Reports from the National Conservation Organisations including the RSPB, The British Trust for Ornithology and Local Wildlife Trusts are warning us that our wildlife populations are in trouble. In the first issue of a new year it is a useful moment to try and take a stock check and assess what has changed in and around Dulwich with experience that goes back to some forty years of reporting and perhaps add an analysis of some of the reasons for the changes.
Because of their mobility and visibility the most obvious signposts of change lie with our birds and by far the greatest part of our records lie in bird reports. Within this we have to take into account our residents, our summer visitors, our winter visitors , our passage migrants and what may be termed freak occurrences. This last category although often the most dramatic carries least significance. Such reports include a collapsed Hen Harrier in Oaks Avenue, a Grey Partridge in a garden in Half Moon Lane, a Woodcock that broke an upstairs window in Dovercourt Road and hid under a bed from which it had to be fished out, a Brent Goose on the Paxton Green roundabout that should have been in the Thames Estuary and a Quail in the Velodrome that may have been an off course passage migrant. We have never quite achieved a twitcher rush but as the unusual vagrant can occur at any time this is always a possibility.
Taking our resident birds there are many whose populations have remained unchanged. Great Tits, Blue Tits , Long Tailed Tits, Robins, Dunnocks and Wrens continue to grace our gardens, and wood and parkland birds such as Nuthatches ,Great Spotted and Green Woodpeckers have remained unchanged through the years. The same is true of the larger birds such as Carrion Crows, Magpies, Jays and Wood Pigeons. However the major change has been the exponential rise in Ring Necked Parakeets. Forty years ago there was a small population in the grounds of the Bethlem Hospital in West Wickham, but in the last twenty years occasional visits have changed to a population explosion until they are now some of the most visible and audible birds in Dulwich. It is yet to emerge whether they are simply occupying an available ecological niche or whether they are going to have a significant effect on the populations of other birds.
The other major explosion over the last forty years, a mammal rather than a bird, has been the urban fox. In the 1970’s foxes were indeed starting to appear on our roads and in our gardens, but over the succeeding twenty years they became commonplace and totally adapted to our urban environment. During my childhood the fox was known principally as the scourge of the farmyard and the rabbit warren. By migrating into towns it has thrived as an urban scavenger and it has been able to withstand the mortality from the motor car. The hedgehog is less fortunate as rolling into a ball is the wrong strategy on roadways and its decline continues.
There have however been other losses among our residents, the most obvious being our House Sparrows. Forty years ago they were in every garden and now we have just a few remaining pockets. Although there are still rural populations the urban House Sparrow is becoming a rarity for reasons not understood though poor fledging success is clearly a factor. Less obvious has been the considerable decline in Greenfinch numbers and this is known to be related to a disease, Trichomonosis which may also be infecting our Chaffinches. Bullfinches ,regularly reported forty years ago are hardly ever now seen in Dulwich. This is compensated for by the rise in the population of Goldfinches which have been boosted by their liking for Nyger nut feeders. It is the one small passerine that has increased its urban population..
Forty years ago it was commonplace to see Starlings descend in flocks to rake our lawns for leatherjackets and although we see large spectacular rural flocks coming to roost, and some may remember there was once a massive Starling roost in Trafalgar Square, these are mostly continental winter visitors and we rarely see more than ten together in Dulwich of this once ubiquitous bird. Mistle Thrush numbers are much diminished and Song Thrushes are reduced by about fifty percent. Thrushes and indeed Blackbirds are cup nesting birds which may not be able adequately to conceal their nests from Magpies and Jays in the well kept garden and their fledglings are much at risk from our large numbers of cats.
The situation with Raptors is more interesting. Forty years ago practically the only bird of prey seen around Dulwich was the Kestrel with pairs nesting on several tall buildings. They are now reduced to a single pair still nesting regularly on St Peter’s Church by the start of Cox’s Walk. The evidence from the pellets from a pair once breeding on Dulwich College showed that a large portion of their diet was House Sparrow, now alas absent. However other birds of prey have benefited from the nationwide banning of toxic pesticides and rising populations are spilling into London. Our most common raptor is now the Sparrow Hawk, a far more efficient urban hunter than the Kestrel, sometimes soaring above us and sometimes in pursuit of our garden birds. Both Buzzards and Red Kites are regularly seen with Peregrine Falcons visiting from their nesting sites in central London. In the summer these records are added to by Hobbys which may also have started to breed here.
Chiffchaffs and Blackcaps are the summer visitors that have retained their breeding populations perhaps largely due to the favourable habitat of the woods, but the numbers of Swifts and House Martins are in decline which mirrors the situation nationwide. We have entirely lost Spotted Flycatchers as a local breeding bird and I have not had records of their being seen as passage migrants for some years. Willow Warblers once a common breeding bird are now seen only as passage migrants and we no longer ever hear the Cuckoo., of which there were records in the 1970’s and before. Other migrating birds on passage both in Spring and Autumn have provided records over the years. Ring Ousels,, Whinchats, Redstarts, Pied Flycatchers, Wood Warblers and even Golden Orioles are amongst the most notable. Many of these have declined in their breeding habitats elsewhere so the records here are now smaller in number.
Winter migrants provide a different picture and the pattern is far more weather related. If we get cold weather Redwings and Fieldfares can appear in large numbers to take advantage of garden berry crops and also the invertebrate food from the disturbed ground of sporting playing fields, but even in milder winters there are small numbers of Redwings in our woods and parks. Siskins and Goldfinches will take advantage of the Alders in Belair or the Birch trees in Dulwich park particularly if there is cold winter weather and these may be joined less frequently by Redpolls. In some years there have been Waxwing winters, most notably in 2010/2011 when hundreds of these spectacular visitors were seen. Firecrests once a rare record are now seen regularly in the woods as winter visitors and from time to time on a winter walk in the woods a Woodcock has been flushed.. Winter has often remained the most exciting time for our wildlife watchers as it is never predictable what may be seen.
It is however to the invertebrates that we must look to assess the health of our wildlife because herein lies the bedrock of the food chain on which so much depends. The most visible evidence is with the butterflies. Most of us continue to see the so called Cabbage White butterflies and Holly Blue butterflies are common in our gardens as their food plant, ivy is widespread. However during the 1970’s there were great numbers of Small Tortoiseshells and Peacocks, (native non migratory butterflies) everywhere. These took a bad hit in some wet summers, but whereas they have recovered outside London in better years I have not seen similar recovery here and now some of our less spectacular species such as Gatekeepers and Speckled Wood Butterflies also appear to be declining. One of our signature species, not a butterfly, but a Stag Beetle is still with us but the number seen flying each Summer appear to be smaller. Last year I realize was the first year I failed to see a Grasshopper in my garden.
Some of this may make rather depressing reading but a great deal of the changes that we record reflect what is going on in the country as a whole. Agricultural practices have been aimed at invertebrates deemed as pests that have had the unintended effect of poisoning or starving the birds on which they fed as has the use of killers of weeds that provide a seed base for the feeding of winter and migrating passerines. With many species falling rural populations are mirrored in what we see here unless a species can find an urban habitat to which it can adapt. Additionally over the last forty years, there has been a steady trend towards warmer winters and hotter summers and this has also had its effect on what we see. Species such as the Jersey Tiger Moth, never seen forty years ago, now is common in our gardens in the late summer as its caterpillars are now able to hibernate safely, but the Willow Warbler has shifted its breeding range northwards away from us to where presumably its summer food supply is more appropriate.
These are factors that are beyond our control but we also have to face up to the hard fact that we are more crowded and the footfall around us is getting higher. We all need space for our lives and recreation and unless space is reserved it means that our wildlife is bound to be squeezed. All our species whether vertebrate or invertebrate need space to feed and breed and although our gardens may often be artificial nature reserves we also need wild places with rough grasslands, native trees and hedges that can encourage populations to find their habitats and can breed, eat or be eaten. We need to be aware that by spraying our roses and fruit trees, creating weed free lawns and poisoning snails we may well be removing valuable food sources. The planting of native trees is and should be a priority and it is to my regret that a not even a Grey Squirrel will be seen on an injudiciously planted Eucalyptus in my garden.
However, one of the major developments over the last few years has been the work of the London Wildlife Trust. The management of our historic native woodland is providing us with a resource that we can hope will last for many generations to come and the appearance of such gems as the Silver Washed Fritillary butterfly is an example of that which we must be able to treasure.
Their work in conservation of Bat species of which many of us were unaware by the provision of bat boxes and the preservation of traditional Bat roosting and breeding sites has been an example of species targeted conservation. This may be the key philosophy and process for the future if we can provide sites where other species may colonise and find habitat.
We are indeed lucky in having an expanse of native woodland and larger areas of parks and green spaces than much of London with lakes and ponds that have been able to provide waterways that have also kept the populations of the water loving birds , frogs and toads stable. It is the fact of Dulwich as a major oasis in London that enables the records of wildlife to go on and on.