Tiger burrowed for long time

[JoshBA]

I'm unsure on how to assess this situation: I have 4 tiger salamanders in a 55 long tank with 12 inches of substrate. Two of them have been burrowed for at least 2 weeks and I am uncertain on what I should do. The temperature is around 64F, so I know their metabolism would be at an "active" state (meaning it needs energy via food). I am aware that salamanders can go for quite a while without food, but not for how long. One of the salamanders was burrowed for 10 days, but eventually came out for food.
Should I leave the ones burrowed be, and allow them to come up on their own? I hand-feed mostly earthworms, so the salamanders don't exactly hunt their food. I was thinking of putting crickets into the tank, so maybe they could venture into the salamanders tunnel network, and be eaten by the salamanders.
Or should I worry about them being under for so long, and do something about it?

 

[RPM]

It’s normal for them to sometimes borrow for more than two weeks. I’ve had ones burrow for a month or so during warmer periods and five months during the late fall to early spring. Continue hand feeding the earthworms. Sometimes the act of one salamander eating will entice another from its burrow.

 

[JoshBA]

Thanks for the reply.
It just makes me wonder if their ability to go so long without food is part of an adaptation to survive their natural habitat. I live out in the country in Montana and have seen their natural habitat. During parts of the year, especially during late summer and fall, it seems so desolate for even a salamander to inhabit. But then again, I suppose that during the dry parts of year, just as the salamanders do, many insects retreat underground to the moisture. These probably provide the salamanders in hiding a good source of food. I also once read an article stating that salamanders store fat in their tails to survive periods lacking in food.

 

[Kaysie]

I usually dig mine up if I haven't seen them in a month or so, just to make sure everyone's doing okay. I'll offer them worms then, but they're refused half the time.