Holey coconut palms

These people from Cabo del Gado, Northern Mozambique, dig on purpose huge holes into the stems of  some of their coconut palms. They do not do it for all the coconut palms. In the villages, and along the beach, about one coconut palm on ten to twenty is punched.
They carefully select the palms to be punched...
It took me a long time to understand why...
But I finally understood the reason why!

Coconut palm with hole, Cabo Del Gado

Coconut palm with hole, Cabo Del Gado

Yes, I do confirm that I finally understand the reason why they punch their coconut palms, and only some of them...

Hi Hi... Good luck.