Surfbirds News

Yellow Wagtails migrate to Britain from West Africa to breed during the summer months – the first birds should be returning any day now. They were once a familiar bird, feeding at the feet of grazing animals in pasture and wet meadows, but the number of Yellow Wagtails has declined by an estimated 65% in the UK since 1970. The results of a Lincolnshire study undertaken by James Gilroy of the University of East Anglia are published in the latest BTO News (the membership magazine of the British Trust for Ornithology).

Yellow Wagtail © Nigel Blake, from the surfbirds galleries

According to Dr Gilroy’s research, Yellow Wagtails need to have two nesting attempts each year if they are to raise sufficient youngsters to stem the decline in numbers. Yellow Wagtails nest on the ground; raising their first broods in autumn-sown cereal crops but switching to other crops in June and July, when cereal crops become too tall and impenetrable.

As Dr Gilroy explains: “When Yellow Wagtails first return to arable farmland from their African winter quarters in April, they tend to establish territories in autumn-sown cereal fields. During the early summer, winter-wheat crops shoot from 20 cm up to at least 70 cm in just a few short weeks. Pairs that are already nesting in cereal fields will stay there until the chicks fledge but any birds looking to establish new nests will prefer to switch to non-cereal crops, including peas, field beans and potatoes, the last being by far the most preferred crop. The loose canopy of a potato field appears to be ideal habitat, providing easy access to the ground as well as allowing adequate concealment of nests.”

Overall breeding success in the study was relatively low, with 59% of attempts failing completely. Ground nesters suffer predation by mammal and birds. In this study, rates of predation were highest in field beans, where nests were often poorly concealed. With low rates of chick production, the recovery of the Yellow Wagtail is heavily dependent on the number of broods that can be attempted in a single season. At the current level of productivity, and given that most second broods seem to only occur in potatoes, the availability of this crop could determine the fate of this species.

James Gilroy concludes that, “Yellow Wagtail is currently amber listed as a bird of conservation concern. Given that there has been a marked decline since the 1980s, potato crops could be crucial to the future breeding.”