Davies's big-eared bat or the graybeard bat (Glyphonycteris daviesi ) is a species of bat in the family Phyllostomidae. It is named after James (Jim) Noel Davies (B. 1936) who discovered it whilst on an expedition in British Guiana, South America (Guyana since 1966) in 1963. This was the Cambridge University expedition to the rainforest reserve near Bartica in British Guiana. This species can weigh 30 grams and has a wingspan of up to 50cm. It is bigger than most micronycteris bats with a fierce disposition. A small frog was found in the stomach of a specimen, and the bat is strong-willed enough to chew its way out of a cloth bag.

The species is found across the tropical regions of South America, including Brazil, Colombia, Costa Rica, Ecuador, French Guiana, Guyana, Honduras, Panama, Peru, Suriname, Trinidad and Tobago, and Venezuela. It is recorded (2021) in the Eponym Dictionary, published by Johns Hopkins University of Baltimore USA.

James ‘Jim’ Noel Davies is a Welsh naturalist and parks manager. He was a taxidermist on the Cambridge University undergraduate expedition to Gabon (1957), and later (1960-1962) researched dune sedges at Bangor University. There he was transferred to lead a bat study on the University’s expedition to the rainforest reserve near Bartica, British Guiana (now Guyana), and collected the type specimen of the Big-eared Bat (1963). Whilst teaching in high schools and colleges he concluded his studies on the dauciform roots of sedges at Nottingham University. These were taken up in Australia in relation to enhanced desert Phosphorus absorption. He finally ‘found his true calling’ as a Public Parks manager in Nottingham, Glasgow, and Llanelli. In retirement, he has been an active environmental campaigner and nature conservationist. He is currently (2022) President of the Friends group of the Nant Llwynog Park, Merthyr Tydfil Borough, South Wales.