Owl hole

The birds prey on farm vermin, and therefore benefit the human owner of the structure in a symbiotic relationship.

[1] Locally superabundant rodent species in the weight class of several grams per individual usually make up the single largest proportion of prey.

[2] With the advent of modern pesticides the perceived value of biological control has dramatically decreased to the point that few owl holes are still in active use.

The perch or landing platform was made from stone or wood and usually sloped slightly downward to prevent rain water from entering the building.

The entry holes are usually oblong and six to nine inches (152–228 mm)[3] that permits a single bird to enter with space for a safe landing and passage to the interior whilst at the same time excluding larger predators.