PRISM Surveys of Arctic Nesting Shorebirds
Posted on: May 31, 2016
Author: Stephen Brown
The purpose of our work in the Yukon Delta National Wildlife Refuge is to collect data for PRISM (the Program for Regional and International Shorebird Monitoring). PRISM is a large-scale international collaboration of researchers throughout the Western Hemisphere who are using a standardized protocol for collecting data with three main goals: 1) estimating the breeding populations of arctic, temperate, and neotropical shorebirds; 2) monitoring trends in shorebird population size, especially large population declines over 20 year periods; and 3) setting conservation priorities and assisting local wildlife managers in meeting their shorebird conservation goals.
Manomet’s Shorebird Recovery Program has been a partner in collecting data for PRISM in the arctic since its inception in 2001. While PRISM has many government agencies participating, funding has always been hard to come by and our partnership as an NGO raising private donor resources has been essential for the program. Our generous donors are essential for ensuring that we have good data on shorebird populations on which to plan their recovery.
As I described in the last podcast, we collect PRISM data using a double sampling method. First, we conduct rapid surveys of a large number of randomly selected plots to estimate the number of breeding shorebirds in important regions like the Yukon Delta, the Arctic National Wildlife Refuge, and the Teshekpuk Lake region of the National Petroleum Reserve-Alaska. This year, as in past years, PRISM rapid surveys in the arctic require the use of helicopters during a short two-week window when the birds are at their most active setting up territories, attracting mates, and establishing their nests. Because the Yukon Delta National Wildlife Refuge is the size of Maine, we have three helicopter crews conducting rapid surveys this year so that we can cover the vast landscape.
We carefully train our observers to hone their skills in rapidly detecting shorebirds by sight and sound because you often get only a small glimpse of a bird as it hurries by or hear its breeding song from a distance and obscured by the constant wind. This year we had the privilege of having Brian McCaffery, who worked at the Yukon Delta over many years as a biologist and the head of the biology program, partner with me to assemble a set of exemplary shorebird songs from both his personal collection and from Cornell Laboratory of Ornithology’s McCaulay Library of Natural Sounds. Brian’s deep expertise in sorting out the many complex vocalizations of breeding shorebirds was extremely helpful to the crew, and we were very grateful for his support with the training and also with planning the surveys.
We have also set up two longer-term camps where surveyors conduct intensive surveys on plots that are visited daily throughout the breeding period of four to six weeks, with the goal of finding every nest over the entire period. These intensively surveyed plots will also have a rapid survey conducted on them by the helicopter crews who don’t know anything about what is nesting there when they start. By comparing the rapid estimate of how many breeding shorebirds are on the plots with the data gathered over the entire breeding season by the intensive surveyors, we adjust the detection rates of the rapid surveyors. Because a rapid survey only lasts one hour and thirty-six minutes, we know each rapid survey misses a percentage of the shorebirds breeding on each rapid plot; this comparison allows us to better estimate the likely number of breeding shorebirds on each rapid plot and thereby better estimate population sizes across the huge landscape being surveyed.
As always, finding shorebird nests in the vast tundra is a challenge. The photos below show the incredible camouflage chosen by a pair of Black-bellied Plovers nesting near camp.
Dunlin nests, like this one I found on a rapid survey plot, are equally camouflaged. Up close the nest is easy to see, but if you step back just a bit it is superbly concealed, and from a few yards away it blends seamlessly into the landscape. You can see from this why we survey during the brief period when the birds are setting up nests and advertising their territories with songs and displays!
We will write more soon about the incredible diversity of wildlife we see on the tundra during our surveys and will also have updates from the other crews surveying in other parts of the Refuge.