Description of the waterfowl monitoring methodology

Waterfowl counting is a national monitoring program that began in 1986. It provides annual data on the number of waterfowl pairs, broods, and chicks. The aim is to track changes in breeding populations and reproductive success from year to year across different types of water bodies.

The results of the monitoring are used, for example, in species threat assessments, in regulating the hunting of game birds, and more broadly as indicators of the ecological status of aquatic environments.

Waterfowl surveys are conducted mainly through point monitoring carried out by volunteer hunters and birdwatchers. The surveys are coordinated jointly by the Natural Resources Institute Finland (Luke) and the Finnish Museum of Natural History (Luomus). Luke coordinates the counts conducted by hunters, while Luomus oversees those by birdwatchers. Survey sites (i.e., points) are distributed across Finland, and since the 2020s, over 2,000 points have been surveyed annually.

Each site is ideally surveyed three times per year, with timing adjusted according to spring progression:

• First pair count: April 20 – May 3
• Second pair count: May 4 – May 17
• Brood count: July 1 – July 20

During pair monitoring, observers record the number of waterfowl by species and sex. Brood counts are conducted at the same sites and include observations of broods and adult females, non-brooding females, males, and individuals of unidentified age.

Observations are submitted via the Laji.fi system once the counts are completed. Hunters log in using their OmaRiista credentials.

Data Processing

Luke interprets the pair count data to estimate the number of breeding pairs per site, and the brood count data to estimate the number of broods and chicks.

From these site-specific estimates, indices are calculated to describe trends in pair numbers and total chick numbers. These indices are derived using a log-linear Poisson model with year and site as main effects.

Annual indices are scaled so that 100% represents the average value between 1989 and the most recent survey year.

The colored area around the indices represents the 95% confidence interval, indicating uncertainty due to variation in the data.

Species Coverage

• Pair count indices are calculated for 16 waterfowl species:
  Whooper swan, mallard, pintail, teal, wigeon, shoveler, goldeneye, tufted duck, pochard, goosander, red-breasted merganser, red-necked grebe, great crested grebe, horned grebe, black-throated diver, and coot.
• Chick count indices are calculated for four key game duck species:
  Mallard, wigeon, teal, and goldeneye.

Regional Analysis

Breeding population trends are examined both nationally and regionally, with Finland divided into southern, central, and northern zones (see Figure 1).

The main goal of point counts is to monitor changes in breeding populations and reproductive success from year to year across different types of water bodies and regions in Finland, and to study the underlying causes of these changes. Waterfowl surveys support population management planning, wildlife conservation, and the monitoring of bird populations and the environment.

Luke analyzes the data and compiles the results annually in August after performing the calculations. Statistical methods and reporting are developed as needed and according to available resources.