Biogeographia – The Journal of Integrative Biogeography

The Ortolan bunting is an Old World bunting distributed across 20.2 million km² in the Central and West Palearctic regions, breeding from sea level to 3,300 m. Most of the population is spending the winter in Sub-Saharan Africa north of 5°N migrating mainly along two flyways, on each side of the Mediterranean Sea. The current theory about the bird’s population dynamics and biogeography has been developed from transitory research in geographically disconnected surveys on the European and African continent over the last 30 years, handled in stochastic models and population viability analyses. The theory posits that the species was abundant in antecedent times but the previously continuous population became fragmented and underwent a very steep decline in central and western Europe from the middle of the 20^th century due to negative anthropogenic effects and hunting. The population segment in Fennoscandia has become isolated from the rest of Europe due to lack of contemporary gene flow from the south and the species is directly threatened with extinction. A review of 948 interdisciplinary literary sources across 435 years (1590-2025) from 18 European countries, the Americas, Africa, Asia and Australia was conducted to explore if the Ortolan bunting’s population development could be understood differently with insight gleaned from empirical material on a large spatiotemporal scale. The review revealed that a hundred-years perspective is necessary to obtain a true picture as shorter time will only expose fractions of events interpreted out of context. Historical data disagree with the claim that current distribution is due to fragmentation of a continuous population. The distribution has been restricted to the same “geographical islands” now perceived as fragments across at least the last 300 years. The structure of the population does not indicate restricted gene flow to Fennoscandia from the south as historically the species has not been established in areas immediately south of the peninsula. It was colonized from the east. Antecedent hunting results cited in current scientific literature to validate immense harvest are erroneous, as are the annual catch estimates from France around the turn of the Millennium used to predict the bird’s extinction in Fennoscandia. In the last 260 years the population in Europe has undergone temporally long fluctuations (range expansions and contractions) with transient shifts between occurrence and absence manifested by distinct peaks and nadirs in abundance, superimposed on a negative trend. The main drivers may have been a variable immigration rate (fluctuations) and asymmetric growth (negative trend).