Rodenticides are Killing California Hawks
The sight of a hawk seated casually on a phone pole, sweeping across a field, or diving down for prey is awe-inspiring. Unfortunately, that rodent dinner might be the majestic creature’s death thanks to the widespread use of rodenticides across the US.
Many of these poisons are designed to act slowly, encouraging rats and mice to bring poisoned bait back to their nests so that the whole colony is killed off, not just a single individual. The problem is that as long as those living rodents are strolling around, they’re appealing to raptors — in addition to housecats, bobcats, and a variety of other creatures.
In the 1960s, the publication of Silent Spring and a growing pile of evidence convinced the US to move towards banning DDT, a chemical that was once widely sprayed to cut down on insect populations. The problem with DDT was that it also affected other species, specifically raptors, who experienced egg shell thinning as a result of DDT exposure. Their populations dipped, and only recently have they started to show signs of recovery, illustrating how long the effects of environmental pollution can linger.
But in recent years, researchers have started noticing a problem: raptors are dying for no particular reason, in regions with no obvious signs of chemical pollution–until the scientists dug a little deeper and started exploring the use of rodenticides in the area. One of the most commonly used classes of rodenticide in the US are anticoagulants, which work slowly over time. They can also end up poisoning animals that eat the targets for the poison, like rats and mice. The scientists noticed a connection between raptor populations dipping in states like California and use of rodenticides in agricultural facilities, food storage facilities, and marijuana operations.
The problem isn’t limited to California, though. Urban raptor populations are particularly badly affected because of their location in the heart of cities, which attract rats, and which in turn encourages people to put down poison. Numerous urban raptor families have died as a result of poison exposure, a heartbreaking experiences for their fans and the researchers who study them.
In fact, necropsies have shown that rat poison is the most common cause of death for hawks, above power line collisions and car accidents. Urban raptors, as well as their rural brethren, could be helping to deal with the explosion of rats and mice drawn to compost piles, home gardens, and more, but instead, they’re being killed off.
In multiple states, activists are working to change this. Lobbying in California forced the California Department of Pesticide Regulation to ban a number of rodenticides in the state, making it impossible for consumers to walk into stores and buy them. Unfortunately, they’re still available to commercial customers like exterminators, who often turn to these poisons because they’ve proved effective in the past and they’re inexpensive. Lobbying on the issue is only making slow progress in some communities as exterminators and chemical manufacturers oppose changes to dealing with pest infestations, but advocates argue it’s critical to protect hawks.
That’s not just because they’re intrinsically beautiful, although of course that’s a very good reason. Protecting hawks also allows them to do what they do best: killing prey, and ensuring that a predator vacuum doesn’t develop. Hawks provide a great means of steady control for rat and mouse populations, and they do it entirely for free, which is an excellent deal.
Can advocates revive the regulatory climate of the 1960s (DDT was banned in 1972) and encourage the government to do the right thing? Many animal lives may depend on it.
Photo credit: Audrey.