Variable Oystercatcher

Maori Name: Torea-pango

Haematopus unicolor

The Variable Oystercatcher or Torea-pango is endemic to New Zealand. It is one of 3 oystercatchers that breed in New Zealand, the others being the Chatham Island Oystercatcher which is also endemic and the (South Island) Pied Oystercatcher which is native but not endemic. 

Its common name derives from its varied plumage, which is either pied or black, or a range of plumages in between. Generally the pied version is seen more in the north of New Zealand whereas the black is seen more in the south. In fact, the black version is the only oystercatcher that can be seen down in Stewart Island. 

The pied version of the Variable Oystercatcher can be very hard to distinguish from the South Island Pied Oystercatcher or SIPO. There are some tricks to spotting them though. For a start, the Variable Oystercatcher is a good deal larger than the SIPO. Another thing is that the line between the black and white can appear quite smudgy in the pied version of the Variable whereas the SIPO plumage has clean lines with sharp contrasts. There is also no white tab in front of the folded wing, which the SIPO has.

The female is the larger of the sexes at 48 centimetres and 725 grams to the males 675 grams and she generally has a longer bill. Otherwise the sexes are very similar.  They are either all black or black on their backs and various amounts of white underneath. Their long bill is a red-orange and rather stout, their eyes are red and they have pink legs.

Like other oystercatchers they call in flight with a loud, shrill 'kleep'. 

Variable Oystercatchers feed on molluscs, worms, crabs, small invertebrates and even small fish.  They use their strong bills to split and twist open the bi-valve molluscs or to hammer a hole in the shell as with oysters, which is what has given them their name.

One of the tasks they spend a lot of time teaching their young is how to do this effectively. 

The Variable Oystercatcher is found on rocky and sandy coasts all around the main islands, and is most abundant at the north and south ends of each island. It is also found on smaller islands off the coast but not on the outlying ones.

Unlike the South Island Pied, the Variable Oystercatcher breeds only on the coasts and is sedentary, meaning it stays around its breeding grounds throughout the year. For this reason during the SIPO breeding season, the Variable will be the only oystercatcher seen on the coasts, except perhaps for juvenile non-breeders. When the SIPO makes its journey to the coasts after breeding, it becomes less easy to tell them apart from the pied form of Variable Oystercatcher. 

Although Variable Oystercatcher numbers were threatened by hunting in early European times and sent into serious decline, numbers have increased dramatically since the hunting of all shorebirds was banned in 1940. The total population has doubled from the 2000 birds that were counted in the early 1970’s. There is still some threat to all beach-breeding shorebirds from recreational vehicles and dogs and efforts are being made to increase awareness and lessen the impact. 

Similar to other oystercatchers this species remain in breeding pairs all year long. The nest will be on the beach and is a shallow scrape in the sand or shingle (or placed on rocky ledges) using little to no nesting material.

The breeding season lasts through spring and summer with eggs being laid between October and February with a peak in December. The 2-5 eggs are typically stone coloured with small brown patches all over. These are incubated by both parents for about 28 days. If the first clutch is lost, they will lay fewer eggs in another batch. After they hatch, the chicks will stay in the nest for 2 days and then venture forth, closely guarded by the parents, who have a few tricks and habits to thwart would-be predators - as does the SIPO.

The chicks fledge at 6-7 weeks old, but they won’t leave the natal territory until about 3 months.   

To Maori, the Torea-pango were highly respected for the time they took digging up and prising open so many bivalve molluscs, and they were often personified as people out digging their gardens.