Takapourewa titiwainui (fairy prion; Pachyptila turtur). How nest site selection affects breeding success, with applications for translocation.
Craig, Emma Diane
Translocation of seabirds is used as a component of habitat restoration. This is often a complicated and expensive process, so maximising the likelihood that the translocation will succeed is important. Takapourewa is an island with vegetation at various stages of re-generation, and a large population of titiwainui (fairy prion; Pachyptila turtur). The titiwainui population on Takapourewa was studied to find how nest site selection (vegetation, aspect, burrow characteristics, and tuatara Sphenodon punctatus density) affected breeding success (burrow occupancy rates, chicks hatched, chicks fledged, chick fledge weight), and how soon titiwainui began nesting in an area after grazing was ceased or habitat restoration began. In order to test the hypotheses a new method of monitoring seabird burrows was designed and trialled; burrow utilisation monitoring boards (BUM boards). This method was compared with using study sticks. BUM boards were found to be a very promising, innovative method that yielded rigorous data quickly and easily. One hundred burrows were studied intensively to find out how nest site selection affected breeding success. There was a general trend of northerly-aspect and forest-covered sites having greater occupancy and more successful breeding conditions than southerly-aspect and pasture-covered sites. Burrow characteristics (complexity, temperature and length) did not appear to be critical factors for burrow occupancy or breeding success of titiwainui on Takapourewa. The density and feeding behaviour of tuatara is likely to have a greater effect on the breeding success of titiwainui on Takapourewa than vegetation, aspect or burrow characteristics. Belt transect surveys were undertaken at each of the accessible re-vegetated or retired pasture sites. It was found that titiwainui were more likely to re-occupy sites that had been without stock grazing for longer, irrespective of vegetation type. This knowledge is useful for restoration projects as reintroducing titiwainui does not necessitate expensive and time-consuming revegetation programmes, but there is no observed detriment to the establishment of titiwainui burrows by replanting sites. There are an estimated 1.83 million breeding pairs of titiwainui on Takapourewa.
Advisor: Seddon, Philip
Degree Name: Master of Science
Degree Discipline: Zoology
Publisher: University of Otago
Keywords: titiwainui; Takapourewa; nest site selection; translocation; breeding success; seabird biology; island restoration; re-vegetation; burrow monitoring; Pachyptila turtur; fairy prion; Stephens Island
Research Type: Thesis