Juvenile lemon sharks forage according to their personalities… Unless many predators are around

Dhellemmes, Felicie; Smukall, Matthew; Guttridge, Tristan; Krause, Jens; Hussey, Nigel

Mangrove fringed shores provide protection against predators for the juvenile lemon sharks (Negaprion brevirostris), but they may not be the best hunting grounds. Sharks with a more explorative personality forage in more dangerous and fruitful offshore habitats, but only when the abundance of predators is low. Photo © Chelle Blais
Mangrove fringed shores provide protection against predators for the juvenile lemon sharks (Negaprion brevirostris), but they may not be the best hunting grounds. Sharks with a more explorative personality forage in more dangerous and fruitful offshore habitats, but only when the abundance of predators is low. Photo © Chelle Blais

The last three decades have seen animal ecologists focus more and more on animal personality. Animal personality describes the fact that individuals within a population differ consistently in their behaviour. For example, some animals of the same species are always more explorative than others, regardless of other traits like sex, age or size. Personality is usually quantified using captive tests, such as the novel-open field test, where individuals explore more or less depending on their personalities.

Concurrently, ecologists have also focused on individual resource specialization, which describes the fact that animals of the same species differ consistently in the type of food they consume.

These two phenomena are undoubtably linked, as behavior mediates food acquisition, and if animals behave differently this may mean that they acquire different food resources. But surprisingly, we know very little about how personality influences resource specialization. This may be due to a methodological divide: personality is quantified mostly in captivity whereas foraging specialization is normally quantified in the wild, often using molecular methods such as stable isotope analysis.

Here we investigated the link between animal personality and foraging specialization in juvenile lemon sharks (Negaprion brevirostris) which have been shown to exhibit foraging specializations, with some individuals foraging in risky sea-grass habitats and others in safe mangrove habitats (quantified using stable isotope analysis). The personality of juvenile lemon sharks has also been studied using short-term captivity tests; some individuals are known to explore more than others (quantified in a novel open-field test).

We investigated the link between foraging and personality in two populations for four consecutive years and concurrently quantified variations in predator abundance and in intra-specific competition, as they are likely to influence the way in which individuals forage. For instance, individuals who take lots of risks while foraging may take fewer risks when there are a lot of predators around.

We found that explorative juvenile lemon sharks foraged offshore, where it is riskier, but only when the abundance of predators is low. When there are a lot of predators, explorative sharks forage close to the shore, where it is safe, and the least explorative sharks are found offshore in risky habitat.

Our results underline the complexity of the link between foraging and personality: You are what you eat… But only in certain contexts!

Read the blog behind the paper here

Read the research in full here

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