Do the thermal conditions in maternity colony roost determine the size of young bats? Comparison of attic and cave colonies of Myotis myotis in Southern Poland

摘要

Body weight and forearm length measurements were taken from the bats from two reproductive colonies of Myotis myotis: a church attic (50 degrees 54' 18 '' N: 18 degrees 56' 16 '' E) and a cave (50 degrees 43' 45 '' N: 19 degrees 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 (he cave. Temperatures front the cave showed 24 hour oscillations which did not differ significantly between the years of study. Forearm lenghts and body weight of the young (lid 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.