Hepsiba once took off like a missile when I went past the tank at a day time I usually am not at home. She was that quick that she bumped her nose into the gravel
I was frightened and inspected her nose every day for a while. And Humphrey did it too another day, he almost went through the glass.
So from there on when I approach the tank and they cannot see me I yell out, " Hey HUMP AND HEP, how you're going"
So they can hear my voice and know I am not far away.