Effect of forest fragmentation on birds

Canopy height and isolation
Vegetation characteristics
Variable response

The impacts of fragmentation on bird populations are very complex and often species specific. The general consensus is that fragmentation of the landscape into isolated patches can adversely affect some bird species. However, structural and floristic changes to the patch are often more important than patch size and isolation for bird communities (Lynch and Whigham, 1984).

White-tailed cockatoos 27kb

Canopy height and isolation

Robbins (1980) statistically analysed the relative contributions that vegetation factors, isolation and area of patch, had on bird community composition. He found that canopy height and forest isolation were consistently the most important predictors of abundance for the 51 bird species he analysed. These factors accounted for 21 significant correlations whereas patch area accounted for 6 significant correlations.

Vegetation characteristics

Lynch and Whigham (1984) showed that within a range of patch areas (5-1000 ha) and isolations (0.1-1km), it was vegetation characteristics rather than patch geometry that had a dominant role in determining the community composition and local abundance of bird species. This means that species distribution is related to a complex interrelationship between area, isolation, canopy height, tree density and other habitat characteristics rather than one specific patch characteristic.

Variable response

Some species seem to be tolerant of a certain degree of habitat disturbance. They can make use of the edge habitat that can be introduced because of fragmentation quite well. Others, eg highly migratory species, tend to respond negatively to habitat fragmentation and a reduction in floristic and structural diversity of breeding habitat.