Observations on the Song Thrush Turdus philomelos Brehm at Shadwell Wood SSSI
Fig. 1. mean contacts per visit for each of the 12 years 1989-2000
Fig. 2. Frequency of contacts by season
the same extent by the song Thrush's major competitor, the Blackbird Turdus merula L., for whom
only 60% of sightings were in the coppiced areas.
Climatic factors - Rainfall figures were available for 7 of the study years. The results showed a
significant negative correlation (r = -0.77) between total annual rainfall and numbers of thrush
contacts in that same year. Less rain meant more thrushes in Shadwell Wood (fig 3). If the figures
are adjusted to compare the number of contacts in the year after a particular rainfall figure, there
was no correlation (Fig. 3).
Competition - Blackbirds do compete with Song Thrashes much of the year for the same food sources,
and it was first noticed some 60 years ago that the ratio of Blackbirds to Song Thrushes was changing
in the Blackbirds favour (Mead 2000). Comparing the numbers of Blackbird and Song Thrush contacts,
however, showed no significant positive or negative correlation (r =0.10) (Fig. 4).
Discussion
The 12 years study did not see a significant change in the number of contacts made with Song
Thrushes in Shadwell Wood. Yet we know that in the wider countryside, particularly farmland, the
population has decreased by 66% (Mead 2000). Woodlands offer a more stable habitat - there is
none of the grubbing out of hedges, loss of stubble, or regular use of chemicals that characterises
arable land. Song Thrush is a lover of scrubby habitats, and perhaps took advantage of the arable
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Essex Naturalist (New Series) 21 (2004)