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Home , Great tit, Tit (bird)

Garden favourite: Great

Female collecting nesting material, by Jill Pakenham

The black belly-stripe The ‘teacher-teacher’ call of the Great Tit Although male and female Great is an important ‘badge’ must be one of the most recognisable Tits appear superficially similar in their used by males when sounds of spring. This familiar has appearance, the males sport a broader black displaying at territorial been the subject of much detailed study, stripe that extends down the chest and rivals. Researchers primarily because of its willingness to use belly, passing between and joining the base have found that males nest boxes, so you might think that there is of the legs. In females the stripe is reduced with broader stripes little that we don’t already know about this in width and does not touch the base of the make better parents . In fact, there is much still to learn, with legs. Additionally, the stripe often contains and that they are the Great Tit providing opportunities to test some pale feathering in females, giving it a more attractive to new ideas within the fields of ecology and more washed-out appearance. prospective mates. evolutionary biology. In males, the main colours The belly-stripe is, tend to be brighter, the cap glossier for therefore, an honest THE BASICS example, than they are in the females. As is signal of male quality. One of the first things you notice about the the case in many other species, the plumage Great Tit, compared to our other tits, is its t colours tend to get stronger with age. Prior larger size. This may be related to, to their autumn moult, young can be or explain, the Great Tit’s foraging recognised by their pale yellow, rather than behaviour. Less agile than the white, cheeks and by the different colour of other tits, it spends more time some of their wing feathers feeding from the ground, a behaviour often seen in the SETTING UP HOME autumn when Great Tits forage The Great Tit’s nest is constructed by the for fallen . female alone. She begins the nest by The larger size also means building a substantial base of moss, with that the Great Tit tends to the addition of some grass and other plant be dominant over the other fibre. Regardless of the floor space available species, often evicting them within the cavity, the female will cover the from nesting cavities or the entire area with the same depth of material,

perch of a . making it quite a job if she happens to Great Tit, by John Harding John by Tit, Great

18 Bird Table Spring 2012 select a large cavity. The nest cup is then super-abundant and, as added, lined with fur, wool, hair and other you might expect, Great soft materials (though rarely feathers), and Tits do better if they it is into this that the will be deposited. can match the period of Once -laying begins, the female peak demand from their will usually lay one egg each day, though she growing chicks with this Great Tit, by John Harding Tit, by Great may occasionally miss a day – a practice that pulse of . is more common in early nesting attempts BTO Nest Record than later ones. Egg-laying takes place early Scheme data show that in the morning, after which the female Great Tits are laying covers the eggs with nesting material and their eggs an average spends time with her mate, before returning of eight days earlier to the box in the evening to roost. than they did in the The close association between the pair 1960s in response at this time sees the male busily protecting to warmer springs. his ‘exclusive’ access to his mate. This is the Caterpillars are also emerging earlier, but t the date on which they do so is influenced period when the female is most receptive, Many authors by temperatures experienced after the birds so the male needs to make sure that other have commented have already produced their clutch of eggs. males do not sneak in and secure a mating on the Great Tit’s By this time, there is very little the Great with his female. The male will often feed intelligence, the Tits can do to advance hatching further, so his mate during this time together, perhaps species showing chicks may be produced after the caterpillars contributing a third of her daily food intake, a high degree of have already pupated, resulting in reduced and you may spot her begging like a chick flexibility in its growth rates and starvation. This mismatch for food. Given the amount that she has to behaviour and an may cause problems if caterpillars continue invest in each egg, this additional food may ability to learn tasks. be particularly important. Each egg, which to emerge earlier with . This is weighs between 1.3 and 2.3g represents another reason why continued study of this roughly 10% of the female’s body weight, seemingly familiar bird is so important. so the complete clutch will weigh more than she does! Incubation does not begin properly until all the eggs have been laid, so the presence of the female roosting in the box overnight does not necessarily indicate FACTBOX: Great Tit major that incubation has started. Even though the female settles over the eggs, without Population: her brood batch (an area of bare skin well- supplied with blood vessels, that develops Breeding: 2 million pairs on her belly) touching the eggs there is Winter: currently unknown insufficient warmth for incubation to begin.

BRINGING UP BABY Conservation status: Each Great Tit chick weighs roughly 1.5g GREEN at hatching. By the time that the chick fledges it will weigh between 16 and 26g, a Diet: (moths, beetles and ), seeds staggering increase given that it takes place and in winter. over a three week period. The amount of food needed to fuel this growth is equally Longevity: staggering, with in excess of 10,000 Typical lifespan: 3 years caterpillars delivered to the typical brood, Great Tit egg, by Mike Toms; Juvenile Great Tit, by Jill Pakenham Tit, by Juvenile Great Toms; Mike Tit egg, by Great raised in mature . Caterpillars Max recorded lifespan: 13 years, 11 months and 5 days dominate the diet, contributing some 60– 95% of the diet, depending on habitat. As Breeding Ecology: you might imagine, those tits breeding in suitable broad-leaved woodland have greater Clutch size: 7–9 (range 6–15) eggs access to caterpillars than those nesting Number of broods: 1 (2) in most gardens, which is why garden- Incubation: 13–15 days breeding Great Tits are often less successful than their woodland counterparts. Young in nest: 18–21 days Caterpillars are not equally abundant Age at first breeding: 1 year throughout the year; in fact, there is a short period over which caterpillars are www.bto.org/birdfacts Spring 2012 Bird Table 19