an important contribution to our understanding of woodland bird communities.
The pattern of change at Bookham has been in favour of shrub nesting
species and against ground feeding birds; as scrub advanced, some woodland
species (e.g. great tits (Parus major), blue tits (Parus caeruleus), marsh tits
(Parus palustris), willow tits (Parus montanus), bullfinches (Pyrrhula pyrrhula)
and chaffinches have successfully moved into scrub and adapted their feeding
stations to lower levels than in the woodland. Ground feeding species, such as
blackbirds (Turdus merula), have either moved to higher levels because of the
attraction of the berries or else, in the case of song thrushes (Turdus philomelos)
and robins (Erithacus rubecula), preserved the same feeding niche. Wrens
(Troglodytes troglodytes), Whitethroats (Sylvia communis), willow warblers
(Phylloscopus trochilus) and hedge sparrows (Prunella modularis) appear to
have penetrated the woodland from the scrub.
Are similar changes taking place in Epping Forest? It is difficult to say, but
it seems unlikely that the kind of behavioural adaptations noted at Bookham
would not be repeated in similar conditions in the Forest. Considering how
much has been said about the influence of scrub development on — or its
removal from — the Forest, it is surprising that there is not more hard evidence
as to its consequences.
CONCLUSIONS
Since 1800 the overall structure of the Epping Forest bird community
appears to have remained fairly stable, although such a conclusion must be
qualified in light of the difficulty of interpreting the historical data. Most of the
species that have been lost or have declined have been on the edge of their
range, have declined over a wider area than the Forest, or are noted for their
population fluctuations. Equally, those that have increased have done so not in
the Forest alone, but over the country as a whole. The fairly high level of
diversity would appear to be a function of habitat variety, and the invasion of
species with small niches and adaptation to ecological change. Whilst some
species will show a high degree of adaptability, others will not and it is a
reasonable prediction that a continuation of the trend towards uniformity
resulting from further losses of open habitat will lead to a less diverse bird
community. Such a pattern would be consistent with the later stages of
ecological succession (McNaughton and Wolf, 1973).
Whether such changes in the Forest ecosystem are desirable or what
management policies might be employed to maintain a desired level of diversity,
and for what purpose, is a matter for debate. What is certain is that more
precise information about the function of the bird community as part of the
total Forest ecosystem must be obtained if ornithologists are to make a sensible
contribution to that debate.
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