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B lack Grouse populations are declining in most of Europe. 1 There is a wealth of evidence of serious recent declines in Black Grouse numbers in Britain; from the reports of land managers calibrated by field survey, 2 from regional studies (such as those in Wales, 3,4 the Peak District 5,6 and Perthshire 7 (Perthshire Black Grouse Study Group, unpubl. data)) and from atlas work. 8-10 Numbers counted in 37 10-km squares in northern England and Scotland in 1989-92 showed annual declines for different regions of 2% to 35% (D. Baines, unpubl. data). 2 These recent declines follow a longer-term downward trend for Black Grouse in most of the country, stretching back to the last century (see, for example, recent reviews of early accounts, 11,12 and analyses of shooting records). 13 The Black Grouse has been identified 14 as a species of high conservation concern in the UK on account of its rapid population decline over the last 25 years, a historical decline, 11 and an unfavourable conservation status in Europe. Although several regional monitoring schemes cover this species, this is the first systematic survey of the whole British population. As well as producing an estimate of the national population, the survey forms a baseline for future surveys, allowing long-term monitoring of the species. METHODS Sampling strategy The survey was based on counts of males displaying in the spring, with full censuses in Wales and Staffordshire, and surveys of a

Climate is an important factor limiting demography and distribution patterns in many organisms. For species with a broad geographical distribution, the mechanism by which climate influences demography is likely to vary dramatically from one end of the range to the other. In this paper we first assess, in a Scottish population of hen harriers Circus cyaneus, how temperature and rainfall influence adult behaviour and chick mortality patterns at the nest. We then test for associations between harrier productivity and weather across Scotland, towards the northern edge of the range, and Spain, towards the southern edge of the range. We show that during the nestling period, female brooding time increased in cold weather. Male provisioning rate was negatively related to temperature and rainfall. Chick mortality increased in cold temperatures and was most likely to occur at nests where male prey delivery rates were low relative to temperature. Annual values of harrier fledged brood size across Scotland were positively related to summer temperature suggesting that the patterns seen in one population held at a national scale. In Spain, however, the opposite patterns were observed with fledged brood size being negatively related to temperature. This shows that whilst the impact of weather on productivity may be equally strong at two ends of a geographical range, the mechanisms vary dramatically. Large‐scale predictive models need to take such patterns into account.

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