The removal, alteration and fragmentation of habitat are key threats to the biodiversity of terrestrial ecosystems. Investment to protect biodiversity assets (e.g. restoration of native vegetation) in dominantly agricultural landscapes usually results in a loss of agricultural production. This can be a significant cost that is often overlooked or poorly addressed in analyses to prioritise such investments. Accounting for this trade-off is important for more successful, realistically feasible and cost-effective biodiversity conservation. We developed a spatially explicit bio-economic optimisation model that simulates the effect of conservation effort on the diversity of woodland-dependent birds in the Avoca catchment (330 thousand ha) in North-Central Victoria. The model minimises opportunity cost of agricultural production and cost of biodiversity conservation effort on a catchment level subject to achieving different levels of biodiversity outcome. We identify the locations and spatial arrangement of conservation efforts that offers the best value for money.