barespots with dry sores... Is it some kind of bug? [photos]

[shirauo]

We have 4 hens, all about 1.5 yrs old and pretty fat & healthy
We noticed that instead of the 3-4 eggs we've been getting regularly, we've suddenly started getting only 2/day the past couple of days. Upon investigating, I noticed that the underbelly of one of the chickens is bare in places (like she's been picking at it) and there was a dry scab-like spot of skin. It's not really a wound like from overzealous pecking (there's no blood), it's like a deep yellow. No pus- but I wonder if it's some kind of bug.

I looked up breast blisters, cuz it turns out they ALL have these on their underbellies- near their breast bones, but it looks like breast blisters are more fluid-filled.

The birds seemed to be happily ranging, eating & drinking as usual with normal droppings. I'm spreading out some extra DE in their coop/food on them. But have no idea what this is & am hoping this is something I can remedy.

The chickens have a coop with deep litter straw bedding, of which I shoveled some out last week & spread some clean, fresh straw... maybe I turned something up? They are confined overnight & are "let-out" to range for a few to several hours each day, depending on the family schedule (we like to be around because of predators).

Here are photos of the "sores":

 

[mypicklebird]

These can be due to damage jumping off of high perches onto hard surfaces in heavy bodied birds. Sometimes perches with sharp edges can cause pressure sores as well. This area can rest on the edge of a perch when they are roosting, as well as smack into the ground when they jump off of things. Check their feet too.
Rounded edges on perches if your perches have sharp edges, and padded under perch landing areas (extra hay, chips ect)