Conservation of the Corncrake
You’ll never see a corncrake in a zoo, but ...
You’ll never see a corncrake in a zoo, but today if you see a corncrake in England, it’s in part because of a zoo. The corncrake (crex crex 1) is a bird whose UK range was reduced in the 20th century from the whole mainland of the UK to Northern Ireland, the Western Isles and Orkney. UK zoos were important players in a project to re-establish a population in England.
The corncrakei lives on dry land; unlike its near relative’s the moorhens, coots and rails. Corncrakes are summer visitors that migrate to southern Africa and some parts of southern Europe for the winter. A corncrake measures up to 30cm from head to toe and favours grasslands that are also tall, about 20cm, but not too dense as to be impenetrable. Corncrakesii are a farmland bird and during the 20th century farming methods changed with earlier cropping of hay which conflicted with the late summer nesting of the corncrake. With corncrakes living only a couple of yearsiii and habitually returning to their UK nesting sites each April, it didn’t take long for the corncrake to disappear from swathes of England, Wales and Scotland. The footholds that the corncrake maintains in the Western Isles and Orkney are due in no small part to later harvesting, slower growing crops and less mechanisation. Their position in Scotland has been consolidated by establishing nature reserves where farming timetables could be adapted to meet the needs of the corncrake. Coupled with financial incentives for Scottish crofters to delay their harvest, the decline of the corncrake was halted; the next step was to reverse it.
It was clear that due to corncrake’s habit of returning to the whereabouts of its birth, the corncrake wasn’t going to extend its range naturally at any great pace. To re-establish a population in England it would need suitable habitats to be identified and then an intervention to populate it with corncrakes. The RSPB Reserve at Nene Washes in Cambridgeshire was identified as an ideal site. The unique feature of this location is that it is a large area of grassland that is surrounded by arable farming of wheat, sugar beet and arable crops. The theory, which has proven correct, was that the corncrakes returning to Nene Washes would not drift into surrounding grasslands with the concomitant hazards of early harvesting.
So given the locating of an ideal environment, it only required the addition of the corncrakes. It is at this point that UK zoo facilities and expertise come into play. Corncrakes were being successfully bred, reared and then released in Germany, but – you’ve guessed it – the birds migrated to Africa to winter, only to return to Germany the following April. This chain of events was broken n 2001iv by importing 15 captive bred birds from Germany; quarantining them at Chester Zoo; before in 2002 transferring them to specially designed aviaries Whipsnade. The birds bred and after further health checks, to ensure no pathogens are released into the wild, six newly reared birds were released. Further breeding stock was imported from Scotland and Poland and by August 2006 over 280 captive bred corncrakes have been bred and released, when they’re about a month old, into the wild by the RSPB having being kept in pre-release pens and fed on a natural diet. The project is collaboration between English Nature (now part of Natural England), RSPB and ZSL2.
It is tempting to think that our zoos only concern themselves with conservation projects in the tropical rainforests and other far-flung places, when in fact conservation of our natural world begins much closer to home. You’re unlikely to see a corncrake in a zoo, but today if you see a corncrake in Cambridgeshire in England today; it’s because of our zoos.
David Lomas, 2012
1 It’s Latin name is also the sound of its call.
2 Zoological Society of London