Spuds they like…
The British Trust for Ornithology has just published results from the latest
study into the breeding success of the Yellow Wagtail. In his article -
Spuds they like - James Gilroy explains that potatoes are coming to the
rescue of this amber-listed species of conservation concern.
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).
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
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."
You can help track the arrival of Yellow Wagtails this spring, and other migrants such as Swallows and Cuckoos, by contributing to the BTO/RSPB/BirdWatch Ireland BirdTrack survey. For more information on how you can get involved visit http://www.birdtrack.net
Created: 27th Mar 2008