Migrating Short-tailed Shearwaters

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One of the great wonders of the natural world is the long distance migrations on land and at sea, undertaken by birds, mammals and even butterflies. Reports of the first swallow of the spring, or the first call of the cuckoo are key events, not just for naturalists but for everybody – The Times of London regularly takes letters to this effect. The Pacific is not blessed with such obvious, everyday, examples of nature’s annual rhythms. However, if you know where to look, then even here in Vanuatu the signs of the change of seasons is apparent.

The Short-tailed Shearwater is the most abundant species of seabird in Australian waters, with a population estimate in excess of 20 million pairs. The shearwaters, also known as muttonbirds, breed on islands around Tasmania and in the Bass Strait. They are known as muttonbirds as they have been harvested for consumption. The chicks can weigh nearly a kilogramme by the time that they are ready to fly. The largest breeding colony is estimated to be 2.8 million pairs in size – harvesting at a site of this size can provide a substantial food source. At the end of the breeding season, between May and July, the birds fly north to seas off north east Asia, and Kamchatka, then follow an anticlockwise loop, flying past the California coast in September and October. Their return to Australia can pass through local waters. It has been recorded that at least 800,000 birds pass between New Caledonia and the Loyalty Islands at this time of year.

Recently we have seen Shearwaters passing through Vanuatu waters in similar numbers. In 2013, Steve Gibb reported a constant stream of the shearwaters flying north to south past Malekula on the 1st October. He estimated that the flock was at least 40km in length – as far as he travelled that day. He saw similar numbers offshore, from Uri Island, near Malekula, on October 3rd and birds still flying past on the 4th. In 2015, on the October 8th, I spent a bit of time looking at to sea from Enam, at the south west corner of Efate. I only had a limited amount of time but noticed a constant stream of birds flying north to south, between 300 and 400m offshore. I settled down to count the numbers flying past. It took around 5 minutes for 1,000 birds to pass a landmark – suggesting 12,000 per hour or around 150,000 during daylight hours. We don’t know whether the stream continues at night, or for how many days.

Clearly there is still a lot to learn about this amazing journey, and the extent to which Vanuatu waters are important for the species on its return to its breeding grounds. There is a facebook site, Birding Aboard, dedicated to capturing at-sea sightings of any bird species seen at sea. If you are on a boat out at sea, and you notice large flocks of birds soaring low over the water, then please do report the date, and your location and, if you get a chance, try to take some photographs for confirmation to the above site.   Alternatively get in touch with myself or VEAN.


Photo by Steve Ebbert. Column bY Mark O’Brien. Mark O’Brien is the Regional Programme Coordinator for BirdLife International in the Pacific. He is based in Suva, Fiji where he moved, from Scotland in the UK, in 2010. Mark’s first experience of the region was a 6-week secondment to Vanuatu, where he worked with Vanuatu Protected Areas Initiative and Wan Smolbag on megapodes on Ambrym and Santo.


The BirdLife International vision is of a world rich in biodiversity with people and nature living in harmony, equitably and sustainably. BirdLife International is the largest global partnership of non-governmental nature conservation/civil society organisations. It works with both VEAN and VESS in Vanuatu to help deliver high impact and long-term conservation for the benefit of nature and people. www.birdlife.org, www.vanuatuconservation.org.

 

 

 

 

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