His mother was Countess Mária Tolnai Festetics, and his father Kálmán Chernel, the author of the first monograph written on Kőszeg. Istán Chernel was a great hunter and skier; he was keen on music and also excelled as a composer; he was a photographer and earned recognition as a researcher and protector of bird species. He published his first paper on the study of birds at the age of 17 in a hunting paper.

In 1889, he returned from Sopron to Kőszeg and leased his estates so that he could devote all his time to the study of birds. His work in the field of ornithology focussing mostly on bird migration as well as on the economic significance and protection of birds. He travelled extensively in Hungary but most of his bird observation was made in the Hanság, in the reedy vegetation of Lake Velence, the flood plains of the River Danube, the Northwest of Hungary and in the area of the lower Danube.

It was at the highly successful international Ornithology Congress in Budapest (1891) where the idea of cross-border action to protect birds and nature in general was first put forward. Chernel published his work entitled “Directory of Birds in the Kingdom of Hungary” in 1898, which not only included Latin names for bird species but also their Hungarian equivalent. His most important piece of work, entitled “Hungary’s birds and their economic significance” was published in 1899 and is hailed as the first Hungarian monography on ornithology.
In 1904, Chernel translated three volumes of Alfred Brehm’s Animal Life (Tierleben) focusing on birds; and adapted their content to Hungarian circumstances. Besides his scientific work in the field of ornithology, he was also an ardent protector of animals with special attention to birds.

He was active as the vice president of the National Society for Animal Protection and set up its local branch in Kőszeg (1902) which he presided over. To follow the American model, he organised the “Day of Birds and Trees” in Kőszeg in 1902, a cherished tradition that has continued to this day.