On June 11, 2015, National Audubon Society conducted a survey of the Black Tern population at Tawas Lake.
The following text is from the eBird checklist submitted by Caleb Putnam, Audubon. All photos are by courtesy of Roger Erikkson. Follow the jump for Caleb’s report and more photos. Caleb’s Report:
“Official Audubon survey of Tawas Lake for Black Tern numbers, conducted by boat with Caleb Putnam, Randy Kling, Roger Erikson, and Philip Odum. Terns were found nesting in four main areas of the north section of the lake. At each area waypoints were taken, and we waited for the colony to erupt in mobbing/alarm flight (so that all adults would be present and not incubating/hidden), then took a maximum simultaneous count. The totals for these areas were 52, 39, 55, and 15. This third number may have actually been 63, but we weren’t certain the additional 8 birds were independent, so are being conservative. Furthermore, 161 is also a conservative estimate because some of the adults in the colony can be assume to be away from Tawas Lake foraging at any given time.
Nests were not able to be worked carefully for a complete count because it is impossible to walk in the mucky substrate underneath the nesting mats. However, we were able to confirm 38 total nests visually. This is a large underestimate of the actual number of nests present, which we presume is likely at least as high as half the number of adults, perhaps higher (since some of the adults leave the colony to forage as far away as Tuttle Marsh and Tawas Bay).”