Mixed effects

A recent paper by Jason M. Gleditsch and Tomás A. Carlo explores the impact on nesting success of Gray Catbirds (Dumetella carolinensis) breeding in Pennsylvania landscapes dominated by invasive Asian honeysuckles (Lonicera sp.). It turns out that they found little evidence to support the claim that honeysuckle represents an “ecological trap” of increased predation risk and poor nutritive value from fruits, contrary to the results of other researchers. Adult birds may have made more trips to the nest, bearing what some have called “junk food,” but body mass measurements of the nestlings, in this study, show that they grow up just fine.

Our results show that relationships between introduced fleshy-fruited plants and native birds are complex and not easily characterized as purely harmful or beneficial because they can include negative, neutral, or positive outcomes.

Sometimes, in the authors’ view, using an alien species is the best the birds can do, under the circumstances.

… the traditional and widespread categorical approach to invasive species management should be revised to prevent harming certain communities and ecosystems, especially areas in a process of self-recovery from heavy human disturbances.