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.

Masked booby seen ‘nesting’ in Tubbataha

On the second working day of the 2016 Tubbataha turtle tagging and laparoscopy trip, I accompanied marine park rangers Segundo Conales, Jr., and Cresencio Caranay, Jr., of the Tubbataha Management Office (TMO) on a special mission to the Bird Islet to look for nesting turtles.  The Marine Resource Foundation – Malaysia (MRF), headed by Dr. Nick Pilcher, and TMO intended to install satellite tags on nesting turtles to determine their habitat range, hence the mission.  From 11:30 p.m. of June 07 up to 06:00 a.m. the following day, we searched the perimeter of the islet for nesting turtles four times – to no avail.

Before returning to WWF research vessel, M/Y Navorca, our research platform, we decided to check on the masked booby (Sula dactylatra) sitting on the northeast portion of the islet.   The bird appears to have chosen this area since early May, when it was first sighted after over 20 years of absence from the Park.   Based on scientific descriptions of the species, ornithologists surmised in early May that the masked booby was male.  But we noticed that it was sitting in the middle of a ‘nest’ fashioned out of twigs, feathers and grass.

The masked booby (Sula dactylatra) at the Bird Islet sitting on its nest - with an egg. ©TMO

The masked booby (Sula dactylatra) at the Bird Islet sitting on its nest – with an egg. ©TMO

On our approach, it became aggressive and stood.  To our extreme joy, we saw that it had been sitting on an egg!  The egg was oblong and narrower than other booby eggs.  It had a dirt-like brown band running horizontally across the middle and some random black spots all over the shell.  We estimated it to be six to eight centimeters long from each tapered end, and four centimeters across.

A photo of a brown booby (Sula leucogaster) with an egg. ©Janet Oquendo

A photo of a brown booby (Sula leucogaster) with an egg. ©Janet Oquendo

We were not prepared for such an encounter!  By chance we had one mobile phone with a camera which allowed us to capture this one defining moment in the life of the reemerging masked booby and the history of the conservation of Tubbataha.

In our enthusiasm, we assume the egg belonged to the bird because of its dissimilarity to all the other seabird eggs on the islet.  However, we did not see the masked booby lay the egg, leaving the possibility that it was not its own.  Investigations are ongoing as marine park rangers confirm ownership of the egg.  Nevertheless, we are delighted beyond measure of the possibility that the masked booby, formerly considered locally extinct, will breed and settle in Tubbataha once again.