[techmind (OP)]

I believe it is well-known that streetlamps do affect the behaviour of wildlife, including birds.

I hear local council (in particular, Cllr Mathew Shuter) has been seriously considering replacing all the streetlamps in Cambridgeshire with LED lighting (the present installed base is dominated by low-pressure sodium, with some high-pressure sodium on a handful of more main roads). Presumably white LEDs (which also have a pronounced blue peak in their spectrum).

Although the LEDs will give vastly superior colour-performance, sodium is reasonably efficient and simple and reliable; I'm skeptical that wholesale replacement with LED is actually a smart move. It seems like the current plan is to hold off for a few years yet.

Given the relatively recent discovery of the effect of blue wavelengths in setting human biological clocks / circadian rhythms, I wondered if there's potentially big effects "unforeseen consequences" on wildlife of replacing the orangey sodium lamps with white (and strong blue) light...?

Does anyone know if there is any research? Should the council be more formally advised that this is a potential issue?

[alancalverd]

It would be far better to remove lighting from most roads, especially motorways, where scattered light from overhead lamps seriously reduces the conspicuity of vehicle lights in fog and rain.   

Since the sodium spectrum is very narrow but apparently adequate for human navigation in cities, it would make sense to replace sodium lamps with "warm white" or even yellow LEDs with very little blue content. Even the best brilliant white LEDs have spectral gaps which distorts color rendition compared with daylight, and scotoptic vision is more sensitive at the red end of the spectrum, so why bother with the blue end at all?