Archives For Chatham Islands

By Juzah Zammit-Ross

A long history of restoration

Mangere Island in the Chatham’s provides an important predator-free refuge to many rare and endemic invertebrates, birds and plants. Restoration first started on the island in the 1970’s with the Wildlife Service planting akeake shelterbelts in Douglas Basin and on the Top Plateau in an effort to expand the habitat available to black robins. Since the early 1990’s tens of thousands of akeake have been planted on the island thanks to the Tuanui and Moffet families and planting contractors.

Mangere plantings 1981

Plantings in Douglas Basin in 1981. Photo: Dave Crouchley

Diversification

As part of the ongoing restoration I led a team of seven people in a week of planting on the island in June.  Although the weather was a bit on the miserable side (gale force winds, very cold and hail most days), we kept warm carrying the heavy bags of plants from the boat landing up to the planting area in the basin.  We managed to plant 1850 plants under the emerging canopy, adding diversity amongst older plantings many of which are self seeding and spreading naturally in the basin.

Mangere and Douglas Basin

Looking over Mangere’s Douglas Basin towards Little Mangere

Local produce

The species planted this trip included Chatham Island nikau, kawakawa, hoho (Pseudopanax chathamica), ngaio, mahoe, ribbonwood and matipo. All the plants were eco-sourced, meaning the seeds were collected locally from Mangere, Pitt and South East Islands and were grown in the DOC nursery at Te One before being transported to Mangere and planted.

Tree planting

Filling in the gaps

But wait, there’s more…

As well as planting, we also cleared tracks, checked rat bait stations, ran rodent tracking tunnels and collected seed for future plantings. We also had the opportunity to visit Robin Bush to view the black robins and walk up to the summit  to enjoy the spectacular views of Mangere, Little Mangere and Pitt Island. Next year will be the last year of akeake planting on the island however diversification plantings will carry on for the next ten years as part of the long-term ecological restoration of Mangere Island.

Mangere planting team

Mangere Island winter planting team 2012: Pete Lusk, Nadia Thomas, Ryan Jones, Juzah Zammit-Ross, Mike Van Velzen, Colin Bishop and Denny Prendeville

 

By Dave Houston

Mid-winter opportunity to work on Chatham petrel burrows

In early July each year a small group of DOC workers head out to Rangatira or South East Island in the Chatham’s to undertake end of season work on the Chatham petrel burrows.  This year we decided to give Chatham Island school children an opportunity to join us and experience the magic of Rangatira.

Rangatira Island

Rangatira or South East Island

We were joined by Year 11 Correspondence School students Harriet Graydon and Mia Foley, both of Pitt Island, along with Chatham Islander Jacob Hill, a Year 12 student at St Bedes College, for the 4-day trip. 

After completing quarantine procedures designed to keep the islands pest-free, we caught an early morning fishing-boat ride from the main island to Pitt, to pick up Mia and Harriet.  After a brief stop and exchange of mail and supplies, we departed for the forty minute trip to Rangatira.

The landing

Landing on Rangatira

Rangatira residents

No jetty means a bow landing on the rock platform and a frantic passing ashore of the buckets containing our food and gear, but the team handled it flawlessly. 

As soon as we were ashore we bumped into our first special species, the shore plover.  Once abundant around the coasts of New Zealand, this plucky little shorebird was eradicated by rats and survived only on Rangatira.  Fortunately, it has now been returned to several mainland sites.

Chatham Island black robin

Chatham Island black robin

While hauling the buckets up to the hut we bumped into our next special resident – the black robin.  With around 200 birds, Rangatira is the stronghold for the species and over the next few days we got to see quite a few as they jumped out of the forest at us in anticipation of a mealworm handout.

After settling in we fitted everyone out with petrel boards – special footwear designed to prevent us collapsing seabird burrows as we walked around the island.  We then set off on our main task, checking 250 burrows of the endangered Chatham Island petrel

After checking that this years chicks had successfully fledged (and unfortunately a few didn’t), we did a bit of housekeeping and then put a barricade in front of the entrance to stop other seabirds taking up residence while the petrels are away over the winter.

Checking chatham petrel burrow

Mia, Harriet and Jacob checking a Chatham petrel burrow

While wandering around the forest for a few days we got the opportunity to see more island residents – including the Chatham Island species of snipe, parakeets, tui, tomtit, warbler and skink. 

On our first night we hoped to introduce the visitors to the many seabirds and abundant invertebrates that call the island home.  Unfortunately, the great weather and full moon kept all the seabirds at sea so we had to be content listening to blue penguins braying in the forest.

Petrel boards

Fancy footwear: Petrel boards reduce damage to the many seabird
burrows in the forest floor

Reluctant return

All too soon it was time to pack up, lug the gear back to the landing and await the arrival of our ride.  Our skipper Glen King treated us to the scenic route on the way home, travelling around the bottom and up the western side of Pitt Island, taking in views of Mangere and Little Mangere Islands on the way as well as taking us into an impressive sea cave.

Rangatira view

Harriet, Mia and Jacob enjoying the view from the summit of Rangatira.
Pitt Island in background

Mia and Harriet’s  families were waiting on the wharf at Flowerpot when we arrived, glad to see their kids home safe and just a bit jealous of the experience.  Jacob had to endure another hour-long crossing of Pitt Strait before he could head home, but the experience can’t have been to bad as he wants to come back when we open up the petrel burrows again in November.  I think he’ll have some competition, as the girls want to go too.

Trip home

Jacob and Harriet enjoying the trip home along with
Ranger Juzah Zammit-Ross

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.