PREDATION AND COMPETITION WITHIN AN ASSEMBLAGE OF LARVAL NEWTS (TRITURUS)

The impact of crested newts (Triturus cristatus) on the smaller-bodied palmate and smooth newts (T. helveticus and T. vulgaris) was studied during the larval stages using a combination of field and laboratory e xperiments. In pond enclosures T. cristatus larvae had no effect on th e two smaller species over the first four weeks of development. By eig ht weeks, however, T. cristatus had achieved a size advantage which en abled it to eliminate T. helveticus and severely reduce T. vulgaris by predation. In laboratory trials under food-limited conditions, T. hel veticus and T. vulgaris were slightly smaller when raised with T. cris tatus, suggesting that this predatory effect was complemented by inter specific competition during early development. Predation of the smalle r species started when T. cristatus reached a threshold size of c. 27 mm. No reciprocal effects on T cristatus growth or survival were obser ved. Although T. cristatus may be a significant predator of congeneric species in natural ponds, other factors, such as differences in micro habitat selection, higher-order predator-prey interactions, and the oc casional desiccation of pond habitats may facilitate coexistence betwe en the species.