The following has been adapted from original text by P. Ian Mitchell in Seabird Populations of Britain and Ireland (with permission from A&C Black, London).
Leach's storm-petrel is a truly oceanic species, only returning to remote island colonies during hours of darkness. It ranges widely in both the Atlantic and Pacific Oceans. In the east Atlantic, breeding colonies are confined to a few islands off the coasts of Iceland, the Faeroes and Norway, as well as just eight remote islands and archipelagos situated along the Atlantic Frontier of Britain and Ireland. Obtaining estimates of breeding numbers has been virtually impossible in the past, due to the species' nocturnal and subterranean breeding habits plus accessing the remote colonies during the hours of darkness is often difficult and dangerous.
Conservation status
Leach's storm-petrel is currently identified as a conservation priority in the following:
- Amber listed in Birds of Conservation Concern 4 (2015 update)
- Wildlife and Countryside Act 1981 – protected under Schedule 1
- further information on Conservation Designations for UK Taxa
- Red listed in Birds of Conservation Concern in Ireland 2020–2026
- EC Birds Directive – e.g. listed in Annex 1 and as a migratory species
International importance
|
UK Population |
% Biogeographic Population |
% World Population |
|
48,000 AOS* |
0.9 (ssp. leucorhoa) |
0.5 |
*AOS = Apparently Occupied Sites
The UK population figure (rounded to the nearest hundred) was derived from data in Mitchell, P.I., Newton, S.F., Ratcliffe, N. and Dunn, T.E. (eds.) 2004. Seabird Populations of Britain and Ireland. Poyser, London. This was also the source of figures for the Biogeographic and World populations.
UK population estimates and change 1969–2002 (census data)
Seabird 2000 used a method called tape-playback to survey apparently occupied sites (AOS) of breeding Leach's storm-petrels. The method involves playing calls of the species to elicit a response from adults hidden in burrows during the day whilst incubating. Unfortunately, not all Leach's storm-petrels present at a colony will respond to the taped calls; thus counts of responses will underestimate the number of AOS and have to be adjusted by a response rate measured at the colony.
Ninety-four percent of the UK population breeds on four islands in the St Kilda archipelago (Western Isles), with the remainder on the Flannan Isles (Western Isles), three other islands in the Western Isles and two islands in Shetland. There is also one Irish colony. Colonisation of islands by Leach's storm-petrels is dependent on the absence of mammalian predators and on proximity to their feeding grounds. The species feeds on macro-zooplankton (e.g. myctophids, amphipods, euphausiids) and during the east Atlantic breeding season is confined to feeding in areas beyond the continental shelf break (deeper than 200 m). All Leach's storm-petrel colonies are within 37–67 km of the shelf break and 65–119 km from the bottom of the continental slope (200–1,000 m).
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
UK Population estimate (AOS*) |
n/a |
n/a |
48,047 |
|
% change since previous census |
n/a |
n/a |
n/a |
*AOS = Apparently Occupied Sites
For census results for individual countries and Ireland, the Channel Islands and the Isle of Man see under relevant sections below.
Distribution/abundance
The Seabird 2000 census provides the most comprehensive recent assessment of the distribution and abundance of breeding seabirds. Numbers of Leach's storm-petrel found in different regions, and a map showing the location and size of colonies, is provided in the Seabird 2000 Leach's storm-petrel results page.
The locations sampled during the annual Seabird Monitoring Programme provide some information on distribution and are accessible via the Seabird Monitoring Programme online database.
Annual abundance and productivity by geographical area
With reference to the regional accounts below please note the following:
Breeding abundance: graphs of abundance index with 95% confidence limits are only shown for a region where the trend produced has been deemed accurate (see methods of analysis). Where a trend was thought to be inaccurate, graphs of abundance at major colonies in a region may be shown instead, particularly if such colonies hold greater than 10% of the regional population, are monitored frequently and may thus help illustrate regional population fluctuations outwith national censuses. Occasionally, too few data have been collected regionally to produce either of these.
Productivity: graphs of estimated reproductive success (hereinafter referred to as productivity) are only shown if data analysis produced a significant result for regional and/or year effects (again see methods of analysis). If results were not significant, then a regional mean productivity value is given. However, on some occasions, too few data are available from which to provide a meaningful average.
Overview of all regions
Breeding abundance
An insufficient number of Leach’s storm petrel colonies are monitored in the UK, Republic of Ireland, Isle of Man and Channel Islands, to allow the production of valid annual abundance trends.
Productivity
An insufficient number of Leach’s storm petrel colonies are monitored in the UK, Republic of Ireland, Isle of Man and Channel Islands, to allow the production of valid annual productivity trends.
United Kingdom
Breeding abundance
The first comprehensive estimate of the Leach’s storm-petrel UK breeding population size was obtained during the Seabird 2000 census, when 48,000 AOS were counted. Due to the logistical difficulty in monitoring this nocturnal and burrow-nesting species, little information exists on population trends. However, repeat surveys of the largest colony in the UK, on Dun in the St Kilda archipelago, which at the last census held around 58% of the UK population, have shown a decline. Surveys have estimated that the population there fell from 27,800 AOS in 1999 to 12,800 AOS1 in 2006, suggesting a 54% decline since Seabird 2000. A decline was also recorded on North Rona, where 1,084 AOS were estimated in 2001 and 713 AOS in 2009 – a 34% decrease2. The causes of both these declines are unknown, although predation at breeding colonies by great skua Stercorarius skua and great black-backed gulls Larus marinus has been suggested as a possible cause. On St Kilda, it was estimated that great skuas can consume as many as 21,000 individual Leach's storm-petrels per year3, predominantly non-breeding individuals, which could subsequently impact on the size of the colony through reduced recruitment. Other potential causes of decline could include reduced adult survival or a decrease in food supply during chick rearing, but no information is available on these.
Productivity
Data submitted to the SMP on Leach's storm-petrel productivity in the UK are sparse; thus, no meaningful average productivity value can be given.
Scotland
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (AOS*) |
n/a |
n/a |
48,047 |
|
% change since previous census |
n/a |
n/a |
n/a |
*AOS = Apparently Occupied Sites
Breeding abundance
The first comprehensive estimates of Leach’s storm-petrel population size were obtained during the Seabird 2000 Census, when 48,000 AOS were counted. Due to the logistical difficulty in monitoring this nocturnal and burrow-nesting species, little information exists on population trends. However, repeat surveys of the largest colony in Scotland, on Dun in the St Kilda archipelago, which at the last census held around 58% of the population, have shown a decline. Surveys have estimated that the population there fell from 27,800 AOS in 1999 to 12,800 AOS1 in 2006, suggesting a 54% decline since Seabird 2000. A decline was also recorded on North Rona, where 1,084 AOS were estimated in 2001 and 713 AOS in 2009 – a 34% decrease2. The causes of both these declines are unknown, although predation at breeding colonies by great skua Stercorarius skua and great black-backed gulls Larus marinus has been suggested as a possible cause. On St Kilda, it was estimated that great skuas can consume as many as 21,000 individual Leach's storm-petrels per year3, predominantly non-breeders, which could subsequently impact on the size of the colony through reduced recruitment. Other potential causes of decline include reduced adult survival or a decrease in food supply during chick rearing, but no information is available on these. In Shetland, where small numbers of Leach's storm-petrel nest, tape-playback surveys of 10 islands in 2011 found the species on only two islands; 13 responses were recorded on Gruney with a single responding bird on Gloup Holm. Examination of four burrows from which birds had responded on Gruney found that two contained non-breeders. While sample sizes here are very small, burrow occupancy by non-breeders is unexpected and further work is required to determine the extent of this behaviour, as it has potential implications for the interpretation of Leach's storm-petrel population estimates derived from tape-playback surveys4.
Productivity
Data submitted to the SMP on the productivity of Leach's storm-petrels in Scotland are sparse; thus, no meaningful average productivity value can be given.
England
Leach's storm-petrel does not breed in England.
Wales
Leach's storm-petrel does not breed in Wales.
Northern Ireland
Leach's storm-petrel does not breed in Northern Ireland.
Republic of Ireland
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (AOS*) |
n/a |
n/a |
310 |
|
% change since previous census |
n/a |
n/a |
n/a |
*AOS = Apparently Occupied Sites
Breeding abundance
The first comprehensive estimate of the Leach’s storm-petrel breeding population size in the Republic of Ireland was obtained during the Seabird 2000 census. Only one colony was found, on the Stags of Broadhaven, which held 310 AOS. Two other suspected colonies, on Great Skellig and Inishglora, were also surveyed but no Leach's storm-petrels were found nesting. In 2015, Great Skellig was re-surveyed but no Leach's storm-petrels were found nesting5.
Productivity
No systematic data on the productivity of Leach's storm-petrels in the Republic of Ireland have been submitted to the SMP.
All Ireland
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (AOS*) |
n/a |
n/a |
310 |
|
% change since previous census |
n/a |
n/a |
n/a |
*AOS = Apparently Occupied Sites
Breeding abundance
Within Ireland, Leach's storm-petrel only nest in the Republic of Ireland. Thus, all data and text for the Republic of Ireland are also pertinent to the status of the species in the whole of Ireland.
Productivity
This species does not breed in Northern Ireland and no systematic data on Leach's storm-petrel productivity in the Republic of Ireland have been submitted to the SMP.
Isle of Man
Leach's storm-petrel does not breed on the Isle of Man.
Channel Islands
Leach's storm-petrel does not breed on the Channel Islands.
UK phenology, diet, survival rates
No data have been collected as part of the Seabird Monitoring Programme.
References
1 Newson, S.E., Mitchell, P.I., Parsons, M., O’Brien, S.H., Austin, G.E., Benn, S., Black, J., Blackburn, J. Brodie, B., Humphreys, E., Prior, M. and Webster, M. 2008. Population decline of Leach’s Storm-petrel Oceanodroma leucorhoa within the largest colony in Britain and Ireland. Seabird, 21, 77–84.
2 Murray, S., Shewry, M.C., Harden, J., Jamie, K. and Parsons, M. 2010. A survey of Leach's Oceanodroma leucorhoa and European Storm-petrel Hydrobates pelagicus populations on North Rona and Sula Sgeir, Western Isles, Scotland, in 2009. Seabird, 23, 25–40.
3 Miles, W.T.S. 2010. Ecology, behaviour and predatorprey interactions of Great Skuas and Leach's Storm-petrels at St Kilda. Unpublished PhD thesis http://theses.gla.ac.uk/2297/. University of Glasgow, Glasgow.
4 Miles, W.T.S., Tallack, R.M., Harvey, P.V., Ellis, P.M., Riddington, R., Tyler, G., Gear, S.C., Okill, J.D., Brown, J.G., and Harper, N. 2012. A survey of Leach's petrels on Shetland in 2011. Scottish Birds, 32, 22–29.
5 Newton, S. Lewis, L. and Trewby, M. 2015. Results of a Breeding Survey of Important Cliff‐Nesting Seabird Colonies in Ireland 2015. National Parks and Wildlife Service Ireland.
Partners
Data have been provided to the SMP by the generous contributions of its partners, other organisations and volunteers throughout Britain and Ireland. Partners to the SMP are: BirdWatch Ireland; The British Trust for Ornithology; Department of Agriculture, Environment and Rural Affairs (Northern Ireland); Department of Environment, Food and Agriculture (Isle of Man); Department of the Environment, Climate and Communications (Republic of Ireland); JNCC; Manx Birdlife; Manx National Heritage; The National Trust; National Trust for Scotland; Natural England; Natural Resources Wales; NatureScot; The Royal Society for the Protection of Birds; Scottish Wildlife Trust; Seabird Group; Shetland Oil Terminal Environmental Advisory Group; States of Guernsey Government; UK Centre for Ecology and Hydrology. More about the SMP partners >>
Image of Leach's storm-petrel appears courtesy of Ian Rendall ©, is subject to international copyright law and may not be reproduced in any form whatsoever.
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