It's actually typical for them to appear around maturity. This is different from Tetrarch spots on a gray horse, which go white before the rest of the body and thus are visible on very young colts. In both cases horses usually have just a few scattered spots though, not covering the entire body like Magic Replica.starrydreamer wrote:Birdcatcher spots can show up later in life? I didn't know!Miss Woodford wrote:He's only 3/4 TB, but check out this guy's Birdcatcher spots. His name is Magic Replica, by the TB sporthorse stallion Mystic Replica out of a TB x Belgian mare by Travelling Music. No Appaloosa in him!. Apparently he was born plain bay and the white spots only showed up when he was 5-6 years old.
The genetics of Birdcatcher/Tetrarch/Bend Or spots hasn't been pinpointed but they are known to run in families. Mystic Replica tends to sire offspring in plain bay wrappers (who can jump the moon!) so it must've been quite a welcome surprise for Magic Replica's owners when he started showing spots.