Complex social challenges such as narco trafficking can have unexpected consequences for biodiversity conservation. Here we show how international counter-drug strategies may increase the risk of narco trafficking, which is associated with deforestation, in two-thirds of the important landscapes for forest birds in Central America. Soberingly, over half of Nearctic-Neotropical migratory species had more than one quarter, and 20% of species had over half, of their global population in areas threatened by narco trafficking, suggesting the need for more holistic strategies to better protect native biodiversity.