It is not often one has a mega birding experience in life, I mean a one-off truly awesome bird event which involved being lucky to be in the right place at the right time. A huge event that you could not plan or organise to see, one that comes out of the blue as a complete surprise, a huge spectacle that leaves you deeply moved by the magnitude and grandeur of nature.
We experienced such an event on the East coast of New Caledonia on Monday the 2nd of October 2017 when we crossed paths with a massive number of Short-tailed Shearwaters (Puffinus tenuirostris) flying south on migration to their breeding islands in Bass Strait, Australia.
Just one of millions of Short-tailed Shearwaters on migration. While the tail is not particularly short, the feet do extend beyond the end of the tail.
On Monday the 2nd of October we made a forty nautical mile sea crossing from Ouvea at the northern end of the Loyalty Islands group to the East coast of New Caledonia in the 46’ catamaran Alchemy 1 under sail in a 20-27 knot SE wind averaging 8.5-9.0 nm/hr. The sea was rough and it was an exhilarating ride. During the crossing very few sea birds were seen - only the odd single Short-tailed Shearwater was observed plus one juvenile Sooty Tern followed the vessel for about 20 minutes. The absence of sea birds in tropical waters is not uncommon – you can sail or motor for hours and not see one bird.
Over the previous 2 weeks of sailing we had seen the odd small groups of Short-tailed Shearwaters (ID confirmed with photos) flying south low to the sea surface, in lines, with purpose – these birds were clearly on migration. The largest flock we saw was between New Caledonia and the Isle of Pines which may have contained 500-1000 birds. Most of the other flocks contained much smaller numbers.
As we approached the coast of New Caledonia about noon, we sailed through the outlying barrier reef via Passe de Kouaoua and past Cape Begat on our port side (left) on our way to the head of Baie Laugier, a protected shelter from the SE winds, where we planned to anchor for the rest of the day and night.
Cape Begat is on the left.
Photo of nautical map showing Laugier Bay on the right and a blue pin drop at our proposed anchorage at the head of the bay. Most of the Shearwaters continued past the bay however many detoured into the bay to its head.
As we came through the barrier reef we could see very large numbers of Shearwaters ahead and as we crossed between the barrier reef and the mainland, a distance of about 2 nautical miles, the scale of the massive numbers of birds started to dawn on us. A vast number of Shearwaters were streaming south.
At first I thought there were thousands of birds, then I adjusted my thinking to hundreds of thousands and later as the day wore on and the birds streaming south did not abate, with some rough estimates and calculations, I realised we were witnessing millions of Short-tailed Shearwaters on migration. We had crossed paths with a truly huge peak of migrating shearwaters.
The Shearwaters stretched in a mass of birds as far north and south along the coast as we could see. The birds were hugging the coast and flying directly into a 20-25 knot SE wind. Despite the head wind they still looked to be flying at speed and doing at least 20 to 30 knots.
Most of the birds passed by the wide entrance to Laugier Bay and continued south hugging the coast. However a percentage turned into the bay and flew low to the head of the bay.
Entering Baie Laugier – at this point the bulk of the Shearwaters are behind us however there were still large numbers of birds in the bay – unfortunately they do not show up in the iPhone photos.
Motoring to the head of Baie Laugier.
The head of Baie Laugier where we anchored for the afternoon and night.
As the birds reached the head of the bay and realised it was a dead end they used the strong winds, which were barrelling down from the surrounding mountains, to lift high, wheel around and then use the easily gained altitude to descend back to the coast proper and continue their southward journey. I can’t explain why some of the birds made this seemingly useless detour? The shape of the bay to the north, Baie de Kouaoua, and Baie Laugier would cause birds following the land shore closely to fly into the bay.
This video captures the birds at the head of the bay.
Perhaps some of the birds were on their first migration south and had not yet learnt the route from previous years’ experience. I guess in the context of their life at sea and their overall annual 32,000 plus kilometre Pacific Ocean journey a few nautical miles extra are of little consequence to their energy budget.
While the percentage of birds flying to the head of the bay were small in comparison to the vast bulk of the birds that streamed by the entrance, the numbers were still huge. The birds came up the bay in bursts of as many as one or two thousand at a time and this continued all afternoon with one group following closely behind the next, so the total number for the afternoon was by my rough conservative estimate, 300,000 to 500,000 birds.
The huge numbers of Shearwaters we could see from our anchorage continued to pass by the bay all afternoon until sunset after which we could not see them though they were probably still passing. My rough estimate for the number of birds passing Laugier Bay from when we arrived at noon to sunset was at least 3 million birds.
A check after dark with a spotlight revealed birds still flying to the head of the bay.
I interrupt this story to provide some information regarding numbers of Short-tailed Shearwaters that breed in Bass Strait each year in case the reader is doubtful of the numbers I have reported on migration along the New Caledonia coast. The following text has been copied from the Tasmanian Parks and Wildlife Service web site:
The shearwater is the most abundant Australian seabird. Approximately 23 million short-tailed shearwaters breed in about 285 colonies in south-eastern Australia from September to April. Eighteen million of these arrive in Tasmania each year. There are known to be at least 167 colonies in Tasmania and an estimated 11.4 million burrows. The largest colony is on Babel Island which has three million burrows. Their colonies are usually found on headlands and islands covered with tussocks and succulent vegetation such as pigface and iceplant. Headlands allow for easy take off and landing.
Early accounts suggest that the population was once considerably higher. In 1798, Matthew Flinders estimated that there were at least one hundred million birds within a single flock sighted in Bass Strait.
From Laugier Bay we had to motor down the East coast of New Caledonia directly into the very strong SE trade winds. As the winds abated overnight and built up during the day by midday the seas were becoming too uncomfortable for both us and Alchemy 1 to pound into so our strategy was to get up early and be away by 5am, motor until about noon and then pull into a sheltered anchorage for the rest of the day. By this strategy it took us three full days and three anchorages plus part of the morning of the fourth day to reach the S-E corner of New Caledonia when we could turn West away from the winds into more comfortable conditions and continue our journey back to Noumea.
Screenshot of New Caldonia and the Loyalty Islands with our approximate route back to Noumea.
As we motored south each day strings of Short-tailed Shearwaters continued to pass us on their migration journey. The massive peak of birds we saw on the 2nd of October had passed, however the number of birds still going south was significant. The tail enders, like the mass of birds before them, hugged the coast and flew low close to the sea surface. The strings of birds varied in size from very large to just a few hundred birds. I counted a number of typical strings which I estimated by counting the number of birds passing each second. Repeated counts showed between 5 and 10 birds per second passing us giving an upper limit of 600 birds per minute. A number of strings took 20 minutes to pass us so some of the strings contained 20 x 600 = 12,000 birds.
The strings of birds continued to pass us unabated for four mornings. On the fourth morning as we changed course to enter Havannah Pass, a natural channel through the fringing barrier reef at the SE end of New Caledonia, we crossed through a large string of Shearwaters still streaming south. The birds continued on their ancient course south to Bass Strait and we headed west. This was the last we saw of the Shearwaters as we had clearly left their migration route which we had shared with them for over three days.
The Short-tails we observed were clearly on a mission, they flew with determination on their migration route south. There was no stopping to feed. I presume that this huge aggregation of birds, which could only be supported over a large area of ocean, had come from birds dispersed in the northern Pacific. As the genetic hard-wired urge to return to Bass Strait to breed took hold the birds funnelled in to their ancient migration path/s which by New Caledonia was certainly a concentrated line of birds spread over a width of about 2 nautical miles. Once in this concentrated mode, feeding had stopped. In any case the tropical sea could not possibly yield enough food for this huge aggregation of birds and the imperative to reach the breeding grounds had become the only objective.
The Short-tailed Shearwater’s breeding event in Bass Strait takes place each year within a very tight timetable – they, along with several other petrel species, maintain the strictest seasonal breeding cycle of any kind of birds alive today. So it is not surprising that the birds migration timetable results in a huge accumulation of birds on migration through tropical waters.
Each bird would fly on a more or less direct course with rapid and shallow wing beats for about 10 seconds, then it would glide for a similar time before resuming wing beating again. The birds seemed to follow a leader and were generally strung out in long narrow lines.
The Short-tailed Shearwater is a fully migratory pelagic seabird species breeding in southern waters (Bass Strait islands) during the Australian summer and migrating north to high latitudes in the northern Pacific to spend the northern summer there before returning south again to breed. Their traverse of tropical waters and the equator is during migration and I suspect they do not spend time here feeding but cross with purpose in a short time. It is the cold productive waters where they spend most of their time and find sustenance and not in the less productive tropical waters.
The adults, after the breeding season and before migrating to the northern hemisphere, head south as far as the edge of the Antarctic ice sheet to feed and no doubt build up fat reserves to power their northern migration flight through tropical waters.
In the 228 years since Matthew Flinders made his estimate of Short-tailed Shearwaters in Bass Strait, their numbers have declined significantly. Sadly the challenges facing these migrant seabirds are only growing with pollution and perhaps most deadly, plastics, over fishing, global warming and now the threat of avian influenza H5N1. Since writing this post in 2017 H5N1 has become a reality in the northern hemisphere where Short-tailed Shearwaters winter, but has not yet reached Australia - as far as we know. Short-tails are both threatened by this virus and are also a potential pathway to Australia from the northern Pacific via their migration.
I hope I have captured for you the reader some sense of the epic scale of the Short-tailed Shearwater lifeway and migration. Few will ever get to experience such an event as the Short-tails are pelagic birds only coming to land to breed on remote off-shore islands. I feel deeply privileged to have had this encounter.
NOTE:
This link will take you to an Avithera post featuring our destination in the northern Loyalty Islands:
