| Astronomy | Birds | Botany |
| Butterflies | Conservation | Fungi |
| Naturalist Clubs | Nature Sites | Citizen Science |
Astronomy
- David Dunlap Observatory – Richmond Hill
- Hamilton Amateur Astronomers
- Royal Astronomical Society of Canada
Birds
- All About Birds (Cornell Lab)
- American Ornothological Society
- Audubon
- Birds Canada
- Canadian Peregrine Foundation
- Carden Plain – An Important Bird Area (IBA)
- eBird
- Fatal Light Awareness Program
- Niagara Peninsula Hawkwatch
- Ontario Eastern Bluebird Society
- Ontario Field Ornithologists
- The Owl Foundation
- Royal Botanical Gardens – Bald Eagles
- Toronto Ornithological Club
Botany
- Connecticut Botanical Society
- Field Botanists of Ontario
- Native Orchid Conservation Inc
- Picture This
- Plant Snap
- Ontario Wildflowers
Butterflies
Conservation
- BurlingtonGreen Environmental Association
- Carolinian Canada Coalition
- Conservation Halton
- Credit Valley Conservation
- EcoSource
- Escarpment Biosphere Conservancy
- Halton Environmental Network (HEN)
- Nature Canada
- Nature Conservancy of Canada
- Oakvillegreen Conservation Association
- Ontario Nature
- Peel Environmental Youth Alliance (PEYA)
- Protect Our Water & Environmental Resources (POWER)
- Sierra Club – Ontario
- Toronto Wildlife Centre
- Wildlife Preservation Canada
Fungi
Naturalist Clubs
- Halton / North Peel Naturalist Club
- Hamilton Naturalists’ Club
- Waterloo Region Nature (formerly Kitchener Waterloo Field Naturalists)
- Owen Sound Field Naturalists
- Peterborough Field Naturalists
- Toronto Field Naturalists
Nature Sites
- Bronte Creek Provincial Park (Ontario Parks official site)
- Friends of Bronte Creek Park
- Friends of Presqu’ile Provincial Park
- Royal Botanical Gardens
- The Riverwood Conservancy
- Willow Park Ecology Centre
South Peel Naturalists' Club 