During the pandemic, as humanity teetered on the edge of demise, the rest of the natural kingdom appeared to be on the rise. At least that’s the way it looked in the parks of the Upper West Side of Manhattan. As the pandemic flattened and people emerged from lockdown, the great lawns grew intensely, surreally green. Gardens bloomed in brighter-than-normal profusions that lingered longer on the stem than usual; deep into autumn, new blossoms continued to erupt. Throughout the summer and early fall, cardinals and scarlet tanagers flashed their brights, boldly posing like models for photographs. Chipmunks, once rarely seen in New York City, scampered across the dusty paths of Central Park just missing sandaled feet. In Riverside Park, obese squirrels, bellies hanging over their fleshy thighs, strode confidently up to pedestrians, rose on their haunches like dogs, and begged for treats. Rats the size of spaniels sunned themselves on the paving stones of the upper pedestrian walkway in...