Hans Löhrl was born on 25 May 1911 at Stuttgart, Germany. On 26 June 2001, four weeks after his 90th birthday, he died in Egenhausen, in the Black Forest.
Hans Löhrl grew up in rural surroundings, the son of the pastor at a church in Westheim, near the town of Schwäbisch Hall. He studied biology in Tübingen and Munich, obtaining his doctorate with a dissertation entitled “Ecological and physiological studies on native Muridae and Soricidae.” His professional career was soon interrupted by the outbreak of war. He served in the military for almost six years and two years as a prisoner of war. In 1949, he obtained a position in Ludwigsburg at the Bird Protection Station sponsored by the government of Baden-Württemberg; he was its director from 1957 to 1962. He then headed the Vogelwarte Radolfzell of the Max Planck Institute for Behavioural Physiology until his retirement in 1976.
Hans Löhrl's understanding of animals was prodigious, and most of his experience and knowledge was acquired by his own initiative. At an early stage, he learned how the patient and precise observation of animals could allow the observer to formulate important biological questions, and later on he continued to value observation above all else. He often advised his students that they should be most concerned with “watching closely,” an apparently simple bit of advice, but one that was a great help to many. Löhrl watched extremely closely, and as a result was able to correct much of what had previously been described as “fact” in the ornithological literature.
Hans Löhrl was an extraordinarily talented keeper and breeder of birds. Like Konrad Lorenz and Oskar Heinroth, he carried on the tradition of caring for captive birds, an art originally developed by amateurs, in the service of scientific investigations. Anyone who visited Hans Löhrl and his wife would find birds flying free somewhere in their residence, mainly nuthatches, tits, or flycatchers. By this means, he observed more than half of all nuthatch species at the closest possible range. He was especially proud of his skill at keeping problematic species, such as the cuckoo or wall-creeper. Löhrl was happy to pass on to students and colleagues what he had learned about providing birds with the right conditions and care; many studies of bird biology conducted by those close to him would never have been possible without this access to his treasury of such experiences.
In addition to seven books, Löhrl's scientific work includes about 120 full-length papers in journals and more than 140 short reports. Most of those publications are concerned with questions related to the general biology, ecology, and ethology of birds, in particular cavity breeders such as tits, flycatchers, and nuthatches.
In the late 1950s and early 1960s, urged on by his close friend Gustav Kramer, Löhrl carried out path-breaking experiments on home-ground imprinting in the Collared Flycatcher. Löhrl was the first to demonstrate that their birthplace is imprinted in young birds, but only if juveniles are allowed to fly freely about the locality so as to experience the environmental factors relevant to such imprinting. The underlying mechanisms have not yet been clarified, but Löhrl pointed out a route towards discovering them.
Aside from his scientific work, Löhrl felt the importance of communicating ornithological information to interested amateurs. He gave numerous lectures, published almost a hundred articles in popular science magazines, and wrote four books primarily directed towards the general public. Many of those appeared in late years, in what he and his wife called “active retirement.” They stimulated many readers to take a greater interest in nature, and guided a number of students in the direction of biology.
Hans Löhrl joined the AOU in 1962, was elected a Corresponding Fellow in 1968 and an Honorary Fellow in 1989. He served on the Advisory Board of the German Ornithologists' Society (DOG) for many years, was Vice President from 1971 to 1979, and an Honorary Member from 1989. He was also Corresponding Fellow of the Finnish Ornithological Society.
Ornithology has been deprived of an original researcher whose life work is a remarkable legacy.