By Ric ChapmanThe American-born European raced superstar, successful freshman sire Giant's Causeway (Storm Cat--Mariah's Storm) received an impressive kick start to his southern hemisphere breeding campaign. The first mare he covered, in the wee hours of Australia's opening day of breeding (Sept. 1), was former group I winniner Polar Success (Success Express--Patou).The mating was Coolmore's first cover of the new season and it went well. Polar Success won last year's $3 million (U.S. $2.1 million) Golden Slipper Stakes (Aust-I) over six furlongs and was recently sold for over $1 million as a breeding prospect. From her 17 starts while racing, she earned $2,171,505 (U.S. $1,528,000) in stakes.Coolmore's stallions covered 35 mares on opening day.On a sadder note, Thunder Gulch's only group 1 winning Australian bred son, Shot Of Thunder (out of My Brilliant Star), was euthanized while covering his first mares. The multiple group winning son of Thunder Gulch won A $556,900 (U.S. $392,000) and was due to serve 85 mares in his first season.