely and relevant. So of course I said yes.


The central essay and our comment, together with other comments, are part of a special issue on the topic of Great Ape Personhood, published by the ASEBL Journal (Association for the Study of (Ethical Behavior)•(Evolutionary Biology) in Literature; St. Francis College, Brooklyn Heights, N.Y.).  As so nicely explained by the editors (Gregory Tague and Christine Webb) in the introduction of this special issue: with his essay, Professor Thompson tries to bridge the false divide between natural science and humanities. Working from the foundations of philosophy and legal theory [and subsequently discussing important focus points for future research], he tries to reach scientists and their thinking in the battle for great ape personhood.

“Thompson relies on Nonhuman Rights Project attorney Steven Wise, who calls on scientists to awaken the thinking of judges deciding the fate of great apes. Perhaps it’s an unfair analogy, but Thompson attempts to do with primatology what climatologists from several generations tried to do – demonstrate how science is part of and can dramatically affect public policy. Thompson shows how what is empirically rational in science is treated differently in the legal arena, and that difference poses a real problem in the question of granting personhood status and other rights to great apes.”

Several interesting comments were made on the essay, both from philosophers and scientists. Edwin and me commented i.a. by suggesting some alternative ways science could support the quest for Great Ape Rights.

This project was definitely out of my comfort zone. And I see that as a good thing. Thompson’s essay and also the philosophers’ brief, written in support by a group of  philosophers, have given me many new insights about the role of philosophy and science in society. How together, philosophy and science can have some very important things to say about the way we live in this world.

The complete issue can be found here.
And (only) the comment made by Edwin and me, here.

van Leeuwen E.J.C., Snijders L. (2019) A comment on Thompson “Supporting Ape Rights: Finding the Right Fit Between Science and the Law.” ASEBL Journal 14 (1), 46-48.