The Great Crane Project

In the early 2000s two conservation organisations, The Wildfowl & Wetlands Trust (WWT) and the Pensthorpe Conservation Trust got together to discuss the possibilities of supplementing the UK population with hand-reared, re-introduced cranes. RSPB joined this partnership and a feasibility study for reintroduction was carried out in 2006.

The Somerset Levels and Moors, in the South West of the UK were selected as the most likely site for a successful release and in 2009, with funding from Viridor Credits Environmental Company, and in close collaboration with Kranichschutz Deutschland and conservationists working within the Schorfheide-Chorin Biosphere Reserve in Brandenburg the ‘Great Crane Project’ began.

At around 10 weeks old the young Cranes were fitted with colour rings and radio tags and then transported in specially designed transport crates to their release site at the RSPB West Sedgemoor Reserve on the Somerset Levels and Moors. Once on site, they were housed in an aviary for a further two weeks before a ‘soft-release’ into a 2ha fenced enclosure, where the birds were returned each evening for their safety. 

Over the five years of the project – a total of 137 eggs were collected with 94 of these successfully hatched, reared and released onto the Somerset Levels and Moors.

The 94 released Cranes were very closely monitored through a combination of GPS and Radio tracking and colour ring reading. Most birds remained close to the release area following release, but some made flights several hundred miles to the east and north. Some subsequently returned and others disappeared. One, that was behaving oddly was taken into captivity and was later found to have had issues with eyesight due to cataracts. This explains the figure of ‘93’ (rather than 94) in subsequent tables. A small group have settled in the area around the WWT Slimbridge site where they were hand-reared.  

Survival rates have been much higher than anticipated but there have been some losses through disease, collision injury, and predation. The majority of losses, however, have to be put down to ‘unknown’ as the birds have simply disappeared and have not been re-located. 

Table 2.  Percentage of release cohorts surviving (at end of 2022)

Other significant costs included a comprehensive disease risk assessment, the non-staff costs of hand-rearing  and health management (£95K); costs associated with the release and post release monitoring  (£72K); the construction and upkeep of the temporary release facility on RSPB West Sedgemoor (£57K); and land management across the Somerset Levels and Moors (£51K), creating a number of new wetland areas such as the one below to provide suitable, safe breeding locations. These habitat enhancements were carried both on RSPB nature reserve and private land, with a number of local farmers and landowners keen to support the long term return of Cranes to the local environment.  

First successful breeding from the released population took place in 2015. Breeding success was initially lower than that found in the wider UK population but 2021 and 2022 have been particularly good years and breeding productivity is now in a similar range to that found across the UK. The slow start may have been a function of the birds being both young and hand-reared.

Table 3.  Productivity of release project birds

The recruitment of fledged chicks into overall population from the reintroduction has seen the population steadily increase and the total flock population is now (October 2023) around 110 birds. 

Well over 50% of this population made up of these 2^nd and 3^rd generation birds. It is not yet possible to establish if they are more successful than the original release population as breeding numbers are still low. There are also a number of pairs made up of hand-reared release birds with unringed, presumed 2^nd generation Cranes as a partner.   

The table and graph below show how this flock make-up has changed over time. Our monitoring enables us to establish the total flock population only at the very end of the calendar year, so the data below is based on the flock size at the end of 2022. However, with 14 new recruits this year and only 4 known deaths / losses of birds (so far) the population appears to be continuing its steady increase.

Table 3 – Population composition measured at end 2014 - end 2022

Breeding has not been confined to the Somerset Levels and Moors, although this is where most of the reintroduced population is found. 2023 recorded 22 pairs in Somerset (the highest number to date) 5 in Gloucestershire, 1 in Oxfordshire and 1 each in Wiltshire and Dorset. In previous years birds from the release project have also bred in South Wales and Cambridgeshire.  

A small team has also been catching and colour ringing some of the chicks produced in the wild from the release project birds in order to establish the long term success of the 2^nd generation and the project itself. They are not easy to catch, and numbers of colour ringed 2^nd generation birds are low. All are ringed with a green ring at the bottom of the 3 colour combination. 

Due to effective conservation action, increases in suitable habitat, and particularly the expansion of the population in the East Anglian Fens and Aberdeenshire, there has been a large improvement in the breeding success of the native population. These population increases, at the same time as the re-introduction in the South West of the UK have driven the dramatic upturn in number of fledged chicks in the UK since 2000 clearly seen in the graph below:

Graph 5.   Crane fledging in the UK 1977-2022

With their rapidly expanding population, cranes are doing well in the UK but there is a pressing need for more, and larger wetlands to support this growing population. Current government policy (eg the 2021 England Peat Action Plan) aims to re-wet and restore many peatland areas such as are found across the Somerset Levels, the Fens of East Anglia and also in bogs across much of the UK’s upland habitat. This drive, aligned with significant conservation effort to create wetland habitats to adapt to and mitigate for the impacts of climate change, and to help restore nature across the UK should mean a relatively secure future for this iconic species across the UK.