The Accipiter - Vets Corner September 2005

Vet's Corner - September 2005

John Chitty, the park’s vet, gives us some insight into the healthcare and maintenance of raptors as well as the injuries and illnesses that they fall victim to, and how he treats them...

John has been busy working on the project to reintroduce Great Bustards to the UK from Russia. So this month is a departure from his usual raptor articles for us.

The Great Bustard Reintroduction Project

The Great Bustard (Otis tarda) is the world’s heaviest flying bird. Until 1832 it was indigenous to the UK and bred on Salisbury Plain. It died out due to changes in climate and agriculture but primarily due to hunting for food and taxidermy. As the adult male is a large magnificent specimen and bustards breed using a lekking system the hunting for taxidermy in particular destroyed their breeding structure. Other populations remain in Spain, Eastern Europe and Russia. They inhabit open plain, and some populations migrate in bad weather. All populations are under some threat through modern agriculture, loss of habitat and power lines.

Salisbury Plain, thanks to the Army, is much as it was when bustards were still present and impact studies have shown that suitable vegetation and invertebrates are present for food and habitation and that bustard reintroduction will not adversely affect some of the rarer species of plant or insect on the Plain. Reintroduction will bring back an iconic bird that would not have become extinct in the UK without human interference and will also establish another population of birds in case of disaster in the Russian groups.

The donor population of bustards is located near Saratov in Russia. The population is under threat but numbers of birds are healthy. Collection of eggs from disturbed nests has occurred for a number of years. These eggs are incubated and the chicks hand-reared. In the past these birds have been human imprinted and entered zoological collections. We have started isolation rearing techniques based on those used for the Whooping Crane and have produced non-human-imprinted birds for release to the wild.

The first birds were brought back in August 2004 and entered quarantine before a spell in soft pens, then release pen prior to dispersal into the wild. As part of the reintroduction project, studies are being undertaken investigating behavioural aspects of these birds including tonic immobility studies and whether migration is a hard- or soft-wired phenomenon.

No infectious disease problems have been encountered. Post-release deaths have been due to predation by foxes (an anticipated problem as foxes are natural chick predators throughout the birds’ range) and collisions with fences. Corrective measures including alterations to local fences and increased predator awareness training should improve success in 2005 and subsequent years. We also found some problems due to the fitting of the radio transmitter harnesses which may have slightly compromised the birds’ flying ability. This year we plan to use tail mounted transmitters that will not have the same life span as the body mounts but should interfere less.

This year’s chicks are now in the UK and entered quarantine in July. They are doing well and growing rapidly. Our only concern has been in Russia where a change in rearing diet caused a problem known as “angel wing” where the wing tips twist outwards. Fortunately not all birds were affected and the 38 we brought back appear to have normal wing shapes.

The chicks will leave quarantine during August and will probably start to disperse from the release pen during September. This period should also coincide with the rehabilitation of one of the injured birds from last year, Tora, who suffered head injuries in a fence collision but is now fighting fit.

From the Autumn it will be possible to visit the project and view the birds at the release site. To arrange visits from Mid-September onwards please contact the Great Bustard Group on 01722 710779.

John Chitty BVetMed CertZooMed MRCVS

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