Scottish Birds Volume 22 Abstracts
Part 1 - June 2001
Roof and ground nesting Eurasian Oystercatchers in Aberdeen.
In 1993 Aberdeen had a population of at least 275 pairs of breeding 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 compared favourably with other ground nesting populations in Britain. Factors possibly facilitating the increase of the population and some of the problems resulting from a wader colonising an urban environment are discussed.
The contrasting status of the Ring Ouzel in 2 areas of upper Deeside, north east Scotland, between 1991 and 1998.
In 1998, surveys on 2 areas of upper Deeside, north east Scotland confirmed the findings of a study in 1991 which showed a relatively high density of breeding Ring Ouzels in the Glen Clunie area and low numbers on part of Mar Lodge estate. The contrasting densities in the 2 study areas were probably a result of subtle habitat differences linked to geology, soils and land use. In 1998 the Glen Clunie study area held at least 59 pairs. This represented approximately 1% of the United Kingdom population as estimated in 1999 and in contrast to many other areas of Britain this population was stable or had possibly increased during the 1990s.
The distribution of Crested Tits in Scotland during the 1990s.
The distribution of the Crested Tit was reviewed using records collected during 1992-99. Records were obtained from 114 woods or sites and 79 10km squares. Individual woods were listed, thereby identifying those for potential conservation management. Inspection of the data from the 2 breeding atlas projects, the winter atlas and a previous survey of Crested Tits, compared with the current survey, showed that the distribution has changed little. The differences between numbers of recorded 10km squares in this survey compared with the atlas surveys are probably due to differences in observer effort.
Western Capercaillie captures in snares.
Details of 17 incidents involving the deaths of 46 birds are recorded. The true figure is likely to be considerably higher. It is recomended that snares are not set under the canopy in areas used by Western Capercaillie.
Amendments to the Scottish List.
[No abstract]
The Scottish List - species and subspecies.
The Scottish Birds Records Committee (SBRC) is responsible for maintaining the Scottish List, first published in Scottish Birds in 1994. Until now, the list has been based on the species level of classification. This is the first attempt by SBRC to tabulate all subspecies recorded in Scotland and also introduces status symbols. It is envisaged that this expanded list will form a baseline for future studies, will be of use as a conservation tool and could be used in courts of law. (Full paper)
Numbers, distribution and breeding biology of Ring Ouzels in upper Glen Esk, 1992-98.
Breeding Ring Ouzels were studied during 1992-98 in upper Glen Esk, Angus. The number of confirmed breeding pairs was similar at the beginning and end of the study period with 53 in 1992 and 56 in 1998. Mean inter nest distance was 406m. Of 144 nest sites described, the mean height above ground was 4.9m and mean altitude was 420m. Nests were built almost exclusively on, under or against rock, usually associated with Heather and usually on crags or steeply sloping ground. The annual earliest egg laying date varied between 12 and 23 April. The peak 2 day period of first egg laying date for first clutches was 29-30 April and for second clutches was 27-28 May. The mean clutch size was 4.01 (n 75), while the mean brood size was 3.37 (n 140) with a mean of 3.31 (n 140) chicks fledged. Annual nest success rates varied from 0.50 to 0.77 with most losses at the nestling stage.
Part 2 - December 2001
Cliff nesting seabirds in east Caithness 1980-1993.
Numbers of cliff breeding seabirds were monitored at plots at 5 colonies in east Caithness during 1980-1993. Numbers of Northern Fulmars (+13%) and Common Guillemots (+2%) increased and numbers of European Shags (-7%, 1985-93), Black-legged Kittiwakes (-9%) and Razorbills (-11%) decreased, but no significant trends were detected for individual species when data for all colonies were combined. However significant upward and downward trends at different colonies were recorded for Kittiwake, Guillemot and Razorbill. Fulmar productivity decreased slightly and Kittiwake chick production from 1985 to 1993 declined by an average of -0.05 chicks/AON/year.
Status, distribution and breeding success of the Red-billed Chough in Scotland in 1998.
A survey of Red-billed Choughs in Scotland in 1988 estimated a total of 58-66 breeding pairs, with at least 52 non breeding birds present. Islay held 44-49 breeding pairs, with 11-14 breeding pairs on Colonsay, and single pairs on Jura, Mull and in Galloway. This represents a substantial decline since 1986, with the number of breeding pairs in Scotland having decreased by 37%. The decline is due almost entirely to changes on Islay where the number of breeding pairs has decreased by 48% since 1986; In contrast to Islay, the small population on Colonsay has increased from 7 to 14 breeding pairs since 1986. On Islay the chance of a nest site having continued occupation or new occupation between 1986 and 1998 was related to nest site type, with a similar number of pairs using nest sites in buildings in both years but with fewer pairs at natural nest sites in 1998. The factors causing this association between nest site type and the chance of occupation are unknown but could be related to the tendency for natural nest sites to be on the coast or to other attributes of the sites at which the different nest types tend to occur. The average fledging success on Islay in 1998, at 2.07 fledglings per pair, did not differ between regions or between pairs nesting in buildings or natural sites and was similar to the levels recorded between 1983 and 1985 when numbers on Islay were increasing. On Colonsay an average of 2.78 fledglings were produced per pair in 1998 which, if typical of other years, could lead to the observed differences in population trends between Islay and Colonsay.
Diet of Barn Owl in East Ross and East Ness.
The diet of Barn Owls was studied between 1993-99; seasonal variation in diet was studied at 2 sites in 1999. Field Voles were found to form a greater proportion of the diet than in other parts of Britain, with Common Shrew and Wood Mouse as the main alternative prey species. Field Voles decreased in the diet through the summer at which time the proportion of Common Shrews increased; the proportion of Wood Mice increased through the year. Field Voles formed a greater proportion of the diet in agriculturally less intensive areas with small areas of rough grassland than in agriculturally intensive areas with large amounts of rough grassland. This was taken to indicate that less intensively farmed areas provided better hunting for Barn Owls, even where these held smaller areas of rough grassland. Barn Owls fed at a higher rate in winter than found in previous studies and this was considered to be due to recent mild winters, which may have been responsible for increases in the numbers of Barn Owls in the present study area. At one site, the male owl was found to eat fewer and smaller Field Voles than the female and young, and to eat more Common Shrews.