Some small aquatic organisms can be transported by birds. In this study we tested 2 hypotheses related to waterbird-mediated passive dispersal of juvenile red swamp crayfish (Procambarus clarkii) a widespread invader of freshwater ecosystems.

The first is that, depending on water depth, recently hatched crayfish can attach to ducks, initiating passive external transport (i.e., ectozoochory).

The second is that recently hatched crayfish can survive bird flight, being affected by crayfish features, flight distance, and environmental conditions. We performed a set of experiments to test these hypotheses. Results showed that juvenile crayfish were capable of clinging to duck feathers and were transported when ducks were removed from the water. Furthermore, some juveniles of P. clarkii were able to survive long-distance transport when suspended outside a moving vehicle or when transported by birds.

Our results support the occurrence of passive transportation of this invader by means of attachment to birds.