John Cancalosi / Timber rattlesnakes emerging from den {Crotalus horridus} Pennsylvania, USA

John Cancalosi / Western diamondback rattlesnake (Crotalus atrox). Arizona, USA

LYNN M. STONE / Fangs of Eastern diamondback rattlesnake. Florida, USA {Crotalus adamanteus}

Jason Venus / Western diamondback rattlesnake {Crotalus atrox} in road at night. BBC Incredible Journeys. Road in the path of snake's migratory route across the Sonoran Desert, Arizona USA. Many killed on road.

Stephen Downer / John Downer P / Sidewinder rattlesnake corkscrews along sand, wave of contact points passes along body (Resolution restriction - image digitised from film, 'Weird Nature' tv series)

John Cancalosi / Timber rattlesnake (Crotalus horridus) females and newborn young at maternity site. Pennsylvania, USA. August.

Daniel Heuclin / Western diamondback rattlesnake (Crotalus atrox) camouflaged amongst rocks, with rattle raised. Sonoran Desert, Arizona, USA. Controlled conditions. June 2019.

Daniel Heuclin / Western diamondback rattlesnake (Crotalus atrox), flicking tongue and with rattle raised, Arizona, USA. Controlled conditions.

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...

John Cancalosi / Timber rattlesnakes (Crotalus horridus), gravid females basking to bring young to term, Pennsylvania

John Cancalosi / Group of gravid female Timber rattlesnakes (Crotalus horridus) basking before giving birth, Pennsylvania, USA, July.

John Cancalosi / Group of gravid female Timber rattlesnakes (Crotalus horridus) basking before giving birth, Pennsylvania, USA, July.