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
Meinir	-	Welsh
Dmitar	-	Croatian, Serbian
Marija	-	Croatian, Slovene, Serbian, Macedonian, Lithuanian, Latvian
Tiburcio	-	Spanish, Portuguese
Devereux	DEV-ə-ro	English (Rare)
Wawrzyniec	vahf-ZHIN-yets	Polish