Scottish Birds THE JOURNAL OF THE SOC Vol 22 No 1 June 2001 Roof and ground nesting Eurasian Oystercatchers in Aberdeen The contrasting status of Ring Ouzels in 2 areas of upper Deeside The distribution of Crested Tits in Scotland during the 1990s Western Capercaillie captures in snares Amendments to the Scottish List Scottish List: species and subspecies Breeding biology of Ring Ouzels in Glen Esk Scottish Birds The Journal of the Scottish Ornithologists' Club Editor: Dr S da Prato Assisted by: Dr I Bainbridge, Professor D Jenkins, Dr M Marquiss, Dr J B Nelson, and R Swann Business Editor: The Secretary sac, 21 Regent Terrace Edinburgh EH7 5BT (tel 0131-5566042, fax 0131 5589947, email [email protected]). Scottish Birds, the official journal of the Scottish Ornithologists' Club, publishes original material relating to ornithology in Scotland. Papers and notes should be sent to The Editor, Scottish Birds, 21 Regent Terrace, Edinburgh EH7 SBT. 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Published by the Scottish Ornithologists' Club, 21 Regent Terrace, Edinburgh EH7 5BT Printed by Meigle Print, Block 11 , Units I & 2, Tweedbank Industrial Estate, Galashiels TDI 3RS Scottish Birds (2001) 22:1-8 Roof and ground nesting Eurasian Oystercatchers in Aberdeen A DUNCAN, R DUN CAN, R RAE, G W REBECCA & B J STEWART In 1993 Aberdeen had a population ofat least 275 pairs ofbreeding Eurasian Oystercatchers of which 205 nested on roofs. This was probably the highest concentration of roof nesting Oystercatchers in Europe. Productivity for a sample of the roof nesters was 0.8 fledged young per pair. This comparedfavourably with other ground nesting populations inBritain. Factors possibly facilitating the increase of the population and some of the problems resulting from a wader colonising an urban environment are discussed. Introduction The early history of ground (1960s) and roof nesting (1971-75) at one of these locations was described in detail by Mills (1978). In the late 1970s, A Knox The Eurasian Oystercatcher* Haematopus estimated about 30 roof nesting pairs in Aberdeen ostralegus is a common breeding wader in Britain, and reported that the population appeared to be with numbers and range having increased during increasing (in Marren 1982). the twentieth century (Cramp & Simrnons 1983, Marchant et al 1990). It had a chiefly coastal The flTSt attempt to quantify the extent of roof distribution in Britain and Ireland but now also nesting within the urban and suburban areas of breeds inland in northern England and Scotland Aberdeen took place in 1986, when 109 confirmed (Cramp & Simmons 1983, Dare 1993). or possible breeding pairs were located, of which 74 were confmned as roof nesters and 23 as ground In the early 1990s, there was an estimated 82,500 nesters (Rae et al 1986). In 1988 BJS and F breeding pairs in lowland Scotland (O'Brien 1996). Tadhunter organised a similar census as did AD In north east Scotland it is a widespread bird on and RD in 1993. This paper presents the results most open habitats apart from moors and mountain from these surveys, discusses the increase of the tops (Buckland et al 1990). population and compares the hatching success and productivity from a sample of the roof nesting pairs Eurasian Oystercatchers normally nest on sparsely with other studies of ground nesting Eurasian vegetated ground or on shingle, but are well known Oystercatchers in Britain. for using unusual sites such as roofs, fence post tops, tree stumps and broken walls (paton & Willis 1973, Smith 1981, Cramp & Simmons 1983). In History of roof nesting Scotland they have even nested in shallow hollows in trees (Smith 1989, Dougall et al 1989, Kirk A request through the Internet in 1998 for 1991). information on roof nesting by Eurasian Oystercatchers and follow up correspondence Eurasian Oystercatchers were first noted nesting on revealed that the earliest records were from Holland, roofs in Aberdeen in 1966 when a pair reared 2 where pairs used ridged roofs in Texel in 1916 and young on a flat school roof (RR pers ohs). The the flat roof of a hospital in Friesland in 1936 (J earliest published records from Aberdeen were of 4 Hulscher in litt, see also Tekke 1978). Other pairs at separate roofs between 1971 and 1974 records from Holland included 10 to 20 pairs in The (paton & Willis 1973, Boume 1975). Hague (W L J anse), at lea t 25 pairs in Amsterdam • Sconish Birds has now adopted the latest BOURC English names (refer to pages 33-49 for the SB RC paper) 2 A Duncan et at S822(1) (M Kuiper), 4 to 6 pairs in Grooingen (J Allex) and Figure 1 Map of mainland Scotland and the 46 pairs in south Kennemerland following a survey Westemlsles showing the locations oftow1ls or in 1986 (F Cottaar in litt). Further records were villages with records of roof nestillg Eurasian received from Sweden: 3 towns including about 10 Oystercatchers. Names and the dates first re­ pairs in Stockholm (J Nillson), Norway: 5 towns, portedareasfollows: 1 Aberdeen 1966, 2 Elgin Denmark: 7 towns and Germany at least 18 towns mid 1970s, 3 Invemess 1983, 4 Tain 1987, 5 (see also Vauk & Mathiske 1980). Sing le records Stirling 1987, 6 Forres early 1990s, 7 South were received from Riga in Latvia and Ordfordness Queensferry 1992, 8 Inverkeithing 1993, 9 in Suffolk, south east England. DUll/let 1993, 10 M01lifieth 1994, 11 Montrose 1995, 12 Nethybridge 1995, 13 DUlldee 1996, In Scotland, away from the Aberdeen area, roof 14 Turriff 1997. nesting has been reported from Elgin in the mid 1970s (Suttie 1996); Inverness, one pair in 1983 and 9 pairs in 1995 (Munro 1984, Crooke & Vittery 1997); Tain and Stirling in 1987 (Nethersole­ Thompson 1988 & M V Bell pers comm respectively); Forres by the early 1990s (Cook 1992); South Queensferry in 1992 (A Hilton pers comm); lnverkeithing and Dunnet in 1993 (P 14 Doyle & N Money pers comm respectively); Nethybridge and Montrose in 1995 (Crooke & Vittery 1997 & H Bell pers comm respectively); Monifieth in 1994 and Dundee in 1996 (Lynch 11 1997) and Turriff in 1997 (per GWR) (Figure I) . The occurrence of roof nesting wou ld therefore appear to ha ve been fair! y widespread in north west Europe by the late 1990s. Methods Prior to each survey in Aberdeen a list of known and possible breeding sites was compiled. Fieldwork began in late January to coincide with the return of Eurasian Oystercatchers to their breeding areas. All potential sites ie building complexes with flat roofs and nearby mown grass areas were checked with as many roofs as possible being viewed from Observations of an incubating bird, eggs, chicks, vantage points. Between late January and mid adults carrying food or alarm calling were classed April all Eurasian Oystercatchers seen feeding, as confirmed breeding. Two or more sightings roosting or displaying near potential breeding sites separated by at least 2 weeks of a pair of Eurasian were noted. Further visits were made as necessary Oystercatchers present at, or near a potential to confirm if pairs were present. As it was not breeding site was recorded as possible breeding. possible to gain access to, or view, all roofs some For the 1986 and 1993 surveys all confirmed and pairs may have been missed. possible roof nesting pairs within the city boundary Scottish Birds (2001) Roof and ground nesting Oystercatchers in Aberdeen 3 and all the ground nesting pairs in the built up areas of roof and 8.36ha of mown grass, where birds were were mapped. Between 1988 and 1993 hatching observed feeding. By 1993, the average density 2 and fledging success was recorded from a sample over all of the built up areas was 2.7 pairs per km • of the roof nesting pairs. Productivity was measured as the number of young fledged per breeding pair Nest sites (Harris 1967, Heppleston 1972 & Briggs 1984). Roof sites were generally flat and coated with Results bitumen, with a covering of small granite chips or other small stones or pebbles. However, in 1993 7 Numbers nests were on sloping roofs up to 15° gradient.