Great Tit Year scientific news are edited by Marko Mägi, marko.magi@ut.ee, Bird ecologist at University of Tartu
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Pied flycatcher male checking on what goes on in a great tit nestbox / photo: Marko Mägi
Pied flycatcher Must-kärbsenäpp Ficedula hypoleuca
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If you are a stranger and you arrive at the nesting site later than the others information on local conditions –is important and both knowledge and experiences are essential. Knowing the best feeding and nesting sites can increase the nesting success significantly.
The tits, that winter near the nesting areas, are better aware of the local conditions than for instance a pied flycatcher who winters in Africa. Because each day counts the long-distance migrants must decide quickly on arrival where to build their nest. Getting better acquainted with the local conditions may well result in a good choice, but time too has a decisive influence – the earlier one starts to breed, the more certain a successful result. But how to choose if the environment is strange and time is short?
The great tits have already started their nesting when the pied flycatchers arrive from Africa but they often share a common habitat. It is known that pied flycatchers often go checking on nestboxes occupied by other species; not, however, with the aim to occupy the hollow and begin nesting there themselves. In Estonia too it has been noted that they look into the nest, spend a few seconds at the nest opening and leave. Why do they behave like that? Is the pied flycatcher not able to distinguish between its own and the neighbour’s nest box or do they just go to check on how the neighbour is doing?
Finnish ornithologists discovered that such behaviour is not random at all – we have to do with a sort of spying. Hollows occupied by great tits or blue tits may be a sign to the pied flycatcher about a worthwhile nesting area where it might be profitable to set up one’s own nest too.
To verify the hypothesis about spying, either a ring.-shaped or a triangular figure was placed at the openings of nestboxes already occupied by tits before the arrival of collared and pied flycatchers. Beside it however an empty nest box was placed. at whose opening another figure was placed. So a situation was created where in the territory of tits precisely nest boxes were preferred that were marked with a particular shape. When the flycatchers arrived two more nest boxes were placed near the others with openings marked with a ring or triangle. Which nest box the birds arriving from migration would choose was monitored..
The choices of the flycatchers that had arrived early seemed arbitrary but late arrivals chose a box that was occupied by tits and marked. This is explainable as optimizing time and energy use, in which case the basis of selection was the choices of other species that knew the local conditions. Later studies have shown that the flycatchers do not decide on the basis of just the nest box choice of tits but also with regard to their breeding success. Near successful tit parents their nest box selection is copied, but in case of fewer tit chicks a nest box with the opposite sign is rather chosen.
It can be concluded from the results that in order to save time and energy on arriving from the migration one means is to visit already occupied nest boxes and obtaining information, It is also a good example how in the inter-species competition an infornation war is going on and that creating better living and nesting conditions for tits also helps to improve the well-being of other species. In addition perhaps tits during the egg-laying period hide their eggs under the nesting materials as a means to avoid revealing their nest territories
Seppänen JT, Forsman JT, 2007. Intererspecific Social Learning: Novel Preference Can Be Acquired from a Competing Species. Current Biology 17: 1248–1252.
Seppänen JT, Forsman JT, Mönkkönen M, Krams I, Salmi T, 2011. New behavioural trait adopted or rejected by observing heterospecific tutor fitness. Proceedings of the Royal Society B. 278:1736-1741. doi: 10.1098/rspb.2010.1610.
