28.08.2016 change 28.08.2016

The smart vs. the sophisticated, or how urbanization messes in the bird world

The process of formation and expansion of cities means that some species of birds, the more specialized ones - are being replaced by others, which easily learn to live in a new environment and use new sources of food - according to a study described in the "Global Ecology and Biogeography".

This mechanism has been studied by international team of scientists: Federico Morelli from the Czech University of Life Sciences in Prague, Yanina Benedetti of Centro Naturalistico Sammarinese in San Marino, Anders Pape Moller of the French National Center for Scientific Research, Jukka Jokimäki of the University of Lapland (Finland), Raivo Mänd of University of Tartu (Estonia), and Prof. Piotr Tryjanowski from the University of Life Sciences in Poznań.

The authors draw attention to the existence of more and less specialized species. The less specialized ones are able to survive in different conditions and use a variety of food sources. They are cosmopolitans, capable of finding food and raising their young almost everywhere. They are also relatively young species from an evolutionary point of view. The situation is different in the case of species that have occupied a certain environment for a very long time. They had more time to develop body structures or behaviours that facilitate the use of very specific sources of food or characteristics of a particular environment to build a nest, or even to hide from predators. However, the greater the specialization, the more difficult it is to change the lifestyle in the event of a sudden change of conditions. Theoretically, one can adapt to any conditions, in practice, often there is not enough time to do it, which usually means extinction.

The process in which the less specialized species replace the "specialists", is happening right next to us: in cities and on their outskirts.

Scientists have studied it in six European countries: Poland, Spain, France, Estonia, Norway and Finland. They confirmed that different species of birds can be found in cities and in villages, and that the birds found in the cities are mainly evolutionarily younger species, and more versatile ones. "Species evolutionarily youngest have a greater potential for urbanization - that is, the potential to change, which they use, among other things, by adapting to urban conditions. Perhaps they can make better use of the opportunities offered by the city" - explained Prof. Piotr Tryjanowski, director of the Institute of Zoology, University of Life Sciences in Poznań.

These species are successful in the cities, quite literally: they occupy nesting and food niches, which in other circumstances could be used by someone else. "Their success becomes a whip for other species, which in part must give way - the professor said. - The fact that one species is successful and another not, depends on a number of factors, including the way the brain is built. The most successful are the species with reduced antropophobia - those that are able to understand that people do them no harm".

The zoologist suggests that winter may also be the key period. The birds that have learned to use food provided by humans survive.

Because the number of species that function well in urban areas is relatively small, their success leads to homogenisation of groupings of animals. It means that although bird populations in the cities grow, at the same time they are becoming more homogeneous, and their evolutionary potential is smaller than the birds in the area.

"In a few decades or centuries there will be more birds in cities, but we\'ll see only a selected group of species" - summarised Prof. Tryjanowski.

Which species known in Poland will fare better in the cities? Prof. Tryjanowski bets on redstart and blackcap. He added that if the same study were conducted half a century ago, half of the species today considered successful would not be found in cities. "Even the hooded crow or common wood pigeon, today considered typically urban species" - he said.

Although most of us are urban residents (according to the UN since 2008 more than half of all people living on Earth live in the cities), few people realize that the process of urbanization is a slippery slope. The cities are among the fastest expanding forms of the use of land in the world. The more we know about how the expansion of cities affects our environment - the greater the chance that we will learn to protect it.

More about the research project in the article (doi:10.1111/1365-2664.12715)

PAP - Science and Scholarship in Poland, Anna Ślązak

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