RENA penguins have reduced breeding success

Little blue penguin chicks Master of Conservation Biology  student Karin Sievwright has been observing  the survival and breeding success of little blue penguins (Eudyptula minor) affected by the C/V Rena oil spill in the Bay of Plenty two years ago.  All 365 rehabilitated penguins, as well as 350 un-oiled (control) penguins were microchipped to allow for identification of individual birds in the wild. 

The penguins are being monitored at their burrows on Mount Maunganui, Leisure Island and Rabbit Island in Tauranga. Whilst rehabilitated penguins have shown similar survival rates as control penguins, there was evidence of reduced breeding success in the 2012-13 breeding season. Rehabilitated pairs -those with at least one rehabilitated penguin - were capable of producing the normal two-egg clutch. However, statistical analysis revealed hatching success was reduced when compared to control pairs. This indicates that the effects of oiling may have persisted and compromised the ability of rehabilitated penguins to successfully fertilise or incubate their eggs. Fledging success (hatched chicks survival to fledging) rates were similar between control and rehabilitated pairs.

A second season of monitoring is currently underway. A number of control and rehabilitated pairs lost their first clutch of eggs due to predation, abandonment or failure to hatch. However, the majority of these pairs successfully re-laid and have managed to produce chicks. Further data analyses will indicate whether or not the reduced productivity observed in the first post-spill breeding season has persisted into the second season.