Factors affecting the breeding success of the Flea Bay white-flippered penguin (Eudyptula minor albosignata) colony, Banks Peninsula, New Zealand: A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science (Honours) at Lincoln University

Abstract

The blue penguin (Eudyptula minor) is in decline throughout much of its range in New Zealand and Australia, largely due to introduced predators, human disturbance and roadkill. The white-flippered penguin (Eudyptula minor albosignata) is a unique morphological variation of the blue penguin only found on Banks Peninsula and Motunau Island. While its population at Flea Bay is not in decline, investigating factors affecting the breeding success of this colony is important for the global conservation of this species. A varying number of nesting boxes were monitored over a thirteen year period. General linear mixed models (GLMM) were used to examine the effects of various explanatory variables (climate, predators, fisheries, habitat and others) on hatching, fledging and breeding success. Hatching success over the thirteen years of monitoring was 74.5%, fledging success was 85.4% and the overall breeding success of the colony was 63.3%. All of these parameters compare favorably with data from other colonies in New Zealand and Australia, indicating that the breeding success of the Flea Bay population is unlikely to be limiting colony growth. This is supported by the census conducted in 2008 which shows a 48% increase in active nest numbers since the 2000 census. No variables were found to significantly affect hatching or fledging success in the GLMM. Only nesting box average pair bond length, guard period length, lay date and hatching date were found to be significantly affecting the breeding success of the colony. Breeding success decreased with longer nesting box average pair bond lengths, possibly indicating variation in nesting box quality. Breeding success increased with longer guard periods due to greater parental investment in the offspring. Later lay dates resulted in increased breeding success, possibly because adults who foraged longer would tend to have better body condition, resulting in them being able to care better for their eggs and chicks. Future monitoring should include banding of all individual birds (or some other way of identifying individuals), monitoring of natural burrows for comparison to nesting boxes and measuring adult body condition at various times throughout the breeding cycle. This would enable more inferences to be made regarding factors affecting the success of breeding pairs and individual birds.