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In March of this year the Butte des Morts Conservation
Club, together with the WDNR, built several nesting islands on Lake Butte
des Morts. We are happy to report that we successfully attracted eleven
nesting pairs of the State Endangered Common Tern.
The island is only about 30 x 40 feet across the top
and 3 ½ feet above the lake surface. It is small, remote, unvegetated, and
predator free – just what common terns like for nesting. Art Techlow,
Biologist with the WDNR, counted eleven common tern nests with eggs on the
island at the end of July. Adult terns had no problem warding off potential
threats to their chicks, they defend their nests by swooping and diving at
the perceived menace. Most often these are large birds such as geese,
pelicans and cormorants which might accidentally trample nests and eggs. But
sometimes they go after humans, as Art found out after being struck in the
head several times over the years while checking nesting sites.
It only takes about three weeks for the young to fledge
(i.e. to be able to fly), and by late August all the adults and their young
had left the island. This is typical; the birds quickly disperse to better
foraging areas as the young take wing. (Common terns feed on minnows and
other small fish by diving on the wing.)
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