Brunker, James Ponsonby (1885–1970), naturalist, was born 17 October 1885 at Minmore, St Kevin's Park, Rathmines, Dublin, the only son of James Edward Brunker, pharmaceutical chemist and president of the Pharmaceutical Society of Ireland, and Jane Brunker (née Anderson). Nothing is known of his education, but from 1906 till he retired in 1945 he was on the administrative staff of the Arthur Guinness & Co. brewery, Dublin. He was involved with the boy scout movement from its inception in 1909, eventually becoming assistant commissioner for Dublin, and was a member of the Dublin Naturalists’ Field Club (DNFC) by 1922. He was urged by Reginald Scully (qv), a founder member, to take up field work in Co. Wicklow; he was encouraged by Arthur W. Stelfox (qv) of the National Museum; and Robert Lloyd Praeger (qv) offered him the use of his notes on the county. Brunker began a long series of excursions at holidays and weekends, initially with Scully, but later often alone, in the Wicklow hills. With Stelfox he explored Tonelagee and the Wicklow Gap in 1923, and Barravore, near Lugnaquilla and Imaal, in 1924, and the two published phenological reports in the Irish Naturalist from 1927 to 1931.
On his retirement Brunker devoted himself to ornithology, to field work, and to completing his major contribution to Irish botanical studies, Flora of County Wicklow (1950), the culmination of thirty years of plant-collecting as he tramped the countryside. The Flora remains an important reference text, and contains a bibliography of Brunker's publications, including thirteen papers published in the Irish Naturalists’ Journal. From about 1935 Brunker and other DNFC members began cataloguing the flora of Co. Dublin. The result of their collaboration was published in 1961 by the NMI as A supplement to Colgan's Flora of County Dublin. He was president of DFNC (1933–4), and was involved in the club's jubilee commemorations in July 1935. He was made an honorary life vice-president of DNFC in 1962, and was elected MRIA (1957).
In November 1970, aged 85, he was engaged in fieldwork at the North Bull island, Dublin, one of his favourite sites, when he was injured by a car. He died 14 November 1970, and was buried in Mount Jerome cemetery, Dublin, after a funeral in Harold's Cross Church of Ireland church. He was a widower, with no children. On its centenary (1986) the DNFC, with the aid of the J. P. Brunker Memorial Publication Fund, founded in 1980 and financed from the sales of Flora, published a volume of historical Reflections and recollections. H. J. Hudson's essay on the so-called ‘ASU’ (active service unit) of the DNFC in Reflections includes a photograph of Brunker; Hudson was custodian of Brunker's herbarium.