Caspian Gull and Yellow-legged Gull should be considered separate species according to a paper by Lars Jonsson in the journal Alula.
The airport in Mek'ele is named after Ras Alula, and an equestrian statue is dedicated to him in that city.
Together with the Red-spectacled Amazon and the Yellow-lored Amazon, it is the only Amazon species in which adult males and females easily can be distinguished by external appearance (sexual dimorphism): Males have bright red feathers on their "shoulders" (alula), while females have green "shoulders".