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Facts About Common Loons


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There are five species of loons worldwide, four of which breed in Canada. The Common Loon (Gavia immer) is the most widespread and well-known species. Loons are reported to be among the oldest groups of birds still living today, with a history some think stretches back more than 50 million years. 

However, their present challenges may well be the most severe they have faced throughout that long period. Human activities have decreased the abundance and the breeding range of Common Loons in North America over the past 150 years. 

These declines might be due to several factors: 


Loons are fish-eating birds and so are susceptible to the acid rain that is reducing fish stocks in lakes. On severely affected lakes, loon chicks may die from starvation because of low fish numbers. Acid water also leaches mercury and other toxic metals from rocks and soil. These metals concentrate up the aquatic food chain and may reach toxic levels in top predators like loons. 


The legs of loons are placed far back on the body, making loons powerful swimmers but virtually helpless on land. Nests are typically built right at the water's edge for ease of access and to provide a quick escape from perceived danger. Cottages built close to the shore displace loons from their traditional nesting sites. Damming for flood control or hydroelectric power causes water level changes that swamp nests or leave them stranded high out of the water and unreachable. Powerboaters often unknowingly run down buoyant loon chicks, panic parents and disrupt care and feeding of young, or create wakes that wash loon eggs out of nests. 


Predation of eggs and chicks is a natural occurrence and something loons have lived with throughout their long history. However, populations of some egg and chick predators like raccoons, bears and gulls have increased because of the availability of human garbage.

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Canadian Lakes Loon Survey 
Bird Studies Canada
P.O. Box 160, 
Port Rowan, Ontario, Canada N0E 1M0 
Tel: 519-586-3531 Fax: 519-586-3532
Questions about the CLLS? Please contact Kathy Jones