10/22/2008

Screech owl pellet

It appears that the Screech owl has moved to a new roost now that the Birch tree is pretty much bear, except for a few die hard leaves. I assume the Screech has moved over to the pines and it would be next to impossible to track it down in the dense foliage. I was lucky enough to find two owl pellets below the old roosting spot which means the little guy was in that spot for at least two nights. I had noticed some whitening on the walk way and thought it was an owl, but never looked up - DAH!

Size of owl pellet in relation to a quarter
World Owl Trust: "Firstly owls have comparatively weak bills and often prey that isn’t too large is swallowed whole which leaves the skeleton of the prey, including the skull, intact. Unlike most other birds, owls have no crop, and the food passes straight into the foregut (they do not posses a true stomach). The acid in the owl’s gut is rather weak with a pH of 2.2 - 2.5 which is the same as vinegar, this compares to diurnal birds of prey which have a pH of 1.3 - 1.8, which is approaching the pH of concentrated hydrochloric acid. This means that owls can only digest the soft tissues. The bones, fur and feathers remain virtually intact. The opening from the foregut into the rest of the digestive tract is small and prevents any undigested material from passing through. Instead, it remains behind where it is compacted into an oval pellet and is then actively regurgitated back up through the oesophagus. Pellets, therefore, contain bones including intact skulls, fur, feathers, the chitinous exoskeletons of insects and even the chaetae (bristles) from earthworms and so discovering what owls have been eating is quite straightforward.

Regurgitating a pellet is a voluntary act on the owl’s part and in the wild most birds will produce one prior to leaving the roost for hunting. Often, another smaller pellet will be produced during the night before the second main period of hunting around dawn. The size, shape and appearance of the pellet is normally characteristic of the owl species, certainly amongst British Owls".

2 comments:

Anonymous said...

"How Great Are Thy Works, O Lord!"

Owlman said...

Very true - a marvel of nature!