Blue splotches / streaks + dots on egg shell

[tofuflower]

I have a feral chicken that we befriended and now she regularly lays in our yard. She's at least 2-3 years old since she was raising one chick 2.5 years ago. She usually has pale pink to off white colored eggs. Today she had these bluish streaks that follow the small dots. Her egg yesterday also had dots but not discoloration. In both pictures yesterday's egg is on the left, today's egg with bluish tint on the right.

I remember the tint was stronger before I washed it, but I neglected to take a picture beforehand because I thought it would wash off!

Is this normal pigmentation or a sign of something else? Sometimes their poop is blue after eating grass or weeds, but the nest looks free of any poop.

 

[rosemarythyme]

Looks like uneven pigmentation to me, or maybe the darker portion of the shell is slightly thinner than the other areas, hard to tell.

 

[tofuflower]

A more closeup pic. Unfortunately this is after washing -- the splotches were more blue initially, but I washed it first because I thought they would go away.

 

[rosemarythyme]

Hmm, still not sure. Have you tried cracking open the egg and taking a look at if there's any sign of porousness or thinness from the inside? If not, then it's probably just a weird pigmentation issue which shouldn't be a problem.

 

[tofuflower]

Oh!! Today I collected another egg and some of her black feathers were stuck on it. After peeling them off, I saw the same bluish pigment left on the shell. Mystery solved!

 

[BigBlueHen53]

Oh!! Today I collected another egg and some of her black feathers were stuck on it. After peeling them off, I saw the same bluish pigment left on the shell. Mystery solved!

Very interesting! May explain weird blackish streaks that sometimes appear on one very dark Marans egg I get ... it looks like a poop streak but washes off, taking egg pigment with it, and has no odor. Bet a black feather gets stuck on while the egg is still wet. Egg pigment sticks to the feather pigment and both wash off together! Indeed, mystery solved!