White-nose Syndrome in Ontario

We had an old home growing up. It had charm in the way that older homes usually do with large ceilings and rooms that felt lived in. It also had an older chimney and a roof that perpetually needed mending and crumbling around the foundation. If you have ever lived in an older home, these are common issues that are not exactly news. We also had bats in the house and to an eight year old, the sound of a fluttering bat is enough to conjure up nightmares of the worst sort. Fast forward to the present and I have a very different opinion of bats. The onset of White-nose Syndrome in Ontario has resulted in the decline of bat populations with some species being threatened with possible extinction. At Niblett Environmental Associates Inc., we’ve seen an increase in projects that require bat habitat assessments and ultrasonic surveys.

Tagged Little Brown Myotis. Photo Credit: J. Boxall, 2014.

Bats are an Indicator Species

Bats have long been considered pests. The truth though, is something completely different. Bats are not the vile and shudder-inducing creatures people make them out to be. They provide numerous benefits to plants and act as natural insect control. The amount of insects a single bat can eat in a night can number in the thousands and it’s been estimated that bats can save the global agricultural industry upwards of $50 billion per year[1]. Guano (the term for bat excrement) is also a vital ingredient to many different fertilizers as it is exceptionally high in phosphorus and calcium. There is additional strong evidence to suggest that bats are key indicators of biodiversity[2]. Bats may be one of the most unappreciated species we have and unfortunately, bat populations are in steep decline.

“Bioindicator” or “Indicator” species are species that can used to help measure the overall health of the ecosystem. Bats are apex predators when it comes to insects and are hyper-sensitive to climate change, agricultural intensification, habitat loss and the onset of disease.

Bat Species in Ontario

Ontario is home to eight bat species all of which are found in central Ontario. These are the Hoary Bat, Big Brown Bat, Eastern Red Bat, Silver-haired Bat, Little Brown Myotis, Northern Long-eared Myotis, Eastern Small-footed Myotis, and the Tri-colored Bat. Once plentiful, Ontario’s bat population has sharply declined in large part due to habitat loss and development. It is also estimated that as White-nose Syndrome takes a foothold in Ontario, a large percentage of the bat population will be at risk.

Species at Risk

In Ontario, the Little Brown Myotis, the Northern Long-eared Myotis, the Eastern Small-footed Myotis, and the Tri-colored Bat are considered species at risk and designated as endangered. Species at risk in Ontario are subject to legislation and if developing in areas where they are present you will need to get assistance from NEA biologists.

What is White nose Syndrome?

Citation: White-nose Syndrome Occurrence Map by Year. Last Updated 07/02/2018.

White-nose syndrome (WNS) is an infectious fungal disease that proliferates in the skin and wings of bats. It can kills bats by causing them to starve. Bats with White-nose Syndrome cut short their hibernation and use their food stores before spring. Bats infected with WNS tend to have whitish fuzz-like markings on their face. It transmits through contact and prefers colder, damp environments such as caves. For more information regarding WNS please we recommend the following sites:


  1. Boyles, Justin G., Paul M. Cryan, and Thomas H. Kunz. 2018. Economic Importance of Bats in Agriculture. Science Magazine, 332: 41-42.
  2. Jones, Gareth., Jacobs, Davis S., Thomas H. Kunz, Michael R. Willig, and Paul A. Racey. 2009. Carpe noctem: the importance of bats as bioindicators. Endangered Species Research, 8: 93-115.