Canadian Lakes Loon Survey

Birds Canada

Project name: Canadian Lakes Loon Survey

Goals : To conserve loons by engaging participants in monitoring and education activities, and use loon productivity as a long-term indicator of the health of loon populations and freshwater lakes.

Dataset summary : Participant-chosen lake surveys (or sections of larger lakes) focused on measuring the number of six-week-old young produced by breeding Common Loons.

Status : Active

Year started : 1981

Years (comments) : ongoing

Season(s) and frequency : at least 3 visits per year, one each in June, July, and August. Aim is to survey lakes or sections of larger lakes with a minimum of 3 visits in each year for multiple years.

Frequency : Monthly

Geographic area covered : Primarily southern half of most Canadian provinces where accessible by lake residents or cottagers.

Type(s) of habitat : Freshwater lakes

Primary species covered : Common Loon (Gavia immer)

Sampling Design : Participant-chosen lakes or sections of larger lakes. Aim is to sample pairs/lakes in proportion to expert estimates of breeding abundance of Common Loons across provinces/territories, with good representation across Bird Conservation Regions and lake sizes within each province/territory.

Field methods : Participants make a minimum of three visits to each lake or lake section in each year: in June to record the number of pairs and nesting activity, in July to determine numbers of chicks hatched by each pair, and in August to determine numbers of young that survive to six-weeks-of-age for each pair. Potential sources of human disturbance are recorded, such as water level fluctuations, shoreline development, and ratings of human activity.

Analysis methods : The number of six-week-old young per pair per year is estimated using generalized linear mixed models with log-link functions, assuming Poisson distributions. Typically, models include the following covariates: year as factor, longitude, log lake area, and a random effect of lake. All continuous covariates are standardized prior to analysis to have a mean of zero and a standard deviation of one. Smoothers are plotted through annual indices to visualize patterns and trends are calculated based on a simple regression fit through the annual indices.

Data validation : Data are reviewed by staff knowledgeable in the ecology and behavior of Common Loons.

Sample size : Over 4000 lakes have been surveyed across Canada with more than 15000 surveys conducted since 1981, on average of 690 surveys are conducted each year.

Trends and time series availability : Yes