Mouse predation affects breeding success of burrow-nesting petrels at sub-Antarctic Marion Island

Abstract

AbstractWe report the breeding success of four species of burrow-nesting petrels at sub-Antarctic Marion Island where house miceMus musculusare the sole introduced mammal. Feral catsFelis catuswere present on Marion for four decades from 1949, killing millions of seabirds and greatly reducing petrel populations. Cats were eradicated by 1991, but petrel populations have shown only marginal recoveries. We hypothesize that mice are suppressing their recovery through depredation of petrel eggs and chicks. Breeding success for winter breeders (grey petrelsProcellaria cinerea(34±21%) and great-winged petrelsPterodroma macroptera(52±7%)) were lower than for summer breeders (blue petrelsHalobaena caerulea(61±6%) and white-chinned petrelsProcellaria aequinoctialis(59±6%)) and among winter breeders most chick fatalities were of small chicks up to 14 days old. We assessed the extent of mouse predation by monitoring the inside of 55 burrow chambers with video surveillance cameras (4024 film days from 2012–16) and recorded fatal attacks on grey (3/18 nests filmed, 17%) and great-winged petrel chicks (1/19, 5%). Our results show that burrow-nesting petrels are at risk from mouse predation, providing further motivation for the eradication of mice from Marion Island.