He writes occasionally for The Irish Times on culture & travel, presents the RTÉ podcast The Almanac of Ireland, and is author of the award-winning, best-selling Thirty-Two Words for Field (Gill, 2000), and Listen to the Land Speak (Gill, 2022). His illustrated books include Tree Dogs, Banshees Fingers and other Irish Words for Nature. (Gill, 2021) and Wolf-men and Water Hounds (Gill, 2023).

He has made dozens of documentaries on issues of world culture for TG4, RTÉ  & Travel Channel. He's on the board of Hometree, a native woodland & land regeneration charity, and is an ambassador for The Rivers Trust. He has lived for the last quarter century in an oak wood, with bees, hens, and occasionally pigs, in a grass-roofed house near Lough Lene, Co Westmeath.

In Aug 2025, Manchán was diagnosed with a rare and aggressive form of neuroendocrine prostate cancer. He departed, imithe ar shlí na fírinne on October 2nd 2025.