Many birds produce a bolus (mass) which is made up of undigested parts of the bird’s food, consisting of feathers, hair, shells, bills, claws, teeth,etc… The birds vomit the pellets which will drop to the ground or in the water wherever they are. They can be gray or brown, and are oval in shape. My first sighting of this event was at the Meadowlands in New Jersey. I photographed a Lesser Yellowlegs coughing up what appeared to be a capsule. Curious as to what it was I did some research. I knew that Owls ate their food whole and expelled pellets that contained the bones and fur which they could not digest. I have also seen those pellets at the base of their roosting sites. I had no idea that smaller shorebirds would spew out smaller boluses basically in the same way. Birds do not chew their food. They usually tilt their head back to force the food down. Some birds will crush their food first with their beak.
Food eaten in a hurry by some birds in order to avoid predators, is stored in an organ called the crop until it can be digested later. Food stored there will eventually make it’s way to the stomach where it will pass into the gizzard. The gizzard will grinds the food up into small pieces. The gizzard serves as a place where items such as hair and bones, are collected together and formed into a ball or bolus. I think of the gizzard as a trash compactor.
This image was sent in by Patrick Sparkman. He captured this image at Cedar Creek Country Club, Mabank Texas, Canon 1d MkIV Canon 800 f5.6, 1/1250 sec at f / 5.6, ISO 800
references:http://foam-friends-of-albatross-on-midway.blogspot.com/2010/06/whats-bolus-burrito.html
http://www.earthlife.net/birds/digestion.html
Thank you for the education. I thought it was only Hawks and Owls that produced a bolus. Good capture!
Hugh, Thanks, I was surprised the first time I saw this. I now look for it!!
Interesting article and great shots.
Fred, Thanks for stopping by and commenting. Much appreciated.