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Cawthra Mulock Nature Reserve

White-tailed deer, red fox, great blue herons, red-tailed hawks and great-horned owls are just a few of the residents that call this nature reserve home.

Cawthra Mulock Nature Reserve © Mark Carabetta


Donated to Ontario Nature in 2003, the Cawthra Mulock Nature Reserve is a valuable contribution towards the conservation of nature. Julyan Mulock and the Cawthra Mulock Foundation generously donated the 107-hectare (265-acre) property, ensuring that the land would be protected in perpetuity.

During the 31 years that the Mulocks lived on the property, they made a number of contributions towards its naturalization. Over 10,000 pines were planted in the old fields. Many of the old fields were allowed to regenerate naturally and are now important habitat for a variety of sparrows and other meadow birds.

Orange jewelweed, Cawthra Mulock Nature Reserve © Maria Papoulias


In 2007, the York Simcoe Nature Club became the official stewards of the Cawthra Mulock Nature Reserve and is actively assisting with a variety of restoration, monitoring and access improvement projects on the property.

Periwinkle pull, Cawthra Mulock Nature Reserve © Smera Sukumar

Plants and Animals

Surrounded by intense agricultural and urban development, the reserve provides refuge to a variety of wildlife. The most notable feature of this property is the diversity of habitats it encompasses. The property hosts a large tract of mature hardwood and mixed forests. Enormous beech trees rub shoulders with tall maples and hemlock. A small wetland area, dominated by birch trees and larch, is part of the larger Ansnorveldt wetland complex. Located in the West Holland River watershed, the property boasts two creeks. White-tailed deer, red fox, great blue herons, red-tailed hawks and great-horned owls are just a few of the residents that call this nature reserve home.

Clay-coloured sparrow © Noah Cole


Located just north of Newmarket, the property is a valuable green space in a highly developed area of Ontario. It is identified as being a key natural area in the York Region Greening Strategy. The Cawthra Mulock Nature Reserve also falls within the context of the Ontario government’s new Greenbelt system. Situated just north of the Oak Ridges Moraine, the Cawthra Mulock Nature Reserve’s rolling hills and forested ridges are a refuge for wildlife.

There is a system of well-marked trails, including interpretive signs, and visitors are invited to walk the property.

Southern Ontario, like our nature reserves, is experiencing an increase in black-legged ticks and with it an elevated risk of contracting Lyme disease. Please stay on trails to reduce your risk. For more information about ticks and Lyme disease read our blog post.

Birdwatching at Cawthra Mulock Nature Reserve © Noah Cole


We are dedicated to ensuring people of all abilities are able to enjoy the nature reserve. We are upgrading the trail network at Cawthra Mulock Nature Reserve to meet the Ontario visual and mobility accessible standards.

Those visiting will notice many felled trees and stumps. This action was undertaken to remove and trim hazardous trees that posed safety concerns for those visiting the trails on the property. Ash trees were most affected, infested by the emerald ash borer, an invasive beetle from Asia. We hope you continue to enjoy the trails at your leisure.

Monarch butterfly on milkweed © Jenna Siu


The reserve can be accessed by travelling north on Bathurst Street from Green Lane/Millers Side Road. The nature reserve is the second driveway on the left (west) side at 18462 Bathurst Street and is marked by a green and white Ontario Nature sign. The parking lot is located across from the white house (please respect the privacy of the tenants). The trails network can be accessed directly from the parking lot, past the gate.

View Cawthra Mulock Nature Reserve in a larger map.

Widow skimmer dragonfly at Cawthra Mulock Nature Reserve © Noah Cole

Bobolink © David Watkins


The Cawthra Mulock Nature Reserve is generously supported by: