Effects of predation pressure on the feeding behaviour of the serpa tetra Hyphessobrycon eques (Ostariophysi, Characidae)

Abstract

The indirect, non-lethal results of predation, such as reduction in feeding time or restraint in seeking sexual partners and/or natural resources, have a drastic effect on prey populations. In this study, we investigated the behaviour of two serpa tetras Hyphessobrycon eques groups, one wild and the other born and raised in captivity, to evaluate how their feeding behaviour is affected by the avian predator, the rufescent tiger-heron Trigrisoma lineatum (using a taxidermy specimen). For a total of 133 observation hours, the feeding behaviour of each fish group was observed according to the absence (control) or presence (treatments) of a predator near the aquarium surface. The results showed that the presence of a predator on the surface inhibits the feeding behaviour of H. eques. The differences observed between the groups are probably due to the fishes' experiences with predators. Our results suggest that fish-eating birds may affect prey populations in streams and ponds perhaps more through non-lethal effects, on feeding behaviour for example, than directly through death rates. © Springer-Verlag and ISPA 2004.