Because you love nature

 Counting the yellow rods he picked up at the side of the narrow creek over a canopy of vines and semi arid evergreens. 
Footsteps came a short way away from the other side of the creek. 

"Hey can you tell us how to get back to the carpark" Toby McGill said.
So abrupt the alien had no time to cloak. The alien was wearing human clothes, though,
he turned his back so they would see his strange face.
"Keep on going, there is no path but you can follow the creek"
"Is that gold you are taking from the river?" Janet Mcgill asked

"No I'm testing different materials in the river, to check water purity." The alien answered
"Oh wow, is the creek poisoned or something? Why are you facing away from us?"
"I have a disease that has changed the structure and color of my face. I'll turn around but you guys will have to brace yourselves."
The Alien turned around slowly Janet raised fists to her mouth, Toby gaped.
"That's not a disease, you are an alien!"

The words gave a new meaning to gravity, he had been discovered.
Almost uttering a "no" in protest he felt the absurdity of denying it.

"You are not measuring the purity of the water are you?" Janet tagged.
"Well I'm actually collecting a material hidden tot he human eye and quite rare, these rods collect it from the margins of these narrow creeks"

"Can we cross and meet you in Person?" Toby asked excitedly.
The alien silently wretched, he'd liked humans but never close contact, their skin was smelly.
"I guess so but I cannot shake hands because of hygiene reasons O.K.
Janet elbowed Toby in the ribs. and whispered "It's a fucking Alien lets just get out of here, and how did you know it was a fucking Alien?"

Toby pretended not to listen and jumped over the narrow one meter gap of the creek.
Approaching the alien cautiously "Wow you are exactly what I expected."
"What do you mean?" The alien replied.
Something rustled in the trees from the other side. Janet screamed "Ahhhhhhhhhhhhhh, there's something big over here!"

Out of the undergrowth bounded a sixty kilogram mountain lion.
Janet threw down her backpack and started backing away facing the lion.
"Just stay still" Toby shot.
The Lion cautiously started sniffing around Janet, Janet fell back and fainted.
The alien sprang like a frog near the mountain lion landing two meters from it.
"rrrrrrrrrrrrrowwwwwww" It turned on the alien.

The alien positoned a four fingered hand in the air above the lion. The Lion started to sway. It seemed to lose it's aggressiveness.
After a few more seconds Janet lifted her head.
"He's hypnotizing it"
"Quiet" Toby said.
The Lion slowly sat still swaying slightly.
Then lay and slept.

The alien quipped " Why are you all so shocked to see a mountain lion out here? this is it's habitat."
"Nature is just so strange" Janet got out after a pause to think.
"Do you mean alien?"