Wellington, Nov 24 : Defying previous beliefs about Australasian gannets, researchers at Auckland University have said that these seabirds are not monogamous, but have a significant "divorce" rate.

Research leader Steffi Ismar said that the divorce rate from one breeding season to the next was about 40 per cent.

The research team studied banded Australasian gannets at Cape Kidnappers during consecutive breeding seasons in 2007-2008 and 2008-2009.

The study showed gannets that divorced and found a new mate were less likely to successfully raise a chick in their first breeding season, compared to those who kept the previous year's partner.

They attributed this to the species requiring teamwork to raise their young, and having to gain experience of co-operating with a new partner, reports the New Zealand Herald.

The high rate of re-partnering suggested that gannets had to choose between waiting too long for their former partner to arrive and missing out on breeding altogether, or making the best of a suboptimal breeding opportunity.

Data from the upcoming breeding season and further analyses would give further insight into why pairs separated, whether the same individuals repeatedly divorced, and whether new pairs had greater breeding success in their second year.

The results were published in the European journal Naturwissenschaften.