Hen harriers and red grouse: economic aspects of red grouse shooting and the implications for moorland conservation

1.  Thirgood & Redpath (2008) propose ways in which red grouse : hen harrier conflicts could be resolved. It has also been suggested that grouse management could accept lower bag sizes (number of birds shot) thus reducing the need for intensive management of predators and habitats. This would allow hen harriers to co-exist more easily on grouse moors.
2.  We compare the bags, costs and incomes from these less intensive forms of grouse shooting with the more intensive driven shooting.
3.  Allowing high density grouse moors to decline to low density ones will result in greater loss of income than the corresponding saving of costs. This can result in moor owners abandoning grouse management and thus gamekeepers losing their employment.
4.  Losing gamekeepers from the uplands would jeopardize the protection of heather moorland and Special Protection Areas for birds, large areas of which are keepered and which currently support high numbers of breeding waders.
5.   Synthesis and applications . We agree with the study by Thirgood & Redpath that consideration of social and economic factors will be needed to resolve conflict but a reduction in management effort from driven to walked-up shooting is not the answer. A more satisfactory approach to the harrier : grouse conflict could be to try to reduce harrier predation by means of diversionary feeding and to address the problem of the rapid build-up in harrier numbers by exploring the use of a ceiling on harrier densities.     

Modelling the impact of hen harrier management measures on a red grouse population in the UK

Human‐wildlife conflict is one of the greatest barriers to effective conservation. The recovery of the hen harrier Circus cyaneus in the United Kingdom has been limited due to illegal persecution, a consequence of the raptors’ predation on the economically valuable game‐bird, the red grouse Lagopus lagopus scoticus. To improve management of the system it is necessary to understand the interactions between the two species in their broader community context. We therefore developed a multi‐species model in which the life history and interactions of each of the two bird species are described through linked process models. This model was fit to population data using a Bayesian state–space framework and used to investigate the effectiveness of a conflict–mitigation technique known as diversionary feeding, in which harrier nests are provided with food in an attempt to reduce consumption of grouse chicks. To explore the utility of diversionary feeding we specified four scenarios in which 1) harriers were absent from the system, 2) there was no diversionary feeding of harriers, 3) only a portion of the harrier nests were provided with diversionary food and 4) all nests were provided with diversionary food. The results from fitting the model under the different scenarios were used to determine the strength of harriers’ impact on grouse density, as well as the effectiveness of diversionary feeding. Given the lack of information on other grouse predators and only two years of data on supplementary feeding, our results need to be implanted with caution. However, we found theoretical support for the hen harriers’ suppression of grouse cycle amplitude and average density. Furthermore, our results suggest that on grouse estates where diversionary feeding is the only active management, diversionary feeding is only marginally successful and not sufficient to mitigate the consequences of hen harrier predation on red grouse chicks.     

Resolving the conflict between driven-grouse shooting and conservation of hen harriers

1.  Birds of prey and driven-grouse shooting are at the centre of a long-standing human–wildlife conflict. Hen harrier predation can reduce grouse shooting bags, limit grouse populations and cause economic losses. Despite legal protection, hen harrier numbers are severely depleted on driven-grouse moors.
2.  In limited trials, provision of supplementary food to hen harriers greatly reduced their predatory impact on young grouse, but did not result in higher grouse densities for shooting. Consequently, grouse moor managers have failed to adopt the technique.
3.  A recent Forum paper has called for a trial 'population ceiling scheme' for hen harriers, arguing that this represents the best way to increase hen harrier numbers on driven-grouse moors. Once densities exceed the agreed ceiling, the excess would be translocated to other suitable habitat.
4.  Whilst a 'ceiling' scheme might work, it would be difficult to implement and we believe that other approaches to population recovery should be tested first.
5.  While driven-grouse shooting makes an important economic contribution to some rural communities, some grouse moor owners receive considerable sums of public money. Despite this, many moors are in poor condition, the ecosystem services they supply may be at risk from both climate change and current management practices, and grouse numbers are in decline. The socio-economic and environmental implications of alternative models of grouse management need urgent examination.
6.   Synthesis and applications . If driven-grouse shooting is only viable when birds of prey are routinely disturbed and killed, then we question the legitimacy of driven-grouse shooting as a sustainable land use. Moorland owners need to consider more broadly sustainable shooting practices for the 21st century.     

Buzzards Buteo buteo and Ravens Corvus corax in the uplands of Britain: limits to distribution and abundance

The current breeding ranges of Buzzards Buteo buteo and Ravens Corvus corax in Britain are restricted to the west, and both are relics of former widespread but not necessarily even distributions. Moore (1957) attributed the Buzzard's contraction in range to persecution by gamekeepers, his evidence being the complementary nature of the Buzzard's distribution with those of gamekeepers in the lowlands and grouse moors in the uplands; others have attributed the Raven's decline to the same cause. Is Moore correct and, if so, are these species' ranges still limited by persecution? Here we adopt an approach similar to Moore's, whereby we compare the current geographical patterns of abundance of Buzzards and Ravens in the British uplands with that of an index of grouse moor density. Unlike Moore, however, we take into account climate, land cover, topography and sheep stocking density, as well as grouse moor distribution, using multiple logistic regression modelling. We show that in the uplands the distribution of grouse moors strongly limits that of Buzzards and Ravens but are unable to conclude that this is a result of persecution because there are several competing hypotheses (moor management, food and nest-site availability) between which we are unable to distinguish.     

Effect of abiotic factors on reproduction in the centre and periphery of breeding ranges: a comparative analysis in sympatric harriers

Variables such as weather or other abiotic factors should have a higher influence on demographic rates in border areas than in central areas, given that climatic adaptation might be important in determining range borders. Similarly, for a given area, the relationship between weather and reproduction should be dissimilar for species which are in the centre of their breeding range and those that are near the edge. We tested this hypothesis on two sympatric ground‐nesting raptors, the hen harrier Circus cyaneus and the Montagu's harrier Circus pygargus in Madrid, central Spain, where the hen harrier is at the southern edge of its breeding range in the western Palearctic and the Montagu's harrier is central in its distribution. We examined the reproductive success of both species during an 8‐yr period, and looked at the influence of the most stressful abiotic factors in the study area (between‐year variation in rainfall and within‐year variation in temperature) on reproductive parameters. In the hen harrier, low levels of rainfall during the breeding season had a negative influence on annual fledging success and thus on population fledgling production. The relationship between rainfall and reproduction was probably mediated through food abundance, which in Mediterranean habitat depends directly on rainfall levels. In the Montagu's harrier, no negative effect of dry seasons on productivity was found. Additionally, in the hen harrier, the proportion of eggs that did not hatch in each clutch increased with higher temperatures during the incubation period. No such relationship was found in the Montagu's harrier. We interpret these between‐species differences in terms of differences of breeding range and adaptations to the average conditions existing there. Hen harriers, commonest at northern latitudes, are probably best adapted to the most typical conditions at those latitudes, and have probably not developed thermoregulatory or behavioural mechanisms to cope with drought and high temperatures in Mediterranean habitats, in contrast to Montagu's harrier. Thus hen harrier distribution might be constrained by these variables, due to lower reproductive success or higher reproductive costs. Accordingly, a logistic regression analysis of the presence or absence of both species in 289 random points throughout the western Palearctic showed that the distribution of both species was related to temperature, but the relationship was in opposite directions for the two species: hen harriers had lower probability of breeding in areas with higher temperature (as expected in a species with a more northerly distribution).     

The impact of raptors on the abundance of upland passerines and waders

The issue of predator limitation of vertebrate prey populations is contentious, particularly when it involves species of economic or conservation value. In this paper, we examine the case of raptor predation on upland passerines and waders in Scotland. We analysed the abundance of five wader and passerine species on an upland sporting estate in southern Scotland during an eight-year period when hen harrier, peregrine and merlin numbers increased due to strict law enforcement. The abundance of meadow pipit and skylark declined significantly during this time. Golden plover also showed a declining trend, whereas curlew increased significantly and there was a near significant increase in lapwings. Contrasting the local population trends of these species with trends on nearby areas revealed higher rates of decline for meadow pipit and skylark at the site where raptors increased, but no differences in trends for any of the three wader species. There was a negative relationship between the number of breeding harriers and meadow pipit abundance the same year and between total annual raptor numbers and meadow pipit abundance. Predation rates of meadow pipit and skylark determined from observations at harrier nests suggested that predation in June was sufficient to remove up to 40% of the June meadow pipit population and up to 34% of the June skylark population. This 'quasi-natural' experiment suggests that harrier predation limited the abundance of their main prey, meadow pipit, and possibly the abundance of skylark. Thus, high densities of harriers may in theory reduce the abundance of the prey species which determine their breeding densities, potentially leading to lower harrier breeding densities in subsequent years. We found no evidence to suggest that raptor predation limited the populations of any of the three wader species. We infer that concerns over the impact of natural densities of hen harriers on vulnerable upland waders are unjustified.     

Intra- and interspecific agonistic behaviour in sympatric harriers during the breeding season

We analysed the temporal and sexual patterns of intra- and interspecific aggression in sympatric harriers during the breeding season, to determine the main resource defended (food, nest sites, mates) and how factors such as body size or breeding system (territorial versus colonial) influence aggressive behaviour. We predicted that if aggression is (at least partly) related to competition for food, the hen harrier, Circus cyaneus, because of its large size and territorial system, should be more aggressive (both intra- and interspecifically) than the smaller, colonial Montagu's harrier, Circus pygargus. The intraspecific aggression rate of both harriers peaked early in the season, was mainly intrasexual and increased with the number of neighbours. These patterns support the mate competition hypothesis to explain intraspecific aggression in both species. Montagu's harriers were more aggressive towards conspecifics than hen harriers. Their aggression rates towards heterospecifics were high at the start of the season then decreased, supporting the hypothesis that interspecific aggression serves primarily for nest site defence. Hen harriers showed lower interspecific aggression rates in the prelaying period and a gradual increase throughout the breeding cycle, particularly by females, who hunt around the nest for food for the nestlings. These patterns correspond to food competition, as food resources around the nest are probably more important and interspecific intrusion more costly for territorial hen harriers than for colonial Montagu's harriers. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Hen harriers and red grouse: moving towards consensus?

1.  The presence of predators may lead to conflict between different stakeholders. Finding ways to resolve such conflicts is a challenge to all involved.
2.  Within the UK a long and, at times, acrimonious conflict has developed around the conservation of hen harriers Circus cyaneus on moorland managed for red grouse Lagopus lagopus scoticus . This paper follows our original forum article and the replies from colleagues in the Royal Society for the Protection of Birds (RSPB) and the Game and Wildlife Conservation Trust (GWCT).
3.  Whilst differences of opinion remain, there are encouraging signs that both sides are striving for consensus. There is broad agreement that evidence is required on three fronts to address: (1) the ecological, economic and social consequences of alternative forms of land management in the uplands; (2) the efficacy of diversionary feeding of hen harriers; and (3) the utility of a brood management scheme to improve harrier conservation status and reduce the extent of the conflict.
4.   Synthesis and applications : The conflict between hen harrier conservation and red grouse management has existed for decades with little sign of progress. For the first time, stakeholders, researchers and policy advisors are engaged in effective dialogue and are striving for solutions. There are encouraging signs that all sides are now willing to listen to alternative viewpoints and appear prepared to seriously consider compromises. It is to be hoped that a solution to the harrier–grouse conflict can be found as this will have considerable positive ramifications for management of heather moorlands in the UK and wider implications for the conservation of predators around the world.     

Golden Eagles Aquila chrysaetos: land use and food in northeast Scotland

This paper contrasts changes in breeding numbers and breeding success of Golden Eagles Aquila chrysaetos on four areas with different land uses. On land primarily used for deer stalking but also for grouse shooting, and supporting abundant prey, the number of eagle pairs was steady in 1944-80. On deer land with fewer prey, the number of pairs declined greatly in the 1960s, when deer carrion became scarcer following increased shooting of red deer. On grouse moors incorporating deer stalking, the number of pairs declined in the 1950s due to persecution by gamekeepers, and then largely recovered as this lessened. On grouse moors with little or no stalking, the number of pairs fell after 1946 and remained low due to persecution, which has continued since then. Eagles on grouse moors bred poorly due to persecution. On deer land they were seldom persecuted by estate staff, and bred well. On an area of deer land, the mean annual number of young reared per undisturbed clutch in summer was related to the estimated weight of prey in the spring of the same year. The eagles have remained fairly pesticide-free, and bred well in 1963-65 when more contaminated birds in west Scotland bred poorly.     

DISPERSION, BREEDING AND PREY OF THE HEN HARRIER CIRCUS CYANEUS IN GLEN DYE, KINCARDINESHIRE

Hen Harriers were studied on a grouse moor in northeastern Scotland from 1970-74. Numbers in spring were fairly stable, and the 24 nesting territories occupied in 1974 were regularly dispersed with a mean nearest neighbour distance of 1.52 ± s. e. 0.09 km. Many pairs apparently failed to breed and left the area. The mean clutch size of those remaining was 4.70 ± s. e. 0.24 (n= 27) and the mean number of young fledged per successful nest was 3.11 ± s. e. 0.26 (n= 19). Young males were more likely to disperse far from the study area than young females. The variety of prey species observed from hides at five nests was very limited, and comprised mainly pipits, grouse chicks and lagomorphs. Estimates by weight suggest that grouse and lagomorphs accounted for 89% of all prey. Males brought more small items and fewer large items to nests than females, and on average provided 72% of all prey items seen during watches from the hides. On the basis of studies of prey at three nests in 1974, and counts of grouse in spring and late summer, harrier predation was estimated to have reduced the number of grouse which might otherwise have survived to late July that year by a maximum of 7.4%.     

Habitat loss and raptor predation: disentangling long- and short-term causes of red grouse declines

The number of red grouse (Lagopus lagopus scoticus) shot in the UK has declined by 50% during the 20th century This decline has coincided with reductions in the area of suitable habitat and recoveries in the populations of some avian predators. Here we use long-term records of shooting bags and a large-scale manipulation of raptor density to disentangle the effects of habitat loss and raptor predation on grouse populations. The numbers of grouse harvested on the Eskdale half of Langholm Moor in southern Scotland declined significantly during 1913-1990 and grouse bags from the whole moor from 1950 to 1990 exhibited an almost identical but non-significant trend. Hen harriers (Circus cyaneus) and peregrine falcons (Falco peregrinus) were absent or bred at low densities on this moor throughout this period but heather-dominant vegetation declined by 48% between 1948 and 1988. Harrier and peregrine breeding numbers on Langholm Moor increased to high levels following protection in 1990 whilst grouse density and grouse bags declined year after year until shooting was abandoned in 1998. The prediction of a peak in grouse bags on Langholm Moor in 1996 based on the patterns of bags during 1950-1990 was supported by the observed peaks in 1997 on two nearby moors with few raptors which formerly cycled in synchrony with Langholm Moor. This study demonstrates that, whilst long-term declines in grouse bags were most probably due to habitat loss, high levels of raptor predation subsequently limited the grouse population and suppressed a cycle. This study thus offers support to theoretical models which predict that generalist predators may suppress cycles in prey populations.     

Factors constraining the distribution of Golden Eagles Aquila chrysaetos in Scotland

Capsule Between 1992 and 2003 persecution appeared to be the main influential factor.

Aims To utilize temporal changes in the distribution and occupation of Golden Eagle territories in Scotland between the 1992 and 2003 national censuses to assess potential causes of regional and national population trends, by examining spatial associations with a number of potential constraints on the population.

Methods The distribution of occupied and vacant territories in the 1992 and 2003 censuses were entered as layers in a Geographical Information System (GIS), along with boundaries of biogeographical regions (Natural Heritage Zones) for regional analyses. Additional GIS layers were created for potential factors that may constrain the eagle population: the distribution and abundance of persecution incidents, new commercial conifer forests, popular mountains for hillwalkers (as surrogates for recreational activity), and the density of sheep and Red Deer (as surrogates for carrion abundance), drawn from comparable time periods to the national eagle censuses. Analyses then looked for spatial associations between eagle territory status and those constraint factors that may have influenced change in territory status.

Results We found little evidence to suggest that recreational disturbance was influential on the occupation of Golden Eagle territories, although some local effects may have occurred and further analyses are warranted. We could find evidence of only a limited number of territories having being abandoned recently due to the planting of commercial conifer forests. We also rejected the hypothesis that changes in territory occupation between national Golden Eagle censuses were influenced by change in carrion abundance. By contrast, results were consistent with the hypothesis that persecution was influential in the observed change in territory occupation between censuses, so that occupied eagle territories tended to decline where persecution was probably still influential and tended to increase where persecution had probably declined.

Conclusion In accordance with earlier predictions based on models of the demographic influence of persecution, in the central and eastern Highlands where grouse moor management predominates, the eagle population continued to decline to levels where increasingly large areas of suitable habitat are unoccupied by breeding pairs.     

Field Vole Microtus agrestis abundance and Hen Harrier Circus cyaneus diet and breeding in Scotland

In many parts of the global range, voles form an important part of the diet of Hen Harriers Circus cyaneus , and breeding numbers are correlated with the abundance of these small mammals. In Scotland, however, little information is available on harrier diet in the spring and our understanding of causes of variation in harrier breeding density is complicated by human interference. In this paper we explore the relationship between Field Vole Microtus agrestis abundance and harrier spring diet, density and productivity in southern Scotland. Over three years, voles occurred on average in 67% of pellets, and 79% in years of high and intermediate vole abundance. From 1992, the number of breeding harriers increased following protection from illegal persecution. After accounting for this trend, harrier numbers correlated strongly with vole abundance. Harrier clutch size was also correlated with vole abundance. Although fledging success tended to be greater in years of vole increase than in years of vole decline, fledging success was not significantly correlated with the relative abundance of voles, or with the abundance of Meadow Pipits or Red Grouse chicks.     

Temperature and hen harrier productivity: from local mechanisms to geographical patterns

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.     

Appearance and vulnerability of artificial duck nests to avian predators

Use of artificial nests in studies of nest success in birds has become increasingly popular, but this practice has been criticised because the appearance and success of artificial nests may differ from natural nests. Typically, artificial nests are presented with few visible eggs throughout the entire exposure period while natural nests during their life have different appearances, possibly producing stage-dependent predation rates. In ducks, nests may appear with openly visible eggs, eggs covered with nest material and covered by an incubating female. To test how nest appearance may affect nest survival, I simulated such duck nest appearances, and used direct observations to record responses of marsh harriers Circus aeruginosus , the dominant duck nest predator at the Lake Engure, Latvia, during the breeding seasons 2000–2002. I recorded 274 harrier flights over all types of artificial nests, 74 nest discoveries and 54 predation events. Logistic regression analyses showed that nest appearance was a significant predictor of the fate of the nest: nests with openly visible eggs were discovered more often than nests covered with nest material. Nests with dummy females had discovery rates similar to the average of all artificial nest types suggesting that they best reflect the predation risk of artificial nests and could be used in future studies. After discovering nests covered with dummy females, harriers never attacked but tried to scare them off to get access to the eggs. In 52% of cases of nest discovery, harriers gave up before touching the dummy. This shows that duck passive nest defence may prevent clutch predation.     

Nests of Marsh harrier (Circus aeruginosus L.) as refuges of potentially phytopathogenic and zoopathogenic fungi

Birds’ nests may be refuges for various species of fungi including that which are potentially phytopathogenic and zoopathogenic. Among the 2449 isolates of fungi obtained from nests of Marsh harriers 96.8% belonged to filamentous fungi. In total, 37 genera were identified from 63 fungi species. Within the mycobiotas of the examined nests populations of fungi which are potentially pathogenic for humans, homoiothermous animals and plants dominated. Among 63 species, 46 (72%) were potentially pathogenic fungi of which 18 species were potentially phytopathogenic and 32 species were pathogenic for homoiothermous animals. Inter alia species of fungi were found in the Marsh harriers nests: Aspergillus fumigatus, Aspergillus flavus, Scopulariopsis brevicaulis, Chrysosporium keratinophilum and Fusarium poae, Fusarium sporotrichioides. In terms of numbers, dominant in Marsh harrier nests were fungi pathogenic to birds, other homoiothermous animals and humans. On that basis it was concluded that Marsh harrier nests are both a source of fungal infections for that species and one of the links in the epidemiological cycle of opportunistic fungi for humans.     

Status of the Hen Harrier Circus cyaneus in the UK and the Isle of Man in 1998

A survey of breeding Hen Harriers in the UK and the Isle of Man carried out in 1998 consisted of two parts: a complete census of 10-km squares at the core of the species'known range, and a random sample of 10-km squares across the rest of its known recent range. From this, the UK and Isle of Man breeding population was estimated at 570 territorial pairs: 436 in Scotland, 19 in England, 28 in Wales, 38 in Northern Ireland and 49 on the Isle of Man. Although there was no overall change in the size of the UK and Isle of Man population between 1988–94 and 1998, numbers declined in Orkney and increased in Northern Ireland. In Scotland, numbers increased on grouse moors and decreased in young plantation between 1988–89 and 1998, so that 55% of the population is now found on grouse moor. A similar situation exists in England, but in Northern Ireland 45% of the population was found breeding in open areas within mature conifer plantations in 1998.     

Columbian sharp-tailed grouse female and nest survival in northwestern Colorado

Wildlife management and conservation can be challenging when the demography of a focal species is unknown or limited given that fecundity and adult survival influence population growth. The Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) have been reduced to ≤10% of their former range since the early 1900s. We conducted a 3-year study (2015–2017) across 4 study sites in northwestern Colorado, USA, to evaluate female hazard and nest survival. We trapped and marked 270 female sharp-tailed grouse and identified 275 nests for our hazard and survival analyses. Females during the breeding stage of the reproductive season experienced more hazard compared to the nesting and the early and late post-nesting stages for females without broods. Females experienced a higher degree of hazard during the breeding stage and mortality risk was >3 times higher than the nesting stage, >7 times higher than early post-nesting (EPN)-no brood stage, and >5 times higher than the late post-nesting (LPN)-unsuccessful stage. Two reproductive season stages (LPN-successful and EPN-brood) provided marginal inference. Nest incubation initiation date and nest age best described nest daily survival. Females that initiated incubation of initial nests earlier in the season experienced lower nest daily survival than later in the incubation season. Because female Columbian sharp-tailed grouse hazard varied among different reproductive season stages, we recommend that wildlife managers develop management actions that reduce hazard during the specific reproductive season stages (i.e., the breeding season). For Columbian sharp-tailed grouse in Colorado, we recommend that Colorado Parks and Wildlife collaborate with federal farm program agencies to implement a no-tillage restriction from 1 May through 30 June for active agricultural fields within 2 km of active Columbian sharp-tailed grouse leks to enhance nest survival.     

The role of pigeon consumption in the population dynamics and breeding performance of a peregrine falcon (<Emphasis Type="Italic">Falco peregrinus</Emphasis>) population: conservation implications

In this paper, we describe and analyze the diet of peregrine falcons during a long-term period (1982–2002). A combination of direct observations of prey brought to nests, prey remains, and regurgitated pellets were used to calculate diet diversity and dietary overlap between peregrine pairs. We also examined diet diversity in relation to breeding performance. All peregrine pairs fed mainly on birds, with pigeons the most common prey. An increase in pigeon availability has been associated with both an increase in population size and an increase in breeding performance (measured as the average productivity of pairs per year) of a small peregrine falcon population in eastern Spain. Average productivity was lower when dietary breadth was higher. We speculate that our results were the synergistic effect of declining persecution and increased pigeon availability through increased popularity of keeping racing pigeons. There is a conflict of interests between pigeon fanciers and peregrine conservation. As a consequence, this could result to an increased risk of mortality by direct persecution. In accordance with this, conservation measures aimed at preventing direct persecution are encouraged.     

Spatial synchrony in red grouse population dynamics

Red grouse Lagopus lagopus scoticus populations exhibit unstable dynamics that are often characterised by regular periodic fluctuations in abundance. Time-series' of grouse harvesting records collected from 287 management units (moors) across Scotland, England and Wales were analysed to investigate the broad scale patterns of synchrony in these fluctuations. Estimation of the spatial autocorrelation of grouse population dynamics across moors indicates relatively high levels of synchrony between populations on adjacent moors, but that this synchrony declines sharply with increasing inter-moor distance. At distances of greater than 100  km, grouse population time-series exhibit only weakly positive cross-correlation coefficients. Twenty-eight geographical, environmental and other candidate variables were examined to construct a general linear model to explain variation in local synchrony. Grouse moor productivity (average size of shooting bag), distance from the Atlantic coast moving in a north-easterly direction, April and June temperatures, and June rainfall significantly increased the explanatory power of this model. An understanding of the processes underlying synchrony in red grouse population dynamics is a prerequisite to anticipating the effects of large-scale environmental change on regional patterns of grouse distribution and abundance.