Atlantic Canada Nocturnal Owl Survey

The results on this page are only showing the population indices for the project "Atlantic Canada Nocturnal Owl Survey". To view population indices from additional projects, you can use this page.

Atlantic Bird Observatory - Bon Portage Island Atlantic Bird Observatory - Seal Island Beaverhill Bird Observatory Bruce Peninsula Bird Observatory Delta Marsh Bird Observatory Haldimand Bird Observatory - Rock Point Haldimand Bird Observatory - Ruthven Haldimand Bird Observatory - Selkirk Inglewood Bird Sanctuary Innis Point Bird Observatory Last Mountain Bird Observatory Lesser Slave Lake Bird Observatory Long Point Bird Observatory Mackenzie Nature Observatory Observatoire d'oiseaux de Tadoussac Prince Edward Point Bird Observatory Rocky Point Bird Observatory Thunder Cape Bird Observatory ----------------- Select species ----------------- Season fall spring Earliest year: 1960196519701975198019851990199520002005 Latest year: 201020052000199519901985198019751970 Trend line: Linear Trend LOESS Smooth No trend line

The Population trends tool allows you to display estimated annual indices of population size over time, with optional best polynomial fit trend line (with trend estimate) or loess smoothed trend line (without trend estimate), for a selected time period and season. Plots for multiple locations and species can be displayed at once. You can start by selecting a project, and then one or more area, and one or more species (you can select multiple areas or species by holding the CTRL key), as well as some other optional features. For more information about this tool, click here. How to read the population trends The trend is presented as an estimate of % change per year over the period analyzed. For instance, a trend value of -1.7 % as in our example refers to an estimated loss of 1.7% in the population every year between 1967 and 2006. The p value represents the significance level of the trend. A smaller p value indicates a higher confidence that the trend is significant. We generally consider that p values smaller than 0.05 represent a significant trend. In our example, a p value of 0.1252 suggests that there is no significant trend for this species. The annual population index is a relative measure of the population calculated each year, based on the statistical model. Higher values simply indicate a larger estimated population on a given year. The indices are usually first calculated on a logarithmic scale, and sometimes converted to a more understandable unit, such as an average number of individuals counted per hour or per day. A logarithmic scale can easily be identified by the presence of negative annual population indices. The population trajectory (blue line) shows the general population trend over time. Depending on which option you selected, you may see no trend line, a linear trend (a straight line) or a LOESS smooth (a regression function that produces a general population trajectory based on the average around a given year).