The Interesting History of Rat Control in Alberta


I am one of the few people in the world that has never seen – or interacted with – a rat. It is not because I don’t go outside (I am very outdoorsy), or that I don’t live in an area that they love – Calgary has a population of 1.4 million people which means a lot of food. The reason that I have never seen a rat is simple: their existence is illegal in Alberta.

You read that correctly. Illegal.

If you look at this map that I drew of North America you will see that that Alberta is an island of rat-free paradise in an otherwise rat infested North America:

Rat Population in North America

The story of Alberta’s war on rats dates back to the first European colonizers of North America. Through the 1950s, Albertan governments took a new approach to how we deal with rats and as a result – there are no rats in Alberta. The primary rat that Albertans are fighting off is known as the Norway Rat.

The Norway Rat

The Norway Rat is not a native species for North America. They are originally native to Northern China. It was first introduced through trading routes with Europe and arrived in North America in the late 1770s. Today, the Norway Rat exists on every continent with the exception of Antarctica. In their original form, Norway Rats could survive well in forested conditions however they found evolutionary success living alongside humans. Humans do after all build cozy places to shelter and reproduce. Additionally, food is always abundant near civilization. Their forager roots make this species of rat very resilient to all kind of environments. In both urban and rural settings, they can find food [1]. Shelter can include within or under any object that is left sitting on the ground. Once the rat is able to find safe shelter, they will then begin their scavenging activities to acquire food. This food is often human food waste left laying around or various animal feeds[2].

Norway Rat Scavenging for Food - Photo by DSD on
Norway Rat Scavenging for Food – Photo by DSD on

Norway Rats have a gestation period of 3 weeks which means that they can produce up to 12 litters per year. Each one of these litters is around 12-18 rats. A single pair of rats can produce about 15000 offspring within a year[2].

That is a lot of rats!

For researchers, the Norway Rat is instrumental in their studies since the common lab rat is a direct descendent of the original Norway Rats. The research rats are often used in both clinical and behavioral trials by scientists. In fact, this rat was the first mammal ever domesticated for researching[3].

The Norway Rat is also known as: brown rat, common rat, sewer rat, Hanover rat, Norwegian rat, city rat, water rat and wharf rat. Their scientific name is rattus norvegicus[3].


Damaging Effects of Rats

Rats cause a great deal of destruction and headaches anywhere that they are present. This destruction can range from property damage to economic damage, to disease.

Perhaps the most obvious damages that rats can cause are property related. Rats build and live in nests. The materials for these nests is curated from whatever junk that they find laying around. This can include things like textiles, cardboard, paper, wood, and any other material that is available nearby. For added protection, rats like to bury their nests inside of things such as car seats, furniture, and home insulation. Nothing that inside of any infested structure is safe from rat related destruction – even the structure itself[5].

House fire by Colin Kinnear is licensed under CC-BY-SA 2.0

Rats will often chew electrical cables and appliance cords as well which has been known to start fires in the hidden areas of the building. In fact, rodents have been known to cause approximately 20% of undetermined fires. Rats have also been known to chew rubber hoses in vehicles (causing fluid leaks) and plastic pipes (causing flooding and water damage)[4].

Rats destroy human and livestock food sources and storages as well. On the small level, they will claw their way into stored food items and although they eat a tiny amount – they will make the entire stock unusable because they spread disease. On the larger scale, rats account for massive amount of destroyed crops each year[5].

In an Ethiopian study conducted in 2019 and 2020, they did an assessment of crop damages to barley crops in which they planted identical barley crops in varying locations. Location 1 was near a forest and location 2 was away from the forest. Each location had a control plot (raised and isolated from potential rats) and the other plot was planted normally. What they discovered is that there was a significant amount of damage to the uncontrolled plots in both instances. Their control plot produced 1500kg/hectare (2.47 acres) of Barley and the estimated loss per hectare was 325kg[6].

Photo by LilacDragonfly on

Lets take a minute and estimate that economic impact on Alberta’s economy. According to a quick Google search, the amount of cropland in Alberta is approximately 25.6 million acres which converts to 10,359,952 hectares. At the same estimate rat loss from the Ethiopian study, Alberta would lose about 3,366,984,400kg of Crops each season. At an average 2022 commodity price of ~$350/tonne ($0.35/kg), Alberta would lose approximately $1,178,444,540 in economic crop value each year. (Note that these are my napkin calculations and may not reflect actual figures precisely)

With costs as high as these, it is no wonder that Alberta stopped the rat spread in its tracks.

History of Rats in Alberta

Our journey starts in the 1770s – right in the midst of war between the British and the Americans. It is believed that the first rats arrived with boxes of grain imported by Hessian troops to aid the British in their war with America[7].

After the war, the Norway Rats took up residence in both urban and rural communities across North America. Where people went – they tended to follow. They hitched rides in trains, ships, cargo, vehicles, and spread organically as well. In areas such as New York City, they became known as ‘sewer rats’ due to their innate ability to survive and thrive underneath the streets in sewers, utility tunnels, and transit infrastructure. Their success can largely be attributed to their ability to survive a wide range of environmental conditions[7].

Also… Rats can swim up to 0.8km (0.5mi)[7]. This ability to cross small rivers helps with survivability and migration.


By the 1920s, rats had entered Saskatchewan and throughout the next three decades, they established themselves as a permanent pest to Saskatchewan[2].

In 1950, the rats reached the Saskatchewan/Alberta Border and Alberta’s government was beginning to express concern. Eight years earlier, they had passed the Agricultural Pests Act of Alberta (1942) in an effort to get ahead of the rat issue.


Agricultural Pests Act of Alberta (1942)

The Agricultural Pests Act of Alberta (APAA) was intended to be used to control rat populations in Alberta by granting them legislative and enforcement tools. Essentially it gave the Alberta agricultural minister the ability to designate any animal that destroys crops or livestock as a pest. Anybody in Alberta – both private and municipal – had a responsibility to report and destroy any designated pest. Failure to do so would result in warnings and court trials.

This act made it illegal to harbor any designated pest (both as a shelter and as a pet) with the exception of educational institutions, universities, and laboratories.

An amendment in 1950 would dictate that municipalities designate a ‘pest control inspector’ who would be in charge of insuring that Albertans are not harboring designated pests. Initially, municipalities were responsible for paying the inspector; however the government would eventually assume half of the wages paid out to the inspectors and gave them these core tasks:

  1. Investigate every structure within 29km of the Alberta-Saskatchewan border for rats
  2. Develop bait stations and use various baits to catch existing rats
  3. Encourage rat-proofing of structures and removal of structures within the Rat Control Zone to prevent future infestations
  4. Destroy all known infestations

The early forms of Alberta’s rat control program were effective in limiting the spread of rats to within 10-20km of the eastern border while they developed the current rat control program. This area today is known as the Rat Control Zone (RCZ)


Alberta’s Geography & The Rat Control Zone (RCZ)

In Alberta, geography plays in extremely important role in the protection against rats. Albertans are relatively protected by natural terrain everywhere except the area along the Saskatchewan border that became the RCZ.

The Rat Control Zone was established on the Alberta side of the eastern border and is 600km long on the north/south axis and is 29km wide. Within this zone, there are special rules for municipalities and residents to stop rats from entering Alberta.

There was no need for any other controlled borders because nature already does provides a ‘wall’ along all of the other borders. To the north it is arctic tundra and sparsely populated boreal forest (Remember that the Norway Rat has evolved alongside humans). This boreal forest also protects the top half of the province on the west side and directly above the RCZ on the east. The southern border with the United States provides a similar protection in that shelters are few and far between making it difficult for Rats to thrive in Montana. The Rocky Mountains to the West provide a natural barrier to British Columbian rats. This leaves only the 600km of the RCZ as an opening for rats to enter Alberta.


Education ended up playing a crucial role in the Alberta government’s campaign against rats. At the time, most Albertans had never seen or interacted with a rat which meant that they didn’t know how to prevent rat infestations. The government had to establish some form of education program for Albertans.

The government established anti-rat propaganda and public education programs throughout the later 1950s. These programs taught Albertans how to prevent, identify, and eliminate rat infestations[2].

Part of the education program included public displays at local events such as picnics, rodeos, and fairs across the province. At these events (and on supermarket display boards), brochures, posters, and pamphlets were in wide distribution across Alberta[2].

They even broadcast these rat educational pieces through the government controlled radio station: Call of the Lands. This station was was targeted to the rural farmers of Alberta. The 5x weekly program was about 9 minutes long and was intended to keep farmers updated about changes in technology, farming techniques, and other relevant information to agriculture[8].

Lastly the Alberta government used preserved, dead rats to help in the identification of the invasive species. They were delivered to Alberta Agriculture Offices so that their agents could identify the rat from other rodent species[2].

So what exactly were the control measures that the government was educating people on?

Control Measures

The government’s methods for dealing with the rat problems were divided up into three distinct categories:

  1. Destruction of Rats – Existing rat infestations needed to be destroyed. The easiest method of destroying rats was toxicants such as arsenic, barium carbonate, naphthylthiourea (ANTU), red squill (a poisonous plant), sodium fluoroacetate (1080), strychnine alkaloid, thallium sulfate, warfarin, and zinc phosphide[2].
  2. Elimination of Shelter & Food Sources – Rats need shelter and food to survive so this was effective in slowing their territorial spread. Rats are very dependent on shelter for their survival. Natural predators include coyotes, large birds (hawks, eagles, owls, etc), snakes, and even fish in river crossings. Additionally, rats are mammals – and like humans – they need warmth during Canada’s frigid winters. This warmth and is provided by humans in their own shelters and storage facilities. By removing unnecessary shelters in the rat control zone, it becomes much more difficult for the rats to migrate westward into Alberta[2].
  3. Rat Proofing of Buildings – By rat proofing structures, future infestations are prevented. The goal of rat proofing is to essentially make buildings as unsafe and uninhabitable for the rodents as possible. Farm outbuildings are elevated above the ground and doorways/windows are reinforced so there are no gaps that a rat could squeeze in. This was effective in keeping rats out of utility buildings, storage bins, and barns. Farmers were encourage to efficiently move grain and hay bales around regularly to further discourage rat activity[2].
Photo by Pixabay on

The control measures did have some problems however. While destroying the rats, tracking powder was commonly used. How tracking powder works is that it adheres to the animal’s fur when it runs through the powder scavenging for food and looking for shelter. The powder is then ingested by the animal when it grooms itself. Tracking powder ingredients primarily consisted of arsenic trioxide which is extremely toxic to more than just rats. Between June 1952 and July 1953, 63,600kg of this tracking powder was blown under thousands of buildings and farms within the control zone. The government failed to inform the public about the health risks associated with tracking powder. For 2-5 years, livestock, chickens, and pets were accidently poisoned when buildings were moved or demolished. Due to its dangerous nature, the tracking program was discontinued in 1978[2].

Consequences of Harboring Rats

To the present day, knowingly harboring rats in Alberta is highly illegal. The Agricultural Pests Act of Alberta makes it an offense to provide rats with food and shelter. Albertans in violation are subject to fines and warnings. For continued violations, authorities may issue mandatory court appearances. Everyone that challenged the legislation thus far has been convicted.


In 1956, the Alberta pest inspectors issues 17 warnings to residents who failed to comply with the rat legislation. Of those, 3 ended up in court and all three were convicted. Since 1956 however, no more than 7 warnings were ever issued in any given year which is a testament to the program’s effectiveness.


Based on the absence of rats in Alberta today when they have been spreading across the entirety of North America – we can safely conclude that the rat control program developed in thee 1950s was highly effective in keeping rats out of Alberta.

Timeline of Rat Control Effectiveness in Alberta:

  • 1950 – 1955

    Alberta rat population increase of 573%

  • 1955 – 1959

    Alberta rat population decrease of 10% of 1955 levels

  • 1961 – 1963

    Alberta rat population 50% of 1959 levels by the end of 1963

  • 1964 – 1980

    Alberta rat population 50% of 1963 levels by the end of 1980

  • 1980 – Present

    There have been fewer than 50 total infestations since 1980 in Alberta


Since the Norway Rat was first discovered in Alberta in the summer of 1950, Albertans have developed an effective rat control policy that has ensured that they remain an island of rat free territory in an otherwise rat infested North America. They did this by identifying the issue early on, educating the public, destroying known rat infestations, preventing future infestations, and creating legal consequences for the harboring of rats.

I intend to travel more outside of Alberta in the coming years and learning to live alongside rats is one of the more unexpected learning curves that I feel I have coming.

– Timothy J. Tetreault

Alberta has a unique history of rat prevention. Sort of like Australia’s war on emus… except Albertans won!



[1] Norway rat. (2016, April 25). Smithsonian’s National Zoo.

[2] History of rat control in Alberta. (n.d.).

[3] Modlinska K, Pisula W. The Norway rat, from an obnoxious pest to a laboratory pet. Elife. 2020 Jan 17;9:e50651. doi: 10.7554/eLife.50651. PMID: 31948542; PMCID: PMC6968928.

[4] Ivory, A. G. (n.d.). How to Prevent Rodent Electrical Fires.

[5] Process, E. (2004, November 22). Rats and Mice: The Damage They Cause.

[6] Assessment of crop damage by rodent pests from experimental barley crop fields in Farta District, South Gondar, Ethiopia. (2021, August 12). PLOS ONE.

[7] (n.d.). Aaacwildliferemoval.Com.

[8] (n.d.). Call of the Land.