how far can the drone travel?

According to the manufacturer, the thermal drone can fly up to 9 miles when there is very little terrain interference. With terrain interference, I wouldn’t push it any further than 3 miles.

How long does the battery last?

One battery set will provide approximately 40 minutes worth of flying time. Two batteries power the thermal drone.

Can the thermal drone still detect a deer that has been dead for more than a day?

This is a loaded question due to various circumstances surrounding the specific case. Weather and the environment have big roles to play on this one. That said, I have found deer more than 24 hours after it was shot.

can you still see deer through thick cover?

It is possible to still locate deer in thicker areas. However, the visibility does go down when compared to an open area. Deer still can be found but it may require more time.