Avian responses to selective logging shaped by species traits and logging practices

Abstract

Selective logging is one of the most common forms of forest use in the tropics. Although the effects of selective logging on biodiversity have been widely studied, there is little agreement on the relationship between life-history traits and tolerance to logging. In this study, we assessed how species traits and logging practices combine to determine species responses to selective logging, based on over 4000 observations of the responses of nearly 1000 bird species to selective logging across the tropics. Our analysis shows that species traits, such as feeding group and body mass, and logging practices, such as time since logging and logging intensity, interact to influence a species' response to logging. Frugivores and insectivores were most adversely affected by logging and declined further with increasing logging intensity. Nectarivores and granivores responded positively to selective logging for the first two decades, after which their abundances decrease below pre-logging levels. Larger species of omnivores and granivores responded more positively to selective logging than smaller species from either feeding group, whereas this effect of body size was reversed for carnivores, herbivores, frugivores and insectivores. Most importantly, species most negatively impacted by selective logging had not recovered approximately 40 years after logging cessation. We conclude that selective timber harvest has the potential to cause large and long-lasting changes in avian biodiversity. However, our results suggest that the impacts can be mitigated to a certain extent through specific forest management strategies such as lengthening the rotation cycle and implementing reduced impact logging.

Keywords: bird conservation; forest degradation; forest management; phylogeny; reduced impact logging; tropical timber harvest.

Figure 1.

The effect of time since logging on the abundance of bird species in different feeding groups and body mass categories in selectively logged tropical forests. Values are shown for species that require trees for nesting, have narrow diet breadth, are not hunted, in a forest in Asia, which has been conventionally logged one time. The width of the bands, which represent the body mass categories, corresponds to the effect size of body mass in each feeding group (table 2). Namely, wider bands signify that there are bigger differences between the response of small and large species within the feeding group. Responses are shown only for realistic body mass values within each feeding group, corresponding to the minimum, maximum and median mass for each group in our database. This results, for example, in the absence of the two largest body weight categories in the nectarivores panel, as there were no nectarivores heavier than 165 g in our database. (Online version in colour.)