Thursday, November 3, 2011

Of Birds and Meat

I saw two birds yesterday.  One was standing on the pavement next to Lake Michigan, and the other was chopped into bits in a pan in my kitchen (also next to Lake Michigan).

Inland gull hanging out in my town.

Chicken hanging out in my kitchen.
The first bird is a type I see nearly every day as I'm walking around town.  I know it's a type of seagull, though I don't know which type (never was a birder).  Seagulls are found anywhere there's water, not just at the ocean.  When they are found away from the ocean, they're often called inland gulls.  Seagulls are regarded as pest birds by some, but I love them.  They are great scavengers, and this gull no doubt is helping to keep our lake shore clean of all kinds of technically edible trash.  Seagulls are incredible fliers.  I watched one fly during the giant storm last week with gusts of wind up to 60mph, and it was doing just fine.  Since gulls are strong fliers, it means their wing muscles are strong, tough and dark in color (more on this in a minute).

All we have of the second bird to compare it to the first is its wing muscles.  Chicken's wing muscles (not the actual wings, but the breast meat - the part that actually pulls on the wings) are giant by comparison to the gull's, but despite their size, they are weak, flaccid and white.  Chickens don't use their wings, really.  Commercial chickens have been bred to have giant breast muscles, since that's the most commercially profitable part to sell in the US.   Chickens don't fly a lot when they have access to the sky, but when kept in confinement as they grow in a factory, they can't fly at all.  

The white color of commercial chicken breast meat arises from a combination of factors.  First, the genetic characteristic of chickens being more walking birds than flying birds means that their wings aren't adapted to being strong.  Secondly, these birds'  enforced lifestyle is one of all standing or sitting and no flying.  Muscles adapted to working hard, and muscles that are exercised are usually darker in color, most apparent in poultry meat.  Dark meat's color comes from its large quantities of a reddish-brown-pigmented molecule called myoglobin.  Myoglobin does the same thing as hemoglobin (the dark red protein found in the blood), but it is found in the muscles.  Hemoglobin and myoglobin both hold oxygen from the air we have breathed in.  For muscles that work harder and at fast speeds, the need for oxygen is intense.  Having myoglobin present to store extra oxygen means that muscles can work harder and faster.  Muscles can genetically have more myoglobin in them, and the quantity of myoglobin increases with increased muscle usage.

Though I have never eaten or dissected an inland gull, it would probably have dark breast meat, since it uses its wing muscles so much.  If you have ever eaten duck breast, you may have noticed that it was very dark - because ducks are good fliers.  Duck leg meat is usually lighter than the breast meat.

Time for lunch?

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