Tackling a persistent rodent problem

Rodents often become a problem for poultry farmers over the winter months as food sources dwindle and they move indoors in search of food and warmth. Clearly, rats and mice pose a significant threat to biosecurity and must be dealt with at the earliest opportunity before it turns into an infestation. Laying down an anticoagulant rat poison is the most common way of dealing with this pest, but what if it doesn’t appear to be working?

What is an anticoagulant rat poison?

Anticoagulants come in different types: Hard bait blocks, soft blocks and pellets. They work by blocking the activation of Vitamin K1 in the rodents liver which in turn stops blood clotting.

Allow enough time

It is worth noting that rats in particular are naturally cautious of new objects, so allow two to three weeks for them to acclimatise to something new in their environment. Most rodent poisons currently available are anticoagulant based - they work by preventing the assimilation of vitamin K1, which is essential for blood clotting within vertebrates.

 

It’s important to remember that, even with single-bait poison, once the rodent has eaten the poison, there is a 3-4 day lag whilst the rodent relies on existing stores of vitamin K1. After these stores are used up, the rodent’s blood will no longer be able to clot and it will die – so it’s important to allow enough time for this to happen.

How to tackle a persistent rodent problem

Understanding Baits: Single feed vs multi feed

Baits can be single feed or multi-feed. Multiple feeds of multi-feed bait will be required before death, so again, time must be allowed for this to happen. One of the advantages of multi-feed bait is that the risk to non-target animals is smaller. However, this also means that rodents can build up resistance over time. If multi-feed bait has not worked within the timescale recommended by the bait manufacturer, it could be worth switching to a single feed bait.

Use enough bait

Ensure that your bait stations are monitored and restocked regularly to ensure sufficient uptake of bait. Any wet, mouldy or unappealing bait should be replaced with fresh bait and that bait should be replenished until it is longer being consumed. Follow the manufacturer’s instructions and do not be tempted to skimp on the number of bait stations.

Be prepared to try different formulations

Baits come in a variety of different forms and formulations – there is no ‘one size fits all’, as rodents have individual food preferences. The best bait is highly palatable and one that the rodent chooses to eat over any other food source in the vicinity.

It is worth trying different formulations with different active ingredients and palatability if the problem is persistent, as well as different forms. Baits come in loose cereal and pellet form, as well as wax blocks and gels and pastes. Mice in particular prefer unwaxed baits, particularly wholegrains, cut wheat and seed based baits which are the closest to their natural food preferences. Wax blocks are often more palatable to rats. Contact foam is useful for hard-to-reach cavity walls. Interhatch stocks a full range of bait which can be filtered by form, active ingredient and type of bait. You can also read our quick guide to ‘Keeping Rodents at Bay’.

Locate bait stations correctly

Rats instinctively use boundaries as guides so placing bait traps near walls and in low light makes sense – rats like to feel secure. If you’re struggling to get on top of your rodent problem it could be worth going back to basics and spending some time monitoring the problem to identify behaviour and ‘runs’ to make sure your traps are located correctly. Inspections should be made at night when rodents are most active and a monitoring bait, such as Detex blocks can be used to help establish rodent patterns.

Do not delay

Rats and mice multiply quickly due to their very short gestation period so if your baiting programme isn’t working within a reasonable amount of time, it’s important to take action. If you’d like to chat through different options with one of our specialists, please get in touch. Baiting programmes should always be combined with regular monitoring and appropriate prevention measures such as rodent proofing your site and removing sources of food and water. For an in depth guide to the prevention and control of rodent infestations, Defra has a useful code of practice.