Nest survival, causes of failure and productivity of British Hawfinches Coccothraustes coccothraustes

ABSTARCT

Capsule: Nest success rate of Hawfinches Coccothraustes coccothraustes within our study areas averaged 36% across five seasons, a level unlikely to be driving population declines and considerably higher than was suggested by recent estimates from the long-term Nest Record Scheme.

Aims: To investigate potential habitat correlates of nest success and identify nest predators from an intensive study on Hawfinches. To compare nest success and habitat of these nests with those found by Nest Record Scheme (NRS) recorders and test whether there is evidence of a decline in nest success over time from the NRS data.

Methods: Females trapped at feed sites were fitted with radio-tags and tracked back to nest sites providing a sample of nests for subsequent monitoring. Habitat measures potentially influencing survival were collected at nest sites and modelled against nest outcome. Nest success was compared with that from the long-term Nest Record Scheme. Nest cameras were deployed to identify predators.

Results: Nest success varied among years, but the mean value was not substantially lower than other Hawfinch studies or from other species with similar nesting strategies. Apparent recent declines in success suggested by Nest Record Scheme data were not evident in our study areas. Only avian species were recorded predating nests and a number of partial predations were recorded. No correlation was found between overall success for study nests and the habitat or temporal measurements collected.

Conclusions: Within our study areas, average Hawfinch nest success and productivity appeared to be sufficient to maintain local population stability though our sample size was modest and further work would be beneficial. General nest recording may have inherent biases that lead to an over-estimation of nest failure compared to those found by more structured study. Drivers of recent UK Hawfinch declines may be operating outside of the nesting season and/or in landscapes outside primary woodland.

Acknowledgements

We extend our thanks to Natural Resources Wales, Forestry Commission England and the many other land managers who allowed access within our study areas. Assistance with collection of data in the field was ably provided by Vivien Hartwell, Judit Mateos, Rob Hughes, Molly Foulds, Mike Duckham and Annie Seddon. Adrian Thomas provided extensive logistical help and assisted with bird capture in the Wye Valley while climbers Matt Thomas and Steve Roberts erected the nest cameras there. At RSPB, Richard Gregory provided advice and continued support throughout the project and Will Peach advised on our demographic model. Nigel Butcher, Andrew Asque and Colin Gooch helped with equipment and technical issues. The British Trust for Ornithology kindly provided access to Nest Record Scheme and Retrapping Adults for Survival data and we thank all the volunteers who helped collect this. Our original manuscript was improved by the helpful comments provided by reviewers.

Additional information

Funding

This study was funded by RSPB and Natural England as part of the ‘Action for Birds in England’ partnership.