October 5 2017


Blue bottles a new food source for pied oyster-catchers!

During the filming of a National Geographic Wild documentary on Rottnest Island by Sea Dog TV International, the crew noted a high frequency of beach washed Blue Bottles (Physalia utriculus) strewn amongst the debris line at the West End. 

A pair of Australian Pied Oyster-catchers were very interested in these and began singling out these Blue Bottles by picking them up in their long red bill, walking down to the surging water and purposefully washing them.  They then continued back up the sand, stopped and poked them one at a time into the wet sand to about half their beaks length, pushing and pulling the Blue Bottle in and out of the sand.

Eventually standing up-right and vigorously shaking the Blue Bottle in its beak to rid it of the sand, walking back down to the wash zone to once again rinse/wash the deflated Blue Bottle’s air bag and remaining body in the water, walk back out of the wash zone and eat the Blue Bottle. 

Repeating this a number of times, both birds consumed more than 10 Blue Bottles each during observations.

Blue Bottles are an unusual food source for bird life due to their stinging venomous tentacles.  It is speculated that the reason for washing the Blue Bottles in the water and sand was to rid them of these tentacles.

Enquiries with various credible scientists both within Australia and overseas seems to have resulted in no previously recorded or documented  knowledge of neither Australian Oyster-catchers or any other bird being observed utilising this species of coelenterate as a food item or other unknown reason, albeit chemical, medicinal or other.

This unusual behavior was filmed by Sea Dog TV International and we look forward to seeing the footage in “…the Mystery Islands” documentary.

All images taken by Doug Coughran - Sea Dog TV International (