Birdstone (foaled May 16, 2001 in Kentucky) is an American Thoroughbred racehorse best known for winning the 2004 Belmont Stakes and has become a successful sire.
Owned and bred by Marylou Whitney of Whitney family racing fame, Birdstone had won the Champagne Stakes, a leading race for two-year-olds, at Belmont Park in 2003, but had not been a factor in the first two Triple Crown races (finishing eighth in the Kentucky Derby and skipping the Preakness Stakes) and was a 36-1 longshot when he upset the overwhelmingly favored Smarty Jones, taking the lead in the final furlong (201 m) in the fastest Belmont since the advent of modern electronic timing (2002 was the first year times were kept to hundredths).
His sire Grindstone won the Kentucky Derby in 1996, and was a son of Unbridled, who had done the same in 1990. Unbridled was in turn sired by Fappiano, a son of Mr. Prospector, the tail-male ancestor of the vast majority of winners of Triple Crown races in recent years (22 out of the 24 races 1998-2005).
Birdstone's victory represented the first in the Belmont for trainer Nick Zito, whose horses had finished second in that classic five times. In the Winners Circle after the Belmont Stakes, his owners actually apologized to the connections of Smarty Jones for winning, as did jockey Edgar Prado.
According to the New York Times, the next major target for Birdstone was the Travers Stakes, which he won despite being the fourth choice at 5-1. He was Zito's first Travers champion.
His retirement from racing after suffering a bone chip at the Breeders' Cup was announced November 4, 2004. He is standing at stud at Gainesway Farm in Lexington, Kentucky.
His first starter was the colt Shoe Strap (Birdstone - Boot Strap by Storm Boot) who went to post first May 21, 2008 at Churchill Downs and is trained by D. Wayne Lukas. He sired Mine That Bird, who had several wins as a two-year-old gelding before winning the 2009 Kentucky Derby as a three-year-old and Summer Bird, who went on to upset Mine That Bird in the 2009 Belmont Stakes, his first crop also included Birdrun who set the Belmont track record at a mile and a sixteenth and repeated his sire's feat by winning the Travers also. Summer Bird then went on to capture the 2009 Jockey Club Gold Cup.
He was one of the top ten ranked freshman sires of 2008 with 11 winners out of 22 starters and stood for $10,000 for the remainder of the 2009 season, despite his first crop success. Birdstone has been booked for all of his 2010 stud career. His 2010 stud fee has been posted as $30,000.