Endemic hantavirus infection impairs the winter survival of its rodent host

The influence of pathogens on host fitness is one of the key questions in infection ecology. Hantaviruses have coevolved with their hosts and are generally thought to have little or no effect on host survival or reproduction. We examined the effect of Puumala virus (PUUV) infection on the winter survival of bank voles (Myodes glareolus), the host of this virus. The data were collected by monitoring 22 islands over three consecutive winters (a total of 55 island populations) in an endemic area of central Finland. We show that PUUV infected bank voles had a significantly lower overwinter survival probability than antibody negative bank voles. Antibody negative female bank voles from low-density populations living on large islands had the highest survival. The results were similar at the population level as the spring population size and density were negatively correlated with PUUV prevalence in the autumn. Our results provide the first evidence for a significant effect of PUUV on host survival suggesting that hantaviruses, and endemic pathogens in general, deserve even more attention in studies of host population dynamics.     

Multiple maternity and paternity in single broods of apparently monogamous eastern bluebirds (Sialia sialis)

Summary In an effort to assess genealogical relationships between breeding adults and their putative offspring, we collected and analyzed blood from 257 wild, uniquely color-banded eastern bluebirds (Sialia sialis). Electrophoretic analysis of the protein products of two loci, esterase-2 (EST-2) and nucleoside phosphorylase (NSP), revealed that at least 5% of adult males and 15% of adult females were caring for at least one offspring not their own. Multiple parentage was evident in 9% of all broods sampled. Twenty-five percent of complete families sampled evidenced multiple parentage. Biparental care of nestlings by adult eastern bluebirds is not necessarily a reflection of the genetic kinship between putative parents and their offspring. The consort pattern among eastern bluebirds does not completely correlate with the pattern of gametic contributions, leading to a reconsideration of their mating system as possibly polygamous. This is among the first unambiguous observations of multiple patenity in a wild bird population, and of multiple maternity in a wild passerine.