Great reed warblers normally migrate by night during its month-long migration from northern Europe to Sub-Saharan Africa. However, researchers have now discovered that during the few occasions when it continues to fly during daytime, it flies at extremely high altitudes (up to 6300 meters). One possible explanation for this unexpected and consistent behaviour could be that the birds want to avoid overheating.
Click here for original story, Migratory songbirds climb to extreme altitudes during daytime
Source: ScienceDaily