Photo, Les Feasey.
Tiny divers making remarkable journeys south
‘Flies like a Buzzy Bee’, ‘flying penguin’, ‘aerodynamically challenged’, ‘skipping stone’ – these are phrases that come to mind when thinking about this compact little seabird on short stubby wings. But the common diving petrel – one would fit in the palm of your hand – are packed with surprises. They breed on most islands in the outer Hauraki Gulf and are extremely numerous on some islands, especially the Mokohinau Islands, the Mercuries and the northwest Chickens. It might surprise those familiar with Tiritiri Matangi Island, famous for its very special birds, that the common diving petrel, which breeds in small burrows and only comes ashore at night, is likely the island’s most numerous bird.
Diving petrels eat small pelagic crustaceans, especially the krill Nyctiphanes australis, abundant in northern waters, and copepods. They spend most of their time underwater at sea chasing their prey. While out boating, you will glimpse them zipping about, flying low and straight with rapidly beating wings. Or, you will see them on the water looking like small penguins sitting low in the water. When approached, they will either disappear underwater or burst out running across the water before taking to the air, then back into the water with a plop to disappear again. I have seen birds bouncing like skipping stones before disappearing.
During breeding, diving petrels feed locally, spending the day at sea before heading back to land at night. It is quite common to find two birds in a burrow, or one bird outside. They have an infectious purring call (the sort that raises a smile) and appear to be very social birds. Not only between pairs but right across a colony, especially as dawn approaches. Then, their murmurings increase both in volume and frequency as if hundreds of birds are enjoying a debate about where they will be going during the coming day!
Like all petrels, they lay one egg and parent birds will share both incubation and chick-rearing, which takes about three months. On some islands, they breed in dense colonies in shallow burrows, under iceplant, grass and low shrubs. The final ‘surprise’ is that when they finish breeding here in northern New Zealand through December, these little guys make the most of the southern summer and head south and east big time. A recent tracking study showed that birds from Burgess Island in the Mokohinau Group, embark on a 3000km journey down to the South Polar Front (that’s two thirds of the way to Chile). While it is easy to imagine the great albatrosses and large petrels flying effortlessly across the Southern Ocean in all sorts of weather, it is not so easy for these little birds, their wings a blur, bellies barely skimming the sea’s surface. What was remarkable about our tracking study is that one of these birds covered the 3000km in three days. It looks like they time their moult while down there and become effectively flightless – not such a problem for these tiny ‘flying penguins’ feeding in the krill-rich southern waters. Late March and through April they start arriving back in the Hauraki Gulf. Welcome home, remarkable