Effects of habitat conversion on the semi-deciduous forest bird community in Brazil

Background/Question/Methods

Colonization of Brazil by European explorers rapidly led to the near-complete conversion of highly diverse Atlantic forest habitats to pastureland and coffee.  Today, Brazil’s economy is one the fastest growing in the world and as a result new threats to secondary Atlantic forest are being realized.  Of note, many areas are being converted to short-rotation eucalyptus plantation to address demands for building materials, furniture, and charcoal for cooking.  Previous research has shown that reduction and fragmentation of Atlantic forests has led to local extinction of forest bird species.  In addition, lower avian species richness has been documented in eucalyptus stands relative to Atlantic forest fragments.  However the relationship between these habitat types and avian species richness as well as the role of landscape composition and configuration on richness has not been thoroughly investigated.

Results/Conclusions

In 2010-2011 we conducted avian point-count surveys in 50 randomly selected Atlantic forest fragments and 48 eucalyptus plantations in the Viçosa region, Minas Gerais State, Brazil.  We used a multinomial removal model with data augmentation to estimate site-specific abundance estimates for all forest-obligate species.  Detection-adjusted abundance estimates were then used to estimate species richness for each fragment.  We modeled species richness as a function of habitat type, patch size, and landscape composition using a negative binomial ANCOVA.  Patch and landscape metrics were calculated using FRAGSTATS.  All statistical models were analyzed using a Bayesian model of inference.  Preliminary results show species richness to be approximately 2.5 times greater in Atlantic forest fragments than in eucalyptus plantations.  In eucalyptus fragments, species richness was not related to patch area or patch complexity (perimeter:area ratio) indicating that eucalyptus plantations may provide suitable habitat for some bird species regardless of patch characteristics.  Conversely, our results indicate a clear species richness:area relationship for forest fragments with larger, less complex patches having more bird species. Our results support previous findings that the loss and fragmentation of Brazil’s Atlantic forest ecosystems and establishment of eucalyptus plantations may result in a simplified forest bird community.