Figure 4. Diel activity patterns of tree voles and nest predators. Density plots (a) showing the hours in which six species or groups were detected (using hour as the bin-width such that only one detection per hour is included) at nest platforms in young trees, central Coast Range, Oregon, USA. Shading indicates average nocturnal period in the study area. Panel b shows weasel density plot split into weasel detections whereby we assigned a high and low likelihood of a tree vole mortality after a weasel was detected.
We observed a relatively strong pattern of birds digging late in wet seasons (February – April) of 2016 and 2017, but weaker trends for other species or groups (Fig. 5). Tree voles were detected on most nest platforms with some reduction in use during the dry season, but presence of juveniles was also highest during this season in 2016 and 2017 (Fig. 5). During most months flying squirrels were detected on most platforms with lower number of platforms with a detection during February of 2016 and 2018 (Fig. 5). Weasels were not detected at nest platforms until summer of 2016 and proportion of platforms with detections remained low until the wet season in late 2017 to early 2018, which was also a peak of birds digging detections (Fig. 5).