As many bird lovers know, a lone finch is a lonely finch. But the intrinsic drive to form a pair bond with another finch, either as an opposite-sex pair bond or same-sex pair bond, may override other instinctive behaviors, such as finding a mate that they can reproduce with. This was found in a study conducted by Julie Elie of U.C. Berkeley, along with her colleagues Clementine Vignal and Nicolas Mathevon from the University of Saint-Etienne in France.
The researchers studied five groups of zebra finches; three groups were mixed sexes, and two groups consisted of only males or only females. The researchers found that the birds paired up into same-sex couples performed all the behaviors exhibited by opposite-sex pairs, such as allopreening and, for the males, singing to each other. When potential opposite-sex mates were introduced, very few of the same-sex zebra finch pairs left their mates for a partner they could reproduce with.
"When there are no opposite-sex partners available, the pressure is still there to establish a pair bond,” Elie said. "The birds will establish a same-sex pair bond rather than be alone. This pressure pushes them to find a partner, no matter what the sex.” Elie and the other researchers concluded that there was more to a pair bond than just the ability to reproduce. For more information about the study, go to her website.