It’s that time of the year when rats and mice are rampant in our homes, and the time of the year when our beautiful birds of prey are exposed to dangerous rodenticides.
Some types of rat and mice poisons can be harmful to birds if they pick up dead and dying rodents and so we must be careful with the products we choose at the supermarket or in the hardware store.
I’ve written about the danger of rodenticides in the past and this winter I had a chance to put this knowledge to the test.
Flickering lights in my lounge pointed to an electrical fault but when I called in an electrician I discovered that rats finding shelter in our ceiling had gnawed through cables and a plastic junction box.
Rat control products conveniently fall into two broad categories – first and second-generation poisons. The first generation ones are less toxic, requiring several doses consumed through baits to kill rodents and have less concentrated poison to kill birds picking up carcasses.
Second-generation rodenticides have increased in popularity due to their ability to kill rodents in just one dose. However, these concentrated levels of poison can also work their way up the food chain when rats and mice are eaten by birds of prey such as eagles, goshawks and owls, and Tasmanian devils and quolls. In a 2021 study, almost three quarters of eagles examined had some level of rodenticide in their systems.
Prevention is better than cure, like avoiding leaving food scraps and pet food in accessible areas and blocking up possible entry points for rodents in the walls of homes.
If poisons are necessary, opt for first-generation poisons with the active ingredients warfarin or coumatetralyl. Because these poisons take multiple doses to kill rodents, they have a lesser impact on the animals that come upon them.
When a poison contains a dangerous second-generation chemical, such as bromadiolone, it is a legal requirement that it be labelled “poison”. If its ingredients are less toxic, it will be labelled “caution”. This distinction will help you identify which products to use. While not using a poison is always the best option, if it is needed look for those with a “caution” label.
Instead of a DIU solution to rodent control, I opted for a professional approach from a firm specialising in environmentally friendly methods after reading an article in the Mercury about the poison dangers not just to wildlife but to pets and even children.
Raptor expert Nick Mooney called for stronger regulation on the rat baits, saying: “We just let people buy stuff you can’t use in other countries.”
My rats have now retreated and I know that the boobook and masked owls in our valley, along with the brown goshawks, have a fighting chance of survival if they prey on rodents in my garden.