Skip navigation

Monitoring shearwaters on Breaksea Island

February 07, 2017
Share

The volunteer team crouch patiently amongst the low coastal vegetation, peering keenly into the fading light. “There’s one!” someone whispers excitedly, pointing to the silent silhouette winging its way over the sloping, granitic island. It is just after sunset, and we are perched on the flanks of Breaksea Island, one of the granite tors that protect Albany from the surging Southern Ocean. As we watch, the silhouette glides silently over a ridge and out of sight.

Over the next few minutes more silent visitors appear, coasting over the cliffs, swooping closer and closer to us and the low, wind-pruned island vegetation. They are Flesh-footed Shearwaters – a seabird common to our southern coastal islands, but generally only seen from the mainland when they wash ashore after heavy storms or misadventure. Relatively silent while airborne, they get more vocal once they land. Strident, plaintive calls (that sound for all the world like they are saying, “Pick me! Pick me!”) echo across the slope. These shearwaters are returning to their breeding burrows, which they excavate in colonies on sloping edges of islands like Breaksea. These burrows can easily be more than two metres deep, and with their mates have been waiting patiently inside, the reunited pairs call to one another at the end of several days apart.

Shearwater_Thumbnail.JPG

For the CCWA citizen science team, this meeting provides the perfect opportunity for researchers to monitor the Flesh-footed Shearwater population on Breaksea. The purpose is two-fold – numbers of these shearwaters, like many other seabirds, have been recorded as declining severely in recent decades. For shearwaters, their love of sardines has brought them in conflict with the local pilchard industry, where large flocks of these birds (along with other local seafood lovers like albatross, gannets, gulls, dusky whalers and dolphins) feed on the same sardine schools being netted by fishermen. Unfortunately for shearwaters, these efforts sometimes have a deadly result, as the shearwaters can easily get tangled in the nets and drown. While efforts continue to quantify and mitigate the impact on these birds, the legacy of this on the local shearwater population is yet to be measured. The second reason for us being there is a grim spectre hanging over the future of many seabird populations – plastic ingestion.

Today the Citizen Science team was out on Breaksea Island to investigate the direct impact plastics might be having on the shearwaters. As well as individually banding the birds, the team took feathers to test for heavy metals and samples from the shearwaters’ uropygial (preen) glands to test for phthalates. Phthalates are binders used in the fabrication of many types of plastic and are powerful hormone disrupters. The presence of phthalate in preen gland oil can be used as an indicator of phthalate exposure from plastics in the marine environment. While the results of these tests will take a while to come back from the lab, the team also took the opportunity to measure the density of burrows in the colonies and set up long term monitoring points. The team also scoured active burrow entrances for plastics. In samples from 35 shearwater burrows, only a single piece of plastic (a nurdle – about the size of a rice grain) was found. So far the risks from plastics do not look too serious for this population, but the test results and a return visit at the end of the breeding season will provide more insight. 

Breaksea Island is an ideal spot to monitor these birds from. It is a Nature Reserve, accessible only by helicopter or boat, and only in calm weather. With no permanent settlement, and no beach, all plastics on the island have to have been ‘flown in’ – by the birds. But here’s hoping that Breaksea’s shearwaters continue to live the plastic-free life for many generations to come.

 

By Tegan Douglas

The CCWA team are indebted to the Albany Department of Parks and Wildlife for logistical support and for permission to stay on Breaksea Island. This project was funded by the State NRM and the Royalties for Regions program. 

Continue Reading