Cochin is a breed not a color, so that knowledge can't help with color predicting as Cochins come in many colors and patterns.
We would need to know the color of dad and mom to have any kind of accurate guess. Also mixed breeds are hard to determine final outcomes as there are a lot of genes mixing about...and not all colors are dominant nor patterns. It all depends on how the genes line up for each chick.
From the chick down, I can guess that they are not likely from the same mom and dad as that is some diverse patterning with some showing influence from what is usually dominant black. Black can also dominate if barred was used in mom (you can get sex linking then).
I am guessing you'll have black based birds with possibly some patterning from the black chicks..what kind I've no idea as I've no idea of the color combinations possible from mom and dad's colors and what you've got from the rest of the flock.
The chipmunk chick will likely be a red/brown based partridge when grown.
The yellow chicks with some black dotting can be anything from wheaten yellow/light red partridging to white birds with possibly some black spotting, or not...that can drop out.
You can play with possible feather results by entering the color patterns of the rooster and hen here:
http://www.breedbook.org/?action=geneticscalculator&tab=CHICKEN
Placing the possible combinations of the color base and pattern of the parents through the calculator is a much better indicator than down color alone as the down colors can represent a lot of different final adult patterns.
Cute chicks. Enjoy them and the fun of your backyard mixes. They are colorful surprises.
LofMc
