How old is she? Is this a new behavior, or something she has always done? If the latter, as long as she seems otherwise fine and doesn't actually fall, it's probably just a quirk of hers.
Sometimes they do that when their about to sleep and then they'll grind their beaks and tuck their head in. Other times they could do that when something spooked them.
She's about a year old, both of my cockatiels have bald patches, also when i first got her and she wasn't comfortable, she never leaned like this, now that she is getting used to the surroundings she would lean like this, especially if I introduce something new in the cage, like when I change their tray, I would place a newspaper below the cage and then she'll stare at the paper for hours, I think she maybe just curious, because her crest is always up to the MAX.
I was hoping it was a call to get some lovely head scratches haha, but she's always alert, her crest is always up to the maxxxxxxx, she's beginning to become less aggressive <3 and that's a plus! I might be able to tame her before I could tame the male hehe (Still afraid of hands and fingers, but the fear is reducing day by day! yippie! )
B&G Macaw, Galah, 5 cockatiels, 50 billion and a half budgies. We breed and do rescue. Too many to list each individual's name and age etc, but they are each individuals and loved dearly.
Leaning forward with outstretched tail and wing feathers is a display behavior(and quite impressive!) Does your bird ever fan out her pretty pretty feathers while leaning?
I see no toys or activities in the cage. Perhaps she is simply very, very bored.
What would you do if locked in a cage with nothing to do? Probably starts at the floor or ceiling for hours at a time. I'm also only seeing 2 identical diameter straight dowel perches. Not having varied perches (varied in width, texture etc...) can hurt their feet very badly due to being stuck in the same position 24/7.
Get some toys and new perches from the cage and I bet you'll find the behavior stops or becomes less frequent once she has a more comfortable place to perch and things to occupy her time!
agreed with Kiwi. Toys and different perches. I'd argue that dowel perches shouldn't be sold any more because they're just not good for them.
You want it to look similar to the picture below, you can see there's lots of different perches all of different sizes and lots to do and play with so it keeps their brain working and stops them losing their minds