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Sunday, 10 August 2014

Hen Harrier (Circus cyaneus) Research Paper Abstracts: Hen Harrier Day, 10th August 2014

Research, links, and General Information on Hen Harriers


BAWC_Slider_Hen_Harrier_Day  BTO Hen Harrier Website LINK       Veterinary Record 2013;173:477 doi:10.1136/vr.101476  Fatal epicarditis in a hen harrier (Circus cyaneus) a red-listed bird of high conservation concern in Britain associated with Cyathostoma species and Escherichia coli infection  R. Vaughan-Higgins, S. Murphy, I. Carter,  A. Pocknell, E. Harris and  A. W. Sainsbury  AbstractThree species of the syngamid nematode Cyathostoma have been reported in raptors (Cyathostoma (Hovorkonema) variegatum, Cyathostoma americanum, Cyathostoma lari). These nematodes typically parasitise the respiratory tract (Lavoie and others 1999, Fernando and Barta 2008), air sacs (Hunter and others 1993) and the orbital and nasal cavities (Simpson and Harris 1992). To speciate Cyathostoma species, the copulatory bursa of adult males must be identified using light microscopy; however, if no males are present, then identification to genus level is only possible (Cyathostoma species) (Chitwood and Lichtenfels 1972). C americanum has been associated with diffuse pyogranulomatous air sacculitis, pneumonia and bronchitis (Lavoie and others 1999) and Cyathostoma (Hovorkonema) variegatum with thickened air sac walls and granulomatous lesions at sites of infection in raptors (Krone and Cooper 2002). Emaciation and anaemia have been reported in dead wild birds of prey in the winter months with Cyathostoma species infection, however, the authors considered theCyathostoma species infections to be of limited importance, and that the observed emaciation and anaemia were likely a consequence of starvation (Simpson and Harris 1992). Infection of cyathostomes in free-living wild birds is believed in most cases to be of low prevalence and low intensity (Fernando and Barta 2008).Numbers of breeding female hen harriers (Circus cyaneus) have declined by an estimated 20% in Britain during the last six years, and the hen harrier is now England's most threatened raptor species (Natural England 2008, Royal Society for the Protection of Birds 2011) on the UK Red List of Birds of Conservation Concern (Eaton and others 2009), and Section 41 of the UK Government's Natural Environment Research Council (NERC) list of species of critical importance in England. The hen harrier's current poor population status is primarily the result of continued human persecution (Natural England 2008). A recovery programme is ongoing, and a component of this is health monitoring through postmortem examination of harriers found dead.This case report describes the pathological findings in a hen harrier found dead in the UK, and provides the first description of epicarditis associated with Cyathostoma species in avian species.     J Forensic Sci. 2013 Mar;58(2):491-4. doi: 10.1111/1556-4029.12030.  Reliable and robust molecular sexing of the hen harrier (Circus cyaneus) using PCR-RFLP analysis of the CHD 1 gene. Henderson A1, Lee CM, Mistry V, Thomas MD, Iyengar A.  AbstractThe hen harrier (Circus cyaneus) is a bird of prey that is persecuted in the United Kingdom, and there is a need for a DNA-based individual identification and sexing system for the use in forensic investigations. This study reports a new set of PCR primers for the chromo-helicase-DNA-binding protein 1 gene, which allows sexing using PCR-RFLP. Instead of exonic primers that amplify across a large intron, this set consists of a primer within the intron, enabling reduction in amplicon sizes from 356 to 212 bp and 565 to 219 bp in W and Z chromosomes. DNA degradation and dilution experiments demonstrate that this set is significantly more robust than one that amplifies across the intron, and sequencing of the intronic primer-binding region across several individuals shows that it is highly conserved. While our objective is to incorporate this primer set into an STR-based individualization kit, it may in the meantime prove useful in forensic or conservation studies.    JNCC Report No: 441 February 2011LINK A Conservation Framework for Hen Harriers in the United Kingdom  Alan Fielding, Paul Haworth, Phil Whitfield, David McLeod and Helen Riley   PLoS ONE, 2010 vol. 5(5) pp. e10761FULL ACCESS LINK  The functional response of a generalist predator  Smout, S; Asseburg, C; Matthiopoulos, J; Fern├índez, C; Redpath, S; Thirgood, S; Harwood, J  AbstractBACKGROUND: Predators can have profound impacts on the dynamics of their prey that depend on how predator consumption is affected by prey density (the predator's functional response). Consumption by a generalist predator is expected to depend on the densities of all its major prey species (its multispecies functional response, or MSFR), but most studies of generalists have focussed on their functional response to only one prey species.METHODOLOGY AND PRINCIPAL FINDINGS: Using Bayesian methods, we fit an MSFR to field data from an avian predator (the hen harrier Circus cyaneus) feeding on three different prey species. We use a simple graphical approach to show that ignoring the effects of alternative prey can give a misleading impression of the predator's effect on the prey of interest. For example, in our system, a "predator pit" for one prey species only occurs when the availability of other prey species is low.CONCLUSIONS AND SIGNIFICANCE: The Bayesian approach is effective in fitting the MSFR model to field data. It allows flexibility in modelling over-dispersion, incorporates additional biological information into the parameter priors, and generates estimates of uncertainty in the model's predictions. These features of robustness and data efficiency make our approach ideal for the study of long-lived predators, for which data may be sparse and management/conservation priorities pressing.    Ecological Economics  Volume 70, Issue 1, 15 November 2010, Pages 107–113  Economic values of species management options in human–wildlife conflicts: Hen Harriers in Scotland  Nick Hanley, Mikolaj Czajkowski, Rose Hanley-Nickolls, Steve Redpath  Abstract In this paper, we use the choice experiment method to investigate public preferences over alternative management regimes for a top-level predator in UK moorlands, the Hen Harrier. These birds are at the centre of a conflict between moorland managers and conservation organisations. Illegal killing of Hen Harriers on moorland managed for Red Grouse is considered to be one of the main factors limiting harrier population growth in the UK. Incentives for persecution arise due to the impacts of Hen Harriers on populations of Red Grouse, which are managed for commercial shooting. Numerous alternatives have been proposed to manage this system. We considered three which have emerged from stakeholder debates and scientific enquiry: tougher law enforcement, moving “excess” birds from grouse moors, and feeding of harriers. Results showed that respondents, sampled from the Scottish general public, were willing to pay both for avoiding reductions in harrier populations and for increases, but that these values were lower than those associated with equivalent changes for another raptor sharing the same moorland habitat, the Golden Eagle. Respondents valued a move away from current management, but were largely indifferent to which management option was taken up, suggesting that management options should be selected in terms of relative costs, and on who bears these costs. Differences within our sample of respondents in preferences across management options emerge when a latent class model is estimated.    Natural England(NE140)LINK  A future for the Hen Harrier In England?  Summary Since 2002 Natural England’s Hen Harrier Recovery Project has monitored the numbers of breeding Hen Harriers in England. For the first time, new tracking technologies have been used to monitor the fate of Hen Harriers during the non-breeding season. The key findings are: 1. The English Hen Harrier population remains perilously small, with no more than 23 nesting attempts in any one year in the period 2002-2008. 2. Productivity from successful nests is high, but very few nesting attempts are successful on grouse moors. 3. There is compelling evidence that persecution continues, both during and following the breeding season. 4. Persecution continues to limit Hen Harrier recovery in England.    Biological Conservation Volume 142, Issue 3, March 2009, Pages 586–596DOI: 10.1016/j.biocon.2008.11.013  Hunting habitat selection by hen harriers on moorland: Implications for conservation management  Beatriz Arroyo, Arjun Amar, Fiona Leckie, Graeme M. Buchanan, Jeremy D. Wilson, Stephen Redpath  AbstractWe examine habitat use by hunting hen harriers Circus cyaneus at three study sites in Scotland to evaluate whether foraging patterns differ between sexes, sites, and stages of the breeding period. We modelled time spent hunting in focal plots as a function of habitat and nest proximity. Male hunting intensity (time spent hunting per hour of observation and km2) varied between sites and breeding periods, being lower during the nestling than the incubation period. Habitat use patterns were mostly consistent among study sites, which is important for developing species management recommendations applicable over the species’ range. Males avoided improved grassland, and selected areas of mixed heather and rough grass (with an optimum at ca. 50% heather cover). The effect of nest proximity was small. In contrast, females hunted mainly within 300–500 m of the nest, with a small additive effect of vegetation cover, areas of fragmented heather being preferred. Habitat management to benefit foraging harriers will involve creating (or maintaining) mosaics of heather/grassland around nest areas. Additionally, it might be possible to manipulate habitat to reduce conflict in areas where harrier predation on red grouse is important by segregating areas holding highest grouse densities (with high heather cover) from those favoured for harrier foraging (heather–grass mosaics). However, it would be necessary to test whether these manipulations might also influence harrier nest distribution, an effect which could negate any benefits from this strategy.    Biological Conservation  Volume 142, Issue 3, March 2009, Pages 488–499 DOI: 10.1016/j.biocon.2008.10.036   Using distribution models to test alternative hypotheses about a species’ environmental limits and recovery prospects  AbstractDistribution models are commonly used to generalise across species distributions, to project future potential range changes, and to identify potential areas for species reintroductions and recovery plans. Building several models that incorporate different potential causal factors is a useful way of formalising alternative hypotheses. We developed a series of models to test hypotheses about the factors influencing the distribution of a species of conservation importance – the hen harrier Circus cyaneus.A climate-based model using continental distribution data was consistent with the continental distribution and observational studies in Britain. According to the climate-model the parts of Britain occupied by the hen harrier are the least climatically suitable.Habitat-based models using detailed distribution data from seven Scottish areas explained the recent British distribution well, with birds largely confined to heather dominated areas. These patterns were inconsistent with historical data on the species’ distribution, its habitat use in other parts of its range and with the climate-based model.Our burn intensity index of gamekeeper activity was highly correlated with climatic suitability within the best 25% of 10 km squares by modelled habitat suitability, negatively associated with the productivity data and associated with a decrease in abundances between 1998 and 2004. Gamekeeper activity may be keeping hen harriers out of the most climatically suitable areas with habitat similar to that which they currently occupy within Britain and or keeping the population numbers too low and isolated for the natural re-expansion of the species into parts of the range where it was historically extirpated.    Ecology. 2007 Oct;88(10):2576-86.  Sensitivity to assumptions in models of generalist predation on a cyclic prey.  Matthiopoulos J, Graham K, Smout S, Asseburg C, Redpath S, Thirgood S, Hudson P, Harwood J.  AbstractEcological theory predicts that generalist predators should damp or suppress long-term periodic fluctuations (cycles) in their prey populations and depress their average densities. However, the magnitude of these impacts is likely to vary depending on the availability of alternative prey species and the nature of ecological mechanisms driving the prey cycles. These multispecies effects can be modeled explicitly if parameterized functions relating prey consumption to prey abundance, and realistic population dynamical models for the prey, are available. These requirements are met by the interaction between the Hen Harrier (Circus cyaneus) and three of its prey species in the United Kingdom, the Meadow Pipit (Anthus pratensis), the field vole (Microtus agrestis), and the Red Grouse (Lagopus lagopus scoticus). We used this system to investigate how the availability of alternative prey and the way in which prey dynamics are modeled might affect the behavior of simple trophic networks. We generated cycles in one of the prey species (Red Grouse) in three different ways: through (1) the interaction between grouse density and macroparasites, (2) the interaction between grouse density and male grouse aggressiveness, and (3) a generic, delayed density-dependent mechanism. Our results confirm that generalist predation can damp or suppress grouse cycles, but only when the densities of alternative prey are low. They also demonstrate that diametrically opposite indirect effects between pairs of prey species can occur together in simple systems. In this case, pipits and grouse are apparent competitors, whereas voles and grouse are apparent facilitators. Finally, we found that the quantitative impacts of the predator on prey density differed among the three models of prey dynamics, and these differences were robust to uncertainty in parameter estimation and environmental stochasticity.    Biological Conservation Volume 111, Issue 3, June 2003, Pages 377–384DOI: 10.1016/S0006-3207(02)00306-3  Evidence for food limitation in the declining hen harrier population on the Orkney Islands, Scotland Arjun Amar, Steve Redpath, Simon Thirgood  AbstractThe 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.    Ecotoxicology. 2002 Feb;11(1):35-48.  Assessment of risks of brodifacoum to non-target birds and mammals in New Zealand.  Eason CT1, Murphy EC, Wright GR, Spurr EB.  AbstractThe risks to non-target birds and other wildlife from the use of vertebrate pesticides, including anticoagulant rodenticides, are determined to a significant extent by species' intrinsic susceptibility, and the toxicokinetics of the compounds used. Brodifacoum is highly toxic to birds and mammals. The acute toxicity of brodifacoum to birds in New Zealand varies from <1 mg/kg in pukeko (Porphyrio p. melanotus), the native swamp hen, to >20 mg/kg in the paradise shelduck (Tadorna variegata). Like other second-generation anticoagulants brodifacoum is strongly bound to vitamin K epoxide reductase and will persist, apparently for at least 6 months, in organs and tissue containing this enzyme, e.g., liver, kidney, and pancreas. The unique toxicokinetics of this class of compound exacerbates the risk of primary and secondary poisoning of non-target species. Vertebrate pest control programmes in New Zealand using bait containing brodifacoum have resulted in the primary and secondary poisoning and sub-lethal contamination of non-target species. These include native raptors, such as the Australasian harrier (Circus approximans) and morepork (Ninox novaeseelandiae), other native birds such as the pukeko, weka (Gallirallus australis), southern black-backed gull (Larus dominicanus), and kiwi (Apteryx spp.), and introduced mammals, including game animals. There are increasing numbers of reports worldwide of wildlife contamination and toxicosis after the use of second-generation anticoagulants. All pest control activities require careful risk-benefit assessment in view of their potential to cause adverse environmental impact. Monitoring of wildlife for pesticide residues will provide data that can be used to reduce the risk of anticoagulant bioaccumulation and mortality in non-target species.    Proc Biol Sci. 2000 Apr 7;267(1444):651-6.FULL ACCESS LINK  Habitat loss and raptor predation: disentangling long- and short-term causes of red grouse declines.  Thirgood SJ1, Redpath SM, Haydon DT, Rothery P, Newton I, Hudson PJ.  AbstractThe 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.      Agriculture, Ecosystems & EnvironmentVolume 64, Issue 1, 15 June 1997, Pages 19–32  Impact of agricultural intensification of pastoral systems on bird distributions in Britain 1970–1990  Deborah J. Pain, David Hill, David I. McCracken  Abstract The distribution of six species of birds known to depend on extensive pastoral systems, as published in atlases of breeding birds, was mapped in Britain for two time periods: 1968–1972 and 1990–1992. The species chosen (corncrake Crex crex, golden eagle Aquila chrysaetos, hen harrier Circus cyaneus, stone curlew Burhinus oedicnemus, chough Pyrrhocorax pyrrhocorax and red-backed shrike Lanius collurio) are known to be declining or vulnerable across large parts of their European range. Summed species distribution was compared with available data on the distribution of low intensity agricultural land in Britain. In 1990, bird and land-use distribution was similar. Thus it is concluded that it may be possible to use summed species distribution to predict areas where ecologically beneficial farming systems exist elsewhere in Europe. Most coincidence in species distribution now occurs in Scotland, northern England and Wales. However, large parts of mid-west Scotland have less selected pastoral species than in 1968–1972. The most obvious changes have occurred throughout East Anglia, the south-east and south-west of England. There has been significant fragmentation of coincidence along the north Norfolk coast and along the coasts of Suffolk and Essex. The extent of summed distribution of the indicator bird species chosen declined and fragmented dramatically between 1970 and 1990. There was a significant negative relationship between livestock units per hectare (both sheep and total), and mean species coincidence (average number of species occurring in each 10km2) for six regions in Scotland and northern England in 1990. In each of these six regions, mean species coincidence declined as sheep livestock units per hectare increased between 1970 and 1990. The need for changes to agricultural policies at the level of the European Community in order to reverse this serious conservation problem, is discussed.

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