The most recent extinctions are five closely related species: the woodland fritillaries whose larval
foodplants are the various species of violet. In some respects they shared the fate of the six woodland
species already described. The three larger species were recorded by Fitch (1891) as rarer than for-
merly although he noted that the smaller species were still common. The closing in of woodlands with
the reduction in coppicing would have reduced the numbers of violets as well as the abundance of
nectar-producing flowers which the adult butterflies need. The difference between these fritillaries and
the other lost woodland species is that the violet feeding fritillaries made quite a comeback in the 1930s
to early 1950s. Heath et al. as do most modern authors, explain the general decline of these fritillaries
in terms of habitat changes due to the cessation of coppicing and the increasing isolation of coppice
woodlands, separated by intensive arable lands unsuitable for dispersal of essentially woodland
species. If this explanation is correct, then the expansion in the 1930s and 1940s could be explained by
a combination of warmer summer weather favouring the species and secondary woodlands (on land
affected by the depression years) developing a suitable flora. There is, I think, an alternative explana-
tion for the decline of woodland species that deserves much closer investigation: the effect of bird pre-
dation, especially by pheasants.
The extinct woodland species fall into two clear groups based on their larval types. The fritillaries
have ground level larvae which rely on being spiny and (probably) distasteful for protection from birds.
The others have well camouflaged larvae which are presumably edible by birds that can find them.
Distasteful and uncamouflaged larvae are only protected from birds that have learned (or instinctively
know) that they should be avoided. Large populations of (often captive reared) pheasants must kill
large numbers of caterpillars even if, having tested them, they then reject the wounded caterpillar.
Species, like all but one of the lost fritillaries, which overwinter in the caterpillar stage, would be
especially susceptible. It may not be coincidence that, as pheasant-shooting, and hence gamekeeping
activities, increased in Victorian times the woodland butterflies declined. Pheasant rearing declined
dramatically during the second world war and fritillaries increased. The final piece of circumstantial
evidence is that the recent decline in fritillaries has been most marked in the eastern half of the country:
where pheasant rearing is the normal use for virtually all small woodlands.
Pheasants are unlikely to find camouflaged larvae, and certainly not those that feed in trees or
shrubs, but smaller birds may do so. It is noticeable that all the woodland and woodland edge species
whose larvae are camouflaged amongst grass (where few small birds forage for insects) have remained
common or increased in numbers. All the species whose camouflaged larvae feed on broad-leaved
plants have declined. Although I have not found detailed survey results to support this contention, it is
widely believed that small birds are more common in woods in lowland England than in many parts of
Europe (where woodland butterflies are still common). The winter feeding of birds in gardens reduces
winter mortality and increases the population density of many species (Lack, 1966). Where, as in
Essex, woods and gardens are in close proximity there will be a spill-over effect. Also, pheasant-
feeding in woodlands is likely to increase the population density of small woodland birds for the same
reason. Finally, unlike the nearby continent, there is not a tradition of the universal right to hunt birds
small and large. In France hunting reduces the small bird population and makes pheasant rearing less
popular as it is difficult to reserve the reared birds for shooting by the people who paid for them.
The above is no more than speculation, and lack of coppicing is certainly also involved in the decline
of woodland species, but I think other factors need more careful study. Certainly, the increase in cop-
picing (for conservation purposes) has yet to lead to a recolonisation of any Essex nature reserve by
any of the lost woodland species.
Surviving species greatly declined in range or abundance
Every species has a centre to its range, where it is at its most abundant, and outlying areas where it is
rarer and may only be present as a vagrant. So distribution and abundance are part of the same story
(Krebs, 1974). Amongst the Essex butterflies, most of those which have greatly declined in abundance
have shown a corresponding reduction in range. This is obvious, in most cases, even with the coarse
scale of the 10km square maps in this book.
Two species have declined very noticeably in abundance without any corresponding change in
range. These are the small copper and the common blue: both have recent records from every square in
the county. They are found only in open permanent grasslands where their larval foodplants grow and
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