Rook, Song Thrush & Mistle Thrush Maps - Sussex Ornithological Society

Rook, Song Thrush & Mistle Thrush Maps

Sunday 14th March 2010

These maps include all 2008 SOS breeding records, as well as all TTV, Birdtrack and roving records from the first two Atlas breeding season periods, in 2008 and 2009. No BTO Garden BirdWatch data are included, and whilst some WeBS data (those which are attributable to a 1-km square) and 2008 BBS data are included, such data do not include breeding evidence. Therefore we would ask that you put in separate roving records, with breeding evidence, for any breeding species that you see whilst in your garden or during a BBS or WeBS count. These maps do not include any records from the nest record scheme or the ringing scheme (some of these records will be incorporated at a later date).

ROOK – First two breeding seasons provisional distribution map.

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Rooks are early-breeding birds, which are now actively Building nests (breeding evidence code B = probable breeding). Late March/early April is a good time to see the nests before leaves come out on the trees, and evidence of Occupied Nests can easily be gathered (breeding evidence code ON = confirmed breeding).

This is a species for which birds can travel some distance from their nests in search of food, so the high percentage of records with no breeding evidence (45.5%) is to be expected. In 2011 the SOS will be undertaking a survey to identify and count all Rook nests across the county. We would therefore appreciate as many records as possible this year with a 6-figure grid reference for the middle of nest colonies, as this will make it easier to organise next year’s survey.

SONG THRUSH – First two breeding seasons provisional distribution map.

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Song Thrushes will have laid their first clutches by now. They start singing (S = possible breeding) before sunrise and sing until after sunset. If you record one singing in the same spot on two occasions seven or more days apart, use the breeding code T (permanent Territory = probable breeding), and soon look out for it carrying food for its young (code FF = confirmed breeding).

Although Song Thrush has so far been recorded in over three-quarters of the county’s tetrads, in only 25% of these tetrads has breeding been confirmed. In 22% of them breeding has been recorded as probable, but in 53% of them Song Thrush has only been recorded as present or possibly breeding. This is a species for which evidence of probable and confirmed breeding appears to be considerably under-recorded to date.

MISTLE THRUSH – First two breeding seasons provisional distribution map.

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Mistle Thrushes will also have laid their first clutches by now, in nests in trees in open areas such as the edges of woods, farmland, urban parks, recreational land or large gardens. Look out for them visiting probable nest sites (N = probable breeding), or for evidence of the nest itself (adults entering or leaving nest indicating Occupied Nest, code ON, or a Nest with Young seen or heard, code NY = confirmed breeding).

Like Song Thrush, this is a species for which evidence of probable and confirmed breeding appears to be considerably under-recorded to date. Thus although Mistle Thrush has so far been recorded in just under half of the county’s tetrads, breeding has only been confirmed in 19.5% of them with probable breeding recorded in a further 23.2% of these tetrads. This means that in 57.3% of all tetrads where Mistle Thrush has been recorded to date there is no breeding evidence, or only evidence of possible breeding.

Records of birds singing in the same spot on two occasions more than a week apart (permanent territory, code T = probable breeding) is a good way to “boost” the breeding evidence for this species.