years and was retired in 2004 after developing arthritis, which made it difficult for him to gallop down the field. He continued to make community appearances until his death in 2009 at age 27. Thunder Sr. was noted for his bold and courageous personality, and was described by Magness-Blake as having "a strong ego". He had been trained to rear on command. Yet he remained calm and controlled in very intense situations, and Judge believed he had a sixth sense for when to be energetic for a performance and when to calm down. The stallion was notably gentle around children who wanted to pet him. During games, when he was waiting to perform, he had a tendency to watch players on the field. Thunder II Winter Solstyce, an Arabian gelding foaled in 1994, became "Thunder II" in 2004. He was Magness-Blake's personal riding horse for several years prior to becoming the Broncos' mascot. His paternal grandsire is *Salon, a Russian-bred Arabian stallion from the Tersk Stud exported first to Germany and later brought to the United States. Winter Solstyce's maternal grandsire is *Gondolier, who was a Polish National Champion and World Champion Arabian stallion at the Salon du Cheval in Paris, imported to the U.S. in 1981. The remainder of his lineage traces back to the Arabian horse breeding programs of Poland and Russia. He is linebred to the stallion Negatiw, who appears four times in his pedigree. Thunder II stands tall and weighs over . Nicknamed "Dos" by Judge, Thunder II has been described as somewhat timid with a more subdued personality than his predecessor. Initially, he was nervous of the white markings on the football field and would try to jump over them. He was also afraid of the cheerleaders' pom-poms. For desensitization training, Judge and the rest of Thunder's team would haul him to the football field at a local high school to work with people carrying pom-poms and to run across a marked field. His handlers used operant conditioning with positive reinforcement, associating pom-poms with a carrot treat. Eventually, he began turning to his handlers anticipating a treat whenever he saw a cheerleader with pom-poms. Thunder II would look attentively with his ears forward, seemingly on cue, for his picture to be taken whenever a photographer pointed a camera at him. He is known for being people-friendly and particularly gentle with children who became acquainted with