Welsh Poultry Centre

One rat with easy access to your poultry food could be eating as much as 25kgs per year.  Given that where there's one rat, there's likely to be a colony, you only need 40 odd rats to be giving away up to a ton of feed a year.  Can you afford to do that?

Where's there's poultry, rats will want to move in

Unfortunately when you have poultry you can also attract rodents. You have put in a structure, the chicken house, which will probably provide an ideal living space for rats and mice and at the same time provided a ready source of food. Rats will happily eat chicken food as they will quite happily eat almost any food. They are opportunists, and like the red mite, have adapted incredibly well to exploiting the environment humans create.

For some reason I find rats particularly loathsome creatures. Mice, even though they are worst than rats at spreading disease, particularly Salmonella, at least look cute; and they’re smaller! 

Origin of rats

The common rat, Rattus norvegicus (Norwegian rat) does not in fact come from Norway. It is thought that it originates from Asia. It first appeared in the UK in the 18^th century when it was thought, for some reason that they came over on ships from Norway. They were also known as Hanover rats, (none of the three Georges of the house of Hanover were particularly popular in Britain, the first didn’t even speak English). Being larger and bolder than the incumbent black rat (rattus rattus) they soon replaced them. The Black rat is infamous for spreading the bubonic plague being a host for the rat flea.

Where there's one rat you'll soon have a colony.

The brown rat can breed throughout the year unless there is very severe cold weather. The female can have up to seven litters a year, (the gestation period is 21 days), and the litter size can be as high as fifteen, although an average would be seven. Within 70-80 days these young can breed themselves. There is evidence that if a large percentage of a group are killed the remaining females can up their output to quickly make up the shortfall. 

How much are you feeding your rats?

They live in established hierarchical family groups, with each group having its own territory. This territory is patrolled and new comers kept away. Rats are true omnivores; they will pretty much eat everything. Each day each rat will consume about 15% of its own body weight. If the rat has a good supply of high quality food available, they can weigh up to 450 grams and would therefore eat 0.470 grams per week, getting on for 25kgs per year. A more standard size rat would weigh in at about 300gram and will eat about 16kg per year. Multiply that kind of figure up for each rat and you can see how much rats can cost, especially on farms.

Fortunately, despite the prodigious rate that they can reproduce, it is estimated that 90% will live no longer than a year. Predators, (such as that other problem, the fox!), farmers and interspecies fighting ensure that only 10% move into their second year.

Using poison to reduce rat populations in poultry enterprises

Where you are have numbers of day old chicks, farm cats can be counter-productive, but where your birds are more mature, cats remain an excellent, sustainable way to control rats and mice on farms.  If these are not an option, then poison is the most effective control method. Placing the poison every night at different sites, away from pet access, until the poison is no longer being cleared up. Rats will travel to a food supply by the same route every night, (hence the expression “rat run”). It is along these runs that the poison is best sited. You will never entirely be free of rats. A new population will sooner or later move in or the few survivors will re populate. To avoid the possibility of immunity arising in the rat population I change the type of poison used regularly.

Preventing rats moving into your back garden

For the urban poultry keeper, with small numbers, the best way to avoid rats becoming a problem is to keep the food supply down. Rats normally eat during the hours of darkness. If you see a rat during daylight hours it is likely that it is low down in the group hierarchy and has been prevented from feeding properly during the night. Chickens, on the other hand, feed during the daylight hours. If you fear you have a problem either remove the feed when you shut them up or, only feed each day what they will eat that day. Obviously your feed store should be kept rat proof. 

Summary

Rats can prove expensive visitors if they move in and are allowed to make too long a stay.  It can save you money and reduce the possible spread of disease if you keep the rat population under control.

How do you deal with rats?  Please go to the blog and add your comments.

Stephen Merritt

The Welsh Poultry Centre