Nick Hawkins / Chum salmon (Oncorhynchus keta) migrate up a small river near Bella Bella, British Columbia, Canada. September
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John Chan / Two male Southern Pacific rattlesnakes (Crotalus oreganus helleri) fighting during mating season. This behaviour is known as a "combat dance", and is used to determine dominance and the right to mate...
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SCOTLAND: The Big Picture / RF - Brown hare, (Lepus europaeus) male pursuing female that is in season, Islay, Scotland, UK., March (This image may be licensed either as rights managed or royalty free.)
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SCOTLAND: The Big Picture / RF - Brown hare, (Lepus europaeus), male and female displaying courtship behaviour, Islay, Scotland, UK., March (This image may be licensed either as rights managed or royalty free.)
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SCOTLAND: The Big Picture / RF - Black Grouse (Tetrao tetrix), two males fighting on lek , Scotland, UK.April (This image may be licensed either as rights managed or royalty free.)
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SCOTLAND: The Big Picture / Brown hare, (Lepus europaeus), group of animals in field, Islay, Scotland, UK., March
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Bernard Castelein / Sarus crane (Grus antigone), male displaying, Keoladeo NP, Bharatpur, India
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Espen Bergersen / Aerial shot of Killer whales (Orcinus orca) near the surface, showing mating behaviour including a male Killer whale displaying penis, Troms, Norway, August.
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Espen Bergersen / Aerial shot of Killer whales (Orcinus orca) near the surface, showing mating behaviour, Troms, Norway, August.