Project updates

By Thomas Weston

Introduction

The use of colour rings are widely used to increase the recovery rate of birds, meaning the individuals do not need to be recaught again. However, through the use of binoculars and cameras, colour rings can be read in the field, and submitted to national colour ringing projects increasing the number of resightings of an individual or population. Dan Gornall aims to understand the movements of Yellow-browed Warbler within Western Europe, through the use of colour ringing individuals throughout the UK. Dan's project aims to look at the trajectory of movements, and investigates whether there are subsequent southbound movements after birds initially follow a western trajectory reaching the westernmost limits of Europe in autumn. The use of colour rings reduces the need of recapture, help to identify wintering locations, and to identify stop-over duration of Yellow-browed Warblers arriving in Britain and Ireland. The colour rings are lightweight and used in a combination of colour rings and metal rings consisting of eight different colours used (red, orange, blue, green, yellow, purple, brown and white). Lundy was provided 10 combinations as part of the national colour ringing project, using all 10 in 2024 and resulted in a resighting of one of Lundy's colour ringed birds on the Isles of Scilly. We were then provided another 10 combinations as part of the project, with a single bird caught and colour ringed in 2025. All sightings are sent to Dan via his email: This email address is being protected from spambots. You need JavaScript enabled to view it..

Aims

To contribute to the wider national colour ringing project by targetting and capturing vagrant Yellow-browed Warblers on the island when they are present.

Methods

Regular mist netting in Millcombe throughout the autumn, alongside ad-hoc ringing when Yellow-browed Warblers were seen on the island were the most successful methods of capture on the island this year. The use of tape lure was used, to attract the individuals towards the net for capture. 

Results

Yellow-browed Warbler caught and ringed in Millcombe by Eleanor Harris

First colour ringed Yellow-browed Warbler in Millcombe by Eleanor Harris

During regular mist netting in Millcombe, two Yellow-browed Warblers were caught and colour ringed on the 4th October 2026. One of the birds was attracted to tape lure in Millcombe, and colour ringed with red, metal on the left leg, and then white, brown on the right leg. The bird was released after ringing and biometrics had been undertaken. The bird was still present around the valley in the afternoon, but no confirmed resightings were made after this date. The next bird caught was ringed 80 minutes later in St John's Valley. The bird was not attracted to a tape lure, but seemingly was moving through the valley with a flock of other warblers. The bird was colour ringed with red, metal on the left leg, and then brown, brown on the right leg. The bird was released after ringing and biometrics, and was seen on the 5th, 6th, 7th and 8th. Moroever, a bird seen and heard in the valley was not determined to be a colour ringed bird, but could have been the second colour ringed individual. During the arrival of these two birds, an additional two unringed birds were seen on the 4th October 2026 with one bird in St Helens and one in Rüppells Quarry. The former unringed bird was seen until the 5th, with the latter seen up to the 14th at least, though was elusive when trying to target this bird. Another unringed bird, the 5th of the year, was seen on 31st October at Rüppells Quarry, with this bird not seen on the morning of the 1st November. However, a sixth and final bird of the year was seen on the 3rd November, passing through Rüppells Quarry heading north and not seen thereafter. The average number of days an individual remained on the island was 4 days, though this was skewed by one long staying individual.

Discussion

The arrival of four Yellow-browed Warblers was noteworthy, with two birds caught and ringed in the Millcombe area. The use of colour rings was intrumental in determining the number of days the birds were present on the island, and the number of individuals recorded throughout the autumn. In total, six Yellow-browed Warblers on the island were recorded, and this was quite low compared to 2024, however more than in 2025. The number of days individuals resided on the island varied between a few minutes to 10 days. The average duration was 4 days, though this was skewed by the bird remaining at Rüppell's Quarry for 11 days. Overall, numbers of individuals on the island, as with the rest of the UK, seem to be increasing in numbers. Two of the birds were caught in Millcombe, though targetting individuals on the east coast will be important to help contributing to the national colour ringing project in future years.

Conclusion

It was great to be able to contribute to the project again this year with two newly colour ringed birds for the project. Albeit, four Yellow-browed Warblers were missed, and left unringed, it will be interesting to see how we can contribute to the project in the future.

By Thomas Weston

No Little Buntings have been recorded on the island this year, and therefore no colour ringing has taken place to help the project.

Project Results to be updated if this changes.

By Thomas Weston

Introduction

One of our breeding Large Gulls on the island, the Herring Gull by Thomas Weston

This survey was part of the three year scheduled monitoring of Large Gulls on the island since the early 2000's. 

Aims

• To complete the four-year RSPB Large Gull survey to compare distribution and numbers compared to previous Large Gull survey results.
• To continue the colour ringing of Large Gulls to understand survival and return rates.

Methods

RSPB Large Gull Survey

The RSPB arrived for one week in mid-May to complete the Large Gull survey. Large Gulls in mid-May should be paired up, present in the colonies, and sat on nests. The standardised survey of Large Gulls on the island required splitting the island into sections and using the Seabird Register, the island was split into six sections. Within each section, viewpoints were labelled to allow the whole section to be surveyed from specific vantage points. Working in pairs, consisting of one Bird Observatory volunteer/staff member paired to an RSPB staff member, the nonintrusive monitoring was undertaken. The observers stood at the chosen viewpoint and recorded the species present, the number of individuals, the number of Apparently Occupied Nests, and mapped the distribution of the colony within the section. The results were compared to previous survey, to determine any recent population changes, as well as to the surveys from the early 2000’s, whereby the population was considered a baseline due to the rat eradication being completed, and population estimates were more standardised. 

Colour ringing

At colonies where access could be achieved, licenced bird ringing staff, and volunteers visited the Large Gull colonies in late June. The chicks were caught by hand, ringed with a British Trust for Ornithology (BTO) metal ring and fitted with a colour ring where possible. The chicks’ biometrics were taken including weight and feather stage. Chicks that were too small for colour ringing were metal ringed only, and chicks that were in poorer condition were also metal ringed only. Colonies were only accessed for an hour maximum and where possible, the number of nests were recorded per colony.

Results

RSPB Large Gull Survey

In 2026, the total island count for Lesser Black-backed Gulls pairs was 93 apparent breeding pairs: a decline of 3% since the 2023 survey, and a 79% decline from counts of over 400 in the early 2000s. There were 240 apparent breeding pairs of Herring Gulls: a decline of 2% since the 2023 survey, and a 69% decline from counts of over 700 in the early 2000s. Great Black-backed Gulls pairs fell to 28 apparent breeding pairs: a decrease of 13% since the 2023 survey, and a 20% decline from counts of over 50 in the early 2000s.

Colour ringing

In total, two colonies in the northeast of the island, one on the west, and one in the southwest of the island were all accessed. Altogether, 13 Herring Gulls and a single Great Black-Backed Gull were fitted with British Trust for Ornithology metal rings and weighed, but no colour rings were fitted this year due to size and condition of the chicks.

Discussion

The RSPB data from the Large Gull Survey 2026 demonstrates a continued decline in the three Large Gull species on the island since the Rat Eradication in the early 2000’s. This is the opposite to the other seabird species found on the island, with data from the survey showing Lesser Black-Backed Gulls had declined the greatest, followed by the Herring Gulls, and the Great Black-Backed Gulls too.

These long-lived, colonial species need to produce enough chicks to replace themselves. The chicks that fledge need to survive their first winter and return to the island to breed at the age of 3 or 4 when individuals begin to think about nesting. On island, during the nesting period, the birds are amongst the rocky cliffs, with some colonies within areas of Bracken. The different feeding strategies used by Large Gulls to gain enough food for their chicks is important to ensure successful fledging from the colony. It is known from studies across the country that the Lesser Black-Backed Gulls from coastal breeding grounds are highly pelagic, finding fish out at sea and in the Atlantic. From observational data, it is shown that the Herring Gulls are feeding in agricultural farmland on the mainland, with evidence of worms and plastic gloves found in regurgitated pellets, and a continual presence around the domestic sheep feed on island too. Unfortunately, without tracking of the Herring Gulls on the island, we can assume that some birds are also finding the preferred fish too, though from observational data it is difficult to determine. Moreover, the Great Black-Backed Gulls are scavengers, they are known to feed on the other gull chicks, as well as the chicks of a range of seabirds on the island. Observational data from the season shows they have been seen amongst feeding frenzies offshore and sometimes took seabird chicks from the cliffs. However, it seems as though the amount of available food is low. Taking feeding behaviour into account, the colony data still shows not only a reduction in numbers, but a reduction in the size of the colony too, with some colonies consisting of only a few breeding birds in a specific area. Thus, potentially because of environmental effects resulting in low productivity and a reduction in the number of breeding adults present.

During the Large Gull chick ringing period, whereby we entered the colonies for ringing and colour ringing, we found that the Large Gull chicks were too small for colour ringing. Where access could be made, there seemed to be high mortality amongst the chicks this year. There were empty nests recorded, and eggs with failed broods in them too showing that breeding success this year was poor. It is assumed, though cannot be backed up yet, but the breeding success of the Large Gulls has been low for a few years with a lack of individuals between 1-3 years of age present. We are unsure the effects of Highly Pathogenic Avian Flu (HPAI) in 2021/22, however it was noted that adults were affected than juveniles. Juveniles who were ringed last year were not seen this year on the island, and observational counts of juveniles amongst Large Gull roost flocks on the plateau showed that juveniles were not present. Therefore, a mixture of low reproduction, low replacement, but potentially good adult survival, has resulted in a gradual decrease in the population. A decrease in the number of adults from HPAI could have shown a catastrophic loss of birds within a few years, however this does not seem to be the case in the previous three years since the last survey.

Conclusion

We thank the RSPB for undertaking this survey on the island. Large Gulls continue to show a downward trend on the island, and we aim to continue monitoring of the colonies to understand the causes of decline.

By Thomas Weston

Introduction

Understanding the breeding ecology and the success of our breeding seabirds is critical to understanding how our populations of birds are doing on island. Manx Shearwaters are a success story for the island, having featured both on a Merrel Advert by Nadeem Perera at the start of the year, and then subsequently on ITV News when talking about how Seabird Numbers Soar on Lundy Island 20 years since the Rat Eradication. For Manx Shearwaters, monitoring of the species can be undertaken through different survey methods. This could include using visual observations whereby the use of counts and estimates are analysed (see our Jenny's Cove count article), through standardised surveys every few years (see our Large Gull survey article), or through productivity monitoring of a specific seabird species (see our 2026 seabird article). With 2027 being the survey year for Manx Shearwaters on the island, understanding the breeding ecology and movements during the breeding season, in years that are not whole-isalnd surveys, is fundemental to our understanding and monitoring of the species.

This year was no different as with help from Eleanor Harris, Emma Abel, Jessie Dermody, Tara McEvoy-Wilding, Simon Parker, Chloe Langmead, Kirsty Cox, and Greg Lee the monitoring of the Manx Shearwater artificial boxes could be completed. In addition to this, understanding the movements of breeding adults during chick feeding was achieved through help from additional researchers from OxNav including Tim Guillford was joined by former Lundy warden Joe Parker. Additionally, engagement has been important, with additional visitors and helpers such as the 2026 Young Birders group coming to visit the boxes, as well as the people who help maintain the boxes; Tony Taylor, Adam Hobbs, the LFS work party, and the Ranger team led by Roger White.      

Methodology

Monitoring the boxes

In total, across the study colony there are 30 artificial Manx Shearwater boxes whereby access into the burrows of the birds can be achieved to monitor individuals.  The first Manx Shearwater of the year was seen on the 4th March. As a result, monitoring of the Manx Shearwater artificial boxes started on the 21st March. Checking of the boxes continued every 4-5 days. At each visit, any signs of nesting were noted i.e feathers, smell or droppings, an adult in the box, or an incubating bird on an egg. For those adults who were present, the metal BTO ring was read, and biometrics were taken. To reduce disturbance, wing and weight was taken before the bird was returned to the box with all 30 boxes checked each visit. For each box check, the activity of the boxes were recorded with the final box status either prospecting, unoccupied, failed, or fledged. Prospecting birds were those who had shown signs up to June, without laying an egg. In comparison, boxes showing no signs of us throughout the season were considered unoccupied. Where an egg was laid, the date the egg was recorded helped predict an expected hatch date. Hatch dates have a range of five days, so we used 49 days as the average hatch date. Based on the last date an egg was not seen, and the first date the egg was seen, an estimated hatching period was calculated. As a result, one of the boxes was expected to hatch between the 19th and the 25th June. On the earliest hatch date a check is made to determine if hatching was successful. If hatching had not occurred on the first date, a subsequent check on the latest expected hatch date was achieved, wth checks made once a week for those eggs that had not hatched within the hatch period. If the egg hatched on or around the expected hatch date, an estimation of the age of the chick at first chick observation was made. For example, chicks who were emerging from the egg would have a hatch date of the day later, day 1 chicks tended to be damp and in the vacinity of the egg, whereby day 2-4 chicks had an egg tooth but were away from the egg shell. Chicks that were found later than this would be considered a 5+ day old chick. Checks were made once a week to weigh the chick, and an expected fledge date was calculated 60 days after the known hatch date, or 60 days after the estimated hatch date. Chick weighing was achieved by use of a bird bag and a persola. The weights were used to determine peak mass, a measure of survival and fledging success. If the chick died before fledging, or the egg never hatched, a cause of death was determined, and the box outcome was considered as 'Failed'. However, if the chick successfully fledged, the box outcome was considered as 'Fledged'.

Understanding feeding behaviour 

In addition to the box checks, OxNav were keen to deploy GPS/GSM tags for each successful pair of Manx Shearwaters monitored. Their aim was to understand the feeding ecology whilst Manx Shearwaters were in the chick raising period. To understand these movements, Tim Guilford from OxNav came over for a week in June. To begin, the team retrieved GLS tags fitted in 2025. These tags recorded the migration routes based on sun light levels (data being anaylsed) and were mounted to a ring on the leg. To continue their GLS work, the team redeployed GLS tags for collection in 2027 with this data currently being collected. In addition, to understand movements, the other parent not fitted with the GLS was fitted with a lightwight GSM/GPS tag attached to the bird using a small back mounted tag. These tags are light-weight and are used for understanding feeding behaviour during the chick rearing process. The tag, solar charged by the sun, had an expected lifespan of 8 weeks before the battery finished and the tag fell off. The data was sent via the mobile phone network so we could 'live stream' the movements of the birds whilst they were away from the island. Interestingly, we were able to see dive depth and how fast birds were flying too, however, due to the data still being analysed, and as a result, we can only share a small section of the work.   

Results

Monitoring the boxes

The boxes were monitored by the team from the 21st March 2026 to the 19th September 2026. In total, signs of activity were seen in 15 out of the 30 artificial boxes. Based on our box status definitions, 2 pairs were considered prospecting, 2 failed at egg stage, and 11 chicks successfully fledged. As a result, productivity this year was calculated at 0.73 which is high for the study burrows. Our efforts this year monitoring the artificial boxes have shown that the laying date for our birds was around the start of May. The expected hatch dates were calculated and the average hatch date was around the 3rd week of June. Chick feeding was very productive, and peak mass of the chicks was roughly around the 25th August this year whereby some chicks weighed up to 600g at peak mass. Even though there was one late chick, the majority of chicks fledged by the 1st September, with the last chick fledging around the 10th September. The birds that failed had both bred successfully over the past 2-3yrs and so this may have been a year where energy levels were lower than normal and desertion at egg stage was potentially high. 

Understanding feeding behaviour 

A rough view of our Manx Shearwater tracks. The area highlighted in green shows the local feeding for the chick, whereas the area highlighted in yellow shows the feeding areas used by the parents to sustain themselves. OxNav

In total, 10 Manx Shearwaters were GPS/GSM tagged by Tim Guillford and the OxNav research group with funding from Natural England. Without showing exact routes and feeding sites, this is a rough idea of where the birds are heading to feed whilst breeding on Lundy.

Discussion

The success of the chicks in the boxes this year was a surprise. The locally wintering seabirds that breed on Lundy saw a decrease in their survival overwinter, presumably due to the harsh winter weather just before they arrived back to breed. However, the Manx Shearwaters were certainly different, birds arrived back to the artificial boxes around their average date in good numbers. Last year, a couple more breeding pairs attempted to nest, though this year the breeding success of those who arrived back was higher. Overall, egg laying was a little later than normal, but synchronised, with the hatch date around the third week of June typical for the island. At locations such as Skokholm and Skomer, hatch date is slightly later i.e the first week of July, and the further North you go, the later the hatching occurs. This means birds in the Faroe Islands are much later than those on Lundy, and fledge later due to this this. Overall, hatching success was high with two eggs failing at this period. The adults had previously nested two or three years running so to take a year off for such a long lived species is not an issue. Last year was apparently a poor year for the Manx Shearwaters across the island. Looking at the productivity of the artificial boxes, productivity was higher than the estimate of 0.64 last year with this year's productivity being 0.73. This has led to an exceptional year for our artificial box birds, and it seems that it has been replicated over the island as a whole. By going out in the daytime and nighttime to Manx Shearwater colonies where they nest in natural burrows, breeding success seems to have been high across the island. Colonies to the east, south and west show that with every 11 alive chicks, 1 dead chick was found. This does not give an indication of how many eggs failed during the nesting period (which is higher than the number of chicks that fail), but it does seem a good measure of a successful year overall. We did not have enough time this summer to check the colonies in the north, but we can only assume breeding success was good here too. Taking into consideration there are roughly 15,000 pairs on the island, we expect roughly 10,000 Manx Shearwater chicks fledged this autumn if the 73% of all Manx Shearwaters successfully bred and fledged a chick.

The tagging data was super exciting. Tim Guilford from OxNav and the team were amazing and we really thank them for providing an extra layer of data to the Manx Shearwater boxes. Tim explained how in the previous 2011-2012 study, birds tagged did not go any further south than Cornwall, and fed mostly in the Celtic and Irish sea. However, there has been a shift. Birds from the Welsh islands tend to feed in these waters nowadays and 'our' Lundy birds have shifted their behaviour slightly. Initial results of the tagging show that all of our birds undertake both chick feeding foraging trips, and self sustaining foraging trips. The chick feeding trips were more local feeding in the areas north of Cornwall and Devon, though a few trips were into the Celtic sea. These trips were a few days in length resulting in regular feeding of the chick. In comparison, the self sustaining foraging trips to replenish the adult's resources after spending days feeding the chick were further afield and mostly off the north coast of France. However, there were birds in the English Channel that were feeding too. By continuing the monitoring of the chicks during the period the tag was on the bird showed that chicks gained weight quickly. Chick wieghts were high, with the largest chicks reaching 600g at peak mass. This is phenomenal, and some very well fed chicks this year. This potentially was a reason why productivity was so high, good foraging and local food? In the marine heatwaves we had throughout the summer, was this really the case? Or was there new food arriving to excape the heat from further south? Something we are unsure about, but it was great to see such a high number of chicks fledge. Moreover, no chicks or adults failed due to the tags, or any obvious tag effects which was excellent. 

Conclusion

A very successful year for the Manx Shearwater artificial boxes both in the monitoring and tracking. We aim to continue the box checks next year whilst undertaking the full island survey too. The retrieval of the GLS tags in 2027 will be able to provide an insite into migration routes used by our Lundy Manx Shearwaters.