Many pairs of bird parents were childhood sweethearts. The majority of whooping crane couples begin making friends at least a year before they first breed together.
Most birds form monogamous couples, and bonded pairs often stick together for life. Little is known about how they form these long-term partnerships, but we know that some birds are already paired up when they arrive at breeding grounds.
at the University of Georgia in Athens and colleagues tracked a population of that were reintroduced in the eastern United States from 2001. Every bird is fitted with a transmitter, and they are closely monitored during the breeding season in Wisconsin.
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Before mating in the spring, cranes perform courtship displays involving loud calls, leaping and flapping their wings. But the data reveal that they choose their partners much earlier.
Out of 58 breeding pairs, 62 per cent started associating at least 12 months before breeding, and 26 per cent began associating over two years before breeding. Sixty per cent of pairs got together before at least one of them was sexually mature.
鈥淚t is tempting to view these pre-breeding associations, often between sexually immature individuals, as testing each other and ways of learning about their potential future mates,鈥� says at the University of Bath, UK.
Young love
The findings may help explain why birds go in for long-term monogamy.
Some explanations focus on the cost of divorce: if birds that break up have a hard time finding a mate in the next breeding season, there鈥檚 a strong advantage to sticking together.
But there are also direct benefits to being in a couple. In some species, there is evidence that pairs that have been together for longer are more successful at breeding, perhaps because they are better at coordinating behaviours like foraging.
鈥淥ur study shows that if you鈥檙e associating for such a long time without breeding, there are probably benefits outside of just breeding success,鈥� says Teitelbaum. For example, being in a pair might boost the birds鈥� social status, helping them to acquire and maintain good territories. They might also be able to protect each other from predators.
Ecologists often imagine pair bonding as a quick decision, similar to how we use dating apps, says Sz茅kely. But that might not be true for animals 鈥渋n which substantial parental investment is at stake, for instance months of hard work incubating and rearing the young.鈥� Such animals 鈥渕ay use more sophisticated rules than 鈥榮wipe left and reject a potential mate鈥�, or 鈥榮wipe right and have a one-night stand鈥�.鈥�
Animal Behaviour
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