sentences:  In 2012, the population on Waikawa was discovered to have crashed by 75% to just 20 birds, apparently due to predation by a Norway rat.Twelve eggs were rescued for translocation to Mana Island.A total of 42 captive-bred shore plovers were released onto Motutapu Island in 2012 in the hope they would become established there and on other pest-free islands in the Hauraki Gulf.