In researching "Marcus Traille, International Woodlands Detective" (see last Super-Fun-Pak Comix), I came across this gem from the wholly unrelated comic strip "Mark Trail."
"Mark Trail" is known for its meticulously realistic depiction of, and keen insight into, the natural world. For example, Mark knows that beavers work tirelessly to maintain their dams and dens. This 1/28/13 comic shows a couple hard at work.
Only sharp-eyed devoted readers will recall that back on Earth Day, 2008, "Mark Trail" had the same beavers working on the exact same spot, in the exact same positions, thus emphasizing the endlessly repetitive nature of their toils.
(Of course, for Super-Fun-Pak comics, I have also been known to recycle images, in the spirit of Earth Day and every day.)