Two racial abilities drawing from the same tracker

[Paris.Crenshaw]

I'm working on the crag spider, which I thought would be one of the simplest critters to do.

However, it has an ability called "tether" which counts against the number of times per day it can use Web.

I know I can simply remember that and decrement the web ability when tether is used, but I'm trying to figure out how to set up the two abilities to decrease the tracker numbers when either of them is used.

This would be similar to the way a staff uses its charges and decrements the pool of charges when a spell is cast. Or a sorcerer's spells. Or the number of bardic performances per day.

However, I haven't been able to find examples of a race that uses this for its abilities.

Are there any examples of racial abilities that do this elsewhere? I know I should try to figure this out on my own, but I'm not exactly sure where to start.