Written by Chris Jones, Senior Field Assistant
Probably one of the more challenging activities we are tasked with on Gough is the Tristan albatross incubation census. This involves counting virtually every Tristan albatross nest of the breeding season. On first impression one wouldn’t necessarily think this could be all that difficult; how hard can it be to scan a few hillsides with binoculars and tally the large white birds sitting still on nests?!
In theory, it should be easy. But the weather on Gough makes all the difference. The island is often touted as one of the rainiest and cloudiest places on earth. Annual average rainfall is around 3000mm, sometimes falling in extremely heavy bouts (more than 100mm over a 24-hour period is not that uncommon). The peaks of Gough are often wreathed in low-lying orographic cloud, a cloud that forms when moist, maritime air cools as it is forced to rise by the mountains. As a result, precipitation is generally 50% higher on the peaks than at the coast.
And the peaks are exactly where we are heading! The majority of Tristan albatross on Gough nest at least 400m above sea level, so I’m sure you can see where the challenges come in. The vantage points that allow us to stand over the nesting sites and look down to count incubating birds are steeped in low-lying cloud most of the time.
So, in preparation for the counts we kept very close eyes on the weather forecast near the end of the egg laying period which is when we needed to carry out the census. A promising forecast appeared from the 23rd to the 28th of January, we were delighted as this would be ample time to complete all the counts! So, on the 23rd of January we optimistically set out for Waterfall camp located in the centre of the island (often used as a remote campsite because it allows easy access to most of the important count areas). Unfortunately, our plans were thwarted as we summited the Rowett mountains (an area that gives the first proper view of the northern part of Gough), we realised we were in thick low cloud that wasn’t going anywhere soon. We pushed on to Waterfall camp through the low cloud in gale strength wind and set up camp rather bedraggled with any left optimism waning fast. We hoped the low cloud would clear up the following day.
Waking up early on the morning of the 24th revealed the weather had only improved slightly, the wind had died down, but low cloud remained, at least it gave us an opportunity to go for a walk and stretch our legs but counting albatross was out of the question with visibility still less than 100m. With our satellite phone we phoned our team members at base for an updated weather forecast. Things were not looking good - the only hope that kept us from heading back to base was a southerly wind forecasted for two days’ time! After spending a soggy day in our tents, we felt the temperature begin to drop that night, hoping the cold also meant clear skies the next day.
The following morning, we awoke to a beautiful sunrise which lifted our moods tremendously! After seeing virtually nothing but mist for 72 hours you forget what blue sky looks like, but in clear weather Gough Island has some of the most spectacular landscapes in the world. We scurried out of our tents, wolfed down some breakfast and set off to count the northern half of the island. We hiked for 13 hours, successfully counting all the zones on the way and arriving back at camp just before sunset - a day well spent!
With even better weather the next day we were able to complete all the counts from Waterfall camp to the long-term monitoring colony at Gonydale. After finishing off counts at all outstanding zones we finally made our way back to base on the 3rd of February; a week and a half after leaving the base!
We are pleased to report that through our efforts we recorded a total of 1741 incubating Tristan albatross! This is a bumper season up from the count of 1453 last year.
Tristan albatross are biennial breeders, meaning pairs will take the next year off breeding if they successfully fledge a chick. It takes about 12 months from laying the egg to fledgling and following the efforts of feeding a chick for half a year, the adults need a year to regain body condition before they can breed again.
Sadly, mice had a devastating effect on breeding success last year, but the pairs who lost their chicks early in the season would have had enough time to build up body condition ready for this year’s breeding season, which is why we think there has been an increase in incubators and eggs laid this year.
We’ll monitor these Tristan albatrosses through the year to find out how many of the eggs successfully hatch, and how many of those chicks survive to fledge. There may be an increase in eggs right now, but mice pose an increasing threat to their survival and the eggs we’ve counted will be at risk for many months to come yet.
Tristan albatross are listed as Critically Endangered by the IUCN and some population models predict extinction of this species as soon as 30 years. If mice are not eradicated from Gough soon, counting these majestic birds will be something of the past.
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Acknowledgement
The Gough Island Restoration Programme is being carried out by the RSPB in partnership with Tristan da Cunha , BirdLife South Africa and the Department of Environmental Affairs in South Africa and Island Conservation . The programme is part-funded by the RSPB, the UK Government, the National Fish and Wildlife Foundation and other generous individuals and organisations.