Identifying Common Rodents in Australia: Essential Guide to Mice Norway Rats and Black Roof Rats | Rodent Treatment

Table of Contents:

Intro

Mice

Norway Rat

Black/Roof Rat

Rodent Treatment Methods

Conclusion

References

Rodents are a common sight in many Australian homes, and understanding how to identify them is crucial for effective rodent control. This blog post will delve into the characteristics, habits, and control methods for three of the most prevalent rodents in Australia: the house mouse, Norway rat, and black roof rat. Homeowners in Port Macquarie and beyond will find this guide particularly useful for managing rodent issues effectively. For more help contact us about our rodent treatment plan

Image of house mouse, Norway rat and black roof rat from left to right.

House Mouse (Mus musculus)

Appearance

The house mouse is small, typically measuring about 15 to 20 centimeters in length, including its tail. Its fur is usually light brown or gray, with a lighter underbelly¹. The ears are large and rounded, and the eyes are small and black.

Differences from Other Rodents

In comparison to the Norway rat and black roof rat, the house mouse is significantly smaller and more slender¹.

Feeding and Reproductive Habits

House mice are omnivorous and will eat a variety of foods, including grains, fruits, and seeds¹. They reproduce rapidly, with females capable of producing up to 10 litters per year² — a key contributor to large population booms in Australian mouse plague conditions¹¹.

Nesting Locations

House mice prefer warm, sheltered areas close to food sources, such as wall voids and attics¹.

Common Places Found

They are commonly found in kitchens, pantries, and storage rooms where food is available³.

Entry Points

House mice can enter through extremely small openings—often much smaller than expected¹².

Sources of Food and Water

They are attracted to grains, pet food and household leftovers¹.

Health Effects and Damage

House mice can spread diseases like salmonella¹⁵, zoonotic parasites⁴, and potentially hantavirus in rare circumstances. They also gnaw on wires and insulation, posing fire risks¹.

Proofing and Prevention

Seal all entry points, store food in airtight containers, and maintain clean food-preparation areas³. Thin plastic, timber, and chicken wire can be chewed through; metal reinforcement is recommended.

Norway Rat (Rattus norvegicus)

Norway rat

Appearance

Norway rats are much larger than house mice, with a thick body, coarse brown/grey fur, and a blunt snout⁵.

Differences from Other Rodents

They have a robust build and a shorter tail compared to the black roof rat⁵.

Feeding and Reproductive Habits

These rats consume meat, grains, fruit, compost and garbage⁵. They reproduce rapidly, producing up to 12 litters per year.

Nesting Locations

Norway rats tend to burrow in soil, gardens, basements, and under structures⁵.

Common Places Found

They are often found in sewers, drainage systems and urban waste areas⁶ — with populations increasing due to changing climates and urbanisation.

Entry Points

They enter homes through larger openings, including unsealed vents, pipe gaps and foundation cracks⁵.

Sources of Food and Water

Norway rats target rubbish, compost, pet food and water sources such as leaking pipes or bowls.

Health Effects and Damage

Norway rats can transmit leptospirosis¹², rat-bite fever, and carry zoonotic parasites⁴. Their gnawing can cause structural and electrical damage.

Proofing and Prevention

Reduce access to food waste, secure garbage storage and block structural entry points¹⁵.

Black Roof Rat (Rattus rattus)

Black roof rat

Appearance

The black roof rat is slender and agile with smooth, dark fur, large ears and a long tail¹⁰.

Differences from Other Rodents

They are smaller than Norway rats, with smoother fur and more agile climbing behaviour¹⁰.

Feeding and Reproductive Habits

Black rats eat fruit, nuts, seeds and household foods. They reproduce quickly, similar to Norway rats³.

Nesting Locations

They prefer elevated nesting sites—roofs, ceilings, wall voids, trees and palms¹⁰.

Common Places Found

Often found in coastal towns and urban areas, black rats thrive in treed suburbs and attics¹⁰.

Entry Points

They can enter through gaps in eaves, roofs, broken tiles and high wall openings.

Sources of Food and Water

They feed on fruiting trees, compost, pet food and pantry goods.

Health Effects and Damage

Black rats carry leptospirosis¹², salmonella¹⁵, ticks¹⁰, and can spread pathogens found in urban rodent studies⁴.

Proofing and Prevention

Trim trees touching the roof, seal high-level gaps, secure fruit waste and store food properly.

Rodent Treatment Methods

Traps

Traps can be effective when monitored frequently.

Pros:

• Immediate results

• No secondary poisoning risk³

Cons:

• Requires regular checking

• Cheap traps are often avoided or ineffective

• Not ideal for large infestations²

Rodent Baiting

Rodent baits include first- and second-generation anticoagulants. Their environmental impacts are well-documented⁷,⁸.

• First-Generation Anticoagulants Require multiple feeds and present lower secondary poisoning risk.

• Second-Generation Anticoagulants Highly potent and effective after a single feed, but with higher risks to wildlife, including owls and native predators⁷,⁸.

• Formulation Variations Modern bait chemistry can reduce secondary poisoning risk or increase specific efficacy⁸.

Humane Live Capture Options

Humane traps allow non-lethal capture for relocation or veterinary euthanasia³.

Pros

• No poison onsite

• No risk to pets/wildlife

• Ethical and suitable for sensitive environments

Cons

• Requires appropriate euthanasia procedures

• Less effective at large scale

• More expensive

• Highest level of setup complexity, daily monitoring

Environmental Effects of Using Baits

Rodenticides can cause secondary poisoning to owls, quolls, rakali and other predators⁷,⁸,⁹.Improper bait placement can pollute soil/water and increase accidental poisoning risks.

Conclusion

Identifying and understanding Australia’s most common household rodents is essential for effective control. Homeowners in Port Macquarie and throughout NSW can protect their homes by recognizing rodent habits, blocking entry points, and choosing the right control strategy. Informed prevention reduces health risks¹²,¹⁵ and prevents costly damage.

References

1. Brown, P.R. & Henry, S. (2022). Impacts of House Mice on Sustainable Fodder Storage in Australia. Agronomy, 12, 254. https://www.mdpi.com/2073-4395/12/2/254

2. Carter, L. (2025). The human and social impacts of an Australian mouse plague. Wildlife Research. https://www.publish.csiro.au/wr/fulltext/wr25016

3. Cohen, S. & Ho, C. (2023). Review of Rat (Rattus norvegicus), Mouse (Mus musculus)… Indicators for Welfare Assessment. Animals, 13(13), 2167. https://doi.org/10.3390/ani13132167

4. Egan, S. et al. (2024). Zoonotic protozoans in urban mammals including rodents. Science of The Total Environment. https://www.sciencedirect.com/science/article/pii/S0043135424000654

5. Mackenzie, H.R. et al. (2022). Detection parameters for managing invasive rats in urban landscapes. Scientific Reports, 12, 20677. https://www.nature.com/articles/s41598-022-20677-8

6. Richardson, J.L. et al. (2025). Increasing rat numbers in cities are linked to climate change and urbanization. Science Advances. https://www.science.org/doi/10.1126/sciadv.ads6782

7. Ruscoe, W.A. et al. (2022). Conservation agriculture practices have changed habitat use by rodent pests. Journal of Pest Science. https://doi.org/10.1007/s10340-021-01370-7

8. Ruscoe, W.A. et al. (2022). Improved house-mouse control in the field with a higher toxic dose. Wildlife Research. https://connectsci.au/WR/article-lookup/doi/10.1071/WR22009

9. University of Sydney (2025). Australian native rats fight back: footage shows rakali attacking black rats. https://www.sydney.edu.au/news-opinion/news/2025/07/30/australian-native-rats-fight-back--footage-shows-rakali-attackin.html

10. Taylor, C.L. et al. (2023). Activity and movement of small mammal tick hosts at the urban interface. Wildlife Research. https://www.publish.csiro.au/wr/pdf/WR22069

11. White, J. et al. (2024). The New South Wales Mouse Plague 2020–2021. Frontiers in Public Health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11127141/

12. NSW Health (2023). Leptospirosis Control Guidelines. https://www.health.nsw.gov.au/Infectious/controlguideline/Documents/leptospirosis-control-guidelines.pdf

13. SafeWork NSW (n.d.). Leptospirosis. https://www.safework.nsw.gov.au/hazards-a-z/biological-hazards-and-diseases/leptospirosis

14. NSW Health (2025). Staying Healthy During a Mouse Plague. https://www.health.nsw.gov.au/environment/factsheets/Pages/mouse-plague.aspx

15. NSW DPI (2024). Rodent Control and Salmonella Enteritidis. https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/916950/rodent-control-and-salmonella-enteritidis.pdf