Friday, 27 July 2007

Recent North Atlantic records of Swinhoe's Petrel (Oceanodroma monorhis)

At 1.15am on 19 July 1989, a large petrel was seen and heard calling as it circled the trapping area where British Storm Petrels were being tape-lured on Tynemouth pier, north-east England. It departed unidentified. However, on 23 July, a similar bird was attracted to the tape and trapped. In the hand, the ringers were astonished to find a storm petrel superficially resembling Leach's Petrel, but with an all-dark rump. The bird was ringed, measured and photographed before release. On 26 July, an unringed bird, identical to the first, was trapped.

At the time, no certain identification could be made, as there were no obvious candidates amongst birds likely to reach the UK, but research began into the possibilities...

In 1990, a third individual was trapped on 6 July. The same bird was re-caught in July every year for the next 4 years, i.e. 30 July 1991; 29 July 1992; 21, 28 and 29 July 1993 and 11, 23 and 25 July 1994. This provided the possibility to use DNA analysis to assist in the identification. In 1991, a blood sample was taken by Dr David Parkin. Analysis of cytochroime-b mitocondrial DNA sequences in comparison to samples taken from Swinhoe's Petrels in Russia and Korea finally proved that the bird was of this species, this particular individual being a female.

More details about the taxonomy of the species, which is sympatric with Leach's Petrel (Oceanodroma leucorhoa), are available from Sibley's sequence and in the Birdguides library. Some literature references are as follows:

  1. James, P.C. & Robertson, H.A. (1985) "First record of Swinhoe's Storm-petrel Oceanodroma monorhis in the Atlantic Ocean", Ardea 73, pp. 105-106
  2. Carruthers, M.P., Cubitt, M.G. & Hall, L. (1989) "The dark-rumped petrels in Tyne & Wear", Birding World 2, pp. 288-289
  3. Bourne, W.R.P. (1990) "The first dark-rumped petrel", Birding World 3, p. 249
  4. Bretagnolle, V., Carruthers, M., Cubitt, M., Bioret, F., & Cuillandre, J-P. (1991) "Six captures of a dark-rumped, fork-tailed storm-petrel in the northern Atlantic", Ibis 133, pp. 351-356
  5. Cubitt, M. (1991) "The mystery petrels of Tyneside", Birding World 4, pp. 295-297
  6. Cubitt, M., Carruthers, M. & Zino, F. (1992) "Unraveling the mystery of the Tyne Petrel", Birding World 5, pp. 438-442
  7. Dawson, R. (1992) "Blood, sweat and petrels", Birding World 5, pp. 443-444
  8. King, J. & Minguez, E. (1994) "Swinhoe's Petrel: The first Mediterranean record", Birding World 7, pp. 271-273
  9. Cubitt, M. (1994) "The mystery dark-rumped storm-petrel", Birding 26, p. 125
  10. Cubitt, M.G. (1995) "Swinhoe's Storm-petrels at Tynemouth: New to Britain and Ireland", British Birds 88, pp. 342-390
  11. Brinkley, ES. (1995) "Dark-rumped storm-petrels in the North Atlantic", Birding 27, pp. 95-97
  12. Bourne, W.R.P. & Simmons, K.E.L. (1997) "A dark-rumped Leach’s Storm-petrel in the South Atlantic", Sula 11, pp. 209-215
  13. British Birds Rarity Committee Files (1997) "The Chalice petrel", British Birds 90, pp. 305-313
  14. Force, M. (1997) "Comments on 'The Chalice petrel'", British Birds 90, pp. 339-342
  15. Morrison, S. (1998) "All-dark petrels in the North Atlantic", British Birds 91, pp. 540-560
  16. Bolton, M. (1998) "Swinhoe’s Storm-petrel ringed at Ponta de Almadena, Algarve, 27th June 1998", A Rocha Bird Observatory Report, 1998
  17. O'Brian, M. Patteson, JB., Armistead, GL. & Pearce, GB. (1999) "Swinhoe's Storm-petrel: First North American photographic record", North American Birds 53(1), pp. 6-10
  18. Palmer, P. (2000) "First for Britain and Ireland: 1600-1999", Arlequin Press

The species had been observed over a number of years on Selvagem Grande in the Madeiran Archipelago, where breeding has been suspected (see below). In addition to these records, further records have come from various parts of the North Atlantic in recent years, including Norway, Holland, France, Portugal, the Mediterranean coasts of Spain and Italy, as well as off the US east coast.

The origin of these birds is debated - vagrancy from the Indian Ocean round the Cape being one possibility and a small North Atlantic breeding population being another. In support of the latter is the fact that the first North Atlantic record, from 1983, was of a male on the nest of a Madeiran Petrel (see James & Robertson 1985); in 1988, a male was captured (Bretagnolle et al. 1991) and, in each year from 1993 to 1996, a female with a vascularised brood patch was regularly caught on a nest (Zino 1997). Bretagnolle (1991) suggests that there might be a breeding population on the Azores or Cape Verde Islands.

More information on European status is provided on Eurobirding and on international distribution on Avibase and Oceanwanderers:

An exhausted bird at Eilat, Israel in January 1958 (Bourne, 1967) was the first record for in the Western Palearctic, and an obvious vagrant from the Indian Ocean. After the 1983 Maderia record, there been a further 16 confirmed records of Swinhoe’s Storm-petrel in the Western Palearctic, all trapped. In addition, Morrison (1998) documents 19 "dark-rumped" small Oceanodroma storm-petrels observed ‘at sea’ in the North Atlantic up to 1998 (though note that dark-rumped Leach's Petrel have also been identified by DNA analysis, so that any sight records must be uncertain). My own compilation of some of the more recent records (not necessarily all accepted yet) includes:

* single trapped, Revekaia, Klepp, Rogaland, Norway, August, 1997

* single trapped, Ponta de Almadena, Algarve, Spain, 27 June 1998

* single (sight record), Huisduinen, Den Helder, Noord-Holland, 11 July 1998

* single photographed, North Carolina Pelagic trip, USA, 8 August 1998

* single trapped, Great Skellig Island, County Kerry, Ireland, 1 July, 2000

* single re-trapped, Revekaia, Klepp, Rogaland, Norway, 27 July, 2000

* single trapped (different to last), Revekaia, Klepp, Rogaland, Norway, 16 August, 2000

* single trapped, Cove Harbour, Aberdeenshire, Scotland, 5 August, 2000

* single (sight record), South Stack, Anglesey, Wales, October, 2000

* single, Eilat's north beach, Israel, 8 September 2001. The bird flew into a window of one of Eilat's seafront hotels. It was picked up and brought to the IBRCE, but died shortly afterwards. The information about this bird was not submitted to the IRDC, however, I. Tsurim and N. Sapir examined the skin, which is preserved in the Zoological collection of the Tel Aviv University (specimen #AV15980) and confirmed the identification. [This is the second record for Israel, after the first found dead at Eilat, January 1958.]

* single (sight record), Platja del Trabucador, Ebro Delta, Spain, 30 April 2003

* single re-trapped (same as above), Revekaia, Klepp, Rogaland, Norway, 4/5 August, 2003

Pictures of the third record for Israel at Eilat on 19 April 2003 are here. Yet another was found exhausted at the same place 21 September 2004, becoming the fourth record!

* single, Niedersachsen, Germany, 24 September 2004; a detailed account and discussion of this record is found on the pages here.

* single, from pelagic 7 miles south of St Mary's (Scilly) for four minutes early afternoon (1.10-1.13pm), 21 July 2005.

* single, trapped and ringed at Hernyken, Nordland, Norway, 13 August 2006

* single, trapped on the Selvagens Islands, summer 2007 (had been ringed there in 1986)

The last-mentioned record here is hugely significant - this bird has been resident in the North Atlantic for over 20 years!!!

It remains a great mystery why this species should apparently have suddenly emerged in the North Atlantic after 1983, with no confirmed records prior to that. The great spread of the area over which the species has now been recorded, from the Mediterranean, off Iberia, the North Sea and off the US east coast adds weight to this mystery because records would be expected to be much more localised if attributable to a small breeding population. We may never know the origins of these birds...

Monday, 16 July 2007

Barn Owl road kill in Lothian

Barn Owl road casualties are always a tragic sight, yet have clear potential for providing insight into the status of the species in particular areas. This might be particularly useful where there is no dedicated monitoring, as has apparently been the case in Lothian in recent years. Whilst casual records showed a marked increase in 2004 there were no confirmed breeding records in either 2003 or 2004 and considerable uncertainty on the current health of the population in the area.

Historical reporting rates of road-kill averaged 2.4/year between 1984-1993 and only 1.0/year 1994-2003 [from Lothian Bird Reports]. This picture is consistent with a general view that the species has declined drastically in the area over the last 40 years. However, within a few weeks of the author moving East Lothian in August 2004 increased numbers of casualties were being recorded and a personal study commenced. Despite the fact that no special effort was made to find them, a total of 51 Barn Owls were thereafter recorded as RTA’s on Lothian roads during the two-year period from October 2004.

This article presents a summary of the findings from this initial two-year study period, with the intention of providing a baseline against which future trends can be monitored. Valuable additional insights have been obtained by means of post mortem analyses of 18 casualties, all courtesy of veterinary surgeon Jason Waine of Redditch. Other reports have appeared recently in Barn Owl Link (p.6), the newsletter of the Barn Owl Conservation Trust, and in the Lothian Bird Report for 2005.

Lothian Barn Owls