The peculiar case of the pink lady

Some years ago now, a kākā kura (red-morph kākā) turned up at Zealandia. What was curious is that she had hatched at Zealandia, was banded, and was originally a normal-coloured kākā (find out more about the kākā kura in this earlier story...). To date, she's been the only kākā kura seen in the Zealandia population.

Kākā "Pinky-B" in June, 2021 after moulting. Her entire head is now mostly pinky-orange and her other feathering is perhaps more orange/burgundy-toned than normal too.

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That is until a month ago, when the kākā kura's mum, Pinky-B, showed up with a pink head! She was obviously going through a moult and when I saw her again about a month later she was even pinker with perhaps some orange/burgundy tones in her brown feathers. Now I've known Pinky-B since 2008 when I first started nestbox monitoring, and she's always been a normal-looking kākā with a grey head, yellow-orange cheeks, grey-brown top feathers, and reddish underfluffies. Why now, after all these years, would she start turning pink?
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Kākā "Pinky-B" in April, while molting. The pinky-orange feathers on the top of her head are just becoming apparent.

I know I have a lot of vet, ornithologist, and bird researcher readers, so I'd love to know your thoughts as to why she'd be experiencing a colour change! My (possibly incorrect) understanding was that a colour morph was a genetic variation so we'd expect a morph to be that colour throughout its life span. Is there perhaps an epigenetic influence in the environment that's switching these genes on? Or is it perhaps a metabolic issue? 

By way of comparison, here's a couple of photos showing the earlier kākā kura (daughter of Pinky-B), who was far more orangy-pink all over, and a normal-coloured kākā (other than the gold tummy feathers). 

The original kākā kura (Pinky-B's daughter) from 2017.

And another comparison, a young kākā with more normal colouring, other than the two gold feathers on his tum - another peculiarity about the Zealandia population and a story for another day.