Osprey and Heron Buffer Guidelines

Description: Ospreys and great blue herons are species of special concern in Ontario because they are considered to be sensitive to disturbance during the nesting season. On crown lands, occupied nest sites must be identified as areas of concern (AOC) and protected by spatial and temporal buffer zones that are intended to mitigate the potential impacts of forest management activities associated with habitat alteration and direct disturbance.

Various guidelines have been proposed and used within the province. All guidelines prescribe reserves in which no forest management activities are permitted at any time of year and modified zones in which some activities are permtted outside the nesting season. Reserve zones range from 150 to 300 m in radius around nest sites. Modified zones range from 150 to 700 m in radius beyond the reserve zone.

These guidelines were based largely on literature review and expert opinion; their effectiveness has not been rigorously tested. Moreover, the impacts of forest management activities on occupancy and productivity of osprey and heron nest site are poorly understood throughout the range of both species.

This study uses a mensurative experimental approach to describe the effects of forest management activities on occupancy and productivity of osprey and heron nest sites and evaluate the effectiveness of the different guidelines in mitigating these effects. Specifically, the hypotheses tested are that 1) the proximity, extent, and timing of forest management activities has no effect on occupancy or productivity of nest sites, and 2) that nest sites cut with or without the guidelines do not differ in occupancy or productivity when compared to uncut controls.


The Project Team: Brian Naylor, Jennifer Simard, and Melanie Alkins, OMNR North Bay, Greg Lucking and Bob Watt, OMNR Timmins



Final Report Draft 2: Naylor, B. et al. 2003. Effects of Forest Management Practices on Breeding Ospreys and Great Blue Herons in the Boreal and Great Lakes – St. Lawrence Forests of Ontario. 24pp.


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