Isle of May NNR - Annual Report 2021
Bex Outram
David Steel
Published: 2023
1. Biological recording
1.1 Introduction to breeding seabirds
NatureScot monitors breeding seabird populations as part of its management of the National Nature Reserve as well as to report on the Special Protection Area (SPA) qualifying species.
Further seabird monitoring is carried out by the UK Centre for Ecology and Hydrology (UKCEH), under contract to the Joint Nature Conservation Committee (JNCC). Data from this monitoring work is integral to JNCC’s national system of long-term monitoring for seabird populations, as the island is one of four strategic monitoring sites in Great Britain. The other three sites are Skomer, Canna and Fair Isle.
NatureScot carries out the population monitoring of the cliff-nesting seabirds, gulls, eiders and terns. UKCEH monitors the breeding success, survival and food intake of the auks, shags, fulmar and kittiwakes. UKCEH, along with the Isle of May Bird Observatory Trust (IOMBOT), provides numerous other pieces of data invaluable to this report, such as the dates of first eggs and chicks and sightings of migrant birds, cetaceans and lepidoptera.
1.2 Population monitoring of cliff-nesting seabirds
1.2.1 Sections and timings
The detailed AIC methodology for the five cliff-nesting bird species (guillemot, razorbill, kittiwake, fulmar and shag) is set out in the Isle of May Monitoring Handbook (NatureScot, 2001, revised 2002 and 2011). The island is divided into the same standardised count sections as have been used in previous years. All species are counted once during the first week in June to capture a snapshot of the populations. 2018 saw the addition of counts from the sea, to allow those birds nesting in caves and areas unseen from land to be included in the population counts.
The majority of the all-island count was carried out by Bex Outram from 4th to 10th June. In sections that were sensitive, data was provided by Mark Newell of UKCEH to avoid additional disturbance.
1.2.2 Cornerstone plot counts
The counts of individual razorbill and guillemot during the AIC are converted to estimates of pair numbers. The number of both razorbill and guillemot pairs breeding at the Cornerstone plot is monitored by UKCEH. A count of each species was made at the Cornerstone plot at the beginning of every count session.
For each species, the number of pairs known to be breeding at Cornerstone was divided by the relevant Cornerstone count, for every count session. This provided a “k” value which represents the difference between the number of individuals counted and the number of actual breeding pairs. By multiplying this “k-value” with the number of individual birds counted during a session, the number of pairs can be estimated for that session. Keeping raw counts to within a few hours of the Cornerstone plot count allows for the variation in attendance of adults on the cliffs.
1.3 Results of cliff-nesting seabirds
The overall 2021 counts for each of the five cliff-nesting species on the Isle of May are shown in Table 14.1. Counts from previous years are also shown for comparison. Table 14.3 shows the different section totals for each species. A comparison from the previous year, percentage change, is seen in Table 14.2. Breeding success and return rates are shown in Table 14.7 and Table 14.8 respectively.
1.3.1 Fulmar
The number of apparently occupied sites (AOS) was 321 pairs, three less than last season.

Area graph showing numbers of fulmar, apparently occupied sites (AOS) from 1990 to 2021. Year is along the x axis, from 1990 to 2021, and AOS is along the y axis, with a scale that runs from 0 to 450. Counts are quite variable.
A visual representation of some of the data from Table 14.1, which gives figures for fulmar, shag, cormorants, guillemot, kittiwake and razorbill.
The first egg was seen on 16th May, the first chick was seen on 2nd July, with the first fledged bird seen in late August. The breeding success was 0.49 (chicks per pairs monitored), above the long-term average.
1.3.2 Shag

Area graph showing numbers of breeding shag, apparently occupied nests (AON) from 1990 to 2021. Year is along the x axis, from 1990 to 2021, and AON is along the y axis, with a scale that runs from 0 to 1,800. Counts are quite variable and show an overall decline.
A visual representation of some of the data from Table 14.1, which gives figures for fulmar, shag, cormorants, guillemot, kittiwake and razorbill.
The number of apparently occupied nests (AON) was 491, a decrease of 4 AON from last year.
The plots monitored by UKCEH showed the highest return rate (94.2%) of adults. They also had a good breeding season, 2.04 chicks fledging per breeding pair, the second highest productivity figure.
The first shag egg was noted on 25th March at Horse Hole and the first chick hatched on 27th April from the same nest.
1.3.3 Kittiwake
Continuing the increase last year, the kittiwakes increased 5% to 5,193 AON, the highest count since 1997 (6,518 AON).

Area graph showing the number of breeding kittiwake, apparently occupied nests (AON) from 1990 to 2021. Year is along the x axis, from 1990 to 2021, and AON is along the y axis, with a scale running from 0 to 9,000. Counts are quite variable and show an overall decline.
A visual representation of some of the data from Table 14.1, which gives figures for fulmar, shag, cormorants, guillemot, kittiwake and razorbill.
The kittiwakes experienced a higher than average return rate, 84.3%, from the plots monitored and went on to have a good breeding season with a productivity of 1.34, the second highest.
The first egg was seen on 17th May, with the first chick on 15th June and first fledged chick seen taking flight on 20th July.
1.3.4 Guillemot
The total number of individual guillemots has increased 12% to 26,134. To calculate the number of breeding pairs, the ‘k’ value is used: to determine this factor, the number of breeding pairs at the Cornerstone plot is used. This is provided by Mark Newell at UKCEH. This year, the Cornerstone plot increased by 78 pairs to 335.
Year | No. of pairs at Cornerstone |
---|---|
2007 |
198 |
2008 |
191 |
2009 |
198 |
2010 |
201 |
2011 |
205 |
2012 |
195 |
2013 |
193 |
2014 |
194 |
2015 |
220 |
2016 |
229 |
2017 |
232 |
2018 |
228 |
2019 |
238 |
2020 |
257 |
2021 |
335 |
Using the ‘k’ value, the number of guillemot pairs has increased by 7.7% to 18,156 pairs.

Line graph showing the counts of individuals and estimated pairs of guillemot from 1990 to 2021. Year is along the x axis, from 1990 to 2021, and Count is along the y axis, with a scale that runs from 0 to 30,000. There are two lines on the graph, for raw count and estimated pairs. Numbers have remained relatively stable overall.
A visual representation of some of the data from Table 14.1, which gives figures for fulmar, shag, cormorants, guillemot, kittiwake and razorbill.
The return rate of the marked individuals was 86.8%, lower than the long-term average. The guillemot breeding season was average, with each monitored breeding pair producing 0.74 chicks.
The first egg was seen on 26th April, the first chick on 29th May, and the first jumpling was noted leaving the cliffs on 17th June.
1.3.5 Razorbill
The number of individual razorbills decreased slightly, down 1.7%. However, when converted into breeding pairs using the ‘k’value, the number of breeding pairs increased 16.7% to 4,813 pairs. The ‘k’ value is determined by using the number of breeding pairs in the Cornerstone plot, provided by Mark Newell of UKCEH. The breeding pairs in this plot have increased to 108 pairs, the highest figure on record: 4,813 breeding pairs of razorbills is the highest figure the Isle of May has recorded.
Year | No of pairs at Cornerstone |
---|---|
2007 | 71 |
2008 | 64 |
2009 | 67 |
2020 | 62 |
2011 | 69 |
2012 | 72 |
2013 | 74 |
2014 | 72 |
2015 | 81 |
2016 | 79 |
2017 | 82 |
2018 | 87 |
2019 | 91 |
2020 | 92 |
2021 | 108 |

Line graph showing the numbers of individuals and estimated pairs of razorbill from 1990 to 2021. Year is along the x axis, from 1990 to 2021, and Count is along the y axis, with a scale that runs from 0 to 7,000. There are two lines on the graph, for raw count and estimated pairs. Numbers have been quite variable, with an overall upward trend.
A visual representation of some of the data from Table 14.1, which gives figures for fulmar, shag, cormorants, guillemot, kittiwake and razorbill.
The return rate of colour-ringed individuals is 90%, which is above the long-term average. Razorbills also had an average breeding season with a below-average productivity of 0.55.
The first egg was seen on 25th April, the first chick on 30th May and the first fledged chick on 19th June.
1.3.6 Cormorants
Cormorants are easily disturbed birds, flighty in nature, and with this “colony” at the north-west end of Rona there were no visits to this area. Observations were made from the North fog horn and from the boats. This showed that 14 nests were occupied this season, up 10 nests from 2020.
1.4 Population monitoring of ground-nesting seabirds
1.4.1 Puffin
The first puffins carrying fish were seen on 26th May; this indicates that the first chicks had hatched. The last puffin carrying fish was seen in late August; however, the majority of the colony had left earlier in the month.
The return rate of colour-ringed puffins was 91.3%; this is above the long-term average. The puffins had a good breeding success, with 0.8 chicks per pair, above average.
UKCEH undertook a puffin census in 2017, which resulted in a count of 39,200 occupied burrows with a 95% confidence level of between 32,200 – 46,300 occupied burrows.
1.4.2 Herring and lesser black-backed gull
The first incubating herring gull was seen on the 26th April, the first chick was noted on 30th May, with the first chick fledging on 4th July. The first lesser black-backed gull egg was recorded on 6th May.

Line graph showing estimated nest totals for herring and lesser black-backed gull from 1982 to 2021. Year is along the x axis, from 1982 to 2021, and Corrected Count is along the y axis, with a scale that runs from 0 to 8,000. There are three lines on the graph, for lesser black-backed gull, herring gull and total gull nests. Numbers have been relatively stable, with an overall upward trend.
The lines for lesser black-backed and herring gull are a visual representation of some of the data from Table 14.4, which gives figures for lesser black-backed gulls, herring gulls, great black-backed gulls, terns and eider.
The data for total apparently occupied herring and lesser black-backed gull nests are summarised in the following table, Table 3.
Year | Total apparently occupied herring and lesser black-backed gull nests |
---|---|
1982 |
2850 |
1983 |
3963 |
1984 |
3718 |
1985 |
3198 |
1986 |
2625 |
1987 |
2651 |
1988 |
2274 |
1989 |
2272 |
1990 |
2169 |
1991 |
2235 |
1992 |
2213 |
1993 |
3318 |
1994 |
3392 |
1995 |
4189 |
1996 |
4610 |
1997 |
4396 |
1998 |
4133 |
1999 |
4634 |
2000 |
4329 |
2001 |
4048 |
2002 |
3565 |
2003 |
3605 |
2004 |
3649 |
2005 |
3414 |
2006 |
4583 |
2007 |
4519 |
2008 |
4905 |
2010 |
5563 |
2012 |
5633 |
2014 |
6247 |
2016 |
5723 |
2018 |
5082 |
2021 |
6907 |
Gull management
As part of the Isle of May management plan, designated gull-free zones were introduced in 1997 to increase tern productivity. These areas are North Plateau South to Lochside, East and West Braes, Beacon, St Andrews Well, Cross Park and Tennis Courts. Five nests were removed from the Lowlight to St Andrews well and 39 nests were removed from Kirkhaven.
Specialist gulls that predated within the tern breeding colony were identified through tern watches and were removed; a NatureScot marksman shot one herring and one lesser black-backed gull at Kirkhaven on 9th July.
1.4.3 Great black-backed gull
The first great black-backed gull egg was seen on 16th April, the first chicks were seen on Rona on 18th May and the first fledged chick on 7th July.
Nest count
The great black-backed gull population has increased to 116 pairs, the highest breeding count for the reserve. The apparently occupied nests were recorded and mapped throughout the season. The population on Rona was counted from the North Horn on 14th May; nests were added through Sam Langlois-Lopez, PhD student, monitoring including the “mainland” population.

Area graph showing number of breeding great black-backed gull, apparently occupied nests (AON) from 1999 to 2021. Year is along the x axis, from 1999 to 2021, and AON is along the y axis, with a scale that runs from 0 to 140. Numbers have increased.
A visual representation of some of the data from Table 14.4, which gives figures for lesser black-backed gulls, herring gulls, great black-backed gulls, terns and eider.
Productivity
Forty-six nests were monitored on Rona to establish a breeding productivity. Numbered stakes were placed next to nests and with regular visits the number of eggs, chicks and fledged chicks was noted. The overall breeding success was low, 0.61, the lowest since the colour scheme was in place.
With the help of the IOMBOT and Mark Oksien we were able to continue with the colour-ringing scheme. The yellow colour-rings were attached to the birds’ left leg whilst a metal BTO ring was attached to the right leg. A total of 40 BTO rings were deployed and 26 colour-rings.
Figures for: | 2019 | 2018 | 2017 | 2016 | 2015 |
---|---|---|---|---|---|
Nests monitored |
46 |
42 |
51 |
45 |
28 |
Breeding attempts |
46 |
42 |
51 |
45 |
28 |
Number of eggs |
120 |
117 |
140 |
124 |
75 |
Average clutch size |
2.6 |
2.79 |
2.75 |
2.76 |
2.68 |
Hatched eggs |
85 |
78 |
117 |
91 |
57 |
Hatching success |
0.71 |
0.67 |
0.84 |
0.73 |
0.76 |
Number fledged |
28 |
62 |
88 |
32 |
33 |
Productivity |
0.61 |
1.48 |
1.73 |
0.71 |
1.18 |
1.4.4 Terns
For previous population counts, see Table 14.4, and for how 2020 counts relate to the previous season, see Table 14.5.
1.4.4.1 Roseate tern
Despite a pair summering on the island, there was no breeding attempt made.
1.4.4.2 Sandwich tern
Sandwich terns were seen throughout the season and ten pairs bred at the Beacon colony. The first egg was discovered on 31st May, the first chick on 25th June, with the first chick fledging on 3rd August. Of the ten nests, each had one egg present and nine went on to successfully fledge chicks (productivity of 0.9).
1.4.4.3 Arctic and common tern
The first Arctic tern egg was laid on 22nd May at the Jetty Triangle, and the first chick hatched on 16th June, with the first fledged chick seen on 9th July in the Mouse House field.
The first common tern egg was seen on 26th May at the Beacon tern terrace, the first chick on 18th June, with the first fledged chick seen on 12th July. The final chick departed the island on 1st September.
Breeding pairs
Each year, around three weeks after the first egg-laying date, all tern nests on the island are counted to get a measure of total tern nest occupation. On 18th June, a whole colony count was completed with additional occupied nests added later in the season from monitored plots and extra counts of the Beacon terraces from the Beacon roof. The count was completed by Bex Outram, David Steel, Chris Cachia-Zammit and Laura Kamp. A total of 382 pairs of Arctic terns bred, 23 common terns (see Table 14.5).

Line graph showing counted number of nests of Arctic, common and Sandwich terns, apparently occupied nests (AON) from 1990 to 2021. Year is along the x axis, from 1990 to 2021, and AON is along the y axis, with a scale that runs from 0 to 950. There are three lines on the graph, for Arctic tern, common tern and Sandwich tern. Numbers for Arctic tern have been very variable. Numbers for common and Sandwich tern have been variable initially but have decreased to low levels.
A visual representation of some of the data from Table 14.4, which gives figures for lesser black-backed gulls, herring gulls, great black-backed gulls, terns and eider.
Productivity
Four plots were chosen to monitor the breeding success of the Arctic terns this season. Each nest was marked and the number of eggs, chicks and fledged chicks noted. All chicks in these areas were ringed, helping keep track of the number of chicks that fledged from each plot. This was then used to calculate a productivity figure. The table below shows the different areas monitored and their productivity and the overall productivity figure: 0.55 chicks fledging per pair, an increase on last year’s figure of 0.03.
Figures for: | Mouse House Base | Jetty Triangle | Overall |
---|---|---|---|
Nests monitored |
89 |
94 |
183 |
Breeding attempts |
89 |
94 |
183 |
Eggs |
129 |
167 |
296 |
Average clutch size |
1.45 |
1.78 |
1.62 |
Number hatched eggs |
108 |
78 |
186 |
Hatching success |
0.84 |
0.47 |
0.63 |
Fledged |
71 |
40 |
111 |
Productivity |
0.80 |
0.43 |
0.61 |
Predation
As usual, the main tern watches were undertaken at the main Arctic tern colonies at Kirkhaven and the Beacon area of the island. A total of 134 hours were completed at all stages of the breeding cycle from incubation to fledging stage. The season proved very successful, with predation at a minimum, and only one specialist gull was identified and removed by a NatureScot marksman. This, combined with protective measures such as tern nest boxes and the use of garden canes to help protect vulnerable young, proved effective in having a good tern season.
1.4.5 Eider
The first sitting female was seen on 20th April, with the first brood of duckling seen on Rona on 9th May.
Nest count
No nest count was conducted this year.

Line graph showing nest counts and corrected estimates of breeding eider, apparently occupied nests (AON) from 1990 to 2018. Year is along the x axis, from 1990 to 2018, and AON is along the y axis, with a scale that runs from 0 to 1,400. There are two lines on the graph, for raw count and population estimates. Numbers have remained relatively stable.
A visual representation of some of the data from Table 14.4, which gives figures for lesser black-backed gulls, herring gulls, great black-backed gulls, terns and eider.
Eider management
No management specific to eiders was undertaken this year. Visitors were warned during their introductory talk that females would be nesting close to the path network and of the potential risk of coming across a female taking her ducklings to water, and advised to give them a wide berth. Some ducklings were found paralysed from nettle stings; these were kept in a box for an hour or so until they had recovered and then put with females and ducklings on the Loch, who took them into their crèche.
1.5 Other breeding birds
These are observations of numbers from around the island from NatureScot staff and volunteers, UKCEH and members of the Isle of May Bird Observatory.
Manx Shearwater (Puffinus puffinus)
Work by David and Margaret Thorne and Harry Urquhart, IOMBOT, identified nest activity on the island and identified one occupied burrow. The same male and a female were seen and recorded regularly at the burrow until mid-August but no breeding attempt was made.
Shelduck (Tadorna tadorna)
During the early season there appeared to be just two pairs around the island. Only one female was seen with ducklings this year: on 10th June, a female and nine duckling were seen leaving East Tarbet.
Year | No. of pairs |
---|---|
2007 |
3 - 4 |
2008 |
5 |
2009 |
6 |
2010 |
6 |
2011 |
4 – 8 |
2012 |
6 |
2013 |
4 |
2014 |
3-4 |
2015 |
3-4 |
2016 |
4 |
2017 |
3-4 |
2018 |
3 |
2019 |
4 |
2020 |
No count |
2021 |
2 |
Mallard (Anas platyrhynchos)
One pair of mallard were seen regularly on the loch. On 22nd June, a female and five ducklings were seen on the loch. On 29th June, a female and three small ducklings were seen on Rona, most probably a different female.
Year | No. of pairs |
---|---|
2007 |
2 |
2008 |
0 |
2009 |
0 |
2010 |
0 |
2011 |
0 |
2012 |
0 |
2013 |
2 |
2014 |
3 |
2015 |
0 |
2016 |
0 |
2017 |
0 |
2018 |
0 |
2019 |
1 |
2020 |
No count |
2021 |
2 |
Oystercatcher (Haematopus ostralegus)
This year, a total of 17 nests were identified. Although no monitoring of the nests was undertaken, several pairs successfully fledged chicks.
Year | No. of pairs |
---|---|
2007 |
19 |
2008 |
19 |
2009 |
17 |
2010 |
17 |
2011 |
14 |
2012 |
16 |
2013 |
9 |
2014 |
20 |
2015 |
19 |
2016 |
24 |
2017 |
13 |
2018 |
20 |
2019 |
25 |
2020 |
No count |
2021 |
17 |
Feral pigeon (Columba livia (domest.))
No specific counts were made of feral pigeons on the island. They nest on the island in burrows and rock crevices.
Swallow (Hirundo rustica)
Three pairs bred on the island; a pair in the coal shed, a pair in the artificial nest cups at the visitor centre and another whose nest location was not found. All had fledged two broods, with the last of the family party remaining until the end of September.
Year | No. of pairs |
---|---|
2007 |
0 |
2008 |
0 |
2009 |
0 |
2010 |
0 |
2011 |
0 |
2012 |
2 |
2013 |
3 |
2014 |
3 |
2015 |
6 |
2016 |
4 |
2017 |
4 |
2018 |
4 |
2019 |
1 |
2020 |
4 |
2021 |
3 |
Rock pipit (Anthus petrosus)
The first rock pipit with nesting material was noted on 19th April, the first chick on 15th May. Breeding territories were plotted on a map, with twenty four being noted through the season.
Year | No. of pairs |
---|---|
2007 |
8-9 |
2008 |
9-10 |
2009 |
12-14 |
2010 |
15 |
2011 |
13 |
2012 |
23 |
2013 |
18 |
2014 |
24 |
2015 |
24 |
2016 |
20 |
2017 |
15 |
2018 |
23 |
2019 |
No count |
2020 |
No count |
2021 |
24 |
Pied wagtail (Motacilla alba)
Pied wagtail territories were plotted on a map throughout the season and approximately sixteen pairs bred.
Year | No. of pairs |
---|---|
2007 |
8 |
2008 |
9 |
2009 |
11 |
2010 |
12 |
2011 |
13 |
2012 |
18 |
2013 |
14 |
2014 |
13 |
2015 |
12 |
2016 |
12 |
2017 |
9 |
2018 |
10 |
2019 |
No count |
2020 |
No count |
2021 |
16 |
Carrion crow (Corvus corone)
One pair was noted for much of the year, “Patch” and partner (Patch named after a white patch on the chest, making this individual easily identifiable), the same individual as in previous years. This pair were joined by four others, possibly the young from last year, for the early part of the season. None made an attempt to breed on the island.
Peregrine falcon (Falco peregrinus)
No breeding attempt was made this year. Individuals were present on the island for the majority of the spring, which included a male and young female. These were often seen at ‘Peregrine’s Nest’, where in the past others have bred; it appeared this pair were just feeding.
Wood pigeon (Columba palumbus)
Two pairs have bred this season. The nests of the first attempts were not found; however, two fledglings were noted on 24th June and then a further one fledging in July, indicating two different pairs. On 5th September, when undertaking a wader count, a nest was found on the ground within a clump of red goosefoot along the east side of the island containing two eggs. A further nest with two eggs was identified in elders at the low Light on 6th September, confirming two pairs breeding on the island.
1.6 Wader counts
Wader counts were undertaken weekly from the end of July onwards, once the breeding seabirds had departed from breeding sites. See Table 15 for the peak counts per month.
1.7 Mammals
1.7.1 Grey seal
The number of adult seals started to increase throughout September and the first seal pup was born on 30th September at Mill Door.
1.7.2 Cetaceans
The report is a combination of observer effort from the residents of Fluke Street and the Isle of May Bird Observatory as well as the staff who work on the various visitor boats. Overall, it was a reasonable year for whales and dolphins, with three species recorded in May waters, which included a good showing of Minke Whales during the autumn months. More interestingly, a potential Sei Whale was spotted in early October.
Harbour porpoise (Phocoena phocoena)
A scattering of sightings in the spring included two on 31st March, a single on 25th April, and two on 27th May. It was not until July that the species started to be reported on a regular basis, with 1-3 on four July dates, with four on 10th July, whilst August produced 1-3 on seven dates, with a peak of four on 22nd August. As usual, autumn produced the bulk of records, with 1-5 on four September and eight October dates, with peaks of six on 25th September and 9th October, and seven on 7th September. The last records of the year occurred in early November, with 1-2 on six dates between 2nd and 10th November, with a peak of three on 8th November.
Bottle-nosed dolphin (Tursiops truncatus)
As usual, there were regular reports from visitor boats of small numbers hugging the coast along Fife and Lothian, but the species is scarce further out in island waters. A single on 22nd June was the only spring sighting. Other records included 18 on 25th September, 1-5 on four October dates, with peaks of 15 on 26th October, and 12 on 27th-28th October.
Minke whale (Balaenoptera acutorostrata)
It proved to be a productive year for this baleen whale, with the first record of the year not until midsummer (which is the norm) with a single off the west side on 8th July. Thereafter, records started to increase, with singles on seven dates from 16th-29th August and 1-2 daily between 3rdand 8th September. The most productive month of the year was October, with 1-2 seen around the island on 10 dates, with a series of sightings early in the month being noteworthy. These included four on 7th October, an impressive eight on 8th October and five still on 9th October. These animals were feeding off all parts of the island, taking advantage of migratory fish, and on occasions could be detected on calm days by the sound of their breathing. A late individual was seen off the north end of the island on 4th-5th November.
Whale spp.
One of the most intriguing and interesting reports concerned a whale sp. off the east side of the island on 1st October, which was potentially a Sei Whale. The animal surfaced twice and the large ‘blow’ was noted at some distance, but not enough was captured to confirm the sighting. A few weeks later, during the week of 11th October, a similar event occurred, with a large whale blow off the east side. This followed the record of a long staying Sei Whale in the upper Forth which was also seen in St. Andrews Bay in late September.
1.8 Lepidoptera
1.8.1 Butterfly
Records of butterflies were made by informal observations from members of Fluke Street and the IOMBOT residents throughout the season. The first butterfly record was a single peacock on 17th March. A transect walk was established in 2020, in conjunction with UK Butterfly Monitoring Scheme (UKBMS), and continued for a full season this year. A transect is walked once a week by NatureScot staff/volunteers and all butterflies are recorded within 5 metres of the transect line. Specific weather conditions have to be met for a transect walk to take place, which can limit the number of walks per season (1st April – 30th September). In total, 17 survey walks were conducted: see the results below in Figure 10.
Nine species were recorded throughout the year. The most frequently recorded species was the small tortoiseshell, noted in almost all months from March to October, and the most numerous was the red admiral. August was the month with the highest count of butterflies. Wall was recorded on six days, with a peak of two individuals; this is a species that is becoming more common on the Isle of May, along with speckled wood, recorded on one day in 2021. See Table 16 for full details of the records.

A bar graph showing counts for large white, small white, red admiral, painted lady, small tortoiseshell, peacock and wall brown on 28 days between April and October. Date is along the x axis, with dates between 1st April and 28th October. Count is along the y axis, with a scale that runs from 0 to 120.
The bar graph has been converted into Table 17.
1.8.2 Moth
Moth trapping at Fluke Street was undertaken by NatureScot staff and volunteers from March through to October. The MV light trap was set up in the garden outside the principal keeper’s cottage; the trap could be moved into the outdoor shelter during adverse weather and when puffins were leaving their burrows (to prevent them from being drawn towards the light). A second trap was available to those at the IOMBO, who had the trap running by the Low Light bushes. Trapping was carried out from 28th March until the end of the season, with the last trap of the year on 20th October.
Trapping was conducted on a total of 54 nights, with a total of 92 different macro species being recorded along with 14 micro moths.
Four new species were first records for the Isle of May: figure of eighty, grass rivulet, grey pine carpet and brindled pug. Centre-barred sallow, copper underwing and gold spot were recorded for the second time.
The most numerous moth caught was bright-line brown-eye. It was regularly caught throughout the season, on a total of 28 nights, and 104 individuals were caught on 7th June.
2. VISITOR REVIEW
It proved to be an interesting but successful visitor season despite the Covid restrictions. The start of the season was delayed from the usual 1st April opening, with the first boats sailing from 26th April. Even then, all boats were restricted and not running at capacity throughout the summer until all restrictions were lifted on 9th August. Despite this, with a combination of staycation and popularity, the island still attracted over 10,000 visitors, which was impressive considering the restrictions in place.
As usual, boats departing from Anstruther brought the majority of visitors, with the May Princess bringing 7,981 whilst the fast RIB Osprey carried a further 1,280. During the season, boats travelled from the Lothian side of the Firth of Forth, with the Seabird Centre RIB bringing 1,043 and BlueWild a further 98. Small private leisure craft and kayaks carried a further 152 visitors, bringing the annual total to 10,544.
Month | May Princess | Osprey RIB | Seabird RIB | Bluewild | Others | Total |
---|---|---|---|---|---|---|
April |
128 |
37 |
16 |
0 |
21 |
202 |
May |
1,219 |
225 |
208 |
0 |
14 |
1,666 |
June |
1,586 |
239 |
218 |
26 |
8 |
2,077 |
July |
1,987 |
336 |
326 |
42 |
53 |
2,744 |
August |
2,249 |
288 |
172 |
23 |
52 |
2,784 |
Sept |
812 |
155 |
103 |
7 |
4 |
1,081 |
Total |
7,981 |
1,280 |
1,043 |
98 |
152 |
10,554 |
Year | May Princess | Osprey RIB | Seabird RIB | Others |
---|---|---|---|---|
2021 |
7,981 |
1,280 |
1,043 |
152 |
2020 |
- |
- |
- |
- |
2019 |
11,551 |
1,474 |
984 |
239 |
2018 |
11,112 |
1,373 |
1,029 |
221 |
2017 |
10,385 |
1,349 |
798 |
251 |
2016 |
9,830 |
1,327 |
743 |
164 |
2015 |
8,803 |
1,219 |
669 |
238 |
3. VOLUNTEER REVIEW
Due to Covid restrictions applying to accommodation use, the volunteering scheme did not return to normal (which is usually two volunteers for the summer months). Last year was similar and as a result the island staffing levels were below normal. However, once restrictions allowed, one recruit was taken on, Christopher Cachia-Zammit, who was on the island from 7th June-8th September. Chris was another good appointment and helped in all aspects of the island from visitor work to seabird monitoring.
As well as our long-term volunteer, NatureScot students and seasonal staff, Maisie, Julie, Esther, Ellie, Ian and Andrew from Tentsmuir NNR, Loch Leven and the Stirling reserves helped for a week in September. All six volunteers were resident on the island from Monday 13th-Friday 17th September and various island tasks were completed, including clearing timber off Rona, tern terrace construction and various painting jobs, amongst others. Other help during the year came from short-term volunteers who helped on a day-to-day basis.