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.
Snijders L, Kurvers R.H.J.M, Krause S., Tump A.N., Ramnarine I.W., Krause J. (2019) Females facilitate male patch discovery in a wild fish population. Journal of Animal Ecology: Online
Snijders L, Kurvers R.H.J.M, Krause S., Ramnarine I.W., Krause J. (2018) Individual- and population-level drivers of consistent foraging success across environments. Nature Ecology & Evolution 2: 1610-1618