A monitoring protocol for the enigmatic Austral Rail Rallus antarcticus

Austral Rail (Rallus antarcticus), globally vulnerable, inhabits wetlands in Argentinean and Chilean Patagonia. It was rediscovered in 1998 and the state of its populations is poorly known, so it is necessary to generate monitoring protocols. The aim was to know the effect of broadcast two voices (duet and song) in two moments of the day (dawn and dusk) and the season (reproductive and post-reproductive) to the probability of detection and latency (time before first response), we conducted playback assays in Santa Cruz province, Argentina, between December 2015 and April 2016. We built Occupancy Models corrected by imperfect detection, n=30 detection histories, and Generalized Linear Models, n=55 survey points. There was no influence of time of day and season in both parameters. Song had a bigger probability of detection and latency (0.91 and 105 sec) than duet (0.62 and 44 sec) but statistically significant in the last case (p=0.59 and p<0.001, respectively). The lack of effect of time of day and season in both parameters represents a logistic advantage because is not necessary to restrict surveys to a specific moment. Instead of the longtime of responses, the song was more effective to detect individuals. Recording new voices and broadcasting it in more stages of it reproductive cycle will contribute to standardize this protocol to monitor mid-term changes in rail populations.