Trends in breeding propensity of Common Loons (Gavia immer) in relation to lake water clarity in and around Algonquin Provincial Park

Abstract

Productivity of Common Loons has been in decline across most of Canada for several decades. Many environmental factors and human impacts on the breeding grounds may be causing the decline, and these factors are known to vary regionally. Common Loons are visual predators and rely on the clarity of lake water to forage. The Canadian Lakes Loon Survey and the Algonquin Park Loon Survey are used here to analyze trends in breeding propensity in Algonquin Provincial Park and surrounding area. The Ontario Lakes Partner Program was used to relate lake water clarity measured by Secchi depth to observed occurrence of Common Loon chicks on four lakes with long-term data. No decline occurs from 1982-2018 in the percent of lakes in Algonquin Park or its surrounding area with evidence of breeding observed. There is no correlation between water clarity and breeding propensity on the four chosen lakes. Where declines are occurring, the potential relationship between water clarity and Common Loon productivity should be investigated.