Unitec / NNZST
Dr. Nigel Adams
Work on gannets to date has focused on describing the food chain upon which birds utilizing the waters of inner and outer Hauraki Gulf depend. Field work has been conducted at gannet colonies at Horuhoru Rock just off the northeast corner of Waiheke Island and Mahuki Island off the north west coast of Great Barrier Island.
The project relies on identifying prey recovered from crop regurgitations of adult gannets returning to breeding colonies after foraging and collection of feacal samples. Frequently prey is recovered intact and the stomachs of fish and squid prey can also be dissected out. Identification of prey taxa in feacal samples and prey stomachs has used new molecular approaches that allow taxa to be identified from fragments of prey DNA in these samples.
A pilot study using GPS trackers suggests that gannets from the two colonies forage largely in mutually exclusive areas consistent with our observation of differences in diets between colonies. The next steps involve further GPS tracking to investigate these differences in more detail.