Does behaviour contribute to the previously documented invasive success of topmouth gudgeon?

Recent studies have incorporated behavioural aspects into the analysis of animal invasion processes, citing high activity and boldness as typical traits of successful invaders. The topmouth gudgeon Pseudorasbora parva is arguably the world's most widespread freshwater fish invader currently listed as a pest species on the list of invasive alien species of Union concern. The study aimed at elucidating whether behavioural traits of P. parva contribute to its invasive success. Laboratory experiments contrasting P. parva activity levels, habitat choice and boldness with that of native competitors Eurasian perch Perca fluviatilus and three-spined stickleback Gasterosteus aculeatus showed P. parva to be relatively shy and avoiding direct competition for prey. An additional field study in a pond in central Germany demonstrated that P. parva was able to establish and maintain a small population, co-existing with a much higher density of P. fluviatilis. The study suggests that the invasive success of P. parva may be a result of its flexible life-history traits, while behavioural traits such as boldness and competitive dominance for food may only play a minor role.