GEORGE NEWS - James Fraser-Lyle sent these photos of two owl 'pellets' that he found on the Gwaiing bridge construction site where he works. He was amazed when a colleague told him what these actually were and wanted to share it with other readers.
George Herald contacted CapeNature for more information and fauna ecologist Dr Martine Jordaan explained:
Owls feed mainly on rodents and other small mammals and typically swallow their prey whole or in large chunks. As owls do not have crops like most other birds, the food passes directly to the first stomach chamber, called the proventriculus, and then to the second chamber, the gizzard.
Here indigestible material such as teeth, fur and bones are churned into a tightly packed mass through the grinding actions of the gizzard and the digestive acid and enzymes of the stomach.
Once the pellet is formed, it moves from the gizzard back to the first part of the stomach where it can remain for as long as 10 to 20 hours before being expelled.
The pellet must be expelled as the hard bits such as bones may cause damage to the owl's lower digestive tract if it passed through as scat.
Pellets typically form several hours after the owl has eaten and if multiple prey items have been consumed in a short while, all these will be processed into a single pellet. The presence of a pellet prevents the owl from feeding again, so the pellet is often regurgitated shortly before hunting again.
The outside of the pellets is covered in animal fur from the prey and digestive slime from the gizzard.
Owls cannot digest the bones as the digestive juices of owls are less acidic than that of other birds of prey.
Their prey base depends on the owl species in question and can be highly variable. Most owls feed on rodents and other similar-sized small mammals and reptiles.
Larger species of owls such as Verreux's eagle-owl is known to take larger prey such as spring hare, hyrax, weasels, small species of primates (e.g. vervet monkeys).
Dissecting owl pellets and identifying the bones provide valuable information on both the owl's diet as well as the animal diversity of the area where it feeds.
The pellets found on the Gwaiing bridge construction site. James Fraser-Lyle suspects the owl nests on the underside of the bridge.
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