Social learning within and across predator species reduces attacks on novel aposematic prey.

Liisa Hämäläinen,Marianne Teichmann,Johanna Mappes,Hannah M Rowland,Allert Bijleveld,Rose Thorogood

doi:10.1111/1365-2656.13180

Liisa Hämäläinen, Marianne Teichmann + Show 4 more

Open Access

https://doi.org/10.1111/1365-2656.13180

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Abstract

To make adaptive foraging decisions, predators need to gather information about the profitability of prey. As well as learning from prey encounters, recent studies show that predators can learn about prey defences by observing the negative foraging experiences of conspecifics. However, predator communities are complex. While observing heterospecifics may increase learning opportunities, we know little about how social information use varies across predator species.Social transmission of avoidance among predators also has potential consequences for defended prey. Conspicuous aposematic prey are assumed to be an easy target for naïve predators, but this cost may be reduced if multiple predators learn by observing single predation events. Heterospecific information use by predators might further benefit aposematic prey, but this remains untested.Here we test conspecific and heterospecific information use across a predator community with wild‐caught blue tits (Cyanistes caeruleus) and great tits (Parus major). We used video playback to manipulate social information about novel aposematic prey and then compared birds’ foraging choices in ‘a small‐scale novel world’ that contained novel palatable and aposematic prey items.We expected that blue tits would be less likely to use social information compared to great tits. However, we found that both blue tits and great tits consumed fewer aposematic prey after observing a negative foraging experience of a demonstrator. In fact, this effect was stronger in blue tits compared to great tits. Interestingly, blue tits also learned more efficiently from watching conspecifics, whereas great tits learned similarly regardless of the demonstrator species.Together, our results indicate that social transmission about novel aposematic prey occurs in multiple predator species and across species boundaries. This supports the idea that social interactions among predators can reduce attacks on aposematic prey and therefore influence selection for prey defences.

Highlights

When encountering potential prey, predators face a decision to either attack or avoid them (Sherratt, 2011)
We found that social information affected how both blue tits and great tits responded to the prey during their initial encounter
Experiments comparing ecologically similar predator species that have potential to learn from one another's foraging behaviour are scarce (e.g. Lefebvre, Templeton, Brown, & Koelle, 1997; Mason et al, 1984; May & Reboreda, 2005; Sasvári, 1979). We combine these in one experiment to test the effects of conspecific and heterospecific information on avoidance learning of two predator species

Summary

| INTRODUCTION

Predators face a decision to either attack or avoid them (Sherratt, 2011). In contrast to other tested avian species (Hämäläinen et al, 2019; Johnston et al, 1998; Mason et al, 1984; Mason & Reidinger, 1982; Skelhorn, 2011; Thorogood et al, 2018), hens (Sherwin et al, 2002) and blue tits (Hämäläinen, Rowland, Mappes, & Thorogood, 2017) were not found to use social information about food unpalatability in their foraging decisions These previous studies on social avoidance learning all differ in their experimental designs. Because parid tits have been demonstrated to learn more efficiently from conspecifics (Farine et al, 2015; Sasvári, 1979), we predicted that (c) individuals would rely more on conspecific information compared to heterospecific information and learn to avoid aposematic prey faster after observing conspecifics

| MATERIALS AND METHODS

Findings

| DISCUSSION