In India, we discovered the umbrella trick by accident in a wildlife sanctuary. It was raining & the guide decided to open his umbrella. We were able to walk withing 25 meters of gaur, wild boar etc. without their knowing that we were humans under the hood!

I have also used it to simulate village water buffalo near large lakes - to get withing 40 meters of a flock of ducks which were otherwise 300 meters away.