Codfish Island surveys 2001-2012
Last surveyed fully in 2001, Codfish Island/Whenua Hou is considered one of the strongholds of the Stewart Island penguin population. It was one of the study sites for the Trust’s 2003-2008 research into factors affecting penguin breeding success. Two of the original surveyors, Dave Houston and Dean Nelson from DOC, and Sandy King from the Trust made up the 2009 survey team, with help from resident Kakapo Rangers Errol and Steve. The survey, completed within a week, found 46 breeding pairs, a drop from 61 breeding pairs in 2001. This may have been a real downwards trend, or just an extreme interannual fluctuation, but recent surveys and monitoring (in which the Trust is working with DOC and the Southern Institute of Technology) have been alarming.
A follow-up visit between 4 and 10 February 2010 checked all nest sites found in November 2009. Fifty-four chicks were caught, weighed and measured, given a health check, and had a microchip inserted just under the skin on the back of their neck. Most of the chicks caught were in good condition; the median weight was 5.15 kg, with weights ranging from 2.3-6.3 kg. Overall breeding success was 58%, with each nest producing an average of 1.15 chicks.
Small changes from year to year may not be too significant, dependent as they are on weather fluctuations and food availability. But, sadly, warning bells are now ringing on Codfish. Numbers fell from 61 nests in 2001 to 46 in 2009 and 39 in 2011. Breeding success has dropped to 49%. This calls for more urgent monitoring to try and isolate the possible reasons.
