Biologist Yelomer Samplonius and colleagues from the University of Groningen summed up the results of a 10-year observation of the breakdown of the natural rhythm of bird coexistence in the Netherlands, for which they blame global climate change. Scientists were targeting two species: the great tits (Parus major), which winter in Europe, and the pied flycatcher (Ficedula hypoleuca), which migrate to Africa for the winter. Previously, their coexistence looked like this: the tits bred their offspring before the flycatchers returned and flew away, and they quietly occupied their empty comfortable nests.
In 2007, Samplonius for the first time found in the nest of a tit, not just a dead, but a flycatcher brutally killed by it - the bird ate the brain from the punched skull of an opponent. Since then, dozens of such cases have been recorded, and the reason is simple: because of the early spring, flycatchers return to the Netherlands, when the nests are still occupied by titmouses. Those are a sedentary species, they are large and evil - and therefore easily kill small flycatchers, adapted to flight, but not to combat.
True, it also happens that the flycatchers do not come into conflict, but begin to "get" the clumsy titmouse, thereby forcing it to abandon the nest. And chicks of tits are already becoming victims. In addition, due to warm springs, edible caterpillars began to appear earlier, and the tits that feed on them began to build their nests proportionally earlier. And because of the warm winters that are already common in recent years, more and more birds survive until spring - and therefore, a nutritional deficiency is formed. But if suddenly the frost in Europe drags on, then a situation turns out when a horde of the same hungry flycatchers suddenly flies to the mass of hungry tits. And then the real massacre begins.
A similar, most apocalyptic scenario, Samplonius's colleagues observed only a few times, but the very fact of the constant conflict between titmouse and flycatchers for life and death has become a routine in the Netherlands. The good news is that while predominantly weak, sick or lonely males become victims on both sides, therefore the population of the two species remains stable. But when this "buffer" disappears, there will be a disaster for both species. And the reason for this is global warming and its consequences.