Autumn staging behaviour in Pink-footed Geese; a similar contribution among sexes in parental care

Abstract

Geese are social birds and form pairs that can last a lifetime, being together throughout the year. Forming pairs and maintaining family groups increase the individual’s social status, giving it easier access to resources and more time to exploit them. Hence, social behaviour is favourable when pairs are building up body reserves before migrating to the breeding grounds as well as after breeding, helping the geese to easier replenish depleted reserves. Parents spend much time on vigilant behaviour, an activity that is costly, as it will reduce the time available for foraging. In geese, vigilant behaviour is more frequent for males than for females. Female geese have an extra high cost during the breeding period, resulting in an urgent need to replenish body reserves after the eggs are hatched. The male takes on the responsibility of vigilant behaviour during brood rearing, giving the female time to replenish her reserves. We studied the behaviour of Pink-footed geese in Mid-Norway on their way from the breeding grounds in Svalbard in the autumn, 2015, in order to evaluate whether this behaviour between sexes has changed after the breeding period in Svalbard. We hypothesized that the processes at the autumn stopover site are different compared to processes in the breeding grounds. We also evaluated the gain in body condition for parents as well as for the juveniles and for geese without young. We predict that the females contribute more to the guarding of young due to a more relaxed pressure on body mass accumulation in the autumn season. Juveniles were expected to increase in body condition over the staging period, and if males were rebuilding the reserves we also predicted that their body condition would increase. We expected to find a clear difference between non-breeding pairs and parents with young, as parents need to spend more time on vigilance behaviour at the expense of the time spent on feeding. Pairs with young expressed by their behaviour a clear cost of having young, as they spent less time on feeding and more time being alert compared to the corresponding behaviour of pairs without young. Since no significant difference in behaviour between males and females were found, our hypothesis that there are different selective processes at an autumn stopover site compared to the processes at the breeding season is supported.