We began our field monitoring surveys at the beginning of April. We got out to Leach Lake, Six Mile Slough, and Corn Creek Marsh and counted waterfowl weekly, until the end of April. As different species move through the area at different times, it is difficult to say when the overall peak occurred, but we certainly observed a lot of activity during the first two weeks of April. The migration often begins in early March, but ponds are sometimes still covered with ice at that time. Bigger bodies of water such as Duck Lake will sometimes start opening in early March and that is when it gets interesting as the birds often get concentrated in the ice-free pockets.
While it was not part of our waterfowl surveys, there were large numbers (thousands!) of Northern Pintails, Redheads, and American Coots interspersed with Mallards and American Wigeons, at the south end of Duck Lake in early March. The low water level in Duck Lake at that time of year is beneficial to dabbling ducks and is very extensive providing ideal foraging conditions for the staging birds.
We will be tallying the data collected this spring and hopefully be able to summarize before the end of 2021.
As soon as the waterfowl surveys ended, we jumped into the “marsh bird monitoring” surveys at Duck Lake Nesting Area, Leach Lake, and Six Mile Slough. These surveys focus on secretive species such as Sora, Virginia Rail, Pied-billed Grebe, American Coots, and American Bittern. The surveys, which use a call-playback method derived from a North American protocol, are conducted three times between May 1st and June 15th and are done at established point locations scattered throughout the survey areas. We are just completing the surveys as this is being written and we will be looking at the data later in the year to see how it compares with other years. Water levels in Six Mile Slough have been declining over the past two years and conditions may not be as suitable to some of these species this year. The waterfowl and marsh bird data collected over time helps us guide how we manage water levels in the wetland compartments throughout CVWMA.
Highlights of the shorebird spring migration at Duck Lake
The 2021 shorebird spring migration was the best seen in recent years. The low water levels in Duck Lake provided extensive mudflats for many species to spread out, feed and rest. The following species were observed by a variety of “birders” throughout the months of April and May, with the greatest number of species during the first 2-3 weeks of May: Black-necked Stilt, American Avocet, Semipalmated Plover, Killdeer, Long-billed Curlew, Marbled Godwit, Dunlin, Baird’s Sandpiper, Least Sandpipers, Pectoral Sandpiper, Semipalmated Sandpiper, Western Sandpiper, Long-billed Dowitcher, Wilson’s Snipe, Wilson’s Phalarope, Red-necked Phalarope, Spotted Sandpiper, Solitary Sandpiper, Greater Yellowlegs, and Lesser Yellowlegs. While not technically considered as a shorebird, several White-faced Ibises were also recorded at Duck Lake in May.
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