PARENT SESSION
Oral Session 2: Avian Ecology I: Habitat and Disturbance.
Presiding: D Miles and C Lepczyk
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room A 106.

Equally rich, equally valuable? -diversity indices fail to reflect effects of habitat modification in the Andes.

O'Dea, Niall^*,1, Whittaker, Robert¹, ¹ University of Oxford, Oxford, UK

ABSTRACT- Although Andean forest habitats are being modified and destroyed at a rate thirty percent higher than their lowland counterparts, the effects of such large-scale habitat modification on hyper-diverse Andean avifaunas are poorly understood. This study assessed the effects of habitat modification on a lower montane forest avifauna in Ecuador by comparing avian community composition in habitats subjected to different levels of human modification: primary forest, secondary forest, and active agricultural lands. In total, 200 bird species, in 5222 individual records, were encountered during point count surveys, including 24 endemic species and six at-risk species. Multivariate gradient analysis revealed marked differences in avian community composition on a gradient from agricultural land to closed forest habitats. Notably, understorey and frugivorous birds exhibited a strong affinity for forest habitats, while high-priority endemic and at-risk species exhibited an affinity for mature forest specifically. Diversity indices, by contrast, showed either no significant difference or inconsistency among index values for richness and equitability between habitat types. Human habitat modification did not reduce the -diversity of bird communities in lower montane landscapes in the Andes, and by some diversity measures even increased it. However, modified landscapes harboured substantially fewer species of certain guilds and fewer at-risk and endemic species. We argue that an emphasis on individual species and guild identity, even in rapid assessment surveys, is critical to ensure that the value of different habitats for birds and other organisms is accurately assessed. We discuss the implications of these findings for land-use and conservation planning in the Andes.

Key words: habitat modification, subtropical Andes, -diversity, birds