Breeding Starling Yellow Beak. 

The odd non Breeding Starling - black beak

Date: 13th June 2019. 8:07 am

Some birds change there plummage depending on the breeding season.  Starlings tend to develop spoted like things on there  plummage but with Starlings there beak changes colour. In the Autumn and Winter there 

Beaks start to turn Black. And in the Spring and Summer there Beaks turn yellow. some birds grow into breeding plummage or change colour  into non breeding plummage but some might be abit behind and not changed plummage or colour yet while some of the others in the flock already have there breeding or non breeding colours

But some are on time. there’s lots of factors involved like weather one hatched just before or after the other or if it hatched at the same time but there’s other factors aswell. 
The beak changeing depending on the season is unique to Starlings. I used mealworm fat balls that year. Last time I read about there beaks People have done studys but still havnt found out much about this phenomenon. I can’t remember what it’s called though. Do you know weather they have done any further study’s on the Beak colour change phenomenon?