Cuckoos: England’s loss is Scotland’s gain

Cuckoo - Edmund Fellowes
Although we have lost over three-quarters of the UK Cuckoo population, we are unsure of the causes of this decline. Alongside this, the strong divide in northern and southern populations of Cuckoo and their local trends are cause to question why the local differences arise. 

This study, led by PhD student Chloe Denerley and using BTO's BBS data, used local data from Devon in comparison against data on Cuckoos and their hosts, habitats, and prey items. In Devon, Cuckoos were more likely to be found in areas with semi-natural habitat and more Meadow Pipits (but fewer Dunnocks) and with a higher number of moth species, which are predated by Cuckoos in late summer. Across the UK, Cuckoos have become more associated with upland heath with Meadow Pipits, and with wetland habitats with Reed Warblers, and the distribution of Cuckoos shifting from south to north within the UK. The abundance of moth species preyed upon by Cuckoos has declined four times faster than that of other moths.

Overall, the results suggest that Cuckoos have contracted out of the farmed countryside and into heathlands and the uplands. Coordinated monitoring of moth, host and Cuckoo numbers across such projects could tell us much about the long-term prospects for reversing Cuckoo population decline in the UK
 

Related publications:

Denerley, C., Redpath, S.M., van der Wal, R., Newson, S.E., Chapman, J.W. & Wilson, J.D. 2018
Breeding ground correlates of the distribution and decline of the Common Cuckoo Cuculus canorus at two spatial scales Ibis.
Link to publication (DOI: 10.1111/ibi.12612).

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