Scientists have found out whether it is beneficial for birds to migrate to warm regions

Scientists have found out whether it is beneficial for birds to migrate to warm regions

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Migratory birds cover thousands of kilometers on their way to warm regions, expend a lot of energy and avoid potential threats.

Previously, scientists assumed that migration, despite its complexity, brings significant benefits for birds. During the winter in warm regions, they save a lot of energy, because they do not spend it to keep warm.

However, a new study by German scientists has shown that this opinion is wrong.

His results published in the scientific journal Nature Ecology & Evolution, informs The New York Times.

Scientists studied blackbirds that spend the summer in the forests of southern Germany. Most of these birds stay for the winter, but about a quarter migrate, flying south in October and November.

Migrant blackbirds spend the winter in southern Europe or northern Africa, and return to Germany in early April.

Scientists implanted 118 blackbirds with tiny data recorders, functionally similar to fitness watches. 83 of them were able to capture information for downloading.

These devices recorded the body temperature and heart rate of the birds every 30 minutes for 9 months, from September to May. Heart rate is an indicator of energy expenditure. The more energy the bird uses, the higher this frequency is.

The data confirmed that the migration route itself, which is an average of 800 kilometers, required additional energy expenditure from the birds. Migrant blackbirds began to save it in advance. Four weeks before their departure from Germany, their heart rate decreased at night. And after a week and a half – night body temperature.

“It looks like they’re turning off their thermostat.” – noted the co-author of the study, Nils Linek.

These physiological changes, which were not observed in native birds, helped the migrants conserve energy before the flight.

However, during the winter, the heart rate of the migrants was not lower than that of those who remained in Germany. And during the entire migration cycle, both groups of birds spent the same amount of energy.

The warmer weather had its benefits. Throughout the winter, migrants maintained a slightly higher body temperature than blackbirds in Germany. They spent much less energy on it.

To keep warm, a blackbird in Germany spent an additional 18,600 kilojoules during the winter – approximately 4,400 calories. But it was not reflected in the heart rate.

The scientists came to the conclusion that the energy that the migrants saved on thermoregulation, they spent on something else. However, it is not known what exactly. Perhaps migrants in unfamiliar territory should have been especially alert to threats. Or spent this energy on reproductive function.

We will remind, scientists discoveredthat crows can count, but they don’t do it like humans.