Helminth gut parasites of black grouse (Lyrurus tetrix) in northern England, their impact on productivity and possible sources of infection

Black grouse (Lyrurus tetrix) declines continue throughout much of temperate Europe, following habitat loss and population isolation, associated with reduced productivity. In northern England, only 1,437 lekking males remained in 2014, genetically isolated from other UK populations, and typified by low productivity but high adult survival. Their distribution overlaps with that of red grouse (Lagopus scotica) on moorland managed for red grouse shooting. Here, quasi-cyclical fluctuations in red grouse numbers are driven by the parasite Trichostrongylus tenuis. Whilst management for red grouse may benefit black grouse survival through reducing predators, we hypothesised that parasite transmission from red to black grouse may contribute to low black grouse productivity. We measured T. tenuis prevalence and mean intensity from 186 black grouse carcasses (40 radio-tagged birds, 30 shot birds, the remainder found by chance) and compared them with equivalent measures in red grouse. T. tenuis oc..., Data collection
Overall, 186 black grouse carcasses were collected between 1998 and 2022. Of these, 40 were radio-tagged birds from published studies of population dynamics in the North Pennine Dales (Warren and Baines 2002, Baines and Richardson 2007). A further 30 birds had been shot and provided by hunters, and the remaining 116 were found by staff, gamekeepers, farmers, and reserve wardens whilst conducting other tasks and provided for examination.
Of the 186 carcasses, 160 (86%) were found in the North Pennines Dales (109 in Teesdale, 29 in Weardale, 20 in Tynedale and one in each of Allendale and Derwentdale), 25 (13%) in the Yorkshire Dales, comprising 14 in the Yorkshire Dales National Park (six in Wensleydale, five in Swaledale, two in Coverdale, and one in Arkengarthdale), nine in the Nidderdale National Landscape, and one from an unspecified location in northern England (Fig. 1). Carcasses were available in 22 of the 25 years, when they averaged eight per year, varying annual..., # Helminth gut parasites of black grouse (Lyrurus tetrix) in northern England, their impact on productivity and possible sources of infection

Dataset DOI: [10.5061/dryad.n02v6wx94](10.5061/dryad.n02v6wx94)

## Description of the data and file structure

To measure the relationship between black grouse (host) body condition and breeding success, and the intensity and abundance of the parasitic worm they and red grouse hosted. 

### Files and variables

#### File: BLACK_GROUSE_STRONGYLE_WORMS.csv

**Description:** Measures of age, sex, wing length, and weight of black grouse caracasses, together with the region where they were found, the likely cause of death, and the number of parasites they contained. Missing values are indicated as empty cells.

##### Variables

* Season: that the carcass was found; 1=Spring, 2=Summer, 3=Autumn, 4=Winter
* Month: that the carcass was found
* Year: that the carcass was found
* Sex: male or female
* Age: adult or juvenile
* Region: North Pennines ...,