Steve Redpath

Understanding and managing conservation conflicts.

Conservation conflicts are increasing and need to be managed to minimise negative impacts on biodiversity, human livelihoods, and human well-being. Here, we explore strategies and case studies that highlight the long-term, dynamic nature of conflicts and the challenges to their management. Conflict management requires parties to recognise problems as shared ones, and engage with clear goals, a transparent evidence base, and an awareness of trade-offs. We hypothesise that conservation outcomes will be less durable when conservationists assert their interests to the detriment of others. Effective conflict management and long-term conservation benefit will be enhanced by better integration of the underpinning social context with the material impacts and evaluation of the efficacy of alternative conflict management approaches.

The effect of aggressiveness on the population dynamics of a territorial bird

A central issue in ecology lies in identifying the importance of resources, natural enemies and behaviour in the regulation of animal populations. Much of the debate on this subject has focused on animals that show cyclic fluctuations in abundance. However, there is still disagreement about the role of extrinsic (food, parasites or predators) and intrinsic (behaviour) factors in causing cycles. Recent studies have examined the impact of natural enemies, although spatial patterns resulting from restricted dispersal or recruitment are increasingly recognized as having the potential to influence unstable population dynamics. We tested the hypothesis that population cycles in a territorial bird, red grouse Lagopus lagopus scoticus, are caused by delayed density-dependent changes in the aggressiveness and spacing behaviour of males. Here we show that increasing aggressiveness experimentally for a short period in autumn reduced recruitment and subsequent breeding density by 50%, and changed population trajectories from increasing to declining. Intrinsic processes can therefore have fundamental effects on population dynamics.

The emergence of biodiversity conflicts from biodiversity impacts: characteristics and management strategies

Conflicts between the conservation of biodiversity and other human activities occur in all habitats and can impact severely upon socio-economic and biological parameters. In a changing environment, with increasing pressure on ecosystem goods and services and increasing urgency for biodiversity conservation, these conflicts are likely to increase in importance and magnitude and negatively affect biodiversity and human well-being. It is essential, however, to better understand what is meant by ‘biodiversity conflicts’ in order to develop ways to manage these effectively. In view of the complexity of the social and ecological contexts of conflicts, this paper explores ‘biodiversity impacts’ linked to agricultural, forestry and other sectoral activities in the UK. The paper then describes the transition from ‘biodiversity impacts’ to ‘biodiversity conflicts’, illustrating this concept with specific examples. While generalisations relating to conflict management are made difficult by their unique contextual settings, this paper suggests approaches for their management, based on the experiences of scientists who have been involved in managing conflicts. We consider the role of science and scientists; trust and dialogue; and temporal and spatial scales in biodiversity conflicts and highlight the combined role they play in successful biodiversity conflict management. Recommendations are also made for future research on biodiversity conflicts in a changing environment.

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.

The effects of autumn testosterone on survival and productivity in red grouse, Lagopus lagopus scoticus

There are costs and benefits to individuals of having high levels of circulating testosterone, and the costs can be particularly apparent outside the breeding season. Unlike many birds, red grouse have high testosterone levels in autumn and in this study we explored the consequences of variation in autumn testosterone levels, in terms of survival and breeding success. We caught 123 male grouse in September, from six sites in Scotland and England, U.K. Grouse were given either testosterone or control implants, then fitted with radiotransmitters and released. Control males tended to survive better, but the difference was not statistically significant. During the first 3 months, cause of mortality varied with treatment, with birds of prey killing only testosterone-implanted birds. In spring, females paired with testosterone-implanted males had larger combs (sexual ornaments) than those with controls, suggesting that they might have been better-quality individuals. Testosterone-implanted birds were more likely to be paired and to be bigamous, and each bird alive in spring produced on average 2.5 more offspring than control birds. The benefits of investing in elevated levels of testosterone are clearly high for those males that survive the winter. However, these benefits are reduced by overwinter mortality and the reproductive success of all males alive at the start of the experiment did not vary statistically with treatment. We discuss the longer-term consequences of high testosterone levels, which are likely to be very different to short-term ones.

Temporal changes in kin structure through a population cycle in a territorial bird, the red grouse Lagopus lagopus scoticus

Populations of red grouse (Lagopus lagopus scoticus) undergo regular multiannual cycles in abundance. The ‘kinship hypothesis’ posits that such cycles are caused by changes in kin structure among territorial males producing delayed density‐dependent changes in aggressiveness, which in turn influence recruitment and regulate density. The kinship hypothesis makes several specific predictions about the levels of kinship, aggressiveness and recruitment through a population cycle: (i) kin structure will build up during the increase phase of a cycle, but break down prior to peak density; (ii) kin structure influences aggressiveness, such that there will be a negative relationship between kinship and aggressiveness over the years; (iii) as aggressiveness regulates recruitment and density, there will be a negative relationship between aggressiveness in one year and both recruitment and density in the next; (iv) as kin structure influences recruitment via an affect on aggressiveness, there will be a positive relationship between kinship in one year and recruitment the next. Here we test these predictions through the course of an 8‐year cycle in a natural population of red grouse in northeast Scotland, using microsatellite DNA markers to resolve changing patterns of kin structure, and supra‐orbital comb height of grouse as an index of aggressiveness. Both kin structure and aggressiveness were dynamic through the course of the cycle, and changing patterns were entirely consistent with the expectations of the kinship hypothesis. Results are discussed in relation to potential drivers of population regulation and implications of dynamic kin structure for population genetics.

Evidence for food limitation in the declining hen harrier population on the Orkney Islands, Scotland

The hen harrier (Circus cyaneus) population on the Scottish Orkney Islands has declined dramatically since the end of the 1970s. We postulate that the cause of this decline was due to a reduction in the amount of available prey and predict that if this was the case the population would currently be limited by food. The evidence for this hypothesis is explored by examining the rates at which males deliver prey to their females in relation to breeding performance both among individuals within the declining population and also between this declining population and another, non-declining population in southern Scotland. Breeding performance within the Orkney population was related to male provisioning rates: males that provided more food to their females were more likely to initiate a breeding attempt and there was a tendency for males with the highest provisioning rates to breed with more females. Comparisons between the two populations revealed that harriers on Orkney had a lower breeding performance and also a lower rate of food provision. Changes in agriculture, in particular decreases in rough grazing and increases in sheep densities are thought to be the most likely cause for a reduction in food supply. Conservation measures should be aimed toward increasing the areas of rough grass habitat.

Insights into population ecology from long‐term studies of red grouse Lagopus lagopus scoticus

Long-term studies have been the backbone of population ecology. The red grouse Lagopus lagopus scoticus is one species that has contributed widely to this field since the 1950s. This paper reviews the trajectory and profound impact that these studies have had. Red grouse research has combined long-term studies of marked individuals with demographic studies over wide geographical areas and replicated individual- and population-level manipulations. A main focus has been on understanding the causes of population cycles in red grouse, and in particular the relative importance of intrinsic (behaviour) and extrinsic (climate, food limitation and parasite) mechanisms. Separate studies conducted in different regions initially proposed either the nematode parasite Trichostrongylus tenuis or changes in male aggressiveness in autumn as drivers of population cycles. More recent experiments suggest that parasites are not a necessary cause for cycles and have highlighted that behavioural and parasite-mediated mechanisms are interrelated. Long-term experiments show that parasites and aggressiveness interact. Two outstanding questions remain to be tested experimentally. First, what intrinsic mechanism causes temporal variation in patterns of male aggressiveness? The current favoured mechanism is related to patterns of kin structuring although there are alternative hypotheses. Second, how do the dual, interacting mechanisms, affect population dynamics? Red grouse studies have had an important impact on the field of population ecology, in particular through highlighting: (1) the impact of parasites on populations; (2) the role of intrinsic mechanisms in cyclic dynamics and (3) the need to consider multiple, interacting mechanisms.

Nest site selection by Hen Harriers in Scotland

The aim of this study was to examine nest site selection by Hen Harriers Circus cyaneus at two spatial scales in Scotland and to assess whether breeding success was influenced by choice of nest site. At the landscape scale, we compared availability and utilization of habitats in 610 km2 of Argyll, and at the local scale, we compared vegetation and topography at 52 harrier nests and random points within three areas of heather moorland covering a total area of 462 km2. At both scales, harriers showed a clear preference for nesting in heather. Within heather moorland, harriers nested in taller heather (average height 46cm) and nearer streams than expected by chance. More nests were on northwest-facing slopes than expected by chance. We found no evidence that breeding success was influenced by habitat or topography. Heather moorland is declining in the uplands due to overgrazing and afforestation. The association of harriers with heather suggests that their future may become increasingly dependent on moorland...

Exploring the relationships between wader declines and current land-use in the British uplands

Capsule Declines of upland waders were associated with habitat cover, forest edge exposure, grouse moor management intensity and crow abundance. Aims To explore whether changes in the abundance of five wader species in the uplands correlate with the three key hypotheses proposed for their declines. Methods Using data from repeat upland bird surveys, we examined at two spatial scales (region and plot) if population changes correlate with vegetation cover, forest edge exposure, grouse moor management intensity or crow abundance. Results For Northern Lapwings Vanellus vanellus and Eurasian Curlews Numenius arquata, there was an association between declines and broad‐scale vegetation cover; declines being greatest on heather‐dominated plots. Exposure to forest edge was associated with declines of European Golden Plovers Pluvialis apricaria and Common Snipe Galinago galinago at the plot scale, and of Northern Lapwings at the regional scale. More intensive grouse moor management was associated with lower declines in Northern Lapwings at both the plot and regional scale, but with greater declines in European Golden Plovers at the plot scale. Northern Lapwings also declined most on plots with the highest Carrion Crow Corvus corone abundance. Conclusion These analyses represent the first attempt to assess empirically the balance of evidence for different broad‐scale land‐use and habitat‐related drivers of upland wader population declines, providing pointers to their respective roles in driving these declines.