Black Rat (Rattus rattus)

Identification

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The black rat, also known as roof rat or ship rat is a common and unwelcome guest in Sri Lankan homes and businesses.

Physical description: Black rats are smaller and slenderer than brown rats, with a pointed snout, large, prominent ears, and a tail longer than their body (16-24 cm long). Their fur is dark brown to black, with a lighter underside.
Habitat: Black rats are excellent climbers and prefer to live in attics, roofs, wall cavities, and trees. They can also be found in basements, sewers, and other areas with easy access to food and water.
Feeding habits: Omnivorous, with a preference for fruits, grains, seeds, and insects. They will readily eat human food and scavenge for scraps.

Life cycle: Black rats reach sexual maturity around 3 months old and can breed year-round. A female can have up to 6 litters per year, with 5-10 pups per litter.
Activity patterns: Primarily nocturnal, but can be active during the day, especially if food sources are scarce. They are agile climbers and can navigate narrow spaces.

Visual signs: Droppings (pellet-shaped, black), gnaw marks on food packaging or furniture, greasy smear marks along walls (from fur), and rat nests made of shredded paper, insulation, or other materials.
Behavioural signs: Scratching noises in walls or ceilings, especially at night. Odors of musky urine. Sightings of live rats or their droppings.

Black rats can contaminate food and surfaces with their droppings and urine, potentially transmitting diseases like leptospirosis, salmonellosis, and rat-bite fever.
They can also damage property by gnawing on electrical wires, furniture, and building materials.

Exclusion: Seal up any potential entry points in your home or business, such as cracks, gaps around pipes, and vents.
Trapping: Set snap traps or live traps baited with peanut butter, chocolate, or other attractive foods. Check traps daily and dispose of captured rats hygienically.
Rodenticides: Use commercially available rodenticides with caution, following the manufacturer’s instructions carefully. Be aware of the risks to pets and non-target animals.
Professional Pest Control: For severe infestations, consider hiring a professional pest control company to assess the situation and implement a comprehensive control program.

There are four subspecies of black rats found in Sri Lanka, all belonging to lineage I of the Rattus rattus complex:
- Rattus rattus frugivorus (Fruit rat)
- Rattus rattus kandianus (Sri Lankan highland black rat)
- Rattus rattus alexandrinus (Alexandrine rat)
- Rattus rattus rattus (Roof rat)
Black rats are more agile climbers than brown rats and can readily infest homes through attics and roofs.
They are intelligent and can be wary of new traps or bait. Consider using a variety of control methods for best results.