It’s a POPULATION COUNT YEAR on the Pribilof Islands.
What is a “Population Count Year”?
The Alaska Maritime National Wildlife Refuge (AMNWR) counts the number of seabirds breeding on both St. Paul and St. George Island every three years. 2014 is one of those years.
Why do we count birds?
The Refuge has been counting seabirds on the Pribilof Islands since the 1970s. By counting the number of breeding seabirds over many years we can learn whether seabird populations are increasing, decreasing, or stable (remaining the same).
Biologists can use this information, along with data collected on breeding success (how many chicks are successfully reared by seabird parents) and diet to understand how seabirds are doing on the Pribilof Islands. For example, a decline in population size could indicate a change or reduction in local food availability.
What seabird species are we counting?
The Refuge focuses on the seabird species that breed on the cliffs: common and thick-billed murre, black and red-legged kittiwakes, northern fulmars and red-faced cormorants.
How do we count birds?
It’s not as easy as it sounds!
There are thousands and thousands of birds breeding on the Pribilof Islands, and it would take days and days to accurately count every bird.
The Refuge therefore counts the number of birds present within plots (mapped areas of the cliff that remain the same over the years). These plots are distributed all around the edge of the islands to include areas of higher and lower density breeding colonies. Plots are counted from the same observation place each year, and these locations are marked by a rebar and GPS (Global Positioning System).
Counts are conducted during the incubation and early chick-rearing period, a time when the maximum numbers of breeding birds are present.
Kittiwakes and cormorants build nests on the cliffs that are fairly easy to identify, so biologists count both the number of nests and the number of birds within the defined plot area. Murres don’t build a nest, and it takes a lot of time and patience to spot an egg or a chick, so biologists only count the number of adult birds present with the plot.
Biologists use mechanical tally clickers to count the number of birds and nests within the plot a number of times until they have two counts within 10% of each other. Counts are recorded in notebooks, along with the time of day, name of the observer, and information about weather condition. These data are then entered into the computer.
Seabird Camp
Students on St. Paul Island attending Seabird Camp 2014 will be learning all about population counts. We will learn how to use tally clickers, and have a field trip to the cliffs to collect some population count data for the Refuge. We’re excited!