A confusing series of animal tracks in sand near nesting sites of the vulnerable northern New Zealand dotterel recently had local wardens puzzled.
One of the wardens, Lisa Kierny, send photographs to Pest Detective of the mystery tracks found at Simpsons Beach on the Coromandel Peninsula. Tracks in sand can be difficult to identify because footprints can be blurred due to the sand settling and wind smoothing off edges. However, there was enough information in the photos for three different pest animals to be identified.
The first was a good example of the track pattern rabbits leave when moving at speed. That photograph has been added to our collection.
The other two identitifications proved to be more worrying for the dotterel wardens. A possum had crossed the area, leaving its characteristic track pattern (see above) of hand-like forefoot prints with the hind foot print coming in close behind and partly overlapping. Less clear was a mustelid track but it was distinguishable by one reasonably clear footprint - five toe prints, and a straight line could connect the 1st and 4th toe prints across the central paw pad (see diagram). Whether it was a weasel, stoat or ferret could not be determined.
Both possums and mustelids are unwelcome near the nesting sites as they can prey on eggs and chicks.
Lisa says there are nine nesting pairs of dotterel at Simpsons Beach and, although there are plenty of volunteers keeping an eye on them, this year has been very disappointing, with eggs and chicks disappearing one at a time, and none surviving. Quite who the predators are is unkown but, in addition to mustelids and possums, likely suspects include hedgehogs, cats, rats and even birds, such as the spur-winged plover.
Northern NZ dotterel have a Threatened-Nationally Vulnerable conservation status. They mainly breed on sandy beaches, like Simpsons Beach, where they are vulnerable to predation.