Zebra Finches
Zebra finches choose mates on the basis of compatibilitycreative commons

New research has found that, much like humans, birds fall in love too. Many species of birds are noted for their choice of one mate for life – mirroring the aim, at least, of humans.

A team from the Max Planck Institute for Ornithology, Germany, conducted an experiment that looked at the mating behaviour of zebra finches and found that they "choose mates on the basis of behavioural compatibility" and are unhappy in "forced" relationships.

To see this, the research team placed 20 males and 20 females in an area and let them choose freely which they could mate with. Half of the couples were allowed to continue but the scientists intervened with the remaining 50% and switched their mating partner.

The birds were then allowed to breed and the team, led by Malika Ihle, found that the pairs which had chosen their partner freely "achieved a 37% higher reproductive success than pairs that were forced to mate," the authors of the report wrote in PLOS Biology. Additionally, the nests of the "forced" partners had three times the amount of unfertilised eggs in them and more chicks died after birth.

"Most deaths occurred within the chicks' first 48 hours, a critical period for parental care during which non-chosen fathers were markedly less diligent in their nest-care duties," they write.

Another thing that the team noted was the couples' interaction with each other. Although they found that the males typically showed the same amount of attention to their mates whether they chose freely or were paired, they found that the females were much less receptive to the males' advances if they had been placed with a mate and had sex less often. "There was also a higher level of infidelity in birds from non-chosen pairs – interestingly the straying of male birds increased as time went by while females roamed less," they continued.