DONCASTER NATURALISTS’ SOCIETY
‘EARLY BIRDS’ PROJECT 1995
C.A. Howes, Museum & Art Gallery, Doncaster DN1 2AE
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INTRODUCTION
Anecdotal evidence from local ornithologists and naturalists, supported by BTO Common Bird Census data suggested that major declines had taken place in the populations of a range of once common species such as Song Thrush, Linnet, Corn Bunting and Skylark.
In order to produce a local baseline index of frequency of these and other species, a simple and annually repeatable recording exercise was divised. This required a series of listening sites in a variety of habitat types across the Doncaster region to be monitored shortly after dawn during the period of ‘dawn chorus’.
Repeats of this exercise on an annual basis would enable trends in status changes to be detected. It would also provide statistical information on habitat utilisation.
METHODOLOGY
Between 26th May and 6th June 1995 singing ‘territory holding’ birds were recorded shortly after dawn at a total of 37 listening points within the Doncaster Metropolitan Borough in South Yorkshire.
A standard 5 minutes was spent at each listening point and each bird species heard singing (or calling) was listed. Notes were also made of the prevailing habitat types present at each site.
RESULTS
30 species were recorded, ranging in frequency from Blackbird at 32 (86%) sites to Cuckoo, Grey Partridge, Pied Wagtail and Goldcrest at 1 (<5%) site each.
Table 1 shows that the five most frequent species were Blackbird, Wren, Robin, Song Thrush and Chaffinch.
Despite gloomy reports as to the demise of the Song thrush, it was heartening to record singing males at 12 (32%) sites. Although widely distributed, positive sites seemed to be centred on limestone and sandy regions of the district.
TABLE 1
Relative frequency of singing (and calling) birds.
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Species No. of sites % sites
Blackbird 32 86%
Wren 24 65%
Robin 20 54%
Song Thrush 12 32%
Chaffinch 12 32%
House Sparrow 10 27%
Dunnock 9 24%
Willow Warbler 9 24%
Starling 8 22%
Blue Tit 8 22%
Blackcap 8 22%
Collared Dove 7 19%
Greenfinch 7 19%
Great Tit 6 16%
Jackdaw 6 16%
Yellow Hammer 6 16%
Rook 5 13%
Wood Pigeon 4 11%
Skylark 4 11%
Mistle Thrush 3 8%
Goldfinch 3 8%
Swallow 3 8%
Corn Bunting 2 5%
Linnet 2 5%
Whitethroat 2 5%
Grey Partridge 1 3%
Cuckoo 1 3%
Pied Wagtail 1 3%
Goldcrest 1 3%
Species density
The number of species singing at each site ranged from three at six sites to nine at three sites (Tickhill Mill Pond, Tickhill High Common and Kings Wood) and eleven at one site (Warmsworth Quarry Park) (see table 2). The most frequent total was six recorded at 13 sites and the mean diversity for the region was 5.89.
TABLE 2
Numbers of species per site
Sites
0 0 6 4 3 13 3 4 3 0 1
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1 2 3 4 5 6 7 8 9 10 11
No. of Species
Bio-diversity
Although the number of new species continued to rise as additional sites were visited, the rate of additions diminished substantially after the first 20 sites. The graph formed by plotting new species against the number of sites visited shows that 33% of species had been encountered by the 4th site, 50% of species by the 7th site and 75% by the 13th site. Only four species were added after the 20th site and all of these were of rare occurrence, being present in less than 5% of sites.
Although the Doncaster district has a remarkably rich avifauna (and no doubt the number of bird species represented in this preliminary survey could have been increased somewhat by visits to peat moor, fenland and ancient woodland sites), the survey warns that apart from the ubiquitous generalists, the majority of species on the local list are probably more restricted and localised than we thought.
Habitat associations
A complete analysis of habitat association has not yet been undertaken. However for the song thrush, of 11 (92%) occupied sites there was extensive availability of permanent grassland in close proximity to shrubberies and trees viz. parks, golf courses, church yards etc.(see table 3). It may also be significant that the grassland concerned is invariably managed by various degrees of mechanical mowing, rather than cattle or horse grazing.
TABLE 3
Song Thrush Habitats
Suburban Garden 3
Rural Garden 2
Suburban Park 1
Castle/Hall Grounds 2
Golf Course 1
Churchyard 2
Deciduous Woodland 1
Further work
In order to broaden the spectrum of species, a greater range of habitat types needs to be encompassed by the survey.
In order to better monitor the performance of species in the various habitats, more examples of each habitat need to be sampled.
(Early draft)
C.A. H.