EPOD 20th - Birds on the Move

September 22, 2020

Storni-di-Stormi

We’re celebrating 20 years of Earth Science Picture of the Day during the month of September! Today’s photo features a popular EPOD from the past. Thanks to all of our followers (on the blog, Facebook, Instagram and Twitter) for supporting us. Thanks also to all of you who’ve submitted your photos. We’re most appreciative. This EPOD was originally published February 10, 2020.

Photographer: Marco Meniero
Summary Author: Marco Meniero

Shown above are images of flocks of starlings as observed earlier this winter from the Viterbo Airport Control Tower in Viterbo, Italy. Even if you live in the city, you’ve likely noticed the choreography of bird flocks (most likely starlings or pigeons) as they twist and turn across the sky. But what drives their movements? How do they coordinate with their feathered flight companions? Why is it that birds of a feather flock together?

In a study published several years ago in the Proceedings of the National Academy of Sciences, researchers from the University of Warwick suggest that these birds move in such a way as to achieve the maximum density allowing them to still have a good view of their surrounding space. This will occur they receive light from many directions, a condition known as marginal opacity. It seems to be that changes in the relationship between shadow and light alert the birds to fly in such a way to achieve this. The scientists decided to test their hypothesis using a computer simulation.

Virtual starlings were therefore been programmed to follow their closest companion and move to the area of the flock from which they have access to the greatest amount of information. The results of the experiment showed that programmed in this way, the virtual starlings join in compact groups and move in a way that’s superimposable to how real starlings are observed to fly. Note also the rose-colored Belt of Venus and the rising of the Earth’s shadow. Photo taken on January 15, 2020.

[9/20]