SYDNEY – Promiscuity and love triangles are threatening the survival of a species of critically endangered Australian parrots, according to a study published on Wednesday.
Australian National University (ANU) research on the mating systems of the migratory swift parrot found that more than half of the nests had babies with more than one father.
“The overall number of babies born fell whenever the sex ratio became more male-dominated and shared paternity went up,” lead researcher Rob Heinsohn said in an ANU statement.
The parity between male and female populations of the parrot fell after the introduction of the sugar glider in Tasmania, the parrots’ breeding grounds, in the 19th century.
The lack of females forced the parrot species to engage in love triangles, which increased fighting between males and resulted in fewer babies.
The sugar glider, a small New Guinean marsupial, has contributed to the three males to one female ratio of the species by killing female parrots in their nests while they are incubating their eggs.
In Tasmania, half of the females die each year in their breeding grounds, according to this study published in the Journal of Animal Ecology.
“Although most population decline was directly attributable to sugar gliders killing nesting females, the impact of conflict and lower success from shared mating reduced the population by an additional five percent,” Heinsohn said.
The experts detected that in many cases females had sexual relations with males that harassed them by prowling their nests.
“We think the females are having sex with the other males for a range of reasons, but probably the main one is just to get them off their backs,” the biologist said.
Heinsohn said the imbalance causes females to be harassed by too many males, and males to fight for females to mate with.
“The overall population takes a hit, as a consequence, because they are having fewer babies,” he said.