The pendulum theory

17 05 2013

“We are not going in circles, we are going upwards. The path is a spiral; we have already climbed many steps.”

– Hermann Hesse, Siddhartha

Many things have happened in the last 10 days. The notable changes in the weather had come with notable changes in the quantity and quality of the captures in what can be considered an inversely proportional relationship. In the first days, we were catching many birds. Everyday was a good one in terms of numbers, with some new arrivals too, but the most exciting species were wood warbler, thrush nightingale, lesser redpoll (first for the season!) and red-backed shrike. Apart from quantifying the impressive migration of barnacle geese (up to 50.000 birds counted from Nabben in a few hours), the rest of the day consisted mainly in ringing willow warblers and enjoy the good weather.

Luscinia luscinia

Carduelis cabaret

Phylloscopus sibilatrix

Lanius collurio

As expected, somebody turned off the migrants tap and the number of birds ringed started to decrease. Probably “somebody” means Arvid, whose presence blocked the flux of birds for a few days. Suddenly, we realized the pendulum was already in the other side and there were no birds at all. However, we managed to catch some house martins and to rescue some amphibians stuck in the pit of the lighthouse garden. A common toad, a green toad and a smooth newt (this one a lifer for me!) were, without any kind of doubts, the best of that day.

Bufo viridis

Triturus vulgaris

Bufo bufo

Arvid left but, while literally crossing the door, he kept on predicting something good for the next days. The weather forecast indicated strong winds and hot temperatures from the southeast and this time it was right. These last days of ringing are among the strangest days of ringing I’ve ever seen. We’ve been catching around 10 birds per day, but surprisingly (or not) 3 red-breasted flycatchers, including a very nice adult male that started to sing after being released. There were at least 5 different birds around the garden, together with some (the first) common rosefinches. If anybody knows the explanation of this high proportion of red-breasted flycatchers, I would be more than happy to pay attention. It’s worth-saying that, until now, we’ve caught 4 pied flycatchers and 3 red-breasted. Nothing else to say.

Ficedula parva

Carpodacus erythrinus

The hot temperatures have also brought some dragonflies. The downy emerald Cordulia aenea was a lifer for me, but the four-spotted chaser Libeulla quadrimaculata is also common species up there and scarce in the Iberian Peninsula, where it’s restricted to the high Pyrenees.

Libellula quadrimaculata

Cordulia aenea

The influence of the easterlies is obvious but the pendulum is only in the middle. We need the wind to drop and see if the inverse proportion between total number of captures and exciting species finally disappears. If so, it would be amazing. Sunday is the day.




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