Birds use human waste to boost "flirtation" and attract females

Researchers from the University of Exeter, in the United Kingdom, have identified that urbanization is altering the mating rituals of the greater satin bird (Chlamydera nuchalis). The study points out that males who live in cities use anthropogenic materials, such as plastics, glass and metallic threads, to decorate their cutting structures (known as bowers).

According to the researchers, it was found that these objects replace natural items, such as fruits and sticks, as they are more visually impactful for females.

Visual advantage
According to a survey carried out in Queensland, Australia, urban nests have, on average, 4.74 times more decorations than those located in rural areas.

Objects found in cities tend to be larger, with more saturated colors and greater chromatic variation.

The preference for "trash" occurs because materials such as red plastic and green glass offer a superior visual contrast in relation to the environment, making it easier for females to detect the nest.

In addition, these artificial items are more durable and persist longer in nature than organic resources that rot quickly.

Preference
A choice experiment revealed that the attraction to man-made materials is not exclusive to city birds.

When offered both natural and artificial items, males from rural areas also preferred anthropogenic materials.

The results indicate that birds in preserved areas use natural resources only due to the lack of availability of more "flashy" options. In controlled tests, birds were 10.2 times more likely to select decorations of urban origin to compose their nests.

Impacts on reproduction and risks
The use of urban waste allows males to create more prominent displays with lower energy costs, as they do not need to replace objects frequently. However, research warns of the risks of this adaptation.

The accumulation of wires and plastic in nests can lead to entanglement of adults and chicks, as well as the risk of accidental ingestion of debris.

Although urbanization provides materials that enhance the success of "flirting", the long-term health consequences of greater satinbird populations still require further studies to be fully understood.

Source: CNN