There is also the influence of artificial light pollution at night.
Research in in North America and Europe, has shown that forest-breeding male songbirds near artificially-illuminated areas start their dawn chorus significantly earlier in the morning than those in forested areas that are not affected by artificial light. Birds that sing earlier may be getting less sleep and may be at a higher risk of predation. Moreover, females gauge the reproductive fitness of males from the timing, duration and quality of their singing; therefore, females may be attracted to mate with lower-quality males who have been impacted by light pollution. Species that start their dawn song earlier in the morning under natural conditions are affected much more by the exposure to artificial light than birds starting dawn song later in the morning. This can be explained in terms of interspecific variation in eye size (early-morning songsters have relatively large eyes), a reflection of greater visual capability at low light intensities.
Research by scientists at La Trobe University has shown that the Australian Magpie is one Australian bird species that is experiencing less sleep at night because of light pollution.
https://www.abc.net.au/news/2020-08-08/research-finds-light-pollution-disrupts-magpies-pigeons-sleep/12537800
Kind regards,
Stephen
Stephen Ambrose
Ryde NSW
From: Birding-Aus <> On Behalf Of Philip Veerman
Sent: 26 September 2022 7:52 PM
To: 'Peter Shute' <>; 'Birding-aus NEW' <>
Subject: Re: [Birding-Aus] Magpies singing at night
I recommend that the answer to all these style of questions is: “because their parents did”. In other words, it is something in their genetic makeup and you can apply that, to most zoology questions of that style. It is something that has been done and survived well in their evolutionary history, giving some benefit. Indeed likely going back to whatever species the magpie was, before it was the current species. Evidenced in that the behaviour is something occurring in many birds, so is in the genetic makeup of many birds. As to what is the adaptive advantage of them singing at night now, well that is a different question and there are many possible answers. But easy to simply suggest that it is territorial behaviour, exactly as it is in the daytime (and why wouldn’t it be?), allowing the magpie individuals to signal to neighbouring groups that they are in the area, or whatever other message it sends. Sending vocal signals may well be more effective at night, as there are normally less competing sounds around.
Philip
I have been asked to post this question:
'I gave a talk at my local library on Bird Watching. I was asked 'Why do Magpies sing at night?' I did not know. Does anyone know?
