Te Arai Kete

A study of NZ Fairy Tern (Sterna nereis) genetics has confirmed that the New Zealand species is genetically distinct. At the June 2006 meeting of Auckland OSNZ, Marleen Baling, MSc. discussed genetics NZ Fairy Terns and Dr Sam Ferreira talked about the survivability of the species.

Marleen’s study on conservation genetics of the NZ Fairy Tern was a two year contract for the Department of Conservation and the University of Auckland, (supervised by Dr Dianne Brunton). The NZFT population is only about 30 individuals and is listed as “Acutely threatened – nationally critical”.

Marleen investigated the level of endemism and genetic relatedness of the NZFT population to the larger breeding populations in Australia and New Caledonia. She sequenced the mitochondrial DNA with samples collected from the three populations. The results showed that the Fairy Tern populations in all three locations are genetically distinct with very restricted gene flow. The single Fairy Tern mitochondrial DNA haplotype found in NZ is not found elsewhere.

This backed up previous studies that had found morphological and behavioural differences between the main breeding populations. In future, more studies are needed on male Fairy Terns, to see if they are migrating between NZ and Australia, she said.

Threats to Fairy Tern numbers

At the same meeting, Dr Sam Ferreira presented a comprehensive statistical analysis of Fairy Tern breeding success and survival rates. He concluded that there was a factor limiting the population that had nothing to do with management. The Fairy Tern population had good and bad years, but was stable around 30 birds.

He identified two possible reasons for this. One was that some birds were moving away from New Zealand, such as males possibly migrating and breeding elsewhere. The other possible reason was the food supply, and a lack of suitable small fish at the right time.

We need to know what they are eating and where they are feeding.” He also identified the plethora of coastal development, especially further development in areas with Fairy Terns, as a real threat to the survival of Fairy Terns.

Given that adult survival rates are so bad (possibly due to predation outside the breeding season), there needs to be a strong stand against coastal development in Fairy Tern areas, until we are sure that it is not going to be part of the problem,” he said.

Management and observations of Fairy Terns is critical to their survival, and we only have Fairy Terns now because of the interest from some OSNZ members,” said Dr Ferreira. “Adult survival is declining and we need more research, observations and information to minimise any potential new threats.”

Summer 2005: Fairy Terns attempted to breed at Papakanui again this year, and many people were involved in giving them the best chance of success. Papakanui Spit is one of only four breeding sites for the critically endangered New Zealand Fairy Tern. The other sites are Waipu Spit, Mangawhai and Pakiri Beach.

"We have an old pair who have nested together at Papakanui for eleven years now," says the Department of Conservation's Mainland Biodiversity Ranger for the Warkworth Area office, David Wilson. "This year (2005) they laid their first two eggs on the 31st of October, which is very early in the season. With assistance from Auckland Zoo staff we candled the eggs and found that one was fertile and the other not.

"These are old birds with a history of fertility problems, so to have one of the eggs fertile was a good result for us. Unfortunately these birds abandoned their nest after three weeks of incubation, with the fertile egg just a couple of days short of hatching," he says.

"We incubated the eggs artificially overnight (we have a portable incubator) and the following day we took the eggs up to Mangawhai. We put them under another Fairy Tern pair in exchange for their own eggs, which were both infertile. Unfortunately our Papakanui eggs were eaten, probably by a Black-backed Gull, soon afterwards." In the meantime a second Fairy Tern pair nested at Papakanui.

"We were a bit concerned for this nest as it appeared to be very close to the sea. The birds abandoned this nest fairly quickly. We found both eggs to be infertile anyway. This pair will hopefully re-nest soon, and with a bit more experience under their belt now, may produce fertile eggs next time," says David. "The third nest is still active, with the eggs due to hatch in roughly two weeks. This is assuming of course that the eggs are fertile. We have not candled these eggs so we are not sure," he says. "We are not sure why Fairy Terns lay so many infertile eggs, but inbreeding might be a factor with a total population of less than 40 birds."

The two DoC wardens at Papakanui, Jeroen Lurling and Angela Hogan, worked hard on predator control, monitoring the birds and their nests, and doing public relations on the beach. This involved encouraging people to drive below the high tide mark (away from the nesting areas higher up on the beach) and to keep their dogs on a leash. "We also asked them to avoid entering the important nesting areas which the wardens have cordoned off. This is of benefit not only to Fairy Terns, but to other threatened shorebirds such as New Zealand Dotterel and Variable Oystercatcher," he says.

"We are very appreciative of the help we get from the Air Force and other Defence Force staff, from Gwenda Pulham of the Ornithological Society, staff at the Auckland Zoo, and Neil and Sharon Waller. With their help there will hopefully be Fairy Terns at Papakanui for many years to come," says David.

Text by Suzi Philips