PART 1 – THE MANX SHEARWATER
NORTH VALLEY, SKOMER – HOME OF SHORT EARED OWLS AND SHEARWATERS
Spending time close up with a beautiful and iconic species on a beautiful and iconic island – what could be better? Not much in my book! The Wildlife Trust of South and West Wales holds a Shearwater Week on Skomer Island in late August or early September every year to give members of the public an opportunity to learn about these rare and beautiful birds and to get close to them in their natural environment. The puffins, razorbills and guillemots have left their nesting burrows and cliff ledges during July and early August for the challenges of the open ocean, leaving the island without the main attractions for the visitors who flock to see them throughout the summer. In their absence, the island and its bays and cliffs can seem strangely quiet, but the true situation can only be seen by those visitors who stay overnight on the island – for it is in the hours of darkness that the island really comes alive at this time of year.
THE BEAUTIFUL AND ENIGMATIC MANX SHEARWATER
The islands of Skomer, Skokholm, Middleholm and Ramsey are of crucial international importance for their colonies of Manx shearwaters, Puffinus puffinus, holding around 50% of the world population during the breeding season from April to September annually. Skomer has the largest population with an estimated 330,000 pairs giving an annual total for the island of approaching 1,000,000 ‘Manxies’ when chicks are included. Nesting in burrows up to 3 feet or more in length that they have dug or that they have taken over from rabbits or puffins, the incubating adults and their chicks are invisible to the outside world and only the occasional call echoing up from the depths will give them away. The presence of land based predators such as rats, stoats, polecats, foxes and cats on the island would spell disaster for these ground nesting birds and so every effort is made by the Wildlife Trust to ensure that these animals are excluded. Predation by aerial species, in particular great black backed gulls, as well as some larger raptors, is not preventable, however, and it is for this reason that shearwaters are rarely seen on land in the hours of daylight.
SHEARWATER BURROW WITH TELL TALE DROPPINGS
Having legs positioned well back on the body for aiding diving and life at sea, shearwaters are very ungainly on land and therefore vulnerable to attack. Rafting offshore in the evening before coming ashore under cover of darkness minimises the risk, although sick birds or careless youngsters that venture out of the safety of their burrows can be caught in the open and killed. Visitors are often shocked by the presence of shearwater carcasses scattered around the island, but this is a natural and sustainable loss to the population that benefits the survival of the predator species and requires no control measures. Recent censuses of the populations of shearwaters on both Skomer and Skokholm suggest that they are holding their own, if not increasing, which is good news in the light of declining sea bird stocks in some other areas of the UK. With such an internationally important breeding community in its care, the Wildlife Trust of South & West Wales has a serious responsibility to monitor and manage this population to ensure its future survival and success. So what is known and what is done to ensure the species’ protection?
A SHEARWATER STUDY BURROW WITH ACCESS LID AND NUMBER LABELS
The Manx shearwater is related to the albatrosses, fulmars and petrels. It is truly a bird of the open ocean, being wonderfully adapted to skimming effortlessly over the waves for considerable distances, including the 6 – 7,000 mile journey to their wintering grounds off the coasts of Brazil and Argentina. Incredibly, it has been found that some youngsters make this journey in less than 2 weeks and the record is only 6.5 days! Shearwaters are long-lived with a lifespan of over 50 years being recorded, and it is estimated that in that time an individual will have travelled a distance in excess of 1,000,000 kilometers! The fitting of various types of tags by researchers over the years has given fascinating insights into the life and habits of individual birds whilst they are at sea, and researchers from Oxford University are currently carrying out valuable work through satellite tracking and data loggers to learn more about their travels and feeding whilst at sea and on their return to land.
Their time on land presents an ideal opportunity for study and it is during their stay on the islands that information on the health and wellbeing of individuals and populations can be determined in greatest detail. Research carried out on the islands and elsewhere over the years has given considerable insight into the biology and habits of the species and it is now known that individuals return to their natal burrow, or one close to it, in March annually at 6 -7 years old and await the return of their partner before mating, after which the female travels to feeding areas along the Continental Shelf, 500 km south-west of Skomer, to fatten up and allow the egg to develop. The male meanwhile stays behind to feed locally and guard the nest site. The female returns in early to mid May, lays a single egg and then departs to feed again leaving the male to carry out the first stint of incubation. Thereafter the pair takes it in turns to incubate the egg, each doing from 4 to 8 days at a time while the other goes off to feed. The egg hatches after approximately 51 days and the adults both feed the growing youngster, fishing closer to home to reduce the time away from the nest. The chick, which is a downy ball of fluff, grows fast and puts on layers of fat peaking after around 50 days, at which time they weigh up to 600 grams, exceeding the weight of their parents by up to 1.5 times. Over a period of approximately 70 days the down is replaced by adult feathers and for the last 2 weeks or so the youngsters start leaving the nest burrows temporarily to exercise their flight muscles. At this stage feeding is reduced or ceases and the young bird is left to fend for itself when hunger pushes it into starting its long migration south in early September. During these early explorations, a number of young birds get distracted by lights on the mainland, lights on tankers, or are blown off course by strong winds and can end up stranded as waifs and strays, sometimes far from the sea.
A YOUNG SHEARWATER STILL COVERED IN ITS DOWNY COAT
Shearwater Week in late August or early September is organized by the Trust as an opportunity for members of the public to stay on the island and share in some of the work carried out by the Trust and Oxford University. It enables participants to learn more about this species and its fascinating life and what the Trust is doing to monitor and protect it. I was fortunate enough to be invited to participate as a Temporary Volunteer Warden for 3 days of Shearwater Week but, in the event, strong northerlies prevented the crossing for two days and sadly reduced my stay to a day and a half. During this time, it was my duty to lead the visitors on night time, ‘meet the shearwaters’, walks, to accompany them as they explored the island to answer any questions they might have, and to assist with the on-going chick weighing programme.
A sub-group of around 80 shearwater burrows have been identified in the vicinity of the Warden’s accommodation for study and these have been marked with individually numbered labels and have had new entrance holes dug into them to allow easy access by researchers to the egg / chick / adult at the end of the tunnel. These holes have covers in place most of the time, but they can be removed when the surveyor wants to examine the contents of the burrow or to remove the chick temporarily for the daily
SOME BURROWS REQUIRE A LONG ARM TO REACH THE CHICK ! NUMBERS OF VOLUNTEERS ALLOW FOR MULTIPLE CHICK PROCESSING!
The chicks have to be carefully removed from their burrows head first with the wings held tightly to the body to avoid damage, a tricky operation as the chicks are often reluctant to oblige and have very sharp beaks that can draw blood from researchers’ hands. The chicks are then placed individually in bags for weighing, the weights being recorded by Joe Wynn, a post-graduate student from Oxford University who is leading the study, against their personal entries in a notebook. It has been found that chicks weighing less than 425 grams at fledging are unlikely to have the reserves to survive the journey to the wintering grounds.
A YOUNG ‘MANXIE’ IS PERSUADED INTO A BAG BY MONICA PRIOR TO WEIGHING
THE AUTHOR WEIGHING A CHICK Photo by Monica Doshi
JOE RECORDS THE INDIVIDUAL WEIGHTS IN THE NOTEBOOK
After a briefing when the purposes of the weighing routine and the correct operational procedures to be adopted were explained patiently to us by Joe, I and a few others were allowed to try our hand at winkling chicks out of burrows and into bags and reporting the weights for him to record. Any deficiencies in handling technique or possibly erroneous weights were quickly pointed out to us and corrected by a watchful Joe, and our confidence soon grew. It was such a privilege to be able to get so close to these birds and it was hard to imagine that the small and delicate creature in one’s hand would be thousands of miles away within a few weeks if all went well for them.
RETURNING A CHICK TO ITS BURROW Photo by Monica Doshi
BACK HOME AGAIN – UNTIL TOMORROW!
Another special treat for the Shearwater Week participants was the night walk to experience the nocturnal comings and goings of the adult birds and the initial above ground explorations of the juveniles. Not quite as busy and noisy as during peak feeding time earlier in the season, it is nevertheless an exhilarating and fascinating adventure with aerial adults flying around ones’ head and scuttling youngsters trying to get under ones’ feet. The air was filled with their strange “cuppacocoa” calls as they communicated with each other, the females being deeper and gruffer than the higher pitched males’ calls. The magic was further enhanced as we were encouraged to use red torchlight so as not to dazzle and disturb the birds, but this of course made photography difficult in the dim, coloured light! Notwithstanding this, some use of brighter white light was necessary in order to spot, and avoid treading on, the numerous toads that were wandering around the paths and which were virtually invisible in the faint, red light. Not to do so would have led to a terrible experience for both toad and walker!
VISITORS ENJOY THE EXCITEMENT OF A NIGHT SAFARI, WATCHING OUT FOR NIGHT FLYING SHEARWATERS and
A YOUNG BIRD CAUGHT IN THE TORCHLIGHT
Throughout my time on the island, I was particularly impressed by the dedication, patience, attention to detail, and care that all the staff and volunteers brought to their work with the shearwaters as well as to their other duties and responsibilities. The welfare and well being of the wildlife was at the forefront of all that they did, and they also somehow managed to bring the same qualities to their care of the human visitors for which we were very grateful.
I would like to extend my sincere thanks to Ed Stubbings and Birgitta ‘Bee’ Bueche (the Skomer Island Wardens), Sarah Purdon (Skomer Visitor Officer), Joe Wynn (Shearwater researcher) and to all the other staff and volunteers who made our visit so informative and enjoyable. I am also grateful to Monica Doshi, volunteer and skilled photographer, for taking the photographs of me in action weighing the chicks.
Part 2 of this article will appear shortly and will cover other aspects of island life, both human and otherwise, experienced during this latest visit to Skomer. It will include seals, choughs, new Wardens, elusive avian visitors, a girl spending time in a water tank and a bird log amongst other delights!
———- o0o ———-
Please note that all photographs are Copyright protected. Prints in various sizes of any photographs used in the articles can be obtained by contacting the Author.
———- o0o ———-
David Gardner, Environmentalist and Photographer
—– o0o —–