New insights into the remarkable migration of brent geese

Photo: Russell Savory

Satellite tracking project informs the importance of landscape-scale conservation in Essex

During 2018, Essex Wildlife Trust and the Southern Colour Ringing Group launched a dark-bellied brent geese satellite tagging project to gain a better understanding of the species’ impressive 2,500-mile annual migration to their breeding grounds in Siberia. Now in its third year, the local conservation charity and partners have an improved insight into the movements of these winter visitors.

During the pilot study in 2018, 18 geese were ringed under a BTO license at Essex Wildlife Trust’s Blue House Farm nature reserve. This was the first time the species had been ringed in Essex for over 40 years and allowed the geese to be identified and recorded throughout their long-haul flight back to Siberia. To gain more comprehensive data on the location of the geese, solar-powered satellite tags were also fitted to five geese, allowing the exact location of the geese to be recorded throughout each day.

This year, 20 more geese were fitted with Darvic rings, unique to the Blue House Farm project, bringing the total number of birds ringed since the project launched to 52. Two more birds have also been fitted with a GPS tracker, including a juvenile bird, which will help gain more information about life span and dispersal patterns.

With still lots to learn about these fascinating geese, the conservation charity and partners have already uncovered via tracking and general observation how the geese are using the Crouch Estuary over winter, the interaction between parent and offspring movements, the distribution of family units within the whole overwintering flock and interactions between unrelated birds. The tracking has also identified important sites, finding that the same birds are using two of Essex Wildlife Trust’s nature reserves, moving up to 11km within the Crouch Estuary over the duration of winter. It has also been discovered that the birds have preferred roosting sites, returning within 200m - 300m of the same areas each evening to roost.

A quarter of the world’s population of dark-bellied brent geese spend the winter months around the Essex coast and the information gathered is already invaluable for their protection. The saltmarsh habitat around the River Crouch has degraded or disappeared significantly over the past century and this research has highlighted the importance of intertidal habitats for the geese and the need for landscape-scale conservation across Essex. The project will subsequently inform management plans and conservation in the wider landscape.

Essex Wildlife Trust is learning more each year about the movements of the geese which has been incredibly insightful regarding how best to protect them in future. Thank you to The Essex Recorders Partnership, Essex Birdwatching Society and the Southern Colour Ringing Group for fundraising for the satellite tags and supporting this valuable project.