I think I've finally figured out how Ella can be all the way at the front end of our apartment and detect the presence of a squirrel in the back yard. Birds are the key. When a rodent invades their garden space, the sparrows set up a particular squawking racket that Ella has learned to associate with the presence of a squirrel. She hears that sound and charges toward the back door yipping and yelping like her tail's on fire.
Late one morning last week, alerted by one of these yelping fits, I rushed to the kitchen to open the back door for Ella. As usual, she tried to squeeze through the opening before it was wide enough for her. Then she clattered down the stairs from our second-story deck, and I could hear her charging around the yard like a wounded rhino. She started barking from near the gate at the side of the house, so I leaned over the railing to make sure the gate was shut.
What I saw when I looked down was a squirrel climbing past the security lights installed on the corner of our brick building. (I wished I had a camera but my iPhone was in the apartment, charging. The photo below is one I took a few minutes later.) Ella was on her hind legs, barking up at the squirrel. The moment the crafty little rodent saw me peering down at it, it changed direction and darted along the railing of the deck below ours.
I hurried toward the stairs, my only intent being to flush the squirrel in Ella's direction. (I'm a good wingman for her in that regard, as is Laura.) But the squirrel didn't stop when it reached the end of our downstairs neighbors deck railing. It launched itself through the air, over Ella's head, leaping six feet to snatch at the branch of a tree in the garden. In moments it had swarmed up the trunk of the tree and made its escape over the roof of the garage.