The invention relates to a light source for generating light having a spectral emittance in at least a part of the range of 380 nm to 780 nm, the light having a spectral power distribution E(λ) as a function of the wavelength λ, and a general color-rendering index Ra, wherein the ratio of the integral spectral power distribution over a first range of 575 nm≦λ≦650 nm to that of a second range of 380 nm≦λ≦780 nm is given by the relation: and wherein Bb, ≦0.15 and Ra≧20. The light generated by the light source has a relatively small disturbing effect on migrating birds, while it still allows acceptable visibility for human beings.