Melbourne, Nov 24 Healthy female wallabies are more likely to give birth to boys than daughters, a new study has found.

The latest evidence supports Trivers-Willard hypothesis that mothers will give birth to different sexes depending on their condition.

The researchers believe that female wallabies in better condition are likely to have boys, because strong males will have more mating success, while females are a safe option if the mother can't ensure her baby will be well fed.

"In wallaby populations, females will always be mated with regardless of how strong and healthy they are," ABC Science quoted lead researcher Dr Kylie Robert of the University of Western Australia as saying.

"Weak males, on the other hand, are unlikely to have much reproductive success as they will be outcompeted by stronger males," Roberts added.

During the study, researchers swapped joeys for offspring of the other sex.

They found that mothers who had originally birthed sons successfully raised more offspring to weaning, regardless of sex, than mothers who originally had daughters.

"If we can learn the physiological signals that tell a mother whether they should have a boy or a girl then we could reproduce them and optimise the sex ratio for successful breeding programs," she said.

The finding is significant for breeding programs that aim to restore populations of endangered kangaroos and wallabies. (ANI)