Discover nature! New article “The life of the great tit as seen from its leg ring – In conjunction with the special exhibition ‘The Society of the Great Tit’” now available.

The great tit is a very common species, and I think most people have seen it before. However, it did not used to breed in Tokyo, and it seems to have become established and increased in number in the 1960s to 1980s. It can be said to be one of the birds that have moved into urban areas, like the Japanese white-eye and the long-tailed tit. Now, how long do great tits live? Do they stay with the same mate every year? Do they live in the same place all year round? These questions cannot be answered through ordinary observation. It is necessary to distinguish each individual bird, that is, to identify them individually and observe them continuously.

To study the social structure of certain bird species, it is common to use colored leg bands for individual identification. The birds are captured, fitted with leg bands of different color combinations for each individual, and then released for observation. Capture is conducted with permission from the Ministry of the Environment or prefectural governments, using established safe methods. Color leg bands for small birds weigh only 22 mg (0.022 g) each and do not affect their behavior.

I have been studying the social structure of great tits at the Tsukuba Experimental Botanical Garden of the National Museum of Nature and Science since 2012. In the botanical garden, where natural tree cavities are scarce, installing a large number of nest boxes results in nearly all breeding individuals using them. By attaching leg bands to both the parent birds that nest and the chicks raised in the nest boxes, and continuously observing them, we can understand the parent-offspring and pair relationships among the Japanese tits breeding in the botanical garden. In a sense, we are creating a “family register” for the Japanese tits.