A competitor calls with a shell at the German championships in Deer-Calling at the “Jagd & Hund” (hunting & dog) exhibition in Dortmund February 6, 2015. Competitors use specially designed instruments or ox horns to imitate the mating call of red deers. About 750 exhibitors will present their latest developments at the 34th “Jagd & Hund” exhibition, which runs from February 3 to February 8. (Photo by Ina Fassbender/Reuters)

A competitor uses an ox horn at the German championships in Deer-Calling at the “Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)

A competitor uses a specially designed instrument at the German championships in Deer-Calling at the “Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)

A competitor uses a specially designed instrument at the German championships in Deer-Calling at the“Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)

A competitor uses a specially designed instrument at the German championships in Deer-Calling at the “Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)

A competitor uses an ox horn at the German championships in Deer-Calling at the “Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)

A competitor uses a specially designed instrument at the German championships in Deer-Calling at the “Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)

A competitor uses a specially designed instrument at the German championships in Deer-Calling at the “Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)

Nils, 12, uses a specially designed instrument at the German championships in Deer-Calling at the “Jagd & Hund” exhibition in Dortmund February 6, 2015. (Photo by Ina Fassbender/Reuters)