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Red-Throated Diver Energetics Project 2019 Field Season Report 2020



Offshore wind deployment around the UK is due to increase substantially. Red-throated divers are known to be displaced, causing effective habitat loss, by construction and operation of offshore wind farms, but the energetic, physiological and demographic consequences of displacement are currently unknown. If divers are already energetically constrained in the non-breeding season, they may struggle to meet the additional energetic demands following displacement. The aim of the Red-throated Diver Energetics Project ( is to collect and compare novel data on foraging behaviour of red-throated divers in the breeding and non-breeding season.

In 2018, the Red-throated Diver Energetics Project tagged 74 divers breeding in Iceland, Orkney, Shetland and Finland with archival time depth recorder (TDR) and geolocator (GLS) tags. In 2019, 27 tagged divers were recaptured and tags removed to obtain data on their approximate location and dive behaviour. To look for any tag and trapping effects we examined resighting rates of tagged divers, changes in body mass of tagged divers between 2018 and 2019 and breeding success at nest sites where trapping was attempted compared with control sites. We found little evidence of effects from carrying tags but breeding success was reduced at nest sites where divers were trapped. Resighting rate was lower than expected for a long-lived species (69%). However, resighting rate was high at one site, suggesting rather than tagged birds failing to return to breed, birds may have returned but not have been seen. Body mass of tagged divers retrapped in 2019 was not significantly lower than body mass in 2018, suggesting carrying tags does not reduce body condition in individuals that returned to breed. Breeding success was found to be significantly lower at nest sites where trapping was attempted (38%), compared with control nest sites (breeding success = 58% at control nests), although this weaker in Finland.

Resource type Publication

Topic category Environment

Reference date 2020·01·28

O’Brien, S., Ruffino, L., Johnson, L., Lehikoinen, P., Okill, D., Petersen, A., Petersen, I.K., Väisänen, R., Williams, J. & Williams, S. 2020. Red-Throated Diver Energetics Project: 2019 Field Season Report. JNCC Report No. 637, JNCC Peterborough, ISSN 0963-8091.

The Red-throated Diver Energetics Project aims to obtain the first empirical data on red-throated diver foraging behaviour during the non-breeding season.

Responsible organisation
Communications, JNCC publisher

Limitations on public access No limitations

Use constraints Available under the Open Government Licence 3.0

Metadata date 2020·01·28

Metadata point of contact
Communications, JNCC

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