Recording migratory restlessness in resident African stonechats (the European stonechat is pictured above) suggests that nonmigratory birds retain an innate program supporting a seasonal urge to migrate.
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<i>Remnants of the Past or Ready to Move? Resident Birds Display Migratory Restlessness.</i> Gross L, PLoS Biology Vol. 4/4/2006, e130 <a rel="nofollow" class="external free" href="https://dx.doi.org/10.1371/journal.pbio.0040130">https://dx.doi.org/10.1371/journal.pbio.0040130</a>