Pigeon Milk?!?

Posted on by frankwmcarr

Believe it or not, while pigeons (and doves) may be birds, the adults who are raising young have a specially designed form of nourishing them that is parallel to (but nothing like!) “true” milks that mammals produce.

The digestive system consists, briefly, of the mouth (inside their bill, of course!), the esophagus, the crop (the center of today’s discussion), the proventriculus (the first of a two-part “stomach” region where some digestion takes place), the gizzard (the second stomach portion, where birds “chew”, because food is swallowed whole as the bills lack teeth), the intestines (supplied by the liver and pancreas), and all the way down to the cloaca, the common exit for wastes and reproductive products (sperm/egg).  Interestingly enough, the forces of digestion can push the contents of the gizzard back to the proventriculus.

Now that we have mapped out the digestive system, let’s focus on the crop, where this mysterious milk is derived.  This substance, having a curdled, rice-like appearance, is derived from the enlarged crop of a lactating pigeon (or similar bird, such as a dove, flamingo or male Emperor Penguin).

Pigeon Milk
(A) Non-lactating crop (B) Lactating form with its two enlarged lobes (C) Discharged pigeon “milk” Source: http://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-12-452

This secretion is rich in protein and also contains fat and more modest amounts of carbohydrates and minerals, among other nutrients.

Aren’t you glad you’re not a pigeon or similar bird?  The milk sure looks quite gross to me.  But hey, it’s all perspective.

(Source:  http://people.eku.edu/ritchisong/birddigestion.html)

Why Owls Can Turn their Heads Toward their Backs

Posted on by frankwmcarr

Owls, aside from their folklore-based wisdom, bear one capacity that we humans can only dream of:  viewing what’s behind them without turning around.  Their heads can turn 270° from the frontal position, which is really just 90° in the opposite direction.

However, what really warrants this need is 1) their very large, almost motionless eyes, and 2) the arterial organization toward the brain.

In owls, the vertebrae give ample space in certain arteries, which in humans are confined to small spaces.  Also, the carotid artery, a “confined” artery, happens to be at the central axis of rotation.  And like humans, predatory birds, and animal able to hunt, their vision is binocular and thus with good depth perception.

These details and more, can be seen in the attached YouTube video below, courtesy of the principal source (at the bottom of the page, which you can also visit.  By the way, this observation was not primarily studied by ornithologists, but by medical doctors who specialize in vascular issues.  Their insight is highly appreciated.

 

With the eyeful they receive on a daily basis, no wonder they’re considered so “wise.”

Source:  people.eku.edu/ritchisong/birdbrain2.htm