Pest Breeding Habit Facts

Effective pest control is often a numbers game. Wild animals are incredibly successful breeders. As such, when it comes to pest species, what starts off as a small and unnoticeable infestation, can quickly turn into a much bigger problem which is impossible to ignore.

The speed at which rodents and some species of pest birds can multiply is frightening – especially if conditions are right. Unfortunately, conditions in people-populated environments can be ideal for pests, as there is usually plenty of shelter and an abundance of food on which the various species can scrounge a successful living.

It’s imperative therefore, that all businesses take proactive pest control measures to deter any vermin from first entering a premise and then establishing a breeding ground for themselves, which will inevitably lead to many more pests and much bigger problems.  

Let’s take a look at the breeding habits of some common pest species that your business may be dealing with.


Rats can breed at a terrifying speed. The most common and successful species of rat in the UK is the brown rat. The black rat is also present, though it is a very rare species in this country. Brown rats have a life expectancy of anywhere between one and three years, though the average lifespan is a little over a year in dense populations where there is great competition for food.


House Mouse

The mammals reach sexual maturity after just four to five weeks, at which point the female rat will start birthing litters of between five and twelve rat pups at a rate of about six litters a year. This means that a population of rats, if left unchecked, has the potential to swell from just two to 1,250 in just twelve months and grow exponentially from there. However, in a real-world scenario, this won’t usually happen, due to the fact that the death rate would also increase as the size of the rat population

grows. Nonetheless, such is their propensity and ability to breed frequently and successfully that a population of rats will quickly grow to the size allowable by the environment. So long as there is sufficient space and food, the rat numbers can become overwhelming in a remarkably short period of time.


The story isn’t must much better for mice.

Females become sexually mature at about six weeks and males at about eight weeks. One pair can have between five and eight litters per year. The gestation period is roughly 19-21 days and the female will give birth to a litter of between three and 14 young (the average is about six to eight).

So one female has the potential to give birth to eight litters of 14 young in just one single year – that’s 112 mice produced from just one breeding pair. It’s not hard to imagine, therefore, just how quickly populations can grow if space and food allow.

Breeding can occur throughout the year, though less so in colder months. Nonetheless, preventative pest control measures still need to be taken during the winter to ensure your premises are mouse-free before the weather warms and breeding begins once more.


The breeding habits of pest bird species in the UK are less intense and more seasonal than those of rodents. Nevertheless, breeding birds still cause problems for businesses, not only due to rapid increases in population size, but also because of the damage they cause when building nests, which can also result in fire hazards and blocked drains and guttering.

Pigeons: In absence of extreme weather, pigeons are able to breed right around the calendar, though the main breeding period is between the months of March and July. Two to four eggs are produced at a time and are incubated for around 18 days before hatching, with the young birds fledging some five weeks later.

Gulls: The breeding season for gulls falls between May and August, with 2-3 eggs laid per season. Though more common in coastal areas, in recent years, the various species have been moving further and further inland in their search for food and nesting sites. Once a site has been established, more gulls will flock to the location as colonies are built. Gulls are a particular problem during breeding season due to the fact that they will become aggressive towards humans, often “dive-bombing” from roofs when people pass by, in defence of their chicks.

Starlings: Due to their migration patterns, Starling numbers are highest in the UK during autumn, although some will normally be present throughout the year. They typically build their nests in tree holes and will set up residence in buildings if conditions are right. The breeding season begins in April and the birds will lay a clutch of between four and six eggs, which will hatch twelve days later. The young fledge after roughly three weeks. Usually, only one brood is raised per year, however, sometimes, if the first is laid early, a second can follow.

Sparrows: Sparrows breed between March and August, but can have multiple broods per year. As such, numbers can multiply rapidly in a given area. Typically, four eggs are laid at a time, though some nests can have as many as seven. Incubation lasts approximately twelve days and the young, once hatched, leave the nest 15 to 17 days later. Once the young birds have fledged the nest, the male will continue feeding them while the female begins the next brood.

Rooks: Rooks are common pest birds in the UK and, although they tend to prefer wide, open spaces, where they are present, the sheer size of their flocks can cause a very noisy problem for close-by houses and businesses. The breeding period begins in early March and each pair will lay between three and five eggs. Incubation lasts for around 16 to 18 days and the young will leave the nest about a month after that.

Safeguard Pest Control

Keeping pest species’ numbers down is imperative to effective and lasting pest control. If you suspect your business premises may be turning into a breeding ground for pests, the only solution is to call in the pest control professionals immediately to get the infestation under control.

At Safeguard Pest Control, we have over 30 years’ experience designing bespoke pest control solutions for commercial clients. Get in touch with us today to organise a free site survey.

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