Prioritize diversity or declining species? Trade-offs and synergies in spatial planning for the conservation of migratory birds in the face of land cover change

Stemming biodiversity loss requires strategic conservation guided by well articulated targets, whether they be proactive (e.g., protect biodiverse areas) or reactive (e.g., protect threatened species). Both types of targets can be effective, but there are trade-offs, especially for broadly distributed taxa such as migratory species, a group for which conservation has been challenged by limited knowledge of distributions throughout the annual cycle. We combined spatiotemporal distribution models with population trend data to first examine focal areas for the conservation of Neotropical migratory birds (n = 112 species) during the non-breeding period in the Western Hemisphere, based on a proactive approach (highest diversity) versus a reactive approach (strongest declines). For focal areas, we then assessed the extent of recent anthropogenic impact, protected area status, and projected changes in land cover using shared socioeconomic pathways. Spatial priorities for high diversity emphasized southern Mexico and northern Central America, and were strikingly different from areas with species in stronger decline, emphasizing the Andean cordilleras. Only 1.4% of the non-breeding region met targets for diversity and decline, mostly in southern Central America. Areas prioritized to conserve high species diversity have experienced less recent anthropogenic impact than areas prioritized for species in decline but are predicted to experience more rapid land conversion to less suitable agricultural landscapes in the next three decades. Our findings indicate how efficient conservation efforts will depend on the careful consideration of desired targets combined with reliable predictions about the locations and types of land cover change under alternative socioeconomic futures.