Science news from the Year of the Great Tit are edited by Marko Mägi, researcher at the University of Tartu bird ecology department
Photo Uku Paal
Estonian text published 27.09.2016
A part of birds fly for winter to remote southern countries while others don’t take the trouble to go on a long journey and when winter arrives remain in place or stray to a smaller extent towards south or north. Such migrating birds which also include the tits that breed here are called roving migrants and they are seen in the literal sense of the word roving around, searching for the best wintering places. True, there are tits that go towards southern areas but in that case too not very far. The reason may be that compared to long-distance migrants the length of the wings of tits, considering body size, became relatively short during evolution since short distances can be travelled also with short wings.
The autumn was special with respect to migration – a mass migration such as in this autumn has not been noted at the Kabli bird station during the history of the station. What is even more interesting is that contrary to the normal annual direction of migration the tits this year instead moved towards north. Observing the overflying birds often may leave the impression that they move quite fast and can travel long distances but how far can a tit fly in one day?
Although different technical devices allow the monitoring of many birds quite precisely it is regrettably not possible to attach the very powerful devices to the little passerines, including such that show their movements in real time. Here only the ringing of birds helps; the largest drawback of this is the great time and energy cost since in order to get the information about the movements of the bird the ringed bird must be caught again, The probability of a refind is however small.
Fortunately the migration of birds passes along certain paths, for instance along the sea coast. With the ringing of the birds and refinds of them at the next station, enough information collects over time to allow conclusions to be drawn about bird migration velocity. On the eastern coast of the Baltic a network of bird ringing stations exists. In Estonia birds are ringed at Kabli and Sõrve säär and there are also bird stations in Latvia, Lithuania, the Kaliningrad enclave and Poland.
Analysis of data from the ringing stations from the last forty years shows that great tits travel on average only 33 km during one day. There are also a few individuals that travel more than 300 km in a day. The most impressive great tit managed to travel 1317 km during 16 days which makes a daily average distance of 82 km. Blue tits however are even slower – during a day they fly on average 28 km. But the great tits that start their journey in Sweden and Denmark travel on average 11 km more per day because their migration path at least partly goes across the sea. Both tit species are even slower on average at the beginning of their migration in the first half of September – great tits then travel on average 24 km, blue tits 19 km a day .
Thus compared to the chaffinches and robins that fly on average 66 km a day the tits move only half as fast, being one of the most slowly migrating birds. Primarily it is due to the fact that tits don’t go far for wintering, and their migration is not a flight in a straight line from one point to another but rather a search for food from tree to tree.
Nowakowski JK, 2001. Speed and synchronisation of autumn migration of the Great Tit (Parus major) along the eastern and the southern Baltic coast. Ring 23: 55-71.
Nowakowski JK, Chrusciel J, 2004. Speed of autumn migration of the Blue Tit (Parus caeruleus) along the eastern and southern Baltic coast. Ring 26: 3-12.