Animal behaviour: Best and brightest.

The article cites a study conducted by Ismael Galván of the National Museum of Natural Sciences in Madrid, Spain and his colleagues to examine the difference in great-tit (Parus major) chicks tarsus' length, which is an approach to judge growth rate. The researchers have considered to paint the yellow feathers of the said chicks with a marker pen that reduces the ultraviolet reflectance of a surface. It is determined that maintaining the ultraviolet reflectance is one way to identify how fit a chick is and which the parents feed most.