Reserva Ecológica Costanera Sur

Sitio realizado por aficionados a la observación de aves desde 10 de enero 2006

Gastroliths



Nicolás tells us: "I was walking to the Canal sudeste and ahead on the path, some 30 mts. I can see a bird pecking and giving little jumps. It was a Golden-billed Saltator. I was surprised to see it was pecking at small stones and pit. It takes them, keeps them in the bill and with a small jump swallows it quickly. It repeats the action and reminds me of someone taking some nasty medicine and being obliged to it does it quickly to get rid of it. Some time later it leaves the road and goes to a Chinese privet Ligustrum lucidum to eat fruits.
Then I checked the place and found that there were only small stones, there were no fruits scattered on the ground and the stones had no substance which the bird would like. I had the feeling that the saltator knew what it was doing and that these stones could possible aid in digestion. "

These small stones this juvenile of Golden-bill Saltator swallowed will help "chew" food. Since birds have no teeth the mastication is carried out in the muscular part of the stomach, named gizzard, and which is in the back part of the stomach. The front part of the stomach is the proventriculus which secretes digestive juices (enzimes and acids). Here we will concentrate on the gizzard which the area related to the stones.
The gizzard has the form of a disc and is better or worse developed depending on the type of food the bird takes. The gizzard has very powerful muscular walls which contract in alternated form to mechanically grind the food. It is the equivalent to our teeth. It is here in the gizzard where the stones lodge. They are known as gastroliths (stones of the stomach). Together with the action of the muscular walls the gastroliths make the process of digestion more efficient. But at the same time gastroliths get polished. The minerals contained are absorbed by the lower intestine and go into the bloodstream. Thus they become a nutritional supplement.
Golden-billed Saltator
01-06-13 © J. Simón Tagtachian
Golden-billed Saltator
01-06-13 © J. Simón Tagtachian
Golden-billed Saltator
01-06-13 © J. Simón Tagtachian
Golden-billed Saltator
01-06-13 © J. Simón Tagtachian