Lazy bustards live longer

Migration in great bustards seems to be on the decline because many of those that do migrate die in collisions with power lines.

Carlos Palacín at the National Museum of Natural Sciences in Madrid and his colleagues captured and radio-tagged 180 male great bustards (Otis tarda) across 29 breeding groups, covering most of the species' range in Iberia. Only some birds migrated north in summer. Of those that did, 21.3% died in crashes with power lines, whereas just 6.3% in the sedentary group died in this way.

The authors found a steady increase in the proportion of non-migratory males over the study period, from 17% in 1997 to 45% in 2012. They propose that males decide whether to migrate by observing other males. Thus, as the number of migrators declines, the behaviour may die out.

Conserv. Biol. http://doi.org/bp53 (2016)