Starv­ing on the fringes

Bird Watching (UK) - - Conservation Hen Harrier -

Streaked in brown, fe­male Hen Har­ri­ers look very dif­fer­ent from pale grey males Ground nest­ing Hen Har­ri­ers are al­ways vul­ner­a­ble Har­ri­ers lay four to five eggs in late spring and raise chicks for up to 42 days. Nest­ing on the ground, they are, nat­u­rally, vul­ner­a­ble to Foxes, and, less nat­u­rally, hu­man pre­da­tion. In Bri­tain, our birds re­main here year-round, mov­ing from up­land breed­ing sites to low­land salt­marshes or heath­lands to win­ter. Har­ri­ers have de­clined across Europe – in coun­tries from Fin­land to France – and degra­da­tion of vole-rich grass­lands is the key cause. Out­side of Bri­tain, per­se­cu­tion is rarely a ma­jor is­sue. Star­va­tion, as for most birds, is driv­ing the con­ti­nen­tal de­cline. In the early years of the 19th Cen­tury, Hen Har­ri­ers had a patchy and lo­calised dis­tri­bu­tion across south­ern Eng­land. By 1900, how­ever, a star­tling change had taken place. The low­land pop­u­la­tion was largely wiped from Bri­tain by habi­tat change, es­pe­cially drainage, and har­ri­ers re­treated to the up­lands. But from the 1830s, writ­ten ac­counts de­tail the killing of har­ri­ers on a mas­sive scale. From 1850 to 1854, as many as 351 har­ri­ers were killed in Ayr­shire – giv­ing some ex­am­ple of the one­time abun­dance of this moor­land rap­tor, and, of course, the in­dus­trial scale of its re­moval. Where grouse hunters went, har­ri­ers van­ished. This was ironic. Many ob­servers, in­clud­ing the im­par­tial BTO, make the point that the abun­dance of prime habi­tat, and Fox re­moval, on grouse moors can lead to ex­cel­lent food sup­plies and nest­ing suc­cess for har­ri­ers. It would have taken so lit­tle for this to hap­pen – but it didn’t. The har­rier was clin­i­cally re­moved from Ayr­shire – then from Bri­tain. By 1900, har­ri­ers were ef­fec­tively wiped out on the Bri­tish main­land, per­sist­ing only on the Outer He­brides, Orkney and Ar­ran – out­posts that would even­tu­ally re­colonise Bri­tain. Two World Wars later, the same aban­don­ment of in­ten­sive land prac­tices that led Snipe to surge back into south­ern Eng­land al­lowed har­ri­ers a re­ver­sal of for­tunes. Be­tween 1939 and 1970, Hen Har­ri­ers re­turned to re­colonise large ar­eas of Scotland, some ar­eas of Wales and very small ar­eas of the English up­lands. Driven grouse shoot­ing ex­ists largely across north­ern Eng­land and south­ern and eastern Scotland. It does not oc­cur on Shet­land, Orkney, the He­brides, much of Ar­gyll and north­ern High­land or the Isle of Man, and is a much smaller con­cern in Wales. So har­rier de­clines in these ar­eas have other causes. Un­der­stand­ing this is not only use­ful for these pop­u­la­tions. His­tory has

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