Cestodiasis in the red grouse in Scotland

Little is known about the cestode parasites of red grouse Lagopus The carca sses of 71 free-living red grouse collected from northeastern Scotland (UK) between June 1991 and September 1992 were examined for the cestode Paronie lla urogalli. Over 70% of young and old birds were infected in summer and w inter. Cestode abundance ranged from 0 to 29 ((x) over bar +/- SE = 5.54 +/ - 0.81) worms per host and did not differ significantly between young and o ld grouse, or between seasons. Cestode intensities did vary significantly b etween the sexes, but in opposite directions at two sites. A significantly greater total biomass (dry weight) of cestodes was found in grouse in the s ummer. Cestode biomass also was greater in young than in old grouse, althou gh there was no significant difference after controlling for the effects of site, year and season. However, in the summer total cestode biomass in you ng grouse was significantly greater per unit bodyweight than in old grouse. No evidence was found for an effect of cestodiasis on grouse condition but a significant positive correlation existed between grouse comb condition a nd cestode abundance. Estimates of mean per capita worm mass suggested an i ntensity dependent reduction in the weight of individual cestodes in birds in their first summer. Per capita cestode mass was significantly lower in w inter than summer, which may suggest that the production of mature proglott ids varies with season. There was also a significant negative correlation b etween numbers of the nematode Trichostrongylus tenuis and the total biomas s of P. urogalli in grouse.