Have you ever read an article about how archaeologists can find traces of human activity from long ago by flying over and taking photos of the area? If archaeologists flew over my yard, they would discover that under the soil is an extensive network of squirrel tunnels.
The one saving grace is that the squirrels limit their tunnel openings mainly to the bare hills in our yard and have only a few bolt holes in our lawn (with the exception of the week this summer when the 15 or more baby squirrels practiced digging tunnel entrances...but I try not to think about that).
However, this summer I started a vegetable garden, and I put it on one of the flatter hills. The digging apparently collapsed and interrupted some tunnels, because the squirrels kept digging new tunnels in certain places. I would fill them with rocks and soil; they would open a new tunnel next to a filled one or even pull out the rocks.
I laughed and laughed the day I discovered this Y-tunnel.
The tunnel emerges from the ground and branches into two open-air "tunnels." One goes under the side support of the garden bed and irrigation hoses into the garden path, where it peters out. The other runs along the side support for a little over a foot before it, too, peters out. The close-up below shows the tunnels better.
I left these tunnels in place for a while, but recently I started planting my fall crops, so these tunnels had to make way for more dirt and plants. But I took several pictures for whenever I want a laugh.