One of the chapters of my PhD has finally made it to the light of day after quite a few years in peer review hell. A lot of what we know about nocturnal behaviour in birds comes from studies of migratory species in seasonal ecosystems of Europe and North America. But what about in less predictable environments, where massive rainfall events drive a 'boom and bust' system where the distribution of resources are both temporally and spatially unpredictable?

We tracked Pacific black duck (Anas superciliosa) to investigate patterns of nocturnal flight in waterbirds of Australian desert ecosystems.Researchers have known for some time that waterfowl move nocturnally but it is most often seen as 'commuting' behaviour with birds moving between daytime roosts and nocturnal foraging areas. In this study we found that they get up to all kinds of nocturnal movement, throughout the night.

In fact, almost anything they did that was of interest happened under the cover of darkness. These particular birds fly huge distances across the arid interior of Australia to find temporary water bodies formed from highly variably rainfall. How they perform these feats of navigation and physiology remains a mystery. We tracked 20 ducks in this dynamic arid ecosystem and a further 18 of the same species in a mesic agricultural area. By studying their movement behaviour in two contrasting ecosystems, before and after heavy rainfall we revealed a key role for facultative nocturnal flight in the movement ecology of this species. After large rainfall events, birds rapidly increased nocturnal flight activity in the arid aseasonal ecosystem, but not in the mesic seasonal one.

Nocturnal flights occurred throughout the night in both ecosystems. Long range flights (>50 km in 2 hours) occurred almost exclusively at night; at night the distance flown was higher than during the day, birds visited more locations, and the locations were more widely dispersed. Click here to read the full paper.