Large raptor -white chest

In our recording area on the Eastern side of the Yorkshire Dales we have a number of light phase Buzzards, as these are showing over a number of years it must be more than just one years birds maybe something generic. Some are so light coloured some less experienced birders mistake them for male Hen Harriers

And Buzzards are mistaken for Ospreys occasionally as well.

Interesting question, Dave. I hope Pete does not mind me butting in, but going to today's usual source, Mr Google, one of the zillions of sites offered listed 43 definitions of 'phase.' Keeping in mind that everything on the net can be incorrect, most definitions involved a 'phase' being a step along the way of a linear or circular process, as in your question. But the definitions below seem to allow for Pete's usage as well; here are a few of the 43 from this link, not all of which offer examples (and the last one offered intrigued me, must investigate further--possibly in my next life!): www.yourdictionary.com/phase
---Any of the ways in which something may be observed, considered, or presented; aspect; side; part:
'A problem with many phases.'
---That which is exhibited to the eye; the appearance which anything manifests, especially any one among different and varying appearances of the same object.
---Any appearance or aspect of an object of mental apprehension or view:
'The problem has many phases.'
---(genetics) A haplotype.
---(genetics, informal) To determine haplotypes in (data) when genotypes are known.
---(obsolete) Passover.

Interesting Ann, having been married to an ex language teacher for nearly 49 years I might carefully pass that in her direction.

Pete, are you referring to the book I mentioned?

Yes It wad Ann sorry if it wasn't clear it was the end of a hard day

Just to add in my experience it is fairly common to use ‘phase’ in this context. I’ve seen some very pale individuals in Northumberland over the years, but not very often at all.

Dave I think it is used in Dick Forsmans guides and early versions of the Collins B o P photo guides It may be more of an UK thing but after using it (wrongly?) for most of my birding time I may find it difficult to change.

Cardboard box? You were lucky! even more etc etc lol