Feeding fast food birds can change the course of their evolution

Researchers have found changes in the size of the beak in different species of birds in the Galapagos Islands and argue that the seemingly innocuous fun on feeding birds with human food can have serious consequences.

Researcher at the University of Massachusetts (USA) Luis De Leon (Luis De León) argues that feeding birds with poor-quality human food affects natural selection, which contributes to the formation of new species in the wild. The findings, published in the journal Evolutionary Applications, argue that at first glance harmless feeding of birds can change the evolution of the famous Darwin finches in Galapagos.

Galapagos finches (Darwin’s finches) are famous for inspiring Charles Darwin for his evolution work. Their common ancestor arrived in Galapagos about two million years ago, and since then Darwin’s finches have turned into more than a dozen recognized species, differing in body size, beak shape and behavior.

De Leon and his colleagues found in isolated natural conditions on the island of Santa Cruz, two species of finders with different beak sizes. When they carried out the same measurements in the neighboring, populated area, there were no differences between the size of the beak of the species. Comparing these results with data collected by other researchers in the 1970s, scientists found that the changes took place in the last 40-50 years. They suggested that this could be related to urbanization and the increasing population in this region – in particular, to the emergence of new food products in people.
Birds are eaten from egg trays left by researchers / © University of Massachusetts Boston
Using regular egg trays filled with natural seeds and unclean food, corn and rice, researchers found that finches really eat human food by identifying their preferences by weighing food before and after bird feeding.

Finches living in urban areas, almost exclusively feed on human food, preferring it to their natural diet. When the experiment was repeated in a place isolated from people, the finches ignored these trays. This indicates that ongoing urbanization in the Galapagos is destroying environmental differences.

“Finches change their diet for human junk food. We know that the diversity of species of these birds depends on the diet. All three or four species of ground finches in urban areas on St. Croix seem to converge on the same love of fast food. If this is the case, the selection pressure that would naturally keep them apart can loosen, which in turn can lead to the collapse of the chaffinch’s adaptive radiation, ”explains De Leon.

The researchers also found a strong desire for human food in birds on EG Beach, a small uninhabited area located 12 kilometers from the city of Puerto Ayora, which is popular with tourists. This suggests that human behavior, and not population density in the region, can be considered a major factor in bird feeding preferences, extending the effects of urbanization.

Now that researchers know that finches are changing their diet for unhealthy human food, they want to study the effects of the actual evolution of species on this island. A group of the same scientists will return to the Galapagos Islands in January and will be engaged in genetic analysis, studying the question of a possible increase in the flow of genes between the four species of ground finch. Now that the birds consume the same food, researchers want to know if they will continue to interbreed.