be (one's) pigeon

To be one's area of expertise or responsibility. Primarily heard in UK, Australia. I can't approve expense reports, but Betty can—that's her pigeon.

Name	Pronounced	Usage
Ganizani	gah-nee-ZAH-nee	Southern African, Chewa
Vimala	-	Tamil
Paquita	-	Spanish
ŠImon	-	Czech, Slovak
Caitria	-	Irish
Harvey	['ha:vi]