page_title: Great tit
section_title: Breeding
hierarchical_section_title: Great tit / Behaviour / Breeding
caption_attribution_description: Nederlands: Koolmees in een nestkastje, op haar nest English: Great tit nesting in next box
context_page_description: The great tit is a passerine bird in the tit family Paridae. It is a widespread and common species throughout Europe, the Middle East, Central and east across the Palearctic to the Amur River, south to parts of North Africa where it is generally resident in any sort of woodland; most great tits do not migrate except in extremely harsh winters. Until 2005 this species was lumped with numerous other subspecies. DNA studies have shown these other subspecies to be distinctive from the great tit and these have now been separated as two distinct species, the cinereous tit of southern Asia, and the Japanese tit of East Asia. The great tit remains the most widespread species in the genus Parus.
  The great tit is a distinctive bird with a black head and neck, prominent white cheeks, olive upperparts and yellow underparts, with some variation amongst the numerous subspecies. It is predominantly insectivorous in the summer, but will consume a wider range of food items in the winter months, including small hibernating bats. Like all tits it is a cavity nester, usually nesting in a hole in a tree. The female lays around 12 eggs and incubates them alone, although both parents raise the chicks.
context_section_description: Great tits are monogamous breeders and establish breeding territories. These territories are established in late January and defence begins in late winter or early spring. Territories are usually reoccupied in successive years, even if one of the pair dies, so long as the brood is raised successfully. Females are likely to disperse to new territories if their nest is predated the previous year. If the pair divorces for some reason then the birds will disperse, with females travelling further than males to establish new territories. Although the great tit is socially monogamous, extra-pair copulations are frequent. One study in Germany found that 40% of nests contained some offspring fathered by parents other than the breeding male and that 8.5% of all chicks were the result of cuckoldry. Adult males tend to have a higher reproductive success compared to sub-adults.
  Great tits are seasonal breeders. The exact timing of breeding varies by a number of factors, most importantly location. Most breeding occurs between January and September; in Europe the breeding season usually begins after March. In Israel there are exceptional records of breeding during the months of October to December. The amount of sunlight and daytime temperatures will also affect breeding timing. One study found a strong correlation between the timing of laying and the peak abundance of caterpillar prey, which is in turn correlated to temperature. On an individual level, younger females tend to start laying later than older females.
  Great tits are cavity nesters, breeding in a hole that is usually inside a tree, although occasionally in a wall or rock face, and they will readily take to nest boxes. The nest inside the cavity is built by the female, and is made of plant fibres, grasses, moss, hair, wool and feathers. The number in the clutch is often very large, as many as 18, but five to twelve is more common. Clutch size is smaller when birds start laying later, and is also lower when the density of competitors is higher. Second broods tend to have smaller clutches. Insularity also affects clutch size, with great tits on offshore islands laying smaller clutches with larger eggs than mainland birds. The eggs are white with red spots. The female undertakes all incubation duties, and is fed by the male during incubation. The bird is a close sitter, hissing when disturbed. The timing of hatching, which is best synchronised with peak availability of prey, can be manipulated when environmental conditions change after the laying of the first egg by delaying the beginning of incubation, laying more eggs or pausing during incubation. The incubation period is between 12 and 15 days.
  The chicks, like those of all tits, are hatched unfeathered and blind. Once feathers begin to erupt, the nestlings are unusual for altricial birds in having plumage coloured with carotenoids similar to their parents (in most species it is dun-coloured to avoid predation). The nape is yellow and attracts the attention of the parents by its ultraviolet reflectance. This may be to make them easier to find in low light, or be a signal of fitness to win the parents' attention. This patch turns white after the first moult at age two months, and diminishes in size as the bird grows.
  Chicks are fed by both parents, usually receiving 6 to 7 g (0.21–0.25 oz) of food a day. Both parents provision the chicks with food and aid in nest sanitation by removing faecal packets, with no difference in the feeding effort between the sexes. The nestling period is between 16 and 22 days, with chicks being independent of the parents eight days after fledging. Feeding of the fledgeling may continue after independence, lasting up to 25 days in chicks from the first brood, but as long as 50 days in the second brood. Nestlings from second broods have weaker immune systems and body condition than those from first broods, and hence have a lower juvenile survival rate.
  Inbreeding depression occurs when the offspring produced as a result of a mating between close relatives show reduced fitness.  The reduced fitness
caption: Great tit nesting in nest box
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