Masked booby seen ‘nesting’ in Tubbataha [2nd update]

To further investigate the arrival of a masked booby (Sula dactylatra) in the Park and the egg found with it, two park staff set foot on the Bird Islet on 17 June 2016.

Park Ranger – Researcher Segundo Conales Jr. and Researcher Jeric Dejucos saw the masked booby incubating an egg during their previous visit just over a week ago. This time, it was a female brown booby on the very same nest, over the very same egg that they saw. The masked booby however was still there, standing its ground about a meter away from the nest.

masked booby egg 3rd update

They were able to measure the egg with a caliper and found it to be 6.2 centimeters long and 4 centimeters wide. The park staff barely had a minute to do the measurements because the two birds immediately flew back to the spot together.


Researcher Mr. Segundo Conales Jr. measuring the dimensions of the alleged masked booby egg with a caliper.

“We cannot conclude anything about the egg.” said Jensen, since there is no available literature about cross-breeding between the two seabird species. However, he is interested in this behavior and wonder whether the masked booby is acting as a ‘foster father’. “It’s going to be very interesting to learn how he (masked booby) will behave and feed this adopted baby.” added Jensen.

Until now, nothing is certain about the case of the masked booby as Mr. Jensen wants TMO to “see what comes out of the egg.” The egg is expected to hatch by the first half of July.