New neuronal recruitment in an adult animal's brain is presumed to contribute to brain plasticity and increase the animal's ability to contend with new and changing environments. During long-distance migration, birds migrating greater distances are exposed to more diverse spatial information. Thus, we hypothesized that greater migration distance in birds would correlate with the recruitment of new neurons into the brain regions involved with migratory navigation. We tested this hypothesis on two Palearctic migrants - reed warblers (Acrocephalus scirpaceus) and turtle doves (Streptopelia turtur), caught in Israel while returning from Africa in spring and summer. Birds were injected with a neuronal birth marker and later inspected for new neurons in brain regions known to play a role in navigation - the hippocampus and nidopallium caudolateral. We calculated the migration distance of each individual by matching feather isotopic values (δH and δ13 C) to winter base-maps of these isotopes in Africa. Our findings suggest a positive correlation between migration distance and new neuronal recruitment in two brain regions - the hippocampus in reed warblers and nidopallium caudolateral in turtle doves. This multidisciplinary approach provides new insights into the ability of the avian brain to adapt to different migration challenges.
Bibliographical noteFunding Information:
We thank Kobi Merom for assisting in field work and bird ringing. We also thank Prof. Jacob Garty, The Botanical Gardens of Tel-Aviv University for providing us facilities for this work; The Israeli Ornithology Center of the Society for the Protection of Nature in Israel, for providing ringing data; Dr. Christopher Still, Dept. of Geography & Institute for Computational Earth System Science UC Santa Barbara for providing the δ13C isoscape; and Naomi Paz for editing the manuscript. We also thank two anonymous reviewers for their valuable and constructive comments, which helped us to improve the manuscript. This study was supported by The National Institute for Psychobiology in Israel and The Open University Research Fund. UR was supported by the Adams Fellowship Program of the Israeli Academy of Sciences and the Humanities.