Ants getting water in old nepenthes pitcher

Noticed this small colony of ants deep inside and surrounding a nepenthes maxima x .
I think they are getting a drink . They didn't like me getting too close either.
None had fallen in.

They are guarding the entrance , which is odd , I 've seen these small colonies before.
They like to live in irrigation pipe . I find odd bits of pipe with a colony living inside.
It has been very dry weather , and today is the first day of spring. The first warm day.