Often, we at NJ Audubon (and other organizations concerned about birds) receive queries from concerned residents about injured or dead birds. Not too long ago, a New Jersey resident reported having spotted a rare owl in a backyard spruce tree. They rushed to get a look at what was later determined to be an exotic barred owl — on New Jersey’s threatened list and never seen in this particular town before. But upon finding the owl, sitting on the ground, their excitement turned to dismay. The bird was clearly in distress. The resident, an experienced field ornithologist, carefully picked up the owl, discovered blood on its belly and under its tail, and knew what had happened because they had seen it before. The bird must have consumed poison. Moments later, the mysterious-looking owl — best known for its distinctive “Who cooks for you?” call — was dead. Perhaps you or someone you know have had a similar experience.
So, how did the owl get poisoned?
To answer this question, we need to turn to rats. Rats are a problem. To control the problem, many building owners rely on a number of approaches to kill or repel them — some are humane and others, well, are not. A last-resort option is the use of bait stations containing second-generation anticoagulant pesticides. These are powerful chemicals that cause internal bleeding and often a slow death for rodents, and for any raptor or mammal that consumes the poisoned rat second-hand. Recently, there have been several cases in which raptors in the state have died or been seriously injured from ingesting these rat poisons. These include a bald eagle, a great horned owl, a Cooper’s hawk and multiple red-tailed hawks. California has banned these poison baits, and other states are looking into it, as well. While there is currently no centralized database in the state for tracking this information, the state Department of Environmental Protection has recently hired a pathologist who will be working with veterinarians and raptor recovery centers to help track these cases.
These rodenticides — known by the trade names brodifacoum, bromadiolone, difenacoum and difethialone — were developed in the 1970s to control rodents that were resistant to first-generation anticoagulants. The properties that make the second generation more effective rodenticides also make them more toxic to nontarget species that feed on the rodents. These rodenticides are also quite toxic to humans. Because the bait stations contain these odious poisons, they are already restricted by the Environmental Protection Agency for use only by professional applicators. They are not allowed to be sold to consumers but can only be present in products in containers and installed by professional applicators. In New Jersey, schools are prohibited from using these poison bait stations altogether because they are considered a threat to wildlife, pets and children.
So, while there are some controls, they are not enough to protect species that feed on the poisoned rats and mice. These bait stations are supposed to be used as a last resort — not the first solution, a cure-all or an ongoing solution. However, because they are very effective at killing rats, some businesses continue to use them regularly.
The widespread use of these poisons endangers all owls, hawks and other wildlife (and pets) that prey on rodents. But businesses can’t have rats crawling all over the place.
What’s the answer?
One option is to replace baits and other pesticide approaches with snap-kill traps, which are available enclosed in a plastic box so that only rodents (and not curious animals and children) come into contact with them. Dumpsters offer free buffets to rats. Properly stored food items and control of spaces where trash is stored are essential first steps to control rats, although sometimes and in some areas additional help is needed to control rodent populations. The National Audubon Society lists many alternatives to these second-generation anticoagulants to control rats.
Some New Jerseyans are taking action. The borough of Allendale, for example, recently passed a resolution to remove these rat-poison bait stations used on municipal property and to urge local businesses to stop using or selling these rat poisons. However, control of these poisons cannot be successful solely on a local level. Rats and the raptors and wildlife that prey on them don’t live within municipal boundaries. A statewide approach is needed to protect our sensitive species from needless death.