The following article is by my ringing trainee Ellie.
Having visited Skokholm Island Bird Observatory briefly last year and had a fantastic time, I was delighted to accept a long-term volunteering position there for three months this spring. This role involved carrying out regular censusing and seabird productivity monitoring, as well as ringing some of the incredible birds found on Skokholm, which made the maintenance work and daily emptying the compost toilets feel more than worth it!
One of the main duties of the observatory is to monitor migrants, and ringing is carried out daily where weather allows. Heligoland traps are the primary catching method used for this since they can be used in more weather conditions than mist nets and require no set up. Early spring saw the arrival of lots of Phylloscs, providing ample opportunity to learn to age Chiffchaffs based on feather condition and to compare their identifying features such as primary projection against that of Willow Warblers. Another early migrant to arrive were the Swallows and whilst we didn’t catch many of these in the traps, we regularly had to free them from buildings where they were prospecting for nest sites, and ringed or processed them before releasing. I had the privilege of watching the progression of a swallow nest belonging to returning breeders outside my bedroom window, the cheeping of the chicks providing an early morning alarm clock. Late in spring there was regular passage of Blackcap and Whitethroat, along with a few Grasshopper Warblers and Spotted Flycatchers and the arrival of Sedge Warblers, some of which breed on the island.
While the Heligoland traps did a fantastic job of catching common migrants, they also surprised us with some unexpected species including Herring and Lesser Black-Backed Gulls, Skylark, Merlin, Oystercatcher, Moorhen, Mallard, and the first Nightjar to be ringed on the island since 1967. They also provided excitement when, whilst we were off the island doing a whole-island seabird count by boat, two Raven fledglings wandered into one of the traps and were caught upon our return. This meant that three of the island’s four resident Ravens were now ringed and provided a rare chance to ring full-grown Ravens away from a nest site. Since Heligoland traps are very rarely used on public nature reserves on the mainland, volunteering at an island bird observatory proved a fantastic opportunity to practice pushing them for the first time.
Another new catching method that I got to witness was leg-noosing. Being fortunate enough to have one of the very few people licensed to do this come and stay on the island we got to learn how this method can be used to catch adult Great Black-backed Gulls. This involved laying a noose around the nest of a gull and firing a remote trigger to tighten a noose around the birds legs when it comes in to land. The gull is then ringed or processed as efficiently as possible to be allowed to return to incubating its eggs. This was fascinating to watch and a good chance to learn to close metal and Darvic rings much larger those you
would use in normal mist netting. The Great Black-Backed Gulls often get resighted away from the island over winter. Once the eggs from these nests had hatched later in the season we went around hand catching the chicks and colour-ringing these so that multiple generations of each family group can be studied. A couple of weeks into our time on the island the first rays of spring sunshine welcomed in the beginning of the seabird monitoring season, and it quickly became obvious why Skokholm is nicknamed Dream Island. With one of the densest Manx Shearwater colonies in the world and more breeding European Storm-petrels than the rest of England and Wales combined, the island proved an incredible place to learn to monitor seabirds.
Survival of Manx Shearwaters on Skokholm is mainly monitored through regular ringing along a set transect at night time. This is an experience quite unlike any other, heading out into the dark, serenaded on busy nights by an almost deafening cacophony of eerie Manx Shearwater calls, and hand netting birds sat on the ground seemingly unbothered by human presence. This year we were regularly catching birds known from their ring sequences to be over 10 years old, but known ages of birds should increase over time as ringing has only been carried out consistently on the island since 2013 and individuals have been known to live for over 50 years. Remains found on census of Shearwaters predated by Great Black-backed Gulls were also checked for rings, giving valuable data on predation dynamics. In addition to the night time ringing of Shearwaters, there was also the opportunity to help with productivity monitoring in the study plots. The study burrows are natural nest chambers with a paving slab covering an access hole in the roof of the burrow, they are all
numbered and visited each year as part of a long-term study. The monitoring involved ringing or recording the ring number of both adult birds incubating in each burrow and noting which pairs had an egg. Later in the spring and summer the chicks are ringed with the number of chicks hatched and then successful fledglings being recorded and used to calculate productivity. The experience was often slightly nail-biting, carefully manoeuvring around the fragile ground and putting our arms down burrows, seeing if our hands met with a tail or a sharp hooked beak. However, it was incredible to handle such charismatic birds
and learn about the breeding history of ringed birds, with many having bred in the same burrows since the plots were established in 2012/13.
This photo is the final adult Manx Shearwater processed, completing burrow occupancy monitoring in the study plots for the year.
Having spent weeks watching the Razorbill chicks hatch and then grow up from the clifftops, it was exciting when, in June, we were allowed to clamber down into the boulder field and ring some. We practiced closing their difficult triangular-shaped rings in the ringing hut beforehand and after a couple of hours in the colony we had all successfully ringed a few chicks. One particular highlight was a long-term ringer on the island processing an adult which he had ringed as a chick years earlier, surprising since he has only ringed in the boulder field on a couple of occasions. Since Razorbills are faithful to their hatching site it is hoped that our ringed chicks will also be recaught in the coming years.
Another greatly studied species on the island is the Puffin. As well as monitoring burrow occupancy and productivity through watching the comings and goings at study burrows, adult survival is monitored through colour-ring resighting. Each day the puffins were watched for two hours and any with colour rings photographed and added to the resightings spreadsheet. This was partiularly crucial as this last winter saw storm after storm in the Atlantic with thousands of puffins washed up dead around the coastlines of Europe. By the end of June we had resighted just over 70% of the total number of birds known to be alive last year, hopefully this was increased further by our successors before the Puffins all headed off into the Atlantic after the breeding season. After monitoring from a research hide, it was nice to get some hands-on experience furtling and ringing chicks, and mist netting and colour ringing adults. Extracting adult Puffins from mist nets makes Blue Tits feel like angels but it was good practice extracting large birds and fantastic to think they may be resighted for many years to come and add to our understanding of Puffin ecology.
Being relatively new to bird ringing my time volunteering on Skokholm taught me a lot and I learnt skills I can apply both to general birding and my future ringing career. The experience was incredible and confirmed to me that I would love to work in Ornithology.
Footnote from me: I have been lucky enough to spend two sessions on Skokholm myself. Firstly as a trainee and secondly as a trainer. They were two of the most exciting and exhilarating times of my ringing life. As a trainee I got to ring Manx Shearwater, as did Ellie, and these two beauties:
I cannot wait to go back!