Posted on Wednesday, December 21st, 2016
Great Bustards have been released in small numbers in Wiltshire almost every year since 2004. The earlier releases were from eggs rescued from agricultural destruction in Russia, and for the last three years from egg collected in Spain. This has been the first concerted attempt to create a new population of Great Bustards anywhere in the world. A feature of most of the releases has been that the newly released birds all disperse away from the release site during the autumn. The only exceptions to this dispersal have been some of the birds fitted with large and complex trackers. These birds seem to have their flight abilities restricted, although university and academic staff working with the project sometimes deny this link.
Explanations for the dispersal have included the Russian origins of some of the birds (not a likely explanation as the Spanish birds have done the same thing), cold weather (not likely to trouble a bird which can cope with the Russian winter) or day length. A significant advancement was made in 2015 when approximately 50% of the released birds stayed close to the GBG reserves where they were released. In 2016 none of the released birds moved away from the area of release. 2016 has also seen the highest ever survival rate of released birds at 65%. This compares very well with the 22% that may be expected in a healthy wild population.
The likely explanation for the new behavior is that Great Bustards are a slow maturing and long lived species; young birds stay with their mother until January and probably take a lead from older birds in their social group. When young birds are released to join a small inexperienced adult flock they may not get the social interaction they need, and simply head off into the landscape. The English Great Bustard population is now close to 50 birds and contains a mix of old birds, youngsters and an increasing number of breeding females. The population has probably reached a size and structure where the necessary social structures are now developed.
2016 also saw a record number of Great Bustard nests (seven) and although most of the nesters were first time breeders at least two chicks have been recruited to the wild population. It is a reasonable prediction that 2017 will see a higher number of nests and more young recruited to the population.
“2016 has been the most successful year of the project so far, but the really exciting news is that 2017 promises to be even better” David Waters GBG Executive Officer.