Changes in the activity budget of the fiddler crab Leptuca uruguayensis throughout the reproductive period in temperate estuaries.

Animal reproductive success implies the performance of several behaviours, such as courting, mate searching, copulation, offspring production and care. These behaviours usually have high energetic and ecological costs. Therefore, to maximise their reproductive success, animals should make choices throughout their lives, such as deciding how much energy to invest in different activities, according to their conditions and needs. In temperate estuaries, the fiddler crab L. uruguayensis has a short reproductive period, with two synchronous spawning events. Considering that reproductive behaviours incur high energetic cost to fiddler crabs, we estimated how this species manages its activity budget throughout the reproductive period, to quantify trade-offs between the time spent on reproductive behaviours versus time spent on other activities. By analysing videos of females and males recorded in the field at different moments of the reproductive period, we observed that pre-copulatory behaviours, such as female wandering and male waving were more intense at the beginning of the reproductive period, suggesting that most matings occurred before the first spawning event but not before the second one. The ecological conditions during the breeding season and the individual strategies adopted by males and females mostly determine when and how much time to spend on courtship behaviours, and behavioural plasticity can be expected whenever the conditions change. The strategy used by L. uruguayensis for energy management, females' ability to store male gametes and environmental temperatures might have been the main factors determining the relative time spent in courtship behaviours during the reproductive period.