Conservation headlands: effects on butterfly distribution and behaviour

Published source details Dover J.W. (1997) Conservation headlands: effects on butterfly distribution and behaviour. Agriculture, Ecosystems & Environment, 63, 31-49.
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This study is summarised as evidence for the following.

	Action	Category
	Leave headlands in fields unsprayed (conservation headlands) Action Link
	Leave headlands in fields unsprayed (conservation headlands) Action Link

Leave headlands in fields unsprayed (conservation headlands)

A replicated, paired, controlled study in 1985–1987 on an arable farm in Hampshire, UK (Dover 1997, same experimental set-up as Dover et al. 1990) found mixed effects of unsprayed conservation headlands on the behaviour of butterflies. In fields with unsprayed headlands, white butterflies (Pieridae) spent more time in the headland (57–220 seconds) than the adjacent hedgerow (4–40 seconds), whilst in fields with sprayed headlands they spent less time in the headland (5–40 seconds) than the hedgerow (18–72 seconds). However, gatekeepers Pyronia tithonus spent more time in the hedgerow (145–900 seconds) than the headland (15–375 seconds) in all fields. Flight and transit speeds of male white butterflies and transits of female green-veined white Pieris napi in unsprayed headlands (male flight: 0.56–1.35; male transit: 0.74–0.98; female transit: 0.14 m/s) were slower than in sprayed headlands (male flight: 0.21–1.75; male transit: 1.19–1.66; female transit: 0.57 m/s). However, gatekeeper males (in 1986) moved faster in the unsprayed (flight: 0.70; transit: 0.43 m/s) than the sprayed headlands (flight: 0.51; transit: 0.22 m/s). In unsprayed headlands, male large white P. brassicae and small white P. rapae spent more time feeding (47–60%) and interacting (20–65%) than in sprayed headlands (feeding: 4–8%; interacting: 23–33%), whereas male gatekeeper spent less time feeding (32%) and interacting (36%) in unsprayed headlands than in sprayed headlands (feeding: 67%; interacting: 71%). Sample sizes were too small for other species and females. On half of 4–8 fields each year, a 6-m strip around the edge (headland) was left unsprayed, while the remainder received conventional broadleaved herbicide applications. Insecticide was not used in spring and summer anywhere on the farm. The behaviour and location (hedgerow or headland) of five butterfly species were observed. Flight speed (distance travelled/time spent in flight) and transit speed (distance travelled/time observed) were calculated.

(Summarised by: Andrew Bladon, edited from Farmland synopsis)
Leave headlands in fields unsprayed (conservation headlands)

A replicated, controlled, paired study in 1985-1987 of butterfly (Lepidoptera) behaviour in headlands of 14 cereal fields in north-east Hampshire (Dover 1997) found that flight speeds tended to be slower and more time was spent resting, interacting and foraging in conservation headlands (no broadleaved herbicides) than those with conventional herbicide applications. Flight and transit speeds of male Pieridae and transits of female green-veined white Pieris napi were significantly slower in conservation headlands. In contrast gatekeeper Pyronia tithonus males (in 1986) were significantly slower in the sprayed headlands, sample sizes were too small for other species. In fields with sprayed headlands, spring emerging large white P. brassicae, green-veined white and small white P. rapae were principally associated with the hedgerow, whilst in fields with conservation headlands they were associated with the headlands. In sprayed headlands, the principal activity was flight, whereas in conservation headlands there was an increase in time spent resting, interacting and particularly foraging. Butterflies that emerged in the summer tended to have less of an association with conservation headlands than spring-emerging butterflies. Limited data were available for meadow brown Maniola jurtina and gatekeeper. Half of the 14 fields were sprayed with conventional pesticides and the other half had conservation headlands. The behaviour and location (hedgerow or headland) of five species of butterfly were observed during the middle of the day along 4-8 headlands. This study was part of the same experimental set-up as (Rands et al. 1984, Rands 1985, Rands 1986, Rands & Sotherton 1986, Dover et al. 1990, Sotherton 1991).