Archives For seabirds

The recent hatching of a Chatham petrel chick in the Sweetwater Conservation Covenant on Chatham Island is another significant step in the long road to recovery for one of the world’s rarest seabirds.

In decline

Probably once abundant throughout the Chatham Islands, human exploitation, habitat destruction and introduced predators saw the species restricted to Rangatira Island by the time of its discovery in 1892. 

Chatham petrel chick

A Chatham petrel chick tucked up in its down duvet

Until 1961 farming activity on Rangatira resulted in the petrels being confined to small forest patches, where they competed for burrows with the similarly sized broad-billed prion. Nesting at different times of the year, many petrel chicks were ousted from their burrows by returning prions. By 1990 the Chatham petrel population was estimated to be around 1,000 birds and heavily outnumbered by some 600,000 broad-billed prions.

Detering prions

Studies found that while adult Chatham petrel survival was high, less than 50% of pairs were managing to fledge a chick, placing the population in peril. So, finding a way to deter prions from entering Chatham petrel burrows was a priority.

Broad-billed prion.

The competition: a broad-billed prion outside its burrow

Natural burrows converted into ‘state houses’

Natural burrows were converted into wooden ‘state houses’ with plastic pipe entrances, to aid inspection of the contents, and efforts were made to dissuade prions from using them by removing any found within and relocating some distance away. This required frequent nightly inspections of the petrel burrows and numerous DOC staff and volunteers will have memories of the nightly burrow rounds, clumping around the forest with ungainly petrel-boards attached to their footwear to avoid crushing the numerous seabird burrows. It was futile.

Wetsuits work

Lincoln University researchers finally came up with a simple solution – stretching a piece of neoprene wetsuit material over the entrance of the burrow pipe and cutting a slot just large enough for a petrel to squeeze through. It has proved remarkably effective, the petrel ‘homeowner’ tolerates the inconvenience of a tight squeeze, but prospecting prions are deterred by it. This, along with barricades erected while the petrels are away over the winter has increased nest success to around 90%.

Chatham petrel burrow and flap.

A Chatham petrel squeezing through the anti-prion flap into its burrow

New colonies

The relative abundance of Chatham petrel chicks has since allowed for the next phase of recovery, the creation of new colonies on Pitt and Chatham Islands.

200 chicks were translocated to new homes in the predator-proof Elizabeth Ellen Preece Conservation Covenant (aka Caravan Bush) on Pitt Island between 2002 and 2005. Hand-fed until ready to fledge, the chicks remembered Caravan Bush as their new home and some returned after two or three years at sea with the first pair breeding in 2005.

Rangatira and Pitt Islands

Rangatira Island (left) and Caravan Bush (right) on Pitt Island

Return of Chatham petrel to “Sweetwater”

Once the success of the Pitt Island translocation was evident work started on the return of Chatham petrel to “Sweetwater” on Chatham Island in 2008.

Chatham petrel.

Ranger Antje Leseberg checking the band on an adult Chatham petrel

In partnership with the Chatham Island Taiko Trust another 200 Chatham petrel chicks were moved over 4 years to nest boxes within a 4ha predator-proof enclosure built by the Trust. As at Caravan Bush, petrel sounds played over loudspeakers encouraged returning petrels to land at the site.

The first indication of success at Sweetwater was seen last autumn when a pair of petrels were seen in a burrow. After wintering off the South American coast, the pair have returned to Sweetwater and laid an egg in February.

Taiko Trust members were delighted to find a chick present during burrow checks in early March. All going well this chick should fledge in May and spend 2-3 years at sea before returning to Sweetwater. By then it should have more company, as four more burrows show signs of activity, surely signalling the sweet smell of success.

By Lyndon Perriman, head ranger at Taiaroa Head Nature Reserve

Taiaroa Head/Pukekura, at the end of the Otago Peninsula, is home to an impressive number and diversity of seabirds. With nearly 10,000 birds, the area has significant populations of gulls, shags, penguins and shearwaters, but is most well known for the iconic albatross. 

Toroa, Taiaroa Head’s 500th chick (hatched 2007) with his dad

Weighing 6-8 kg and with a 3 metre wingspan, the northern royal albatross are one of the largest of the albatross species. The small population at Taiaroa Head is significant as it is the only mainland breeding colony for any albatross species in the southern hemisphere. 

Studying foraging strategies

For the northern royal albatross, the beginning of autumn is the start of a phase we call ‘post guard’, where both parents forage at sea for food, leaving the chick alone for several days between meals.

There are many questions about foraging adults that we would like to know the answer to: Are longer trips at sea more productive for the adults? Do foraging areas used by males differ from females? Do the foraging areas change throughout the season?

Ranger Lyndon Perriman monitoring an albatross nest

Junichi Sugishita, a PhD student with the University of Otago, is studying the foraging strategies of the breeding adults at Taiaroa Head and, for the first time, adult birds are being tracked during the post guard stage. The research involves a number of devices situated on land at Taiaroa Head, and also attached to birds.

GPS and radio transmitters

The rangers have a good working relationship with (most) of the albatross at Taiaroa Head, so we were able to attach GPS and radio transmitters to the back feathers of the adult birds without the need for restraint. The combined weight of these two units attached to the feathers is less than 0.6% of the adult’s normal body weight.

Albatross carrying a GPS unit

Weight platforms

Weight platforms were also installed at selected nests. These platforms consist of electronic scales connected to a data logger situated under a plywood base. We had hoped to monitor changes in the weights of adults throughout the breeding season but the albatross had other ideas.

During installation of the scales the birds on the nests showed absolutely no interest, with some adults even choosing to sleep throughout the installation process. However, when they returned from sea to change nest duty with their partner they reckoned there was something decidedly fishy about the platforms. They avoided standing on the scales by choosing an alternative access to their nest.

Skylark on the albatross weighing platform

We then thought we could dupe them by painting the plywood so that it blended in with the surroundings. However, they still weren’t convinced and continued to choose an alternative route into and out of the nest which avoided crossing the scales.

Next we tried coercion by erecting a plastic mesh fence around the nest, so that the best option for access would involve walking over the scales. However, the albatross decided they would rather climb over the fence than cross those scary looking scales.

We finally realised that the albatross would continue to outsmart us. We removed the fences and let them be. It was a gentle reminder to us that what we perceived as non invasive wasn’t considered so by the albatross!

Slow breeders

The royal albatross is a slow breeder, with only one chick raised every two years.

Breeding takes a full year — from mating in October, to incubation of the egg from November to January, followed by nine months of feeding until the chick fledges in September.

Chicks that fledge successfully won’t be seen on the headland again for another five years, when they return to find a mate — and they can be quite picky, taking 2–3 seasons to make a choice. They finally start to breed at around eight years old.  

It is this naturally slow breeding biology, coupled with complexities of life on a mainland site, that has restricted the population growth at Taiaroa Head which by 2011 was around 160 individuals.  

Albatross have a long memory

Over-handling and restraining of albatross can affect their behaviour and trust of people. As conservation managers we need to weigh up handling, research and manipulation against the negative effects on the bird and their breeding success. This is particularly important at Taiaroa Head as a huge part of management involves manipulation of eggs and chicks at the nest to achieve a high success rate. The success rates are due, in part, to having adult birds tolerant of staff while they inspect their egg or chick. 

Flies threaten newly hatched chicks

One of the greatest threats to newly hatched chicks is fly strike. Flies can lay maggots directly onto the hatching egg. Of the 21 chicks hatched in the 2011/12 season, only one died and this was from fly strike.  Our best protection against flies during this vulnerable time is to move the hatching eggs into an incubator during the day, returning them to the nest at night.  

Hatching eggs in the incubator

Like most years, the hatching/guard stage this season hasn’t been without issue. Three chicks lost significant weight. This indicated a microbial infection in the gut, which a course of antibiotics fixed.  All three chicks are now several weeks old and growing rapidly. 

One of this season’s sick chick’s in a brooder

Find out more

Learn more about albatrosses

Watch a video about Taiaroa Head albatross colony

Read about Tairoa Head’s 500th royal albatross chick