Biology of Bats

Bats are unique mammals commonly found in Alberta, especially near attics, barns, and older structures. While beneficial to the environment, bats can become a concern when they roost inside homes. Understanding their biology helps with proper identification, prevention, and safe removal.

General Characteristics

• Bats are the only mammals capable of sustained flight.
  
  

• Most species active in Alberta are small, weighing 5–30 grams.
  
  

• Their wings are made of a thin membrane stretched between elongated fingers.
  
  

• They have excellent night vision and rely heavily on echolocation to navigate in darkness.
  
  

Species Common in Alberta

The most frequently encountered species include:

• Little Brown Bat (Myotis lucifugus)
  
  

• Big Brown Bat (Eptesicus fuscus)
  
  

• Hoary Bat (Lasiurus cinereus)
  
  

Life Cycle

Bats have a slow reproduction rate compared to insects and rodents:

1. Mating occurs in late summer or fall.
   
   

2. Females store sperm over winter and fertilization occurs in spring.
   
   

3. Gestation lasts 50–60 days.
   
   

4. One pup per year is typical.
   
   

5. Young bats can fly after 3–4 weeks.
   
   

Their slow breeding means colonies grow gradually over time.

Diet & Feeding

Bats in Alberta primarily feed on:

• Mosquitoes
  
  

• Moths
  
  

• Beetles
  
  

• Other night-flying insects
  
  

A single bat can consume hundreds of insects per hour, making them ecologically important for pest control.

Habitat & Behaviour

• Bats prefer warm, dark, sheltered roosting areas.
  
  

• Common roosting sites include attics, wall voids, soffits, chimneys, and barns.
  
  

• Most species are nocturnal and leave their roosts at dusk to hunt insects.
  
  

• Colonies can range from a few individuals to hundreds.
  
  

Signs of Bat Activity

• Rustling or fluttering noises in walls or attics
  
  

• Small black droppings (guano) that crumble into powder
  
  

• Grease or rub marks around entry points
  
  

• Strong ammonia-like odor from accumulated droppings
  
  

Health Risks

While bats avoid humans, they can pose certain risks:

• Rabies (rare but serious)
  
  

• Histoplasmosis, a respiratory disease linked to bat guano
  
  

• Structural contamination from droppings and urine
  
  

Professional removal is essential because bats are a protected species and require safe, humane exclusion methods.