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...

Ingo Arndt / Prairie rattlesnake (Crotalus viridis viridis), threat display, South Dakota, USA September. Sequence 1 of 3

Bence Mate / Western diamond-backed rattlesnake (Crotalus atrox) Texas, USA, April.

Silke Arndt / Western rattlesnake (Crotalus viridis viridis), threat display, South Dakota, USA, September.

Daniel Heuclin / Western diamondback rattlesnake (Crotalus atrox) tasting air, in habitat, Arizona, USA, October. Controlled conditions

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

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

John Cancalosi / Female Timber rattlesnake (Crotalus horridus) at nest site with newborn young, Pennsylvania, USA, September.

Chris Mattison / Sidewinder (Crotalus cerstastes) in sand dunes, Anza-Borrego Desert State Park, California, USA, May.

Daniel Heuclin / Mojave rattlesnake (Crotalus scutulatus) Mojave desert, California, June.

Michael D. Kern / South American rattlesnake (Crotalus durissus cumanensis) captive, from Venezuela and Colombia

John Cancalosi / Male Western diamondback rattlesnake (Crotalus atrox) courting female, Sonoran Desert, Arizona, USA. Sequence 1/3.

MYN / Seth Patterson / Western diamondback rattlesnake (Crotalus atrox) Rio Grande Valley, Texas, USA, October. meetyourneighbours.net project

Pete Oxford / Eastern diamondback rattlesnake (Crotalus adamanteus) close up of rattle, The Orianne Indigo Snake Preserve, Telfair County, Georgia USA, captive

B&S Draker / Western Diamondback Rattlesnake (Crotalus atrox), adult in defense posture. Sinton, Corpus Christi, Coastal Bend, Texas, USA, March.

Rolf Nussbaumer / RF- Western Diamondback Rattlesnake (Crotalus atrox), adult in striking pose with rattle raised, in wildflowers. Laredo, Webb County, South Texas, USA. April. (This image may be licensed either as rig...

Rolf Nussbaumer / Western Diamondback Rattlesnake (Crotalus atrox), adult in striking pose in wildflower field. Laredo, Webb County, South Texas, USA, April.

Rolf Nussbaumer / Western Diamondback Rattlesnake (Crotalus atrox), adult in striking pose in wildflower field. Laredo, Webb County, South Texas, USA, April.

Michael D. Kern / Striped western diamondback rattlesnake (Crotalus atrox) captive, from USA

Rolf Nussbaumer / Western Diamondback Rattlesnake (Crotalus atrox) flicking tongue in strike posture, in field of Showy Primrose, Fennessey Ranch, Refugio, Coastal Bend, Texas, USA

Rolf Nussbaumer / Flower head of Rattlesnake flower (Brazoria truncata) Fennessey Ranch, Refugio, Coastal Bend, Texas Coast, USA

Rolf Nussbaumer / Close up of Rattlesnake flower (Brazoria truncata)Fennessey Ranch, Refugio, Coastal Bend, Texas Coast, USA

John Cancalosi / Sonoran Desert Sidewinder (Crotalus cerastes) with forked tongue extended, Arizona USA

Edwin Giesbers / Canebrake Rattlesnake {Crotalus horridus atricaudatus} captive;

Edwin Giesbers / Western diamondback rattlesnake {Crotalus atrox} skin detail, captive, from Texas, USA

Edwin Giesbers / Western diamondback rattlesnake {Crotalus atrox} captive, from Texas, USA

Edwin Giesbers / Mexican West Coast Rattle Snake {Crotalus basiliscus} close up of rattle, captive, from Central America

Michael D. Kern / Mojave Sidewinder rattlesnake with tongue flickering and rattle raised {Crotalus cerastes cerastes} captive from California, USA

Rolf Nussbaumer / Close up of coiled Western Diamondback Rattlesnake {Crotalus atrox} Texas, USA, May

Kim Taylor / Harris' hawk (Parabuteo unicinctus) attacking a rattlesnake (composite image)

John Cancalosi / Western diamondback rattlesnake close up {Crotalus atrox} rattle visible, Texas,

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

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)

Lynn M Stone / Fangs of Eastern diamondback rattlesnake. Florida, USA {Crotalus adamanteus}

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

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.

Ingo Arndt / Prairie Rattlesnake (Crotalus viridis viridis) in defensive posture, South Dakota

Michael & Patricia Fogden / Black-tailed Rattlesnake (Crotalus molossus) portrait, Chiricahua Mountains, Arizona

Pete Oxford / Eastern Diamondback Rattlesnake (Crotalus adamanteus), Little St. Simon's Island, Georgia

ZSSD / Colorado Desert Sidewinder (Crotalus cerastes laterorepens) on sand, venomous species native to deserts of California and Mexico

Jim Brandenburg / Western Rattlesnake (Crotalus viridis) in defensive posture, South Dakota

Jim Brandenburg / Western Rattlesnake (Crotalus viridis) in defensive posture, South Dakota

Larry Minden / Red Rattlesnake (Crotalus ruber) coiled on ground, Baja California, Mexico

Larry Minden / Red Rattlesnake (Crotalus ruber) with tongue extended, Baja California, Mexico

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

Paul Williams / Timber rattlesnake (Crotalus horridus) with babies aged two days. Rhode Island, USA. Photographed as part of a captive breeding and release programme, Roger Williams Park Zoo.

Paul Williams / Timber rattlesnake (Crotalus horridus) female close up of scales, Rhode Island, USA. Part of captive breeding and release programme, Roger Williams Park Zoo.