Effects of Traffic Disturbance and Night Illumination on London Starlings

Abstract

THAT the breeding period of birds with a relatively-brief annual reproductive season could be shifted to any time of the year by manipulating lighting conditions, regardless of temperatures, was first shown in 1924¹. The subject has since been investigated by numerous other workers, but a specific answer as to how the light induces the effects that can be so readily demonstrated has not yet been found. While it has been shown that the principle applies widely to birds, some forty species of which have now been examined by various investigators, it has also been shown to be effective in certain mammals, reptiles, amphibians and fish. Evidence that light falling on the eye, or other receptor, stimulates the pituitary, which in turn activates the gonads, is gathering weight, but is not yet wholly convincing.