NatureScot Research Report 1264 - Greenland barnacle geese Branta leucopsis in Britain and Ireland: Results of the International Census, Spring 2020

Published: 2024

Authors: Mitchell, C., & Hall, C. (Wildfowl & Wetlands Trust)

Cite as: Mitchell, C., & Hall, C. 2024. Greenland barnacle geese Branta leucopsis in Britain and Ireland: Results of the International Census, Spring 2020. NatureScot Research Report 1264.

Keywords

Greenland barnacle goose; Islay; Scotland; census

Background

Between 1959 and 2020, fifteen full international surveys of the Greenland population of barnacle goose Branta leucopsis have been conducted at wintering sites in Scotland and Ireland using a combination of aerial survey and ground counts. This report presents the results of the 2020 census in Scotland, conducted primarily between 13-20 March, and includes the total count in Ireland in order to estimate the total population size.

Main findings

• In Scotland, 38 sites out of 188 checked, were found to hold 58,135 Greenland barnacle geese. In Ireland, 15,256 geese were counted. The total wintering population was estimated at 73,391 birds. This represents a 1.7% increase on the 2018 census total.
• The number counted on Islay in spring 2020 (33,202), the most important site in the winter range, was 4.5% lower than that recorded in spring 2018, whereas the number of geese throughout the remainder of Scotland had increased by 17.7% since 2018.
• The increase in the number of birds wintering in Scotland in March 2020 was largely driven by increases at a small number of core areas. Five areas (Islay, North Uist (consolidated), Tiree and Coll, Oronsay/Colonsay and South Walls (Orkney)) held most of the geese, accounting for 92.2% of the Scotland total and 73.0% of the international total. Islay alone held 57.1% of the Scottish total and 45.2% of the international total. Overall, numbers at these five core areas have increased more than six-fold since 1959, whereas numbers outside these areas have remained relatively stable.
• During the 2020 census, 12 sites held numbers that exceeded 1% of the latest census total in Scotland and also exceeded 1% of the latest international census total. Of these, Oronsay/Colonsay, South Walls (Orkney) and Grenitote/Sollas (North Uist) are not classified as SPAs for Greenland barnacle goose, although Switha, the principal roost site of the South Walls flock, is an SPA and Grenitote/Sollas may hold birds that use the North Uist Machair and Islands SPA. The suite of SPAs in Scotland (i.e. UK) which have Greenland barnacle goose as a qualifying species held 84.5% of the national and 66.9% of the international population. Four of the 11 SPAs in Scotland (Monach Isles, North Sutherland Coastal Islands, Shiant Isles and Treshnish Isles) did not hold internationally or nationally important numbers of Greenland barnacle geese.
• The number of barnacle geese breeding in Iceland is increasing. Recent ringing confirms that these birds winter in areas traditionally used by birds from Greenland. It is highly likely, therefore, that the barnacle geese nesting in Iceland form part of one Greenland/Iceland/UK/Ireland population.

Acknowledgements

Aerial counts were greatly assisted by pilot Sam Schoneveld (Ravenair). Morven Laurie and numerous NatureScot counters undertook ground counts on Islay and mainland North Uist. John Bowler, Pat Batty, Ben Jones, Bruce Taylor, Bob McMillan, John Poyner, Stephen Kirkup, Stuart Williams, Andy Knight, Donald Mitchell, Alan Leitch, Tim Wooton, Johnathan Ford, Stan Groundwater, Simon Cohen and Malcolm Ogilvie provided counts and valuable advice about the status of winter flocks in Scotland. Grateful thanks to all and apologies to anyone inadvertently omitted.

NatureScot and WWT funded the survey in Scotland. The count total from Ireland was kindly provided by Alyn Walsh and David Tierney of the National Parks & Wildlife Service. 

1. Methods

The method employed for the international census has been previously described in full (Walsh & Merne, 1988). Weather conditions, length of daylight hours and type of aircraft (in the past) have meant that aerial surveys were more easily carried out in late March or early April (Boyd, 1968). Aerial surveys are conducted using a twin-propeller aircraft, flying at approximately 150–200 m above ground or sea. Counts are undertaken as the geese are flushed by the approaching aircraft. One observer makes a visual estimate of flock size, while the second attempts to photograph the geese. The photographs are examined later and, if of good quality, are used to derive the count for the census total. The visual count is used where the quality of the photograph is poor or where there were difficulties photographing the entire flock. Where practicable, and given flying and weather conditions at the time, all islands where Greenland barnacle geese have previously been recorded are surveyed, as are adjacent mainland coast where suitable vegetation is present.

Ground counts were coordinated with the aerial survey in each country, and most were conducted within a few days of the flights (see Table 1 for dates). However, counts outwith, but close to, this period were accepted if counters could not undertake counts on the scheduled dates.

Photo verification of the flocks encountered during the aerial survey provides greater accuracy than visual estimates made at the time. The accuracy of visual counts has, however, been shown to be acceptable when numbers have been compared to those derived from photographic verification of individual flocks (Delany & Ogilvie, 1994; Cranswick et al., 2000).

2. Results

2.1 Timing of counts and coverage

The aerial survey in Scotland was undertaken on 13 March 2020 and followed the following schedule: Liverpool to islands off Islay, west coast Argyll, Mull, Gunna, Small Isles, islands from Barra Head to Barra, Sound of Barra, North Uist/Sound of Harris to Stornoway. The aerial survey in Ireland was undertaken using an Air Corp Reims Rocket Cessna 172 and was carried out on two days, 15-16 March 2020. Ground counts in Scotland were mostly undertaken between 17 and 20 March 2020, although where coverage was not possible, some counts outwith the survey period were included.  

2.2 Population size and distribution

During the 2020 census, 188 islands and mainland sites in Scotland were checked and 38 were found to hold Greenland barnacle geese (range 2–33,202 birds, Table 1, Figure 1). Sites visited in Scotland, but where no geese were found are listed in Annex 1. Sites not checked due to restricted flying time (see Discussion) are shown in Annex 2.

The total in Scotland was 58,135 geese, while that of Ireland was 15,256 geese. Thus, the total population estimate was 73,391 birds.

Table 1. Sites in Scotland holding Greenland barnacle geese in March 2020.

Area	Date	Site	Grid reference	Number of geese	Survey method 1
Islay	-	-	-	-	-
1	17/18-Mar	Islay	NR3362	33,202	G
Islay islands	-	-	-	-	-
2	13-Mar	Eilean Bhride	NR4547	197	P
Sound of Jura	-	-	-	-	-
3	13-Mar	Eilean Mor (off Danna)	NR6675	915 2	P
Inner Hebrides	-	-	-	-	-
4	20 Mar	Colonsay/Oronsay	NR3588	2,868 3	G
5	13-Mar	Bac Mor	NM2438	81	P
6	13-Mar	Fladda	NM2943	31	P
7	13 Mar	Muck/Eilean nan Each	NM4279	73	P
8	19/20-Mar	Tiree	NL9844	5,656	G
9	17-Mar	Coll	NM1554	1,146	G
Outer Hebrides	-	-	-	-	-
10	19-Mar	Borve Point, Barra	NF6501	220 4	G
11	19-Mar	Fiaray, Sound of Barra	NF7010	240 4	G
12	13 Mar	Monach Isles	NF6163	564	P
13	20-Mar	Baleshare, North Uist	NF7762	400	G
14	13-Mar	Kirkibost/Knockline	NF7565	331	P
15	20-Mar	Paible/Balemore, North Uist	NF7466	2,640	G
16	20-Mar	Balranald/Goula, North Uist	NF7070	910	G
17	20-Mar	Vallay, North Uist	NF7776	525	G
18	20-Mar	Grenitote/Sollas, North Uist	NF8175	1,076	G
19	20-Mar	Newton, North Uist	NF8877	965	G
20	20-Mar	Ahmore, North Uist	NF8474	26	G
21	20-Mar	Berneray, North Uist	NF9182	1,467	G
22	13-Mar	Opsay, Sound of Harris	NF9876	78	P
23	13-Mar	Boreray, Sound of Harris	NF8581	578	P
Minch	-	-	-	-	-
24	13-Mar	En an Tighe, Shiants	NG4297	175	P
Skye	-	-	-	-	-
25	13-Mar	Isay	NG2157	273	P
26	13-Mar	South Ascrib (Ascribs)	NG3063	53	P
27	13-Mar	Eilean Creagach (Ascribs)	NG2965	23	P
28	14-Feb	Eilean Trodday	NG4479	40 5	G
Wester Ross	-	-	-	-	-
29	13-Mar	Gruinard	NG9494	90 6	G
30	19 Mar	Achiltibuie	NC0208	137	G
Sutherland	-	-	-	-	-
31	26-Mar	Eilean Hoan/Durness	NC4467	420	G
32	13-Mar	Eilean nan Ron/Kyle of Tongue	NC6365	156	G
Orkney	-	-	-	-	-
33	12-Mar	South Walls	ND3289	1,738	G
34	20-Mar	Loch of Skaill	HY2318	88	G
35	20-Mar	Loch of Harray	HY2915	2	G
36	17-Mar	South Ronaldsay	ND4684	737	G
37	15-Mar	The Loons	HY2524	2	G
38	26-Mar	Papa Westray	HY4952	12	G
Scotland total	-	-	-	58,135	-
Ireland total	-	-	-	15,256	-
Total population	-	-	-	73,391	-

 

¹ G denotes ground count and P denotes aerial photographic verification.
² The flock counted on Eilean Mor also uses Danna. 910 barnacle geese were counted on Danna on 16 March 2020.
³ Traditionally reported on jointly; individual island counts were 2,283 on Oronsay and 585 on Colonsay.
⁴ Regular wintering flocks, reported by B Taylor, but not located during aerial survey.
⁵ Counted on 14 Feb 2020. A regular wintering flock, but not located during aerial survey.
⁶ Regular wintering flock, reported by J Poyner, but not located during aerial survey.

2.3 Long-term trends

The total number of Greenland barnacle geese in March 2020 (73,391) had decreased by 9.0% from a peak of 80,670 in 2013, but increased by 1.7% compared to 2018 (Table 2, Figure 2). The long-term increase on Islay, ongoing since the 1960s (except for a drop in numbers in the 1980s), appears to have stopped during the past five years with a 26.1% decline between 2013 and 2020 and a 4.5% decline between 2018 and 2020. In contrast, overall numbers elsewhere in Scotland remained relatively constant throughout the 1970s and 1980s, but have increased since 1994, and increased by 17.7% between 2018 and 2020.

3. Discussion 

3.1 Census total and accuracy

The population estimate of Greenland barnacle geese, based on the census of known and potential wintering sites carried out in Britain and Ireland in March 2020, was 73,391, 1.7% higher than that recorded in March 2018 and the second highest total to date. 

Overall, 94.2% of the census total in Scotland comprised estimates from ground counts and 5.8% (13 flocks) were counted from photographs taken during the aerial survey (Table 1). All the counts made during the aerial survey were taken from photographs (e.g. Figure 3) and no visual estimates (where no photograph was available) were necessary. This increases the accuracy of the individual site counts and indicates that the accuracy of the overall census total is likely to be high.

Count conditions in Scotland on 13 March were good, with light winds and no rain. However, the forecast for weather conditions on 14 March deteriorated such that flying could not take place as scheduled, and the original flight plan needed to be altered on the afternoon of 13 March. Parts of the scheduled survey area were omitted from the flight route in order to maximise coverage on 13 March of areas thought to hold geese (see below). The ground counts were largely synchronised, with the majority of the counts in Scotland made over a four-day period (17-20 March). In Ireland, the survey was carried out on 15/16 March. In an analysis of spring arrival dates in Iceland, Gunnarsson & Tómasson (2011) noted first arrivals around 15 April, and no Greenland barnacle geese were reported in Iceland at the time of the 2020 census (A. Sigfusson pers. comm). Thus, it seems likely that the census took place before any geese had left Scotland and migrated to Iceland.

Coverage was thought to be good with almost all known haunts of Greenland barnacle geese checked during the census (but see below). Prior to the census, RSPB reserve wardens, Highland Rangers and NatureScot staff reported no new sites that were thought to hold barnacle geese. However, Greenland barnacle geese were not found during the aerial survey at three sites known to hold geese. Counts for these sites obtained outwith the core census period were used for the international population estimate: counts of 220 barnacle geese at Borve Point, Barra, 240 geese on Fiaray, Sound of Barra in mid-March 2020 and 40 birds on Eilean Trodday, Skye, on 14 February 2020. All three sites normally hold geese throughout the winter period and thus merited inclusion in the final population estimate.

Due to the cancellation of flying on the second day, the sections of the coastline not checked during the aerial survey were the west coast of Harris/Lewis from Toe Head (NF9594) to Loch Roag (NB1233), and the west coast of Wester Ross from Loch Gairloch (NG5776) to Eilean an Roin Mor (NC1758). The west coast of Harris/Lewis has not held any barnacle geese since 65 were counted at Old Hill (NB1143) in March 1999 and 10 were recorded on Floday (NB1033) in March 2008, so it is unlikely that large numbers of geese were missed there. On the west coast of Wester Ross, ground counters were asked to check the two main resorts Gruinart/Mungasdale (NG9693) and Achitibuie (NC0208) and counts from there were obtained (Table 1). Two other sites in this section of coastline have held barnacle geese since 2013: Eilean Chrona (NC0633) in Eddrachilis Bay held 32 birds in March 2018, and Eilean an Roin Mor, (NC1758) held 69 birds at the same time. Neither island was checked in March 2020, although the omission of potentially 100 birds (0.14% of the population total) is not considered to substantially affect the census total.

No barnacle geese were recorded on Luing (NM7408) during the aerial survey despite thoroughly checking all potential feeding fields from the air. This area held 490 birds in March 2013 and 530 birds in March 2018. However, local observers suggested that the number of barnacle geese at Danna (NR6978) had increased by ‘about 500 birds’ in the weeks prior to the census. The move may have been caused by disturbance to the flock on Luing. Thus, it is likely that the 915 barnacle geese counted on Eilean Mor (NR6675), the island next to Danna, during the aerial census included birds from both Luing and Danna.

Considering the caveats outlined above, none are considered to substantially affect the census total and it is therefore recommended that the population estimate for Greenland barnacle goose is 73,391 birds.

3.2 Site use

The number of occupied sites in Scotland supporting >10 birds, whilst variable between censuses, increased since 1959/60 and has remained fairly stable since 1983/84 (Figure 4). The number of occupied sites in Scotland in 2020 (36 sites holding more than 10 birds) was the equal fourth highest on record.

The increase in abundance of the population in Scotland appears to have largely been driven by numbers at a small number of core areas. Currently, five core areas, Islay, North Uist (consolidated), Tiree and Coll, Oronsay/Colonsay and South Walls, hold the majority of geese: 73.0% of the international total and 92.2% of the Scotland total in March 2020. Islay alone held 45.2% of the population total and 57.1% of the Scotland total. Overall, numbers at these five core areas have increased more than six-fold since 1959 (Figure 5). The number of geese outside these core areas has remained at around 4,000 birds (range 1,695 – 6,166) since the late 1950s (Figure 5). 

Census data indicate that use of some of the smaller sites, such as the Treshnish Isles and the Shiants, has decreased since the late 1970s/early 1980s. 

3.3 Nationally and internationally important sites

A site is considered internationally important if it regularly supports 1% or more of the individuals in a population (following criterion 5 of the Ramsar Convention; Wetlands International 2012), and in Britain, a site is considered nationally important if it regularly holds 1% or more of the British population estimate. Assessments of site importance are usually made on the basis of a minimum of three years’ count data within a five year period, but, in the absence of regular counts at many of these sites, presented here are the 2020 site counts against 1% of the international and British population estimates based on this census (1% threshold for international importance would be 734 geese, and for British national importance would be 581 geese). (Note that these are not the currently accepted international and national 1% thresholds, which remain 810 (Wetlands International, 2018) and 560 (Frost et al., 2019), respectively, and that a comprehensive assessment of site importance would use annual peak site counts).

During the 2020 census, 12 sites held geese in numbers that exceeded the 2020 international threshold, and the same 12 sites also exceeded 1% of the 2020 British population estimate (Table 3). The number of sites exceeding internationally important numbers declined to the mid-1990s and then increased thereafter until the latest census. The number of sites exceeding nationally important numbers (based on the 1% threshold estimated at that time) fluctuated between 1959 and 1993, but since then has slowly increased (Figure 6).

Many of the sites exceeding 1% of the international or national census totals in 2020 are protected wholly, or in part, by classification as Special Protection Areas (SPAs) under the EC Birds Directive. Of those sites where numbers exceeded the international threshold, Oronsay/Colonsay (Argyll), South Walls and South Ronaldsay (both Orkney), Eilean Mor/Isle of Danna (Argyll) and Grenitote/Sollas (North Uist) are not classified as SPAs for Greenland barnacle geese.

It is important to note that goose SPAs generally contain roosting rather than feeding habitat. The site boundaries used in this census may not, therefore match site boundaries of SPAs, so the numbers quoted are indicative only. For example, 33,202 barnacle geese were counted on Islay in March 2020, and some, but not all, of these use three SPAs where the geese are a qualifying species. Similarly on Tiree, geese counted roost and feed both within and outwith the SPA boundary. On some offshore island groups, geese can be quite mobile, moving from within the SPA boundary to just outside it. This is particularly the case for North Uist Machair and Islands SPA where the geese range between several offshore islands and mainland areas, either within a day or between days. Wherever possible, allowances have been made to allocate counts of Greenland barnacle geese to functional feeding/roosting units that include SPAs.

The suite of SPAs in Scotland that have Greenland barnacle goose as a qualifying species, the percentage of the population that they held during the 2020 census and the current frequency of monitoring are shown in Tables 3 and 4. Overall, in March 2020, the suite of SPAs in Scotland held 66.9% of the international population and 84.5% of the national population. Eleven SPAs in Scotland have Greenland barnacle goose as a qualifying feature, but during the 2020 census, four of these SPAs (Monach Isles, North Sutherland Coastal islands, Shiant Isles and Treshnish Isles) did not hold internationally or nationally important numbers. The long-term trends on nine SPAs in Scotland are presented in Annex 3.

3.4 Counts on North Uist

The number of Greenland barnacle geese wintering on the mainland of North Uist and nearby islands has increased since the late 1980s. The proximity of sheep-grazed islands to managed grassland fields on the mainland can lead to movements of birds between them, notably when they are disturbed. Regular (several times in a winter) counts on the mainland are organised and undertaken by NatureScot, but surveillance is somewhat complicated by the geographical range of the mainland count areas, only some of which are within the North Uist Machair and Islands SPA. The aerial survey allows offshore islands to be checked simultaneously, allowing a total count for the whole of North Uist to be achieved. In order to set a standard form of reporting on counts of Greenland barnacle geese in this area, the following has been done: 

• Regular counts from the NatureScot count areas, which are shown as black hatched areas in Figure 7.
• The count for the North Uist Machair and Islands SPA in March 2020, which includes birds recorded at sites 13, 14, 16, 17, 19, 21 and 22 (see Table 5).
• The total count for ‘North Uist consolidated’, which is bounded by the green line shown in Figure 7.

The number of Greenland barnacle geese recorded in North Uist in March 2020 is summarised in Table 5. The switch in habitat use from offshore islands, where the geese take advantage of semi-natural grasslands which were often summer grazed, to managed grasslands on mainland areas is particularly noticeable at this site. The proportion of birds counted in the North Uist (consolidated) area (see Figure 7) using the mainland area has increased from none up to 1994, to 0.79 in 2020 with a corresponding decrease in the use of offshore islands (Figure 8).

¹ See Table 1 and Figure 1 for site numbering.
² NatureScot count areas are shown as shaded black/stippled areas in Figure 10.
³ North Uist Machair and Islands SPA are shaded red in Figure 10.
⁴ All counts from area bounded by green line in Figure 10.

3.5 Barnacle geese breeding in Iceland

Barnacle geese now breed in Austur-Skaftafellssýsla county, south-east Iceland, in an area where birds from the Greenland flyway are known to stage on autumn passage. In 2009, about 40 barnacle geese were known to nest in the area. Fieldwork in the summer of 2014 revealed at least 509 nests, an increase of over 1,200 % in five years (Stefánsson et al., 2015). By 2017, the number of nests had increased to nearly 2,000, each comprising two adults. In addition, the summering population will include many hundreds of non-breeding geese and failed breeders, in addition to the goslings produced from each successful nest. In total, 941 birds have been caught and ringed there during their annual wing moult in July and sightings of the marked geese indicate that the Iceland-breeding birds winter throughout the range of the Greenland population (Figure 9). Most of the sightings have been on Islay, Oronsay and North Uist, although this reflects observer effort. Most of the uninhabited offshore islands, where barnacle geese winter, have not been checked for marked birds. 

Thus, it is highly likely that the increasing number of barnacle geese nesting in Iceland form part of one Greenland/Iceland/UK/Ireland population. This appears to be a case of ‘short-stopping’, where geese start to breed along the flyway route, short of the normal breeding areas. This has also occurred in the Russia/Netherlands population, where barnacle geese started to breed on Gotland, Sweden (57°30′N 18°33′E), along the flyway route, but short of the normal breeding areas in arctic Russia (Larsson et al., 1988). The contribution of the Iceland breeding birds to the winter population merits further investigation since the annual breeding success and other demographic rates of the birds from the two geographical areas may diverge.

4. Recommendations

The primary objectives of the census are to provide a contemporary assessment of population size and to provide information on site importance. Meeting these two requirements may, however, need different methods. 

4.1 Timing and frequency of population counts

A monitoring programme of one international census every five years, was carried out up to winter 2017/18.  To monitor changes in population size at a time when adaptive management of geese is ongoing and to track the possible effects of the rapid increase in the number of birds breeding in Iceland, a survey every five years was deemed insufficiently sensitive. A census every three years is recommended in the Adaptive Flyway Management Programme for this population under the AEWA European Goose Management Platform (Nagy et al., 2020) and has therefore been adopted (as resources allow) for this population.

An analysis of arrival dates of spring migrants recorded in Iceland suggested that, in recent years, Greenland barnacle geese had begun to arrive earlier in the year. This was by approximately 0.67 days per year between 1988 and 2009, or by up to 14 days over the 21-year study period, although the first arrivals in the mid-2000s were on or about 15 April (Gunnarsson & Tómasson, 2011). Thus, it seems prudent to continue to carry out future aerial surveys in either early or mid-March to avoid missing birds which may start their migration in early April.

4. 2 Monitoring of nationally and internationally important sites

Numbers of Greenland barnacle geese at several of the key sites are surveyed annually and, in some cases, at multiple times over the winter. However, there are limited data available for most other sites. Within protected areas, this data is important to assess the condition of the goose feature for Site Condition Monitoring (JNCC, 2004). If the feature is based on the number of geese at a site, it is recommended that surveys are conducted in at least three different relevant seasons within the assessment cycle; an average of three or more counts could then be used to assess the feature condition against pre-set targets and allow confident judgement of the trend in condition of the interest feature. Some SPAs are counted annually (see Table 4) although offshore islands, necessitating aerial survey, are often counted less frequently.

5. References

Boyd, H. 1968. Barnacle geese in the west of Scotland, 1957-67. Wildfowl, 19, 96–107.

Cranswick, P.A., Mitchell, C., Merne, O.J., Kershaw, M., Delany, S.N., MacKay, M. & Lilley, R. 2000. Status and distribution of the Greenland population of barnacle goose in Britain and Ireland, 1993 to 1999. The Wildfowl & Wetlands Trust, Slimbridge.

Delany, S. & Ogilvie, M.A. 1994. Greenland barnacle geese in Scotland, March 1994. The Wildfowl & Wetlands Trust, Slimbridge.

Frost, T.M., Austin, G.E., Hearn, R.D., McAvoy, S.G., Robinson, A.E., Stroud, D.A., Woodward, I.D. & Wotton, S.R. 2019. Population estimates of wintering waterbirds in Great Britain. British Birds, 112, 130–145.

Gunnarsson, T.G. & Tómasson, G. 2011. Flexibility in spring arrival of migratory birds at northern latitudes under rapid temperature changes. Bird Study, 58, 1–12.

JNCC, 2004. Common Standard for Monitoring designated sites: guidance for setting and assessing conservation objectives. Joint Nature Conservation Committee, Peterborough.

Larsson, K., Forslund, P., Gustafsson L. & Ebbinge, B. 1988. From the High Arctic to the Baltic; the successful establishment of a barnacle goose population on Gotland, Sweden. Ornis Scand, 19, 182-189.

Nagy, S., Heldbjerg, H., Høy Jensen, G., Johnson, F., Madsen, J., Meyers, E. & Dereliev, S. 2020. Adaptive Flyway Management Programme for the East Greenland/Scotland & Ireland population of the Barnacle Goose Branta leucopsis AEWA, Bonn.

Stefánsson, J.H., Hermannsdóttir, K. & Guðmundsson, S. 2015. Helsingjar í Austur-Skaftafellssýslu – stofnstærð og varpútbreiðsla 2014. Náttúrustofa Suðausturlands. Höfn í Hornafirði. 17 bls.

Walsh, A. & Merne, O.J. 1988. Barnacle geese Branta leucopsis in Ireland, spring 1988. Irish Birds, 3, 539–550.

Wetlands International, 2012. Waterbird Population Estimates - Fifth Edition. Wetlands International, Wageningen.

Wetlands International, 2018. Report on the Conservation Status of Migratory Waterbirds in the Agreement Area. Wetlands International report to the African-Eurasian Migratory Waterbird Agreement

Annex 1. Sites with nil Greenland barnacle geese in Scotland during the March 2020 census

Annex 3. Long-term trends on SPAs in Scotland

Maximum winter numbers of Greenland barnacle geese at nine SPAs in Scotland (Figures 10–18) 1956/57–2019/20. Note that some long-term count ‘sites’ do not match SPA boundaries exactly.