Where Have All the Eiders Gone? - Food Resource Availability Assessment

At the GB scale, eider numbers have declined by c60% over the last 25 years. At an England scale, numbers have declined by c75% over 30+ years.

Action to understand the causes of these declines and, if possible, to implement measures to halt or reverse the declines is urgent. Adult eiders preferentially feed on mussel, a resource which since 2012 has declined critically in Northumberland.

This suggests that environmental changes leading to loss of mussel resources on this coast may have played some part in the eiders' decline. The present study is being commissioned to provide an assessment of food availability for eiders over the winter period.

Eiders preferentially feed on mussels, a resource which since 2012 has declined critically in Northumberland. However, mussel beds persist in the Teesmouth and Cleveland Coast SPA, where wintering eiders occur.

The study will determine the availability of mussels and alternate food sources at five sites in the region used by eiders. Intertidal rocky reef transect surveys will be conducted during the period of lowest possible tides in November or December (contingency) 2025.

The period is chosen to assess the food availability to the overwintering eiders in the region. If interested, suppliers should provide: details of the methodology and approaches proposed to deliver the requirements of this project; qualifications and experience the proposed project team; a proposed timetable for the project, risk log, mitigation actions and a Gantt; and proposed project teams' experience and qualifications for operating safely in the environment and conditions required for the project.