Blue tit
- The maximum lifespan of the eurasian blue tit reaches 15 years. This is a record among birds of its size.
Age
The Eurasian blue tit’s typical lifespan ranges from 11 years to 18 years and 3 months, although the maximum recorded lifespan is 14 years and 7 months, with a theoretical lifespan of between 10 years and 13 years and 4 months; the species reaches sexual maturity between 9 months and 1 week and 1 year and 3 months. Development begins with an “embryo” stage, during which the embryo develops inside an egg, consuming no food and relying entirely on parental warmth. The “nestling” stage follows, lasting from 2 weeks and 2 days to 3 weeks, where the young bird is in the nest and fed insects by its parents, growing rapidly and developing down feathers before acquiring plumage. Then comes the “rapid growth post-fledging” stage, which lasts from 3 weeks to 1 year, as the young bird learns to fly and forage independently, exhibiting less vibrant plumage than adults. The "adult" stage begins when the bird is capable of reproduction, lasting from 1 to 9 years, during which it actively forages, builds nests, and raises young.
Phenotype
The Eurasian blue tit has a short, sharp beak that young birds use to take food from their parents, and adults use to catch insects and crack seeds; the young's plumage consists of soft down covering its body to retain heat. After rapid growth, the species’ plumage is bluish-grey on the head and back, with a yellow belly that is less vibrant than in adult birds. Adult blue tits have a bright blue cap and blue neck, along with white cheeks marked by a black stripe through the eye. The body plumage of an adult is bluish-grey on the back, with bright blue wings and tail featuring white stripes, and a yellow belly. Short, rounded wings allow for quick maneuvering between branches.
Physiology
The Eurasian blue tit measures from 10 to 12 centimeters in body length, with a wingspan of 18 centimeters and a weight ranging from 10.3 to 11.3 grams; the young birds have a body length from 3 to 8 centimeters and a weight from 1 to 10 grams, while the stage of rapid growth shows a body length from 10 to 12 centimeters and a weight from 8 to 12 grams. Adult blue tits have a body length from 11 to 12 centimeters and a weight from 9 to 13 grams.
Habitat
The Eurasian blue tit occupies habitats at elevations up to 2 kilometers and is found in temperate mixed forests with warm summers and many oak, birch, and maple trees, flooded meadows with abundant grass where water frequently covers the ground, and taiga characterized by cold winters and numerous coniferous trees such as spruce and pine; the species lives on land, in woodland and scrubland. The climate varies, including conditions where rain falls almost constantly and it is very humid, a climate with many rains and a cool summer accompanied by snow in winter, a warm summer with abundant rain, a warm summer and a mild winter, and a comfortable summer with temperatures between 20 and 25 degrees Celsius.
Shelter
The Eurasian blue tit shelters in tree cavities, walls of buildings, or artificial nesting boxes; the species builds or utilizes a nest structure for laying eggs and raising young. Nests are constructed from moss, dry grass, feathers, and wool.
Geography
The Eurasian blue tit is found within the Palearctic biogeographical region and occupies several distinct ecosystems, including Celtic broadleaf forests, broadleaf forests of Western Europe, coniferous forests of the Qilian Mountains, Balkan mixed forests, Baltic mixed forests, and coniferous and mixed forests of the Pyrenees.
Feeding
The Eurasian blue tit primarily feeds on small insects and spiders, and during winter months it transitions to seeds, nuts, and pork fat provided in bird feeders. The species obtains food among the leaves and branches of trees and shrubs, foraging for caterpillars, aphids, spiders, small beetles, seeds, nuts, pine cones, plants, and various invertebrates including beetles, flies, hymenopterans, butterflies, woodlice, ribbon worms, mollusks, polychaetes, bedbugs, orthopterans, dragonflies, and caddisflies. The daily food requirement ranges from 6 grams to 12 grams, and the strategy for obtaining nourishment involves searching and acquiring food.
Reproduction
The Eurasian blue tit forms pairs in spring; the female builds a nest and lays eggs. Development of the embryo lasts 1 week and 1 day. The species produces clutches of 7 to 14 young, and both parents feed the chicks. The female has 7 to 14 offspring per breeding season. The interval between breeding seasons is 1 year. Maturity occurs from 10 months to 1 year and 1 month. Birds reproduce once every year.