The Decline of the chough in Cornwall
It is all too common to hear of the decline of a species due to its habitat being destroyed. In a way, this is also true of the chough, but the habitat has not been destroyed, merely left to become overgrown.
Choughs are at home on the coast. Their preferred habitats are natural coastal cliffs which are rich in insect life, especially ant communities, where rocks and exposed soil meet wind-scoured maritime grassland.
Short-grazed old pasture is very important as a back-up resource, especially in the winter and where the quality of the cliffscape is not optimal.
Four hundred years ago Peter Mundy wrote of the chough as “The Cornish Daw, breeding in shafts of Tynne seldom seine elsewhere”
The Cornish Chough is linked with one of Cornwall’s major industries – tin mining, especially on the coast. In the late nineteenth and early twentieth centuries, tin mines were abundant throughout Cornwall, and so too were the workers and animals associated with these mines. We now think of the Cornish coastline as a wild and deserted place, but back in the days of the industrial revolution, the coastline would have been a hive of activity.
The 19th Century
The late nineteenth century saw the coming of the railways. These brought the first tourists to Cornwall. Along with Victorian naturalists collecting specimens, there would also have been many hunters, all keen to bag an exotic bird or two, as well as the ubiquitous Victorian egg collectors. Choughs were also taken as pets.
The mines used the new steam engines to keep water out, and these were often stoked with “furze” – or Gorse (Ulex europaeus & Ulex gallii). Gorse was used in the smelting process, and bracken (Pteridium aqilinum) as bedding for livestock. There were large numbers of herd animals at the mines, including ponies, cattle and sheep. All of these animals were put out to pasture, and kept large clifftop areas cropped down to ground level. This was perfect habitat for choughs.
As the mines dwindled, and people and animals moved away, the coastal margins became overgrown with impenetrable masses of gorse and bracken, forcing the choughs to move on.
In his 1880 book Birds of Cornwall Rodd seems to be one of the first to notice the bird’s decline: “Not abundant…in view of the too rapid decrease and impending extinction of this handsome bird, it may be prudent to withhold the precise nesting localities referred to.”
The 20th Century
Later in the twentieth century, there were many changes in farming practices, and these too had an effect on chough populations. Farmers began to use pesticides to protect their cattle, resulting in a reduction in the insect life in cow pats. The use of seed treatments such as Aldrin and Dieldrin was also known to affect the fertility of birds, and once again, the chough suffered. (Ironically, so did the chough’s main predator, the Peregrine falcon).
In the early 1920’s T A Coward wrote in Birds of the British Isles: “A melancholy interest surrounds the chough, whose black dress, long curved bill and red legs distinguish it from all other birds; it is a species that is going under.”
Another factor in the decline of coastal habitat for the chough was the introduction of the disease Myxomatosis. Rabbits play an important part in keeping large areas of coastal margins cropped down – they also nibble at the shoots of newly-sprouted Gorse, helping to keep it in check. Myxomatosis was introduced into the UK in the 1950’s, and by 1955 it was estimated that 90% of the wild rabbit population was affected. This lead to a massive drop in rabbit numbers, leaving the coastal areas to become overgrown.
In 1951 only four birds were seen in Cornwall. In 1954 only three and by 1957 only one pair remained. They stayed together for ten more years, each year being seen carrying nesting material into their nest site at Stem Cove, near Mawgan Porth. Hopes were raised in 1963 when Tony Archer-Lock reported the distinctive cry of a young bird as the female left the nest site, but no youngster ever fledged.
The last pair of choughs in Cornwall seemed to be immortal, and bird-watchers would regularly make a pilgrimage to see the last two birds between Watergate Bay and Mawgan Porth. Sadly, the solitary survivor was last recorded on 17th June 1973, having out-lived its mate by six years.
Roger Penhallurick wrote: “Those of us who remember its characteristic “chawk” and recall how it swept around Stem Point on outstretched wings, feel we belong to a race apart – superior beings with a close affinity to ancient gnarled Indians who remember the vast herds of stampeding bison, and the skies black with flocks of Passenger Pigeons”.