Lovebird getting darker

[Tichanpet]

I have two lovebirds Daisey and thunder.

They are adorable but it seems that my female lovebirds back feathers are turning darker.
Bot eat the same things the best seeds fresh fruit fresh vegetables plus I let them fly for a few hrs everyday in the house.

The only difference is that Daisey gets once a month a shot to bring down her hormones so that she will not have any babies.

I also spray her with a bird tropical spray soother because she has a tendency of plucking the feathers arounder her rump.
She is over pruning.

Help me please.
My male lovebird thunder is fine he doesn't change colors have all his wings and feathers and do not over prune.

 

[EmilyC]

How old are your birds?

 

[andreavizzuso]

Ciao;
It's very strange;
It would be interesting to analyze the pics, before and after the transformation;
I'm sure there is a logical explaination;
how old is she; maybe she is molting and maybe she has a dark factor that you ignored;
could you post some pics?