Wildlife fans were able to see for the first time how a male cahow reacted to his mate laying an egg when the birds returned to Nonsuch Island.The rare event came after the male arrived back at the burrow days before his partner — a reversal of the birds’ normal behaviour.Jean-Pierre Rouja, the Nonsuch Expeditions team leader and CahowCam developer, said: “Traditionally, after spending December apart out at sea foraging, the females arrive first, laying their single egg within hours of their return with the male then arriving one to three days later to take over incubation.“However, in this case the male had arrived three days prior and was awaiting her return.”He said the circumstances gave scientists, including the Cornell Lab of Ornithology team and Jeremy Madeiros, a senior terrestrial conservation officer at the Department of the Environment and Natural Resources, and CahowCam followers around the world “the rare opportunity to observe for the first time ever, how a male cahow would react to the normally solitary egg-laying process”.CahowCam 1 has been live-streaming from burrow 831 on Nonsuch Island for the past eight years.Mr Rouja added: “After preening each other and redistributing the nest materials for the first hour, the female settled in to lay her single egg around 3.12am whilst being attentively observed by her mate and by 3.14am it had been laid.”He explained: “When the first bird to arrive in the CahowCam nest did not promptly lay an egg as expected, a quick outing to Nonsuch was organised to confirm that it was in fact the male.”Mr Rouja said both cahows were in the nest at the weekend and that “it will be interesting to see if the female departs immediately or spends a day or two sharing the egg with her mate before leaving him to take on the first incubation shift, which is usually around two weeks”.The birds can be seen live at www.nonsuchisland.com.The nest monitored by CahowCam 2 remained empty at the end of last week.It is usually occupied about a week later than the burrow monitored by CahowCam 1.Mr Rouja said: “Incubation is on average 53-55 days after which, if all goes well, tens of thousands of viewers will be watching to see the chicks hatch.”He said anyone interested in alerts can sign up to the newsletter.