Specialized insectivores drive differences in avian community composition between primary and secondary forest in Central Africa

Eleanor Mairi Barrie^1,2*Billi A Krochuk^2,3Crinan Jarrett^1,2,4Diogo F. Ferreira^2,5,6Patricia Rodrigues^2,7Susana Lin Mufumu^2,8Silvestre Esteban Malanza^2,8Agustin Ebana Nsue Akele^2,9Cayetano Ebana Ebana Alene^2,9Kristin E Brzeski^10,2Jacob C Cooper^11,2Jared D Wolfe^10,2Luke L Powell^1,2,5,6

• ¹College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
• ²Biodiversity Initiative, Houghton, MI, United States
• ³Biodiversity Research Institute, Portland, ME, United States
• ⁴Department of Bird Migration, Swiss Ornithological Institute, Sempach, Switzerland
• ⁵Centro de Investigacao em Biodiversidade e Recursos Geneticos (CIBIO-InBIO), Vairão, Porto, Portugal
• ⁶BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, University of Porto, Vairão, Portugal
• ⁷Department of Renewable Natural Resources, Louisiana State University, Baton Rouge, Louisiana, United States
• ⁸National University of Equatorial Guinea, Malabo, Equatorial Guinea
• ⁹National Institute for Forestry Development and Protected Area Management (INDEFOR-AP), Bata, Equatorial Guinea
• ¹⁰College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan, United States
• ¹¹Department of Biology, University of Nebraska at Kearney, Kearney, Nebraska, United States

The human population of sub-Saharan Africa is projected to triple by 2100, drastically increasing anthropogenic pressure on biodiversity. When rainforest is disturbed by anthropogenic drivers, species respond heterogeneously; these patterns have rarely been quantified for Congo rainforest fauna. At a long-term bird banding station on mainland Equatorial Guinea, we captured over 3200 birds across 6 field seasons in selectively logged secondary forest and in largely undisturbed primary forest. Our objective was to understand how community composition changed with human disturbance-with particular interest in the guilds and species that indicate primary rainforest. Our multivariate ordination indicated a significant split between primary and secondary forest communities. We caught 47% fewer birds in secondary forest overall, with Dorylus ant-followers, mixed-species flocking species and terrestrial insectivores showing at least two-fold reductions. We identified 12 species that were characteristic of primary forest. Of those, 10 were strict insectivores: terrestrial insectivores (Sheppardia cyornithopsis, Illadopsis cleaveri, I. fulvescens/rufipennis), mixed-flockers (Phyllastrephus icterinus/xavieri, Elminia nigromitrata, Terpsiphone rufiventer, Pardipicus nivosus, Deleornis fraseri), ant-followers (Alethe castanea, Chamaetylas poliocephala), White-bellied Kingfisher (Corythornis leucogaster), and Blue-headed Wood Dove (Turtur brehmeri). Only the kingfisher Ispidina lecontei was captured more in secondary forest. This contributes to a growing body of Pantropical literature suggesting that insectivores living on or near the forest floor are vulnerable to rainforest degradation. Notably, few species disappeared entirely in secondary forest (unlike patterns seen in the Neotropics); rather, capture rates of 12 of 30 species (40%) were significantly reduced relative to primary forest. By understanding disturbance-sensitive guilds and species, we might identify the proximate mechanisms responsible for the loss of Afrotropical birds, thus helping to manage communities as forest disturbance continues.