Movements of birds among natural vegetation patches in the Pantanal, Brazil

The ability of birds to move through the landscape is a key parameter for ecological and conservation studies. We studied bird movements among natural vegetation patches surrounded by native grassland and tested the effect of inter-patch distance on bird movements/hour and assessed the distances travelled for species of different body mass. We made observations of 1,138 bird movements among 11 forest patches and banded 368 birds obtaining 69 recaptures (42 recaptures in the same patch where the birds were banded and 27 recaptures in other patches). We used seven patches as observation points and capture sites in the Pantanal wetland, Brazil during one year. Movements/hour decreased significantly with inter-patch distance. Median or maximum distance travelled increased significantly with body mass. Small-bodied Passeriformes, however, did not increase the distance travelled with body mass, since they seldom moved more than 286 m. The majority of forest dependent or semi-dependent birds seem able to adapt to natural fragmented landscapes. However, small forest patches may be inappropriate habitat for many large-bodied species, and it is more difficult for small-bodied species to use more isolated forest patches. Thus, size and spatial arrangement of habitat patches may act as a filter in which large and close fragments seem to protect the highest number of bird species. The findings of this study indicate that stepping stones provide a viable alternative to continuous biological corridors if the latter are not available. However, the type of species in an area and the size and distance between vegetation patches are all critical factors that must be considered in projects that aim to use forest patches as stepping stones to increase or maintain local bird biodiversity.