In Vietnam the United States Military used ammonia sniffers on Helicopters to sniff out concentrations of human beings on the ground, I do not know if the Ecuadorians and or Peruvians used such, but they have been around for quite some time.
A Special Operations Troop would also be able to tell if people moved through an area of the Jungle recently, by just looking around at things.
Observation aircraft (Rotary and or Fixed) can also be used to see movement on the ground, and then mark the Target for any Strike Aircraft loitering in the A.O..
Peruvian Lieutenants may be trained to know where they are on a Map, and thus tell where the Enemy is on a Map, and give a Grid to the Strike Aircraft. They can also mark their own position with a beacon, or perhaps mark the Enemy with smoke.
Human intel on the ground with a Radio being the key.
Patrols are sent out to gather the intel, the US Army has Pathfinders, Scouts, and other like-minded people for such things, they work very well in the Jungle, they are trained not to get lost (or found).... and they just sneak around real good.
The Ecuadorians and Peruvians would both need very competent Jungle Experts in the Military, as it is the lay of the land down there.
I'd say the Military on both sides there is trained very well in Jungle Warfare, perhaps the Ecuadorians just wanted the win more.

"How do fight in the rain when its pouring how do you see? At fifty feet how do you know who’s the enemy?"

Well, you know who is not the Enemy, as you would no doubt know where your Troops are, and if you are taking fire from a general direction that would be a good clue as to where the Enemy is, even at night, and in the rain.

Shoulda coulda woulda maybe... words that indicate mental masturbation.

Originally Posted by bulldogg

Shoulda coulda woulda maybe... words that indicate mental masturbation.

That about sums it up Bulldog.

Okay wanna drop bombs in a jungle? You need a map and a compass and you need to know how to use same.

Wanna know this sort of stuff? join up and find out

Originally Posted by the_13th_redneck

Wanna know this sort of stuff? join up and find out

Not the easiest way but the best.

The rest of us paid for it. So should he.

I hear ya Sergeant. Let him stumble around in the dark lookin for a stake and number.