Severe declines of understory birds follow illegal logging in Upper Guinea forests of Ghana, West Africa

• Between 1995 and 2010, legal and illegal logging intensities increased >600%.
• Estimated forest understory bird species abundance declined >50%.
• Understory bird species richness declined significantly.
• Understory bird communities showed no evidence of post-logging recovery.
• Illegal logging following legal logging operations likely prohibits forest recovery.

We investigated how legal logging history and recent illegal logging affected forest bird community structure in Ghana. Ghanaian forests belong to West Africa’s highly fragmented Upper Guinea rain forests, part of a global priority “biodiversity hotspot” under intense pressure from anthropogenic degradation. Between 1995 and 2010, officially-reported legal logging intensities increased up to ∼600%, while illegal logging, which now accounts for 80% of timber extraction in Ghana, has driven logging intensities to ∼6 times greater than the maximum sustainable rate. We collected data in 2008–2010 and used a comparable dataset collected in 1993–1995 to assess impacts of recent logging on understory bird communities in large forest fragments (100–524 km2) in southwest Ghana. Forest understory bird species abundance declined by >50% during this period. Species richness also showed declining trends. Whereas analysis based on data collected in 1993–1995 estimated a partial post-logging recovery of the understory bird community at that time, data from 2008–2010 showed no indication of post-logging recovery, likely due to ongoing illegal logging following intensive legal logging operations. Forest generalist species and sallying insectivores declined significantly in logged compared to unlogged forests. These severe declines of Upper Guinea forest understory birds indicate the rapidly deteriorating conservation status of a biodiversity hotspot and could signal collapsing ecosystem processes. Immediate conservation actions are urgently required to protect surviving forest fragments from further degradation and avian declines.