Wetland
Breeding woodcock outcomes To find out more about the roding behaviour of woodcock at dusk (above) we caught and tagged them with GPS tags (see below far right). © Roger Tidman (rspb-images.com)/Freya Stacey
BACKGROUND In 2013, I began a part-time PhD co-supervised by the GWCT and the University of Nottingham. My thesis focused on the status, ecology and display behaviour of breeding woodcock in Britain. This involved analysing data from the 2013 GWCT/BTO Breeding Woodcock Survey and tracking the roding displays of male woodcock using GPS loggers. I submitted my thesis in 2019 and graduated in absentia in 2020.
My PhD began in 2013 to coincide with the GWCT/BTO Breeding Woodcock Survey, the analysis of which was a major part of my thesis. The survey revealed a decline in the British woodcock population from an estimated 78,346 males (95% confidence interval: 61,717-96,493) in 2003, to 55,241 males (95% CI 41,806-69,004) by 2013. Regional declines have exaggerated the British population’s uneven distribution with more than two-fifths of the population breeding in northern Scotland in 2013. Widespread losses in the English Midlands and Wales have left a sizeable but isolated ‘southern stronghold’ centred on Surrey, Sussex and Hampshire, that supports around 11.6% of the national population estimate. The method used to gather these data relies on counts of passes of ‘roding’ woodcock: males performing display flights at dusk. There are still several aspects of the roding display that are poorly understood, and the second main strand of my PhD study was to improve our knowledge of this behaviour. To do this, I caught a sample of male woodcock between 2015 and 2017 and tagged them with small GPS logging devices that recorded their movements during the display period (see Review of 2018 for more about GPS tags). GPS loggers revealed that roding flights averaged 13.3km in length per evening and, on average, covered an area of 111 hectares (ha) (see Figure 1). Two of the 16 males for which roding movements were recorded covered daily roding areas greater than 200ha. All tagged males included multiple woodland clearings within their roding areas, and those with the largest ranges crossed to neighbouring woods using connecting features such as shelter belts and small copses.
Figure 1 A male woodcock displaying over three consecutive days in June. Each colour represents a separate 90-minute roding period, beginning 15 minutes before sunset. Coloured circles showing the daytime roost location at which the bird started. The blue star shows the site at which we caught and tagged the woodcock five days prior to recording. Mixed woodlands surround a grassy colliery spoil site, with farmland and urban areas beyond
68 | GAME & WILDLIFE REVIEW 2020
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