They lose 1 point of food every 15 seconds, so to time how long until they start starving, multiply their current amount of food by 15 and then divide by 60 twice. This will give you the number of hours left untill the food stat reaches 0.
((15 x food)÷60)÷60
Obtaining this creature will require you to enter the tek trench where puprle liquid and the nests of these creatures lay past the bioluminescent chamber, there you must steal an egg and raise in a cold environment feeding it nameless venom you can get by killing nameless
The rock drake trench can be found at 57,56 at the area of the map called grave of the lost. Recommend u bring a glider suit and climbing picks and if u have a good tame to fight the drakes. In the wild they can be invisible and can glide in the wild so watch out also wear a HAZARD SUIT it's needed. Lastly there are a lot of nameless in the area so bring a light source. Good luck and ohh it needs to be cold to hatch so air cons
You have to steal an egg like a wyvern. I used a lot of ziplines and a high level ravager to get down there, used the pick to climb up to an egg and ran. The drakes nearby WILL aggro on you. I got on my ravager and ran away on the ziplines. Make sure you have a hazat syit to protect you since there is radiation down there.
Use climbing pick's to climb up to a nest and make sure that there are no Drake's then take the egg and glide out on a wingsuit. You can out-glide a Drake.Stay clear of the water and a have a shoulder pet to stop the Nameless. Have a hazard suit on and you need like 20 air conditioning units to make it hatch. Feed it Nameless venom to raise.
I went down there with three friends, we all had (somewhat) decent crabs. It took a while to get down there, but since the crab can jump, it is easy to get the eggs. Also, because the crabs is so powerful, you can easy kill all of the drakes (especially with four people).
To continue from my previous formula of food x 10 or 45 ÷ 60 ÷ 60 one venom replenishes 400 food. At ~18% OF TOTAL FOOD is when my rock drake ate, for me this was 846/4800 but i read it would eat at 10%. Here's a simple formula to find when yours will eat based on 18% : (max food) x 0.18 = eat.
Requires stealing a Rock Drake egg, and raising like the Wyverns in Scorched Earth. Won't eat meat as a baby, but WILL eat Nameless Venom, so I would suggest hunting Nameless until you have a nice supply of it. It also requires cold temperatures to hatch, so make use of air conditioners.
EDIT : Venom gives 400 food, has 5h spoil in preserving bin and 2h in dino. Drake will eat at 10-18% of max food (for its first eat). Algorithm: (max food) × .10 or .18 = (first eat). Drake below adolescent drain 1 food per 11 seconds. Drake adolescent or above drain 1 food per 22 seconds. Algorithm: (current food) x (seconds) = (time until depleted).