Bumper year for Westland petrels!

Westland petrel chick during banding Nov 2017Westland petrel chicks are fledging now and the annual chick check found high survival rates … and chunky chicks.

The Trust is working with Museum of New Zealand Te Papa Tongarewa seabird specialist, Dr Susan Waugh, and our former Ranger, Reuben Lane, was out with Sue last month to help survey this season’s petrel chicks.  (Thumbnail photo – Westland petrel chick showing down not quite fully replaced by feathers during the survey in November.)

Here’s Sue’s report:

With help from Reuben, the petrel chicks were measured, weighed and counted. It was a bumper year for the birds, with an estimated 82% breeding success, and highest ever average chick weight (at 1689g, for 27 birds weighed). 

Previously they had weighed in at 1450 – 1550g. The chicks were still quite “under-done” this year; in 2014 on the same date, they were all fully feathered, whereas this year many chicks were still 50% or fewer feathered. So this ‘massive’ size may be due to the chicks being nearer their asymptotic weight [petrel chicks reach a maximum weight greater than their parents and them slim down to fledging weight], than their fledging weight. We have measured/banded the chicks in the same few days of mid November each year, so this might suggest a later season for the birds, but in any case a better breeding output with high chick survival. 

Westland petrels productivity measures for chicks 2017 season

Westland petrels productivity (nesting success) measures for chicks 2017 season (with thanks to Dr Susan Waugh)

One of the biggest hazards to seabirds like the Westland petrel is created by our lights – street lamps, car lights, factory and other building lights etc. In foggy conditions, they can be disoriented and head to the lights, often coming down on roads as a result.  Fortunately this spring has not been too foggy but chicks will continue to be fledging until mid January so there remains a risk that they could be confused by lights.

Tragically, a number of these magnificent large black birds have become road death statistics and we’re appealing to road users on the coast to be aware that petrels could be on the roads – very hard to see at night.  If it is safe to do so, park off the road with hazard lights on, put on a high vis vest (good idea to have one in your glove compartment for changing tyres or helping birds etc), and encourage the bird to get off the road – then report it to DOC.  Also, if the bird is injured, you could either call the DOC Hotline (0800 DOCHot (362 468)) so that a DOC ranger or Trust volunteer can collect it.  

The international threat status of these birds has recently been lifted to Nationally Endangered.  They are vulnerable to a variety of human and natural threats, compounded by the fact that they breed only in a small area of the West Coast near Punakaiki. 

Westland petrel (borrowd from nzbirdsonline, photographer: Patrick Shortley)

Westland petrel (borrowed from nzbirdsonline, photographer: Patrick Shortley)