Do parasites zap energy of birds?

Researchers have been studying European shags on a Scottish nature reserve, and for the first time have measured how parasites affect the energy levels and behaviour of individual birds.

Liverpool University and the Centre for Ecology & Hydrology (CEH) carried out the study on the Isle of May from 2014-17 by counting the worms in the birds’ stomachs and fitting them with electronic tags, which recorded the movement and energy used each day for flying, diving and resting.

Results showed that the total energy used per day did not depend on the amount of parasites, but females with higher levels of parasites spent less time flying each day, presumably to avoid using too much energy. Dr Sarah Burthe, of the CEH, said: “It is extremely unusual and challenging to be able to measure both parasites and energetic expenditure in wild animals.”