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)
When it comes to finding patchy and sporadic food resources, being at the right place at the right time is of the essence. Our recent paper published in the Journal of Animal Ecology provides experimental field evidence that male guppies (Poecilia reticulata), in the presence of females, more often reach sporadically available food patches. In contrast, female guppies did not reach more (or less) food patches in the presence of males.
“Imagine you are in a new city and looking for a place to have a good meal, what do you do? You can walk around and see what restaurants you encounter, but chances are that this will take a lot of time and you might still end up at a mediocre place. Alternatively, you can see where others are going. When you have incomplete information about your environment, taking advantage of the information of others (i.e. social information) can be incredibly helpful.”
Many animals find themselves in situations of incomplete information about where to find resources, for example, because important resources are patchy and sporadically distributed. One such animal is the Trinidadian guppy.
Trinidadian guppies live in rainforest streams. Those guppies that live in the resource-poor sections of the streams can take advantage of high-quality food resources, such as fruits and insects that fall sporadically into the water. But such resources are difficult to find. Interestingly, a previous study we discovered that guppies that spent more time near others were more successful in locating these unpredictable food resources. Possibly, spending time with conspecifics results in greater exposure to social information about when and where to find important resources.
But in this study, we also found that males reached more food patches than females, particularly males that were in groups with proportionally more females. The presence of females may have increased the time male guppies spent socially and consequently affected how many novel food patches they reached.
To experimentally test if sex composition indeed influences social time and food discovery, we conducted a new study in which we manipulated the guppy sex compositions (all male, all female or mixed) in the wild. For a total of 18 experimental guppy groups, we performed social observations and foraging trials.
First, we tested whether sex composition affected food patch discovery in individual males and females. This was true for males, which reached more food patches when there were females present. Females reached a similar number of patches either with or without males present. Second, we tested whether sex composition affected the time an individual male or female spent socially. The variation in time spent socially mirrored variation in patch discovery, with males spending less time socially in the absence of females, but no effects again for females. Third, we analysed if this time spent socially was linked to patch discovery success. Indeed, in agreement with our previous study, more social guppies reached more food patches.
Conclusion: The foraging success of an individual thus depended on a combination of its own sex and the sex composition of its social environment.
Take home message: When hungry—and male—spending time in the company of females can get you at just the right place at the right time.
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.
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.
Reference 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.
After my good experience with the first preprint publication, I recently uploaded my second preprint on the BioRxiv server. I am really excited to share these cool new findings, especially since this study almost did not happen.
Fieldwork is always full of surprises, including flash floods (2018) and cars being stolen (2016). The year of this study (2017), we got stuck on Curacao because our airline was grounded (due to airplane safety concerns, we found out later). Curacao is a great island to spend some time, but it just lacked our favourite little fish: guppies. Luckily, we were able to get new flights and make it to Trinidad a couple of days later.
I love working with guppies, because they allow us to answer some very interesting questions about social living. Guppies live in rainforest streams and in the dry season they often end up in separate pools. These little fish thus naturally experience a variety of physical environments (pools) and social environments (the other fish in the pool). We take advantage of this natural system by trans-locating individual fish to different pools with different social compositions. Most animals would try to go back to their original environment, but for guppies experiencing new physical and social surroundings is just part of their ecology. That we can experimentally control their (social) environment is important, because it allows us to go beyond correlation and ask questions about causality, e.g. how does social composition influence individual foraging success?
To answer this question, we introduced individually marked wild guppies in single sex (male or female) or 50:50 sex compositions, to different pools and studied individuals’ social behavior and their ability to locate novel (experimentally introduced) food patches.
Male guppies found fewer novel food patches in the absence of female guppies, while female patch discovery did not differ between single-sex or mixed compositions. We argue that these results were driven by sex-dependent mechanisms of social association: males reduced sociality when females were absent, while less social individuals found fewer patches. Females were, however, similarly social with or without males. Finally, males, but not females, preferred to join females over males at food patches.
Our study’s take-home message: for a more thorough understanding of social evolution, it is important to consider how individual (e.g. sex) and (sub)population-level traits (e.g. sex composition) interact in shaping the adaptive value of social living in the wild.
Maybe also: don’t fly with Insel Air.
Reference Snijders L, Kurvers R.H.J.M, Krause S., Tump A.N., Ramnarine I.W., Krause J. (2018) Females facilitate male patch discovery in a wild fish population. BioRxiv.