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.     

Ecological-economic modelling of the conservation of threatened habitats: heather moorland in the Northern Isles of Scotland

This paper describes the results of an ecological-economic modelling exercise of the management of a scarce habitat, namely heather moorland. The Orkney Islands of Scotland are used to illustrate a modelling approach which could be easily applied elsewhere, and to other habitats. We describe the evolution and present condition of heather moorland on Orkney, then quantify the extent of over-grazing (leading to ecological damage) on a spatial basis. This is accomplished using a model of heather utilization and heather productivity. Critical grazing limits are then used as constraints in an economic model of farm production decisions, which enables us to quantify the minimum necessary compensation payments which farmers should be offered to offset income losses due to grazing restrictions. Such a policy is in line with European Union and UK agri-environmental policy, which typically uses payments for income forgone as a means of persuading farmers to protect environmental quality.     

Museum samples provide novel insights into the taxonomy and genetic diversity of Irish red grouse

The taxonomic status of red grouse in Ireland has been the subject of considerable debate over the past century. Irish red grouse are usually classified as Lagopus lagopus scoticus, which is the same subspecies as that found in Britain, but some ornithologists believe that native Irish red grouse constitute an endemic subspecies, namely L. lagopus hibernicus. The considerable decline of Irish red grouse over the past century, along with possible hybridization with introduced grouse from Britain, have highlighted the need to resolve their taxonomic status as part of a biodiversity management plan. However, genetic analysis of samples from a single point in time will provide limited insight into potentially confounding historical events such as hybridization and introgression. We therefore compared mtDNA sequences from both current and historical samples of the two putative subspecies, scoticus and hibernicus, to see if they are or were genetically distinct. Red grouse from Britain and Ireland shared mitochondrial haplotypes, and our historical data suggest that this is unlikely to be the result of recent hybridization and introgression. These findings, combined with a general lack of documented differences in behaviour and ecology, suggest that Irish red grouse should remain classified as L. lagopus scoticus. At the same time, we found evidence that a significant amount of genetic diversity has been lost from Irish red grouse over the past century, presumably as a result of diminishing population sizes and fragmentation of extant populations. A loss of habitat, combined with the declining numbers and genetic diversity of Irish red grouse, justify their designation as an All-Ireland Priority (Red List) species and a Northern Ireland Priority Species for conservation.     

Recency, range expansion, and unsorted lineages: implications for interpreting neutral genetic variation in the sharp-tailed grouse (Tympanuchus phasianellus)

Both current and historical patterns of variation are relevant to understanding and managing ecological diversity. Recently derived species present a challenge to the reconstruction of historical patterns because neutral molecular data for these taxa are more likely to exhibit effects of recent and ongoing demographic processes. We studied geographical patterns of neutral molecular variation in a species thought to be of relatively recent origin, Tympanuchus phasianellus (sharp-tailed grouse), using mitochondrial control region sequences (CR-I), amplified fragment length polymorphisms (AFLP), and microsatellites. For historical context, we also analysed CR-I in all species of Tympanuchus. Within T. phasianellus, we found evidence for restricted gene flow between eastern and western portions of the species range, generally corresponding with the range boundary of T. p. columbianus and T. p. jamesi. The mismatch distribution and molecular clock estimates from the CR-I data suggested that all Tympanuchus underwent a range expansion prior to sorting of mitotypes among the species, and that sorting may have been delayed as a result of mutation-drift disequilibrium. This study illustrates the challenge of using genetic data to detect historical divergence in groups that are of relatively recent origin, or that have a history dominated by nonequilibrium conditions. We suggest that in such cases, morphological, ecological, and behavioural data may be particularly important adjuncts to molecular data for the recognition of historically or adaptively divergent groups.     

Ecological and economic implications of a tropical jellyfish invader in the Gulf of Mexico

A large population of a previously unreported jellyfish occurred across the northern Gulf of Mexico (USA) from May through September of 2000. The jellyfish, identified as Phyllorhiza punctata by von Lendenfeld (1884), is not indigenous to the Gulf of Mexico or to the Atlantic Basin. Current theory states that this invasive species was introduced into the Atlantic from the Pacific Ocean through the Panama Canal about 45 years ago, and several confirmed reports indicated that a cryptic population may have existed in the northern Gulf since 1993. However, mesoscale hydrographic anomalies in spring 2000 may have directly transported the population from the Caribbean Sea where populations of P. punctata have been reported previously in Puerto Rico. We undertook a rapid-response sampling program from June through September to obtain ecological information regarding P. punctata in the highly productive northern Gulf waters. Jellyfish bell diameter increased by about 50% (from an average of 32 ± 12 to 45 ± 6 cm) as animals invaded nearshore waters during July. As the summer progressed, a net westerly distribution shift followed nearshore currents to an accumulation point near the mouth of Lake Borgne, Louisiana, in the far western Mississippi Sound. In the Lake Borgne aggregation, we estimated 5.37 × 10⁶ medusae over an area of about 150 km². All of the medusae appeared to lack the symbiotic algae that are present in all other described populations, and therefore must have depended solely on planktivory for their nutrition. Clearance rates estimated from ambient zooplankton, gut contents and published digestion times ranged from < 1 m³ d^–1 for adult copepods to over 90 m³ d^–1 for fish eggs. Based on these clearance rates, the central core of this aggregation (30 km²) was being turned over at least once per day with even higher turn-over in very concentrated `super-swarms'. Clogging of shrimp nets was the greatest economic impact, and perhaps contributed to millions of dollars in economic losses. The indirect effect of predation on eggs and larvae of commercially important finfish and shellfish remained intangible in the determination of economic effects. In 2001, P. punctata has recurred along southern Louisiana and has apparently spread into the coastal and lagoonal waters of the Florida east coast.     

Mitochondrial phylogeography and subspecific variation in the red panda (Ailurus fulgens): implications for conservation

The red panda (Ailurus fulgens) is an endangered species and its present distribution is restricted to isolated mountain ranges in western China (Sichuan, Yunnan, and Tibet provinces) and the Himalayan Mountains chain of Nepal, India, Bhutan, and Burma. To examine the evolutionary history across its current range, and to assess the genetic divergence among current subspecies and population structure among different geographic locations, we sequenced mitochondrial DNA from the control region (CR) and cytochrome (cyt) b gene for 41 individuals in Sichuan, Yunnan, Tibet of China, and Burma. 25 CR haplotypes (10 for cyt b) were identified from 11 geographic locations. Only three haplotypes were shared among sample localities, including one among current subspecies. Nine haplotypes were shared with the study of Su et al. [Mol. Biol. Evol. 18 (2001) 1070]. CR haplotype diversity was high (0.95+/-0.02) and nucleotide diversity among all haplotypes was relatively low (0.018+/-0.009). Phylogenetic confirmed trees show a shallow pattern with very little structure or statistical robustness. The application of two coalescent-based tests for population growth allowed us to interpret this phylogeny as the result of a recent population expansion. Analysis of molecular variance and nested clade analysis failed to detect significant geographic structure in both data sets. The lack of significant differentiation between subspecies does not indicate the presence of evolutionary significant units. We suggest that the present population structure has resulted from habitat fragmentation and expansion from glacial refugia. Due to its habitat requirements it is likely that the red panda has undergone bottlenecks and population expansions several times in the recent past. The present population may exhibit a pattern reminiscent of a relatively recent population expansion.     

Genetic variation among endangered Irish red grouse (<Emphasis Type="Italic">Lagopus lagopus hibernicus</Emphasis>) populations: implications for conservation and management

Extant populations of Irish red grouse (Lagopus lagopus hibernicus) are both small and fragmented, and as such may have an increased risk of extinction through the effects of inbreeding depression and compromised adaptive potential. Here we used 19 microsatellite markers to assay genetic diversity across 89 georeferenced samples from putatively semi-isolated areas throughout the Republic of Ireland and we also genotyped 27 red grouse from Scotland using the same markers. The genetic variation within Ireland was low in comparison to previously published data from Britain and the sample of Scottish red grouse, and comparable to threatened European grouse populations of related species. Irish and Scottish grouse were significantly genetically differentiated (F_ST = 0.07, 95% CI = 0.04–0.10). There was evidence for weak population structure within Ireland with indications of four distinct genetic clusters. These correspond approximately to grouse populations inhabiting suitable habitat patches in the North West, Wicklow Mountains, Munster and Cork, respectively, although some admixture was detected. Pair-wise F_ST values among these populations ranged from 0.02 to 0.04 and the overall mean allelic richness was 5.5. Effective population size in the Munster area was estimated to be 62 individuals (95% CI = 33.6–248.8). Wicklow was the most variable population with an AR value of 5.4 alleles/locus. Local (Munster) neighbourhood size was estimated to 31 individuals corresponding to an average dispersal distance of 31 km. In order to manage and preserve Irish grouse we recommend that further fragmentation and destruction of habitats need to be prevented in conjunction with population management, including protection of the integrity of the existing population by refraining from augmenting it with individuals from mainland Britain to maximise population size.     

Low Genetic Variation in the Heath Hen Prior to Extinction and Implications for the Conservation of Prairie-Chicken Populations

Low genetic variation is often considered to contribute to the extinction of species when they reach small population sizes. In this study we examined the mitochondrial control region from museum specimens of the Heath Hen (Tympanuchus cupido cupido), which went extinct in 1932. Today, the closest living relatives of the Heath Hen, the Greater (T. c. pinnatus), Attwater’s (T. c. attwateri) and Lesser (T. pallidicinctus) Prairie-chicken, are declining throughout most of their range in Midwestern North America, and loss of genetic variation is a likely contributor to their decline. Here we show that 30 years prior to their extinction, Heath Hens had low levels of mitochondrial genetic variation when compared with contemporary populations of prairie-chickens. Furthermore, some current populations of Greater Prairie-chickens are isolated and losing genetic variation due to drift. We estimate that these populations will reach the low levels of genetic variation found in Heath Hens within the next 40 years. Genetic variation and fitness can be restored with translocation of individuals from other populations; however, we also show that choosing an appropriate source population for translocation can be difficult without knowledge of historic population bottlenecks and their effect on genetic structure.     

On the use by birds of intertidal areas of the Tagus estuary: implications for management

The use of intertidal areas of the Tagus estuary by birds was re-analysed, based on data from 1990 to 1993, to describe (i) the temporal and spatial patterns of use of intertidal areas, (ii) the diet of birds during winter and (iii) the habitat selection patterns of feeding birds, during winter. The most common birds in the estuary were gulls, waders and ducks. Highest densities were recorded for most species in autumn and winter. The spatial distribution of birds in the intertidal areas of the estuary did not vary significantly across seasons, although broader distributions occurred when bird populations were present in high numbers. In autumn, use of intertidal areas was highly variable. Specific areas in the estuary were identified as holding important densities of birds, or having a high species richness. The most abundant species selected feeding areas according to sediment type, although the presence of channels, saltmarsh or humans also influenced the distribution of birds. The invertebrates Carcinus maenas, Hediste diversicolor and Scrobicularia plana were identified as key prey species. Plant material was important as food for ducks. Implications of these findings for the management of the estuary are discussed.