Ornithologists like to explore new territory, searching for other species to study or new questions to answer. But occasionally, it makes sense to revisit an old area and examine it again with new methods. This is exactly what Ali Golamhosseini (Shiraz University, Iran) and his colleagues did. They revisited a hybrid zone between Black-headed Bunting (Emberiza melanocephala) and Red-headed Bunting (E. bruniceps) in northern Iran that has been studied by Paludan (1940) and Haffer (1970).
Compared to these two studies, the hybrid zone has expanded westward by approximately 170 km. To find out what caused this expansion, the authors applied Species Distribution Models (SDM). These models can disentangle the importance of intrinsic (e.g., competition between species) and extrinsic (e.g., climate) factors in shaping the observed species distribution.
The results from the SDM show a mismatch between the potential and realized distribution of the species. From a climatic point of view, the Black-headed Bunting could occur farther to the east, but it doesn’t. Probably, it is out-competed by the Red-headed Bunting which might be expanding westward due to land use changes by humans (i.e. deforestation and extension of agriculture).
I wonder what this hybrid zone will look like after another 70 years…
Gholamhosseini, A., Aliabadian, M., Darvish, J., Töpfer, T. & Sætre, G.-P. (2017). An Expanding Hybrid Zone between Black-Headed and Red-Headed Buntings in Northern Iran. Ardea 105, 27-36.
Haffer, J. (1977). Secondary contact zones of birds in northern Iran. Zoologisches Forschungsinstitut und Museum Alexander Koenig.
Paludan, K. (1940). Contributions to the ornithology of Iran. Ejnar Munksgaard.
This paper has been added to the Emberizidae page.