The influence of native versus exotic streetscape vegetation on the spatial distribution of birds in suburbs and reserves

Aim: Management practices in the landscape matrix can have significant effects on the spatial distribution of animals within adjacent protected areas. This has been well established in agricultural and forested areas, but less is known about how management of the suburban matrix affects adjacent reserves. We argue that it is critically important to understand the impact of suburban management on reserves, as flawed planning decisions can have negative conservation outcomes and waste limited resources. Location: Canberra, Australian Capital Territory, Australia. Methods: We examined bird distribution patterns in suburbs and adjacent reserves to the effects of two suburban management practices: (1) street tree planting and (2) boundary design. We focused on three groups of birds with known responses to urbanization: native urban-intolerant species (native avoiders), native urban-tolerant species (native adapters) and exotic urban-tolerant species (exotic adapters). Results: We found that suburbs with ≥30% native (Eucalyptus) street trees and reserves adjacent to these suburbs had significantly higher bird species richness, native adapter species richness and probability of reporting exotic adapters than those with exotic trees. The type of street trees, however, did not affect the probability of reporting native avoiders. These species were more likely to be reported when habitat complexity was high. Only native adapters responded to boundary design, with higher species richness when the boundary type was a local or unsealed road as opposed to an arterial road. Main conclusions: Native street trees provide foraging resources for birds that would be reduced or absent in exotic streetscapes, enabling native streetscapes to support a rich community of birds. Furthermore, native streetscapes increase bird richness and diversity in adjacent reserves. This result has important conservation implications for suburb and reserve management practices. Our study provides evidence that the establishment and retention of native suburban streetscapes is an important management strategy for improved bird conservation.