Barn owls are magnificent creatures that are considered the most widely distributed species of owl, as well as the most widespread of all birds. Unfortunately, there are many things that threaten their existence. The biggest threat, which is not uncommon amongst many creatures, is habitat loss. Another big factor for their decline is the increased use of rodenticide poison or "rat poison." The regulations on rat poison are not very strict and the damage that is done by the poison not only harms the rodents, but also can harm wildlife and pets, whether it's intentionally or unintentionally.
Statistics from the Predatory Bird Monitoring Scheme show that in 1983 the proportion of dead barn owls found to have rodenticide was 5%; by 2010 this had increased to a staggering 91%. The Barn Owl Trust says that 80-90% of farms use rodenticides in the UK. The problem with this is that most have no idea about the risk to wildlife and pets. Some people will cover the bait so that other animals will not be poisoned, but the poisoned rodents take 3-14 days to die once they ingest the poison. By then, they are often eaten by predators, who are then secondarily poisoned.
But how much of an impact is the poison really making? Well, unlike many other raptors, barn owls are not territorial so they can live in close proximity to each other. This is great because they are excellent hunters and often hunt for more than they need. Barn owls also tend to have large families. Using rodent poison is counterproductive because if an owl or owlet eats poisoned rodents and then ends up dying, that is 3-5,000 rodents that could have been eradicated by the family!
Some organizations and individuals have taken steps to promote safer pest control, educate the public on the problems with rat poison, and come up with safer options for getting rid of unwanted rodents. In fact, there are strides being made in California with the California Department of Pesticide Regulation instilling a new rule that would prevent consumers from buying many types of pesticides for at-home use due to the potential harm on pets and wildlife. They are ordering these products off the shelves by July 1st. One manufacturer of d-CON rat poison is suing the California Department of Pesticide Regulation, arguing that the agency has overstepped its authority. A spokesperson for d-Con says, "We remain concerned that this decision will result in the increased use of alternative products which contain a powerful neurotoxin with no known antidote in the case of accidental exposure."
If you are interested in helping the barn owl population, look into installing owl boxes in your community and encourage your friends and family to not only look at alternatives to rodent poison, but also learn about the harm it does to wildlife and pets.