Why African Birds Can Be Slow to Fly the Nest
It isn’t only human twenty-somethings which can be slow to leave the family home. New research has shown that some birds are equally tardy in seeking an independent life. Like young people who prefer to maintain their comfortable lifestyle at their parent’s home, the birds stick around longer than they really need to.
With young people, it is often their finances which prevent them from flying the nest. Well, that and an easy life together with the unappetising prospect of a flat share with strangers! But the birds are slow to leave for different reasons.
Canadian Study of Wild Southern Pied Babblers
A study conducted by the University of British Columbia (UBC) looked at wild southern pied babblers which are native to the Kalahari Dessert. The birds were often observed sticking around the nest until they were assured of better prospects by moving on.
Researchers have found that male babblers often leave when there’s more rain. This is probably because there is more food available in the environment. The birds also tend to leave when there are a greater number of breeding vacancies for males and when the distance between groups is smaller.
Eleven Years of Data
The family dynamics between brothers and stepfathers also appears to play a crucial role in determining when young birds choose to disperse. Eleven years worth of data was analysed to establish how the dispersal of both male and female birds was influenced by their position in the avian hierarchy, the prevailing weather conditions and the potential benefits of remaining in their group.
The researchers found that the behaviour of males was different to that of females. Female babblers were found to be more independent generally but they tended to remain at home when there was a larger and therefore safer group established there. Males only flew the nest when they had a better chance of leading their own group in another location.
A male’s position in the hierarchy was key to their decision to leave. Brothers essentially queue for an opportunity to become leader of their group or a neighbouring group. If they leave their existing group early, younger siblings can improve their prospects of leadership. Males with stepfathers also tend to leave earlier and this is probably because the older birds prioritise their own offspring.
In contrast, the female babblers are lower in the pecking order and so do not leave as early and choose to bide their time, waiting for the best opportunities to overthrow dominant females in other groups. Female birds can achieve dominance by using extreme aggression. Subordinate females will go to another group accompanied by a dominant female and attack a bird until she leaves.
The complex social interactions of birds never cease to amaze!