Reproductive biology

All of the tits nest in cavities, mostly in trees, but also between rocks, in walls, on raised ground, and even in pipes. Many species excavate their own nests in rotting wood, while others use natural holes or those made by other species such as woodpeckers. Many will take readily to nesting in nest-boxes specially created for them by man, although some require saw-dust filling so that they can still perform excavation behavior. Cavities are lined with various soft nesting materials. Most species nest between March and July, but Southern Hemisphere African tits may nest year-round or

Black-capped chickadees (Poecile atricapilla) are common throughout North America. (Photo by T. Vezo/VIREO. Reproduced by permission.)
Bridled titmouse (Baeolophus wollweberi) in flight. (Photo by Joe McDonald. Bruce Coleman Inc. Reproduced by permission.)

seasonally. Clutch size varies between the different subgenera, but most have four to 10 eggs. The African species have relatively small clutches of three to six eggs, while the blue and great tits have the largest clutches with up to 13 eggs. Eggs are typically white, or blushed pink, with some red-brown spotting at the larger end. Incubation periods are generally around 14 days, while the brood period is between 14 and 24 days. The young become independent very quickly in most species, dispersing after just two to three weeks. Some species, like the coal, great, and blue tits, regularly have two broods per year. Breeding success is highly variable, but has been good in many studies. However, all species are vulnerable to nest loss from specialist predators like squirrels, woodpeckers, and snakes.

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