View article

Ecologists have long recognised that populations can persist in poor-quality habitats with below-replacement population growth rates (‘sinks’) provided there is continual immigration from areas with positive intrinsic growth (‘sources’). Source-sink dynamics complicate the assessment of species-environment relationships, because species’ presence or density can be poorly correlated with underlying population productivity. Yet, applied conservation research often uses presence or abundance data to assess species responses to environmental change, particularly in the tropics where few long-term ecological studies are established. This approach assumes that abundance data reliably indicate habitat quality, but in sinks, this assumption can be violated. We review the recent literature and identify a regional bias in reporting of source-sink phenomena, with 71% of the 210 studies considered coming from …