ShouldyoueverbecaughtonthemarshyplainsofnorthwestCanadaduringspringtime,mindyourstep.You’llbeinpositiontowitnessoneoftheworld’slargestgatheringsofsnakes.Butfirsttheyhavetocomeslitheringoutoftheground. 

Red-sidedgartersnakeshibernatetogetherinlargegroups.Hundredsofsnakesmaycometogetherinanundergroundden.Theysharebodyheatandthereforestaywarmerduringwinter.Inthespring,whentemperaturesstarttorise,writhingmassesofred-sidedgartersnakesbreakfreefromtheirdensandmigratetotheirsummer homes.

Whatguidesthem?Theirsenseofsmell.Thesnakes’long,forkedtonguespickupscentmoleculesfromthegroundandair.ThemoleculesarepassedtoasupersensitivetastereceptorineachsnakecalledaJacobsen’sorgan.

Incollectingthesesmells,eachsnakecreatesadetailedscentmapofitssurroundings.Thatincludesthefamiliarsmellofitsownden.

Scientistshavetrackedsnakes
migratingupto12kilometers(about7.5 miles)awayfromtheirdens.Thesnakesusetheirscentmaptoreturntothesamedenyearafteryear.