OnthemarshyplainsofnorthwestCanada,it’sspringtime.Watchyourstepandwitnessoneoftheworld’slargestgatheringsofsnakes.Snakescomeslitheringoutoftheground.

Red-sidedgartersnakeshibernatetogetherinlargegroups.Thisallowsthemtostaywarmer.Inthespring,whentemperaturesstarttorise,massesofred-gartersnakesbreakfreefromtheirdens.Thentheymigratetotheirsummerhomes.

Whatguidesthem?Theirsenseofsmell.Thesnakes’long,forkedtonguespickupscentsfromthegroundandair.ThescentsarepassedtoatastereceptorineachsnakecalledaJacobsen’sorgan.

Eachsnakecreatesascentmapofitssurroundings,includingthesmellofitsownden.Scientistshavetrackedsnakesmigratingupto12 kilometers(about7.5miles)fromtheirdens.Thesnakeswillusetheirscentmaptoreturntothesamedenbeforethenextwinter.