The marsh wren was described by the Scottish-American ornithologist Alexander Wilson in 1810 and given the binomial name Certhia palustris.

[4] Etymology: from Greek 'κιστος' (cistos, "a shrub") and 'θουρος' (thouros, "leaping, or running through") and Latin 'palustris' ("marshy").

[6] Measurements:[7] These birds forage actively in vegetation close to the water, occasionally flying up to catch insects in flight.

[8] In California, 53 Western Marsh Wren stomachs were examined which showed that the birds consume bugs (29%), caterpillars and chrysalids (17%), beetles (16%), ants and wasps (8%), spiders (5%), carabids and coccinellids (2%), with various other flies, grasshoppers, dragonflies and unidentifiable insect remains making up over 11 percent.

[15] The Blowfly larvae infect the young by subdermal myiasis-induced lesions and subsequent sepsis.

[9] However, its numbers have declined with the loss of suitable wetland habitat and wholesale draining of marshes will lead to local extinction.