We studied variations in the abundance of parasitic spinturnicid mites in relation to the gender, age and body condition of bats living in different habitats. Populations of Spinturnix myoti Kolenati, 1856 (Acari: Spinturnicidae), an ectoparasite of the bat Myotis myotis (Borkhausen) (Mammalia: Chiroptera), were investigated in two types of roosts differing in microclimatic conditions: caves (low temperature and high humidity) and attics (high temperature and low humidity). Our data suggest that bats from cave nursery colonies harbour more parasites than those from attic colonies, irrespective of host sex or age. In underground colonies, adult females and their young differ in the mean abundance of parasites, whereas no such differences were found in attic colonies. Non-lactating females from underground roosts and lactating females from attic colonies had similar parasite loads, were lower than those of adult lactating females from caves. A negative correlation between the host body condition index and parasite load was found only in the most infected sex/age group of bats. In spite of significant differences in parasite load, the mean abundance of particular life stages of mites seems to be independent of the type of roost occupied by the host, its sex or age. However, in attic colonies the number of female deutonymphs was twice that of male deutonymphs, whereas in cave colonies the proportions of the sexes were similar. We suggest that the microclimate of the host's roosts may influence ectoparasite abundance through pressure on the sex ratio in the nymphal stages of mites.
Body weight and forearm length measurements were taken from the bats from two reproductive colonies of Myotis myotis: a church attic (50° 54’ 18’’ N; 18° 56’ 16’’E) and a cave (50° 43’ 45’’ N; 19° 16’ 31’’ E) in 2001–2003. During pregnancy air temperatures outside these shelters were more variable than during lactation. Mean 24 hour temperatures in the attic never dropp below mean daily temperatures outside and the rate of temperature change inside the roosts resulting from outside temperature fluctuations were four times higher than in the cave. Temperatures from the cave showed 24 hour oscillations which did not differ significantly between the years of study. Forearm lenghts and body weight of the young did not show any correlation with roost location but varied with the year of study. Differences in the size of the young were explained by cool weather during pregnancy resulting in food shortage for the mothers and reduced growth rate of their foetuses. Low roost temperatures also induced torpor. Forearm length in the adult females varied between roost but was independent of year of study. The number of clustering females is propably crucial for the persistence of colonies of Myotis myotis located in caves in the northern Carpathians.