Sexual maturation and moult in juvenile Starlings Sturnus vulgaris in response to different daylengths

Starlings, like most other species, show no gonadal development until spring of the year after they hatch, even though they hatch and attain full body size during long days. This could be because they develop in a physiological state analogous to that of photorefractory adults and so need to experience short days in order to activate the reproductive system. To test this possibility, young were hand-reared under different photoperiodic regimes. Young raised under constant long days showed no gonadal development, nor did birds initially raised under short days and then transferred to long days at 3 weeks of age. However, birds transferred from short to long days at 10 weeks of age did show gonadal development, followed by gonadal regression, while birds raised under constant short days showed slow continual gonadal development. This last group, unlike the other three groups, did not moult into adult plumage. Since 4 weeks of long days are required to terminate photorefractoriness in adult Starlings, these results demonstrate that the reproductive system of young birds is in a similar state to that of photorefractory adults, and hence that puberty is analogous to the termination of photofractoriness.     

Modeling Wolverine Occurrence Using Aerial Surveys of Tracks in Snow

ABSTRACT We designed a novel approach to determining extent of distribution and area of occupancy for wolverines (Gulo gulo) by using aerial surveys of tracks in snow and hierarchical spatial modeling. In 2005 we used a small, fixed-wing aircraft with pilot and one observer to search 575 of 588 survey units for wolverine tracks in approximately 60,000 km² of boreal forest in northwestern Ontario, Canada. We used sinuous flight paths to scan open areas in the forest in the 100-km² survey units. We detected tracks in 138 (24%) of the 575 sampled units. There was strong evidence of occurrence (probability of occurrence >0.80) in 30% of the 588 survey units, weak evidence of occurrence (0.50–0.80) in 12%, weak evidence of absence (0.20–0.50) in 15%, and strong evidence of absence (< 0.20) in 43%. Wolverine range comprised 59% of the study area and area of occupancy was 33,400 km². With information on probability of occurrence and core areas of occupation for wolverines in our study area, resource managers and others can examine factors that influence wolverine distribution patterns and use this information to formulate best management practices that will maintain wolverines on the landscape in the face of increasing resource development. Comparing future survey results with those of our 2005 survey will provide an objective way to assess the efficacy of management practices.