Monday, 31 December 2018

Photographing the Australasian Gannets at Muriwai, near Auckland, New Zealand




Introduction
A number of years ago while staying with my grandparents in Hastings in Hawkes Bay, New Zealand I would walk out along the beach to view the gannets at Cape Kidnappers. It was a long walk and the beach was only accessible at low to mid-tide. I was fascinated by this bird with its ability to crash-dive into the water after fish and its aptitude to show all sorts of displays to the nesting partner. It is a bird of action and character....a great subject for nature photography.
I was in Auckland visiting my brother in late November 2018 so I decided to go to the colony at Muriwai, about 45 minutes drive away to get photographs of this beautiful seabird. I was there during a week day and at times had the place to myself although later in the morning there were busloads of tourists arriving who were more after selfies than having an inherent interest in the gannets.


The shoot
I drove to Muriwai on 27th November when the colony would be at its peak breeding time. I arrived at  around 7.15am. There is an adjacent carpark that is reported to be open only at that time. I parked the car and walked about 500 metres to the site. There are two viewing platforms, an upper one and a lower one. They are really well placed. From the upper platform excellent flight shots can be obtained. I had a 28-300 zoom lens on my Canon EOS 1DX for most of the time. You have to be competent at tracking the incoming birds and a rapid-fire mode on the camera is ideal.  I was in my element and in about 4 hours I shot over 3000 images.  As Muriwai is on the west coast the sun rising in the east is directly behind you, which is ideal. The opposite occurs at Cape Kidnappers and for most of the morning you are looking into the sun. I also had subdued sunlight which is more desirable that harsh sun as the mainly white gannets can get very contrasty in photographs. I was getting exposures at f8 from 1/3200th to 1/8000th of a second. All my shooting at this point was done hand-held. Later a blue-sky opened up, which was ideal as a background colour. I shot for about 4 hours before exhausting my arms and cards.
Later I moved to the lower viewing platform which opened up the opportunity to isolate some of the birds and record their behaviour. For this I used a Tamron 150-600mm f5-f6.3 lens, which is also ideal for handholding, although I also used it on a Manfrotto tripod for the close-up shots.
The behaviour to watch out for is detailed below.

The Australasian Gannet
The Australian Gannet (Morus serrator) is Also known as the Australian Gannet or the Maori name, Takapu is a large seabird of the booby and gannet family Sulidae. There are three world species that also include the Cape Gannet and the Northern Gannet.




Appearance
The adults are mostly white, with black flight feathers at the wingtip and lining the trailing edge of the wing. The central tail feathers are also black, the head is yellow, with a pale blue-grey bill edged in black, and blue-rimmed eyes. The eyes have a light grey iris surrounded by a pale blue eye ring, and bare black skin on the face which merges into the bill in adults, the bill is pearly grey with dark grey or black edges, and a black groove running down the length of the upper mandible. The four-toed feet are dark grey and joined by a membrane of similar colour. There are light green lines running along the ridges of the toes that continue along up the front of the legs. Young birds have a mottled plumage, with a dark bill. The birds gradually acquire more white in subsequent seasons until they reach maturity in five years.



Colonies and Nesting
Nesting takes place in colonies along the coastlines of New Zealand, Victoria and Tasmania......mostly on offshore islands. Both countries have some mainland colonies. The main colonies in offshore islands around New Zealand include; Three Kings Island, White Island and Gannet Island. There is a large colony on the mainland at Cape Kidnappers as well as smaller colonies at Muriwai and Farewell Spit. Almost 90 % of the species breeds around New Zealand. They are plunge divers and spectacular fishers rocketing into the ocean at high speed. They eat mainly surface-swimming fish and with few natural enemies the population appears to be growing. When a group of birds are diving after fish together the gannets risk fatal collisions.


The Australasian Gannet is usually silent at sea and loud and vocal in the colony in the day and sometimes overnight. The call is a harsh arrah-arrah which is emitted upon approaching or arriving at the colony or as a threat. The call can be heard here

Colony location is related to sea temperature, which in turn dictates the presence of fish. Cape Kidnappers in Hawkes Bay is thought to have been settled in 1850, with 100 pairs in 1885. 5,186 pairs were reported in 1981. Muriwai near Auckland, comprises a mainland colony on Okatamiro Point, estimated at 1,385 pairs in 2016, while nearby Motutara (Pillar Rock) has 187 pairs.








Male Gannets arrive in New Zealand colony sites in July/August each year to prepare the nests. The colony will disband in May and June the following year with the youngsters dispersing to the north and west. They will reach southeastern Queensland to Rottnest Island off Western Australia. Some immature gannets will spend 3 to 4 years in Australian waters before returning to New Zealand. Some will remain in New Zealand waters.

Gannet pairs will remain together over several seasons, until one member dies....although divorce has been recorded. The site at Muriwai is indicative of how they nest on  flat or gently sloping ground, on stacks or cliff-tops, 15 to 90 metres above seas level.  The nests are cup-shaped mounds 10-20cm high, made from seaweed, plants, earth and debris from the sea. Males usually collect the material and pass it to the female to construct the nest. 




One chalky-coated egg is laid and is incubated mainly by the female keeping the egg warm on top of her feet. Incubation lasts for 37-50 days. If the egg is lost early, it will be replaced but there is only one brood per year. Newly-hatched chicks are featherless and have black skin. They are covered by a white down in 2-3 weeks and the first proper feathers appear between day 43 and 47. The chick will be half-covered by feathers by 9 weeks. Young chicks are fed regurgitated, semi-digested fish by their parents, who open their mouths wide for the chick to access the back of their throats. The young birds fledge 95-109 days after hatching, before heading to a clifftop and remaining there for between 6 hours and three days before flying. The longest recording travelling distance was 8,128 km.
The gannets begin breeding between four and seven years of age and are thought to have a lifespan of at least 20-30 years. 

The Muriwai colony was very mixed in terms of the stage of the breeding cycle. Some of the chicks were approaching adult size while incubation of the solitary egg was occurring in adjacent nests. Mating and nest-building was also underway elsewhere. There was also several colonies of White-fronted terns nesting on the periphery of the gannet nesting site. On several occasions a gannet strayed into the terns' territory and it was harassed. There were also several Black-backed gulls in attendance looking for something to pillage. On the edge of the colony gannets were pulling vegetation to use as potential nesting material.









Displaying
The Australasian gannet is highly territorial when nesting, engaging in antagonistic displays to mark their ground against neighbours and interlopers. 


In the bowing display, the male’s head and beak points down, and its wings are held up away from the body and folded backwards. He moves his head from side to side before bowing forward. The male may escalate the fight by lunging at an interloper with a closed or open bill or proceed to locking bills and wrestling for an extended period. Fights can be fatal. A bird may engage in an appeasement display to calm an attacker by lowering its head and tucking its bill into its chest.


Mating pairs engage in a fencing display when the male arrives back at the nest. The two birds stand breast to breast with wings spread and bills extended vertically. They fence and scissor with their bills rapidly, calling loudly at the same time.





 The birds usually follow this display by allopreening. Mated pairs will engage in sky-pointing, where a bird paces slowly with its neck and bill vertical and its wings partly raised. Copulation takes place after allopreening, the female shaking her head vigorously and the male biting her neck and climbing on her back and waving his wings before joining their cloacae. Afterwards the female preens the male who slides of his partner and reciprocates preening.






Diving
Although I have seen them dive in the past the gannets were not fishing near to the colony when I was present. 

This species has some anatomical features that enable it to hit the water at 85-100km/hour. They are;
1. the missile-like shape they adopt
2. They don’t have conventional nostrils but slits covered with tissue.
3. They have strategically located internal airbags that are extensions of their lungs.
4. They are able to adapt their sight in a split second from dry vision to that required         underwater.
5. Their elegant necks are long and appear vulnerable to impact but they is hunched up and braced for impact.

Such modifications are calculated to allow even greater speeds of entry.

All the photographs below which show diving attitudes are from library images.

A BBC/Attenborough film can be seen here.

and one from National Geographic here.






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