Résumé
Political borders dictate how biological diversity is monitored and managed, yet wild animals often move freely between jurisdictions. We quantified bias in brown bear (Ursus arctos) abundance estimates introduced when analytical methods ignore that the same individuals may be accounted for in more than one jurisdiction. A spatially explicit population model revealed that up to 49% of female bears detected in Norway via microsatellite analysis of scat and hair samples have their center of activity in neighboring countries (Finland, Russia, and Sweden). Not accounting for detections of "foreign residents" resulted in abundance estimates that were inflated by as much as 119%. Like management and conservation, monitoring of transboundary wildlife populations should take place at ecologically relevant scales to avoid biased abundance estimates and a false sense of control. When political realities isolate jurisdictions from their neighbors, spatially explicit analytical approaches can allow local or national programs a glimpse beyond their borders.