December 2016

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.

Transmission courtesy of  Elisa and EENet

Video recorded by  Fleur, LK forum
Translation Liis

Red deer      Punahirv         Cervus elaphus

Red deer gather in bachelor flocks for the winter – the mating period ended about a month ago, the aggressivity of the stags has calmed down and even the neck muscles are not as thick and ready for fight as before.

Winter is spent peacefully but the hierarchy ladder is recognized throughout the year, see the video.

Video recorded by  Aita, LK forum
Translation Liis

Brown trout   Jõeforell or hõrnas   Salmo trutta trutta morpha fario 

Usually it is sufficient for a spawning milt fish, i e a male, to look his competitor squarely in the eye or to push it with his nose, and the smaller curious explorer disappears quickly (this we often see at the spawning ground). In the video the obstreperous individual is punished by a painful tug at the fin.

Photo Arne Ader
Translation Liis

Bohemian waxwing in apple tree

Definitely an interesting exhibition, and hopefully winter apples can be tasted too.

November 30 to December 11, open every day 10-17

Videos recorded by Aita, LK forum
Translation Liis

Otter    Harilik saarmas    Lutra lutra

The otter belongs to the indigenous Estonian species and is a mammal protected by law. We have to do with an extremely mobile animal whom scientists have difficulties in monitoring.

With a good hearing and sense of smell it distinguishes moving objects in water as well as on land easily. In contrast an unmoving observer at the river bank may not be noticed.

Text and video record Tiit Hunt, www.rmk.ee
Translation Liis

The long-lasting low level of sea water and the small amount of water in rivers has stretched out the spawning period of sea trout. The rise in water level from the recently thawed snow and the frequent rainfalls have made the sea trout to move more actively again on the way to the spawning sites .

In the video made a few days ago at the Vanaveski old dam on the Vasalemma river we see jumping sea trout. The obstacles that the sea trout must overcome  on their path don’t seem manageable to  all, at least not at the first try …

During the roughly one hour long observation all those who had flown up into the air tumbled back into the frothing water below the dam. Perhaps some clever individuals managed to get over the dam unnoticed, without rushing out of the water.

Science news from the Year of the Great Tit edited by Marko Mägi, marko.magi@ut.ee University of Tartu Bird Ecology department
Translation Liis

Tits as well as birds of prey gather at birdfeeders and this forces the tits to be constantly on watch. Distinguishing a dangerous bird of prey from a harmless species is vitally important.  While taking to flight  is crucial if a dangerous bird of prey approaches it is not necessary to waste energy in vain  if it is harmless.

From what do the tits recognize the birds of prey that are dangerous to them? The question might seem strange at first but finding an answer has been a real challenge to scientists and because of that until now relatively poorly studied. Evidently it works by way of the birds’ sight but what precisely are the details tonte in the raptor?