This essay is from Audubon California:
Open top vertical pipes are a hazard to birds, lizards, small mammals and other wildlife that get into these pipes and are unable to get out. Birds looking for nest cavities, animals escaping from predators or lizards just scampering into open pipes are frequently trapped. This leads to a miserable death from starvation and exposure, which is completely unnecessary.
Last fall on a property adjacent to the Kern River Preserve, a 20 foot tall by 8 inch diameter vent tube on an abandoned irrigation system rusted and fell over. When Audubon stewardship staff picked up the pipe they were shocked to find inside a 7 foot long, black mass composed entirely of decomposed carcasses of hundreds of dead birds and animals including kestrels, flickers, bluebirds and fence lizards. The date etched into the concrete at the base of this vent pipe showed that it had been in place for over 50 years. All that time animals had been silently suffering and dying in this trap as unsuspecting people went about their business nearby.
After learning about this problem, Kern River Preserve staff started seeing open topped pipes all over the landscape on our Preserve and on neighboring lands. We were disgusted by the senseless loss of life in pipes as small as 1 inch and up to 10 inches in diameter. We immediately began to remove, cap or screen open topped pipes found on our preserve as well as neighboring properties – there is still a lot of work to do.
Please look around and you will find open top vertical pipes on signs, fence posts, survey markers, buildings and irrigation systems. All responsible landowners should cap, close, remove or screen all open topped pipes on their property.