The Canadian Lakes Loon Survey

The Canadian Lakes Loon Survey was an on-going study of behaviors of the Common Loon. After a nation-wide effort between 1992 and 2010, the surveys were analyzed and graphs were produced to demonstrate patterns of loon reproduction across Canada. The study  encouraged participants to observe the reproductive success of the species between June and August each year. The Common Loon is an aquatic bird that spends its life on or near water. Consequently, the health of lakes are important for the survival of the loon and its offspring. The survey results suggest that loon reproductive success is a strong indicator of the health of a lake. Lake longitude, pH level, and pollutant content were recorded and compared to the success of loon population reproduction. Loon offspring had the greatest success of survival in lakes that were larger and had limited mercury and acid content. The Canadian Lakes Loon Survey produced valuable results for citizens and scientists to better understand factors that impact the health of both loons and lakes.


In 1981 the Canadian Lakes Loon Survey began in Ontario for citizen participants to monitor breeding patterns of Common Loons. It was not until after 1990 that this survey became a national attempt to observe, monitor and collect data of loon behavior. This summary focuses on the data presented by the surveys conducted between 1992 and 2010. The Canadian Lakes Loon Survey intent was to find patterns between the health of Canadian lakes and loon reproduction. Data produced from the survey suggests that the Common Loon is an indicator of the health of Canadian lakes because the species is affected by changing pH levels and pollutants in the water. The study concludes that loons are impacted by different variables including lake longitude, pH level, and pollutant content. In addition, the survey suggests it is important for citizens to participate and observe wildlife studies to become more aware of environmental issues.

The Common Loon, Gavia immer

The Common Loon can be identified by its howl-like wail call, laughter tremolo and yodeling sound when defending territory. The population of this unique species is about 250,000 breeding pairs in Canada, a number which represents approximately 95% of the world’s population. The Common Loon is an aquatic bird that migrates to lakes to find food and shelter for reproduction. Their nests are low-laying mounds of vegetation that rest along the shores of lakes. Loons reproduce at approximately 4 to 11 years of age and tend to pair with previous mates. Both the male and female share the responsibility of incubating up to two eggs for 26-29 days. Once hatched, the young are fed fish from the nesting lakes and as a result the methylmercury (mercury) in the lake effects their health. Loon chicks affected by mercury tend to have weaker immune systems and higher mortality rates. Consequently, the success of off-spring and population regeneration relies greatly on the quality of the aquatic habitat.


In order to record, collect, and process data on lake health and the reproductive patterns of the Common Loon, the research used surveys and analysis. The survey required participants to monitor entire lakes or portions of a lake. The survey was a three-part system; each June the survey was issued to determine the number of territorial pairs on a lake, in July the survey focused on counting the hatchlings, and in mid-to-late August participants surveyed the survival success of those hatchlings by counting the number of six-week-old offspring. Each year the three-part survey was issued to participants to make observations and report on the success of loon pairs reproducing.

The analysis required statistics to evaluate the success of reproduction across Canada. Variables included the longitude, year, lake area and pH (acidity) of the lake. This quantitative data was converted into graphs to demonstrate the trends of reproductive success in accordance to the variables listed.

Results of study

Once the surveys were complete and the data was analyzed, the study concluded that the reproductive success of the Common Loon was negatively impacted by mercury pollution and lower pH levels (indicators of higher levels of acidity in the water). It was found that the most successful lakes for reproduction were larger lakes with higher pH levels in comparison to more acidic and smaller lakes. The smaller lakes with lower pH levels had higher levels of pollutants including mercury. The study suggests that these pollutants affected fish populations; results of the survey stated that in polluted lakes there were less fish for loons to forage and feed their offspring. The study infers that higher levels of mercury can be caused partially by lower pH levels and increased  temperatures. Both acidic precipitation and higher temperatures can increase bacteria. As a result, changes in the climates temperature and acidic levels are effecting the success of reproduction for the Common Loon.


Mercury and lower pH levels alter aquatic habitats of North America. The survey concluded that as a species, the reproductive success of the Common Loon is limited by the presence of mercury and higher levels of acidity. The data collected from participants of Bird Studies Canada’s Canadian Lakes Loon Survey can provide information to further learn about the success of the aquatic bird in relation to lake health.

Taking Action

In order to support the success of loon reproduction, citizens should take action as active participants in advocating for the loon population. This can include researching and lobbying for loon and lake conservation, limiting impact on the environment, and participating in and reporting to conservation projects such as the Bird Studies Canada’s Canadian Lakes Loon Survey.