Good weather for ducks?

Lennart Saari has been regularly counting ducks and swans in SW Finland for 38 years - and made some fascinating discoveries. We asked him some questions:

Where do you count?
On the lakes and coastline of the island of Aasla, where I live.

How often do you count the waterfowl?
On at least 14 days each month during the winter, in November, December and January.

What’s changed since 1975?
The weather! Our winters are milder now. In the 70s and 80s the lakes sometimes froze as early as November. Now they can be ice-free in December, or even in January. The shallow, coastal sea freezes for a shorter time as well.

How does the weather affect the birds?
Waterfowl which have bred further north begin to concentrate on our brackish Baltic coast and local lakes from October-November. When the lakes on the Finnish mainland freeze, we have an influx and then they gradually move further out into the Baltic. In spring, when the sea-ice melts, flocks stop off here on their northward migration back to their breeding grounds. So the winter temperatures strongly influence winter movements. I’m recording much bigger numbers of wildfowl now.

Goosander by Veli-Matti Väänänen

Can you give us some examples?
Mute Swan Cygnus olor has established itself as a wintering bird since the census began and the numbers increased dramatically until  recent years, when there has been some levelling off. I’m seeing much bigger flocks of Goosander Mergus merganser, Goldeneye Bucephala clangula, Mallard Anas platyrhynchos and Tufted Duck Aythya fuligula than in the early years.

What motivates you to go on counting during the coldest months of the year?
Studying the birds in winter is like an extreme sport: temperatures have sometimes been as low as -30 °C! But I census birds all year round with the same intensity − I’m now preparing an article on the post-breeding populations of waterfowl. With climate change being a major issue, I have extra motivation, as long-term data has become scientifically very important.

You were one of the founders of A Rocha Finland – what’s your role there now?
I am still on the board.

Can you give us some news?
Panu Pihkala, the new Chair, writes, ‘We are currently re-booting A Rocha Finland! The group is contributing significantly to Christian environmentalism here through a new book on ‘Nature and Worship’, and to a greener emphasis in the school activities throughout the country which prepare young people for confirmation into the Lutheran Church of Finland. We are also starting a new A Rocha newsletter.’

For more information see Saari, L. (2012). ‘Pitkäaikaismuutokset Saaristomerellä talvehtivien vesilintujen kannoissa’. Suomen Riista 58: 75–89. [With an English summary]

Small image: Mute Swan by Markus Varesvuo