Richard Collins: Does the quality of parents' relationship affect their offspring's fortunes?
Although the female goose makes the nest without her partner’s help, and incubates the eggs on her own for up to 30 days, the gander remains ‘on call’.
— Philip Larkin.
Youngsters whose parents get along well together tend to ‘do better’ in life. Could this be true also of some wild creatures?
In a paper just published, researchers from the Universities of Vienna and Flinders try to answer this difficult question. They studied the ‘personalities’ of ‘habituated’ greylag geese over a three-year period, relating them to clutch-sizes, hatching-rates, and the numbers of goslings fledged. There were between 92 and 144 adult birds in the study group. Although they were offered growth pellets and grain, the geese could still forage for their own food and "were fully exposed to predation pressures".
Each individual goose has its own quirks and foibles, akin to what are called ‘personality traits' in humans. Greylags are famously monogamous, although bigamy and ‘threesomes’ have been recorded occasionally. Pairs remain intact outside the breeding season and most partners stay together until death does them part.
Although the female goose makes the nest without her partner’s help, and incubates the eggs on her own for up to 30 days, the gander remains ‘on call’. Having a mate helps her cope with the trials of life.
Geese make excellent watchdogs, as those Celtic invaders discovered when they attempted a stealth attack on Rome in the 4th Century BC. Both sexes defend the territory. The male will hiss at, and attack, an intruder. One used to terrify me on visits to my grandfather’s farm as a child. Gulls crows rats, even foxes, are quickly ‘seen off’.
Remaining close to his partner when away from the nest, the gander helps her forage in peace. Both parents chaperone and defend the goslings. Juveniles return to the nest to roost. They stay with their parents throughout autumn and winter. But, does the quality of the parents’ relationship affect the youngsters’ fortunes in life?
The Vienna-Flinders team identified three important behavioural traits among the study geese:
- activity
- boldness
- aggressiveness
A bird’s ‘activity’ level can be determined by observation.
The distance at which an individual took flight when approached by a person under standardised conditions, indicated its ‘boldness’.
To gauge ‘aggressiveness’, wooden boards and food-trays were offered to birds over a three-day period. Just before feeding time on the fourth day, mirrors were attached to the boards. A goose approaching the food would encounter its own reflection and think that it was a rival’s. Willingness to approach the tray, and spend time there, was deemed to indicate ‘aggressiveness’.
‘Boldness’ turned out to be a key parameter. But, for optimal breeding performance, both partners had to be equally bold.
"Pairs in which the partners were similar in average boldness had higher hatching rates," the researchers say. But they also report that "this trend was not found for clutch size or fledging success".
So, it seems that having ‘normal’ harmonious parents is a blessing, even if you’re a goose!
