Editor's note: this is an additional summary and commentary on the West Coast blue penguin story that was reported on last week by Wawrick Allen.
West Coast Blue Penguin Trust indicate that there are only a few hundred left on the West Coast of the South Island mainland. But what is making one of the cutest and most beautiful birds of New Zealand decline in abundance? Is the blue penguin another victim of New Zealand’s numerous introduced predator species? Do possums (Trichosurus vulpecula) and stoats (Mustela erminea) account for this huge decline in the last 30 years by feeding on little blue penguin eggs and chicks? Or is the decline due to road kills caused by a bigger exotic species called Homo sapiens that runs them over with their speedy cars?
Apart from these reasons, the blue penguins might also have problems with the difficult tasks of finding a good nesting site, laying one or two eggs, keeping them warm until the chicks hatch, and rearing them until they are prepared for the big, wide world. Before the research described in this blog, not enough was known about the breeding biology of the West Coast's blue penguins to determine whether environmental or biological factors were the most important reasons contributing to the population decline.
Masters student Sol Heber, under the supervision of ornithologist Kerry-Jane Wilson and behavioural ecologist Laura Molles at Lincoln University, examined the breeding biology and breeding success of the West Coast penguin population. This work was published in a 2008 issue of the New Zealand Journal of Zoology.
Even though only 10.7% of chicks were taken by predators, this hazard should also not be taken lightly. Other factors that may affect the West Coast blue penguin population are all human caused problems such as predation by dogs and habitat loss caused by erosion, subdivision and development of housing allotments. Furthermore, drowning in fish nets (by-catch) might constitute a sea mortality factor. More research is urgently needed to quantify adult mortality caused by all these factors, in particular road kill. Hazardous road crossing points regularly used by blue penguins should also be identified and modified.
This blog post was written by postgraduate student Sara Bauer as part of the course, Research Methods in Ecology (Ecol608).