Fox squirrels race around frantically, the males busily following one another, led by a female, up and down, across the ground, and through the tree canopy -- a seemingly endless mating chase. Late December, about the time of the shortest day, is usual for the start of this behavior, which I've recorded because I want to learn the repertoire of this competitor with the eastern screech owl for tree cavities and nest boxes. I find sleeping squirrels in some boxes and screech owls in others, but normally no squirrel babies until late this month and no owl eggs until early March.
Especially during cold stormy weather, screech owls use tree cavities and nest boxes as day roosts, so there is a tussle for housing. The first owl egg is usually laid in the first week of March, though the long-term average is March 14, several days after the last time I've noticed new-born squirrel pups in nest boxes. About April Fool's Day the weather is sufficiently warm and fleas are bad enough that fox squirrels forsake cavities for airier tree canopy nests built of leaves and twigs, and these are used exclusively for their second brood in mid-summer. Even so, from winter into April if the weather is foul, fox squirrels temporarily take over cavities from roosting or incubating screech owls that are only half their size. I've often wondered what happens, when a predatory ringtail -- the raccoon's weasel-like cousin -- finds them, because I know what happens to screech owl eggs and chicks. The owls' survival strategy is to re-nest elsewhere, which is why each pair owns two or three tree cavities or nest boxes, although they never produce two broods a year.
Ringtails shop for cavity roosts and supper, apparently remembering where they've found them before. On tree branches adjacent to the cavities and on nest-box lids they deposit scat (fecal) piles as territorial markers. These heaps are easy to see from a distance, so I know when a barking ringtail will greet me as I open a nest-box. I really like these lithe, tan, big-eyed, big-eared, band-tailed creatures, but if I am to hear certain screech owl messages, I must dissuade ringtails by spraying pet repellent on the lid and nearby branches.