Does the flicker frequency of fluorescent lighting affect the welfare of captive European starlings?

It is common practice for captive birds to be kept under fluorescent lighting, which typically flickers at either 100Hz (UK) or 120 Hz (USA). Such lighting was developed for human vision and it is thought that birds may be able to detect higher frequencies of flicker than humans. For humans, 100Hz fluorescent lighting has been linked to eyestrain, headaches and migraine, even though this rate of flicker is above the human perceptual flicker-fusion frequency of around 60 Hz. Keeping birds under 100 Hz lighting is therefore potentially detrimental to their welfare. We studied the preferences of wild-caught European starlings, Sturnus vulgaris, for high-frequency (HF, >30 kHz) fluorescent lighting versus conventional low-frequency (LF, 100 Hz) fluorescent lighting. The flicker frequency of the HF lighting would be undetectable to the nervous system of any animal. We also exposed starlings to either HF or LF light for 2 weeks, and investigated the degree of stress caused by each environment by monitoring their behaviour and plasma corticosterone levels. Groups of starlings showed a preference for HF lighting over LF lighting (P < 0.001), which indicates that they can detect a difference between the two lighting conditions and find the HF lighting preferable. However, there were no measurable differences in behaviour or plasma corticosterone levels when the birds were housed under either HF or LF for 2 weeks, thus providing initial evidence that housing starlings under 100Hz lighting may not be detrimental to the welfare of starlings during early captivity. (C) 2003 Elsevier B.V. All rights reserved.