Shortfalls in tracking data available to inform North American migratory bird conservation

Animal tracking has become an effective way to identify where and when migratory species encounter threats throughout their annual cycle. Yet, untracked or poorly tracked species and undiscoverable or inaccessible data for the species that have been tracked mean that gaps in the knowledge of where and when species occur are still an issue for conservation. These gaps in knowledge of species movements have been termed the movement shortfall. Here, we quantify the movement shortfall for North American migratory birds by comprehensively reviewing full annual cycle tracking data and identifying gaps and biases in how, where, and what species are tracked with electronic tracking devices. We found 30 species for which tracking is not feasible given body size constraints, no data for 291 trackable species, and restricted or reduced data accessibility for an additional 59 species. Thus, despite the ability to track most species, the movement shortfall remains a constraint to informing conservation strategies for 56 % of North American migratory bird species. The number increases to 65 % when considering species with restricted or reduced data accessibility, further limiting access to this information. Moreover, 23 % of the tracking data stems from low precision tracking technologies reducing the implementation and effectiveness to conservation actions. A lack of species and population data hinders conservation and biases management decisions, ultimately making inefficient use of conservation resources. We encourage researchers to consider these gaps in their decisions about future tracking efforts, conservation management, and data archiving practices.

Automated summary

Animal tracking is effective in identifying threats to migratory species, however, gaps in knowledge still exist due to untracked or poorly tracked species and inaccessible data. These gaps hinder conservation efforts and management decisions, making efficient use of resources challenging.