Bar-tailed godwits are champion commuters. Each year they fly some 18,000 km from their wintering grounds in New Zealand to Alaska to breed.
All the godwits leave on migration during the same 30-day period each year. More remarkably, individual birds leave during the same week or even on the same day, year after year.
But birds setting out on epic migrations don’t rely on watches or calendars. They must schedule their epic migrations to ensure that they arrive on the breeding grounds in time to find a mate and raise their chicks. So how do they know when to leave?
Many birds and other animals respond to changes in day length (photoperiod), but we don’t know how particular responses to photoperiod drive individual behavioural differences, such as departure dates.
Dr Phil Battley from Massey University and Dr Andrew Fidler from the Cawthron Institute have been awarded $920,000 over 3 years by the Marsden Fund to explore the genetic basis of individual photoperiodic responses that may drive this finely-tuned departure timing.
By combining behavioural data from individual bar-tailed godwits with genetic testing, Dr Battley and Dr Fidler’s team will test for connections between DNA-level and individual variation in migratory departure dates.
This project will provide insights into the potential for evolutionary change in bird migration schedules. It also has important implications for understanding the limits of species’ potential to adapt to climate change.