Seasonal use of urban forest vegetation by bush birds

In highly modified landscapes such as urban areas, the ability of native birds to alter foraging behaviour in accordance with environmental and anthropogenic change will play a fundamental role in their survival; however not much is known about behavioural flexibility in foraging by native birds. This study aimed to assess the use of vegetation by native and exotic birds over four seasons in Dunedin, New Zealand. Bird counts were carried out at 71 locations throughout a chain of urban forest fragments consisting of mixed native/exotic vegetation. Actual behaviours exhibited by different bird species were documented in six common native and exotic tree species. In spring there were strong indications for native bird preference of mostly native vegetation and exotic bird preference for mostly exotic vegetation, however this was no longer the case in summer and autumn, when native birds increased their use of exotic vegetation, and exotic birds were found across all vegetation types. In winter neither native nor exotic birds exhibited significant vegetative preferences. Behavioural recordings found that native tree fuchsia (Fuchsia excorticata) provides important resources for native birds in spring and summer, native kanuka (Kunzea ericoides) and exotic oak (Quercus robur) trees may provide useful resources to insectivores year-round. Common bird species were analysed individually and considerable variation in vegetative preferences was found. The concept that native birds want or need native vegetation is not “cut and dried”; multiple factors simultaneously predispose individual species towards success or strife in urbanised habitats and even physically similar or closely related species can respond in unique ways. Season also alters bird feeding behaviour and studies should include all four seasons to avoid seasonal biases. Exotic vegetation can be useful to native birds that are behaviourally adaptable and opportunistic and should be considered for urban plantings. Management incentives in cities need to consider the varying needs and preferences of native birds as a group and those of all species individually, with a focus on enhancing habitat for struggling species as well as avian biodiversity as a whole