What spooked the squirrel ?

While working at Aspenwood I always like to look out of the lounge window to check on the local wildlife and see if the feeders need filling and the bird bath needs cleaning. I was amused to see this young red squirrel run along the platform fence to feed and then stop in its tracks. It could hear something I couldn't and was shaking its tail in alarm and stamping its feet.....what had it seen ? Soon the mystery was solved.
Not long after there were 3 squirrels outside the lounge window eating at various feeders.
Best watched with the sound off............enjoy.