Bat colony size reduction coincides with clear-fell harvest operations and high rates of roost loss in plantation forest

Abstract

Clear-fell harvest of forest concerns many wildlife biologists because of loss of vital resources such as roosts or nests, and effects on population viability. However, actual impact has not been quantified. Using New Zealand long-tailed bats (Chalinolobus tuberculatus) as a model species we investigated impacts of clear-fell logging on bats in plantation forest. C. tuberculatus roost within the oldest stands in plantation forest so it was likely roost availability would decrease as harvest operations occurred. We predicted that post-harvest: (1) roosting range sizes would be smaller, (2) fewer roosts would be used, and (3) colony size would be smaller. We captured and radiotracked C. tuberculatus to dayroosts in Kinleith Forest, an exotic plantation forest, over three southern hemisphere summers (Season ). Individual roosting ranges (100% MCPs) post harvest were smaller than those in areas that had not been harvested, and declined in area during the 3 years. Following harvest, bats used fewer roosts than those in areas that had not been harvested. Over 3 years 20.7% of known roosts were lost: 14.5% due to forestry operations and 6.2% due to natural tree fall. Median colony size was 4.0 bats (IQR = 2.0-8.0) and declined during the study, probably because of locally high levels of roost loss. Post harvest colonies were smaller than colonies in areas that had not been harvested. Together, these results suggest the impact of clear-fell harvest on long-tailed bat populations is negative.

Insectivorous Bats and Silviculture: Balancing Timber Production and Bat Conservation

“…There is a surprising lack of European studies on the effects of any logging strategy on bats and the only study found for this review which directly related Borkin et al 2011).…”

“…Males selected edges with open unplanted areas within their home ranges, which females avoided, instead selecting older stands for foraging. Borkin et al (2011) also documented the response to the clear-fell harvest of a pine plantation and found a pattern of declining numbers of roosts used, as well as smaller roosting areas and colony sizes. Over 3 years, 21 % of known roosts were lost with 15 % due to forestry operations and 6 % due to natural tree fall.…”

“…To mitigate harvest operations, it was suggested that some suitable foraging and roosting areas should be retained within bat home ranges. Borkin et al (2011) further suggested that priority management for this declining New Zealand bat should focus on plantation areas closest to water and harvests should be planned when bats are not heavily pregnant nor have non-volant dependents.…”

Impacts of wind energy developments on wildlife: a southern hemisphere perspective

“…Current theories include bats being attracted to the turbines (due to the turbines, or their locations on ridge-tops, attracting insects or because of the ultrasound they produce), their placement along the migratory pathways of bats or because bats may perceive towers as potential roost trees (Kunz et al 2007a). When combined with other negative anthropogenic effects on bats, such as habitat modification or clearance and disease, losses caused by wind turbines could negatively impact long-term population trends (Blehert et al 2009;Borkin et al 2011).…”

Effects of Clear-Fell Harvest on Bat Home Range

“…Within plantation forest long-tailed bats select home ranges that have higher proportions of near-harvest age stands and within these home ranges choose roosts in stands closest to harvest age [12], [13]. Colonies of C. tuberculatus roosting in mature Pinus radiata adjacent to recently clear-felled areas have significantly fewer bats than those where harvest has not recently occurred [5]. It is suspected that this is due to bats either being killed during harvest operations or moving to other roosting areas.…”