2022 Early Hearing Detection & Intervention Virtual Conference
March 13 - 15, 2022
9/28/2018 | 1:55 PM - 1:10 PM | The Impacts of Respiratory Cryptosporidiosos on Red Grouse Population Dynamics: Are there too Many Grouse? | Eccles Conference Center Auditorium
The Impacts of Respiratory Cryptosporidiosos on Red Grouse Population Dynamics: Are there too Many Grouse?
Red grouse are an economically important gamebird in parts of the UK uplands, where their intensive management can be a primary land use. Over the last 10 years, already high densities of Red Grouse Lagopus lagopus scotica, which averaged 175 birds km-2 post-breeding on moors in northern England have appropximately doubled, with extremes > 1000 grouse km-2. This followed revised management that successfully suppressed infestations of Trichostrongylus tenuis worm parasites, which had previously limited grouse abundance and has now brought about an apparent cessation of quasi-cyclical fluctuations in grouse abundance. Associated with these increased grouse densities, respiratory cryptosporidiosis, involving infection by Cryptosporidium baileyi, was first diagnosed in wild grouse in 2010. By 2013, signs of infection were observed amongst grouse on half of English grouse moors. In 2014-15, we fitted VHF radio transmitters to 111 diseased and 67 healthy grouse and found that infection not only reduced bird condition and halved survival rates, but also delayed onset of breeding and halved subsequent breeding success. Despite the magnitude of these impacts, currently low disease prevalence, varying from 3-6% between sites and years, meant that infection was having only a low economic impact on grouse shooting returns. However this situation could change markedly should prevalence increase. We explore how grouse density, age structure, hygiene, disease naivety and disturbance from shooting may influence infection prevalence. Finally, we consider whether current densities of grouse are unsustainably high in the longer-term by exploring evidence for density-dependence processes that may regulate components of grouse population dynamics.
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Presenters/Authors
David Baines
(), Game & Wildlife Conservation Trust, dbaines@gwct.org.uk;
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