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.     

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.     

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.     

Long-term increase in the fecundity of hen harriers in Wales is explained by reduced human interference and warmer weather

The conservation status of the hen harrier Circus cyaneus in Britain, and its pivotal role in the raptor–grouse moor conflict, has rendered research on the factors influencing its population dynamics of crucial importance. Using over 20 years of data, we examine influences on the reproductive output of the small, but recently expanding, population of Welsh hen harriers. Productivity (fledglings per breeding attempt) has steadily increased with time, being the highest in recent years. Available evidence suggested that food availability could not account for these recent increases. Human interference (apparently, largely or entirely in the form of nest destruction by grouse moor gamekeepers) had a large influence on productivity, despite being restricted to a minority of the breeding population. This negative effect, and a positive effect of May temperature, was most influential on variation in breeding productivity. This study quantifies, for the first time, that cessation of persecution can result in a marked improvement in hen harrier reproductive output. Nest predation by red foxes Vulpes vulpes had no effect on variation in breeding productivity and there was no evidence that control of fox numbers by gamekeepers compensated for their depression of productivity through destroying harrier nests. Our analyses also indicated that gamekeepers probably destroyed an unknown number of nests before they were discovered. We argue that a low proportion of territorial females that apparently breed, in cases when clutch size and fledged brood size are high, may be an indication of persecution. The recent increase in the breeding productivity of Welsh harriers has probably been influential in the recent recovery of the Welsh harrier population and has apparently been due to a combination of cessation of human interference and warmer temperatures.     

Global dispersion of nesting Hen Harriers Circus cyaneus; implications for grouse moors in the U.K.

In the U.K., a full recovery of Hen Harrier Circus cyaneus breeding numbers is prevented by illegal culling by some gamekeepers who fear the species threatens the future of grouse moors. This study's main purpose was to estimate how many more Hen Harriers there would be in the U.K. if this culling were to cease. A review of 33 studies of the Hen Harrier in nine countries showed that the densities of nesting females decreased strongly as the size of the areas studied increased and also that such information could not be used to estimate the potential density over a large area, such as the U.K. Correcting for the size of the areas studied showed that the potential density of nesting Hen Harriers on grouse moors could be predicted from studies overseas. Estimates of the densities of Hen Harriers in occupied areas globally were therefore used to estimate the density appropriate for the U.K. If all potential habitats were occupied, present numbers could more than double, to an estimated 1660 nesting females. This estimate represents an average of one nesting female per 2 5 km² of habitat, a density which would cause little or no significant economic damage on grouse moors. However, because Hen Harriers tend to aggregate, they would not spread out evenly but would nest in relatively high densities on a number of moors. The economic impact on Red Grouse Lagopus lagopus would not be a function of overall numbers, rather it would arise from the uneven dispersion of nesting Hen Harriers.     

Killing of raptors on grouse moors: evidence and effects

Owing to the intensity of game management in Britain, managers of grouse moors have illegally killed raptors to increase the numbers of Red Grouse Lagopus l. scotica available for shooting. This paper summarizes evidence for the recent scale of illegal raptor killing on grouse moors and its effects on populations. It provides insights into how raptors themselves respond demographically to different levels of killing. Over Britain as a whole, most raptors have increased and expanded considerably since the 1970s, in response to reduced killing and nest destruction, and the diminished impacts of organo‐chlorine pesticides; however, in recent decades the populations of some species have declined on and around grouse moors. This is widely evident in Hen Harrier Circus cyaneus, Peregrine Falcon Falco peregrinus and Golden Eagle Aquila chrysaetos populations and in more restricted areas also in Northern Goshawk Accipiter gentilis and Red Kite Milvus milvus populations, in all of which illegal killing has been sufficient to affect numbers over wider areas. The evidence consists mainly of: (1) greater disappearance of nesting pairs, lower breeding densities or reduced occupancy of apparently suitable traditional territories on grouse moors compared with other areas; (2) reduced nest success compared with other areas; (3) reduced adult survival compared with other areas; (4) reduced age of first breeding, reflecting the removal of adults from nesting territories and their replacement by birds in immature plumage; (5) greater levels of disappearance of satellite‐tracked birds on grouse moors than elsewhere; and (6) the finding of poisoned baits and traps, and shot or poisoned carcasses of raptors. Not all these types of evidence are available for every species, and other types of evidence are available for some. The Common Buzzard Buteo buteo is currently the most numerous raptor in Britain and also seems to be killed in the greatest numbers. Other raptor species, including Merlin Falco columbarius, Common Kestrel Falco tinnunculus and Eurasian Sparrowhawk Accipiter nisus which nest on or near grouse moors, have little or no significant impact on grouse and are killed less often or not at all. In the absence of illegal killing, some raptor species breed as well or better on grouse moors than in other habitats. Merlins, in particular, seem to thrive on grouse moors, benefiting from the management involved (including predator control). Other aspects of illegal raptor killing are discussed, including suggestions for ways in which it might be reduced.     

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.     

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.     

Enhanced control of sheep ticks in upland sheep flocks: repercussions for red grouse co-hosts

Sheep ticks Ixodes ricinus (Acari: Ixodidae) and tick-borne diseases cause major economic losses in both upland sheep farming and moorland shoots of red grouse Lagopus lagopus scoticus. Sheep were treated with acaricide four times between March and October and double-vaccinated against louping ill virus (LIV), instead of the conventional regime of two acaricide treatments and no vaccinations, on two moors in northern England. Enhanced treatment started at Westerdale Moor in 1995 and at Danby Moor in 2000; the latter had previously represented a spatial control site. From 1992 to 2003, grouse chick condition, tick burdens, reproductive success, shooting bags and LIV seroprevalence were measured. A total of 1297 grouse chicks from 398 broods were examined for ticks. Enhanced acaricide treatment reduced tick burdens by 90%, and LIV seroprevalence decreased in relation to the number of years since treatment began. Breeding success and post-breeding densities of grouse in the current sample area remained unrelated to acaricide treatment, tick burdens or LIV seroprevalence, but 25% and 60% more grouse were shot on Westerdale and Danby, respectively, after treatment enhancement than before. By improving shooting bags, tick management schemes help to maintain the economic viability of grouse moors, which, in turn, provide upland landscape and wildlife benefits.     

The influence of different aspects of grouse moorland management on nontarget bird assemblages

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Utilisation of different ages of heather on three Scottish moors by red grouse, mountain hares, sheep and red deer

Utilisation of heather at three Scottish moors, by red grouse, mountain hares, sheep and red deer, was measured by collecting their faecal droppings regularly from plots on heather patches of different ages. Rates of heather growth differed between moors, and preferences of the four species, all grazers of heather, were related more closely to its height than to its age. Thus hares spent most time on ground with heather less than 15 cm high, sheep less than 20 cm, grouse preferred heather 10–30 cm high and deer spent most time on heather over 25 cm high.
Differences between outer, middle and inner plots on patches at one of the moors in dicated that grouse are reluctant to move far from cover into areas of newly burned ground, and reluctant to move far into patches of tall, dense heather, when these are next to shorter material. Hares preferred the middle of patches on newly burned ground and very young heather.
At two of the moors, but not the third, there was evidence that heavy grazing by hares in winter reduced the amount of young heather available to hares and grouse in spring. This potential reduction in the quality of the spring diet of grouse is discussed In relation to previously reported associations between numbers of hares and grouse at those two moors.     

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.     

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.     

Can acaricide‐impregnated leg bands fitted to female red grouse reduce sheep tick parasitization of chicks and increase chick survival?

In parts of northern England, North Wales and the Scottish Highlands, increasing numbers of sheep ticks Ixodes ricinus (Ixodida: Ixodidae), and the louping ill virus they can carry, are considered to be important factors that reduce red grouse Lagopus lagopus scotica productivity. The present study tested this hypothesis by fitting adult female grouse with leg bands impregnated with the acaricide cypermethrin to experimentally control ticks on their chicks on two managed grouse moors in northeast Scotland. The chicks of females fitted with acaricide leg bands showed reduced tick infestations and improved survival in one of the two study years, relative to chicks of control females. Acaricide leg bands constitute a potential management technique that may be adopted by grouse moor managers in circumstances of high tick infestations on grouse chicks.     

Cestodiasis in the red grouse in Scotland

Little is known about the cestode parasites of red grouse Lagopus lagopus scoticus. The carcasses of 71 free-living and grouse collected from northeastern Scotland (UK) between June 1991 and September 1992 were examined for the cestode Paroniella urogalli. Over 70% of young and old birds were infected in summer and winter. Cestode abundance ranged from 0 to 29 (mean +/- SE = 5.54 +/- 0.81) worms per host and did not differ significantly between young and old grouse, or between seasons. Cestode intensities did vary significantly between the sexes, but in opposite directions at two sites. A significantly greater total biomass (dry weight) of cestodes was found in grouse in the summer. Cestode biomass also was greater in young than in old grouse, although there was no significant difference after controlling for the effects of site, year and season. However, in the summer total cestode biomass in young grouse was significantly greater per unit bodyweight than in old grouse. No evidence was found for an effect of cestodiasis on grouse condition but a significant positive correlation existed between grouse comb condition and cestode abundance. Estimates of mean per capita worm mass suggested an intensity dependent reduction in the weight of individual cestodes in birds in their first summer. Per capita cestode mass was significantly lower in winter than summer, which may suggest that the production of mature proglottids varies with season. There was also a significant negative correlation between numbers of the nematode Trichostrongylus tenuis and the total biomass of P. urogalli in grouse.     

Analysing noisy time-series: describing regional variation in the cyclic dynamics of red grouse

We develop a method for describing the periodicity of noisy 'quasi-cyclic' time-series based on integrals of their power spectra corresponding to different frequency intervals that we use to classify time-series as 'strongly cyclic', 'weakly cyclic' or 'non-cyclic'. We apply this analysis to over 300 time-series of shooting records of red grouse from 289 moors located in 20 regions of the UK. Time-series from 63 of these populations were not distinguishable from white noise, but significant evidence of cyclic behaviour in the 2-15 year range was detected in time-series from 183 other populations. Time-series from the remaining 43 populations, though distinguishable from white noise, did not exhibit consistently recognizable cyclic behaviour in the same period range. Cyclic populations exhibit an average periodicity of 8.3 years, but only 20% of these populations cycle with a period of four to six years. Geographically, grouse populations are remarkable more for their dynamic heterogeneity than for any observable regularity. The relationship between the location of populations and their dynamical behaviour is weak. The prevalence of cyclic time-series within a region did not significantly differ from the overall average value. Moor region explained 22% of the variation in periodicity, differing from the overall mean in three regions. Average periodicity increases significantly from 6.8 to 8.9 years from the most southerly to most northerly populations. However, latitude explains only 5.3% of the variation in periodicity of the cycles.     

Temporal changes in age and sex ratios of forest grouse harvested in northeastern oregon

Ratio of immature (young of the year) grouse to adult birds (I:A) in the harvest of upland game birds is commonly used as an index to annual reproduction; however, I:A ratios can vary as the season progresses producing biased estimates. We analyzed I:A ratios in the daily harvest of dusky grouse (Dendragopus obscurus) and ruffed grouse (Bonasa umbellus) in northeastern Oregon over 28 years (1981–2008) and found that I:A ratios in the harvest declined for both species as the hunting season progressed. We also analyzed ratios of adult female to adult male (AF:AM) grouse to determine if female and male grouse were harvested in equal numbers throughout the harvest season. We found that more males than females of both species were harvested, but that AF:AM ratio of both dusky and ruffed grouse did not change during most of the hunting season. Approximately 50% of the annual harvest occurred during the first 14 days of the hunting season. Therefore, we recommend using the ratios of I:A birds in the first 14 days of the harvest season as the best index to annual reproduction of forest grouse in northeast Oregon. © 2011 The Wildlife Society.     

Ultra-violet reflectance of male and female red grouse, Lagopus lagopus scoticus, sexual ornaments reflect nematode parasite intensity

In many birds, females prefer males with the biggest or brightest sexual ornaments, which might reflect a higher phenotypic quality, such as fewer parasites. Unlike humans, most birds detect near-ultraviolet (UV) light, and UV signals can play an important role in sexual signalling and mate choice. Using a spectrophotometer, we analysed the colour of red grouse Lagopus lagopus scoticus sexual ornaments (their combs). We first show that combs reflect both in the red (600–700 nm) and UV (300–400 nm) part of the spectrum. Second, we investigated whether comb size and colour, and UV reflectance in particular, reflected an aspect of individual quality: the intensity of infection by a main nematode parasite, the caecal threadworm Trichostrongylus tenuis . We first analysed comb size and colour variation, and parasite intensity variation, in relation to sex and age. Males had bigger and redder combs than females, but UV brightness was greater for female than for male combs. Comb colour also differed between age groups, with young birds of both sexes showing brighter UV than old birds. Young grouse also had fewer T. tenuis worms than old grouse. We further tested whether intensity of infection could be predicted from comb characteristics (size and colour) in male and female red grouse. We found that parasite intensity was not significantly related to comb size or red brightness, but fewer worms were predicted from brighter UV in combs, in both males and females. The results indicate that UV reflectance of combs have a quality revealing function and might play an important role in grouse mate choice: UV brightness of combs could enable both male and female red grouse to assess the parasite loads of a potential mate.     

Distribution of mountain hares Lepus timidus in Scotland: results from a questionnaire

A questionnaire survey of land owners, managers and gamekeepers was conducted in order to assess the distribution of mountain hares in Scotland, assess their current management, collate numbers harvested in 2006–07 and estimate distribution change by comparing with similar data collected in 1995–96. The land area covered by returned questionnaires was 71098km² (90% of Scotland). Mountain hares were reported as present on 34359km² (48%) and absent from 36739km² (52%). Mountain hare presence was strongly associated with heather moorland managed for red grouse shooting. Moorland managed for driven grouse shooting had the highest percentage area of mountain hare presence (median 64%) followed by moorland managed for walked‐up grouse shooting (median 9%) and moorland with no grouse shooting (median 0%). Approximately 25000 mountain hares were harvested in 2006–07. Based on the estimated UK population in 1995 of 350000 (range ±50%), this represents around 7% of the population (range 5–14%). Reasons given by respondents for harvesting hares were tick control (50%), sport (40%) and forestry or crop protection (10%). Comparison of the estates surveyed in both 2006–07 and 1995–96 (a total area of 20462km²) indicated no net gain or loss in hare distribution. Furthermore, there was no evidence that levels of harvest had reduced the range of mountain hares in this area. It is not possible to comment on any distribution change outside this area (58737km²). Similarly, as no data were collected on abundance, it is not possible to draw conclusions on changes in density. Regular monitoring of mountain hare distribution within Scotland is required to identify any distribution changes. Measures of abundance throughout the range are necessary to estimate the population size, investigate the relationship between harvest intensity and changes in abundance and further assess the conservation status of this UK Biodiversity Action Plan species.     

The response of willow grouse chicks to auditory stimuli 1. Preference for hen grouse calls

Willow grouse (Lagopus lagopus lagopus) chicks newly hatched from mechanically incubated eggs were exposed to different combinations of sounds in a heated runway. They approached a loudspeaker playing grouse hen calls, which they had never heard, in preference to one playing the noise of the hatching machine from which they had just been removed. Similarly they preferred the hen call to another novel sound. When the three sounds were played singly instead of in pairs, only the hen call was approached.