| UPLANDS - CRYPTOSPORIDIOSIS IN RED GROUSE
Respiratory cryptosporidiosis in red grouse Infection is more prevalent in young red grouse. Š Laurie Campbell
BACKGROUND Infection by Cryptosporidium baileyi, a parasitic protozoan, causes respiratory cryptosporidiosis in red grouse. It was first diagnosed in 2010 and has spread with infection rates higher in young birds. Understanding underlying causes of disease emergence and routes of infection transmission are fundamental to its subsequent control.
68 | GAME & WILDLIFE REVIEW 2018
Review2018.indd 68
Respiratory cryptosporidiosis was first diagnosed in red grouse on a North Pennines moor in the autumn of 2010. In the next three years, respiratory infection by the protozoan parasite Cryptosporidium baileyi, which is confined to birds but includes several orders, had manifested itself in red grouse on half the moors in northern England and 80% of moors in the North Pennine Hills. C. baileyi is typically associated with high densities of birds, either released gamebirds or captive collections of birds in aviaries and zoos. Initially, we hypothesised that outbreaks in red grouse were also density related following the recent increases in both breeding and pre-shooting stocks across many moors in the English uplands. In this account of the impact of respiratory cryptosporidiosis on grouse population dynamics, we fitted 111 diseased and 67 healthy grouse with radio-transmitters at two North Pennine moors where disease prevalence averaged 8.1% and monitored their survival and productivity between autumn 2013 and autumn 2015. Six-month natural survival rates (excluding birds that were shot) were 70% in healthy grouse, but only 44% in diseased females and 22% in diseased males. Some 39% of diseased birds died from their infection, whereas 28% of healthy birds were shot. A similar proportion of each group were killed by predators, either by stoats or raptors. On average, diseased
www.gwct.org.uk
03/05/2019 14:32:32
