Damselfish behaviour is influenced by rats

Loss of seabirds through rat predation affects reef fish hostility and could have wider impacts

- Kenny Taylor 

GLOBALLY, INVASIVE RATS ARE ONE OF the major problems affecting seabirds breeding on islands. When rats jump ship and colonise, their predation of eggs and chicks can lead to massive slumps in seabird numbers. In turn, this makes the rain of seabird poo washing out to surrounding waters shrink from a torrent to a trickle. Surprisingly, for jewel damselfish living on coral reefs there, that affects their habits - including how they react to other fish.

Jewel damselfish are aggressively territorial and will attack intruders - even much larger fish - that stray into territories they hold over small patches of reef.