Improved tawaki season at Jackson Head
Monitoring of Fiordland crested penguins (tawaki) for the fourth breeding season has come to an end and initial comments are that it was better than the two last disastrous years … but could have been better.
The Trust’s camera data, recording activity at tawaki nest sites in three locations in South Westland is now in hand for the lengthy task of review and analysis, looking for evidence of predators and predation. More on that in early 2018.
Our Tawaki Coalition partner, Dr Thomas Mattern of The Tawaki Project, has also completed his fourth monitoring season with a focus on breeding success. His project extends from Jackson Head south of Haast through the breeding range of these penguins to Harrison Cove in Milford Sound and on to Whenua Hou (Codfish Island).
Breeding range of tawaki and study sites (The Tawaki Project)
Here is his initial report with our notes in square brackets:
Breeding success seems sub-par on the West Coast. We found 13 chicks out of 24 monitored nests. We witnessed quite a number of nests failing while we were still there, so I think we did not miss out on too many chicks. Breeding success is <0.5, which up until recently, was considered the optimum in any crested penguin species. Since Milford Sound (and presumably Whenua Hou) we now know that this does not necessarily apply to tawaki. 9 out of 19 nests at Milford Sound likely raised both their chicks to fledging. [Although crested penguins lay two eggs, it is rare for them to raise both chicks but nearby and plentiful food supply in Harrison Cove has led to this outstanding breeding success.]
Weights of a pair of twins we managed to measure at Harrison cove last week [mid November 2017] were 3.4 and 2.8 kg. The heaviest chick we’ve weighed at Jackson Head on Saturday was 3.25 kg; all JH chicks we weighed were from single chick nests.
But after the El Nino disaster in 2015 [no chicks raised due to starvation] and the stoat catastrophe of 2016 [stoat invasion and loss of virtually all chicks, assumed to be due to nearby beech seed mast event prior to the breeding season] I would still consider this season an improvement for the Jackson Head birds.
The Tawaki Project - Fiordland crested penguin incubating eggs
I also presented the Tawaki Project at the last Fiordland Marine Guardians meeting. Amongst other things I pointed out that set net fisheries in Southern Fiordland are likely to have a negative impact on the birds there which raised an interesting discussion with some of the fishermen. We had a great chat with them afterwards; they all reckon that the Fiords are full of penguins and that this is a development of the past few years. They also said that there is great abundance of ‘feed fish’ and whitebait in the fjords which they attribute to the warmer temperatures that have prevailed in recent years.
So, tawaki may be booming in Fiordland at the moment. But I think we have to dampen our excitement because usually a boom is followed by a bust. We definitely need to keep a close eye on the population developments in the coming years.
So, after two dreadful years for the Jackson Head penguins, things are looking up, and tawaki are doing particularly well in Fiordland.
The Trust will now review this year’s data and compile a report summarising the findings of the four year study and presenting conclusions and conservation management recommendations. More next year.
Images borrowed from The Tawaki Project
