وَلَا بَأْسَ أَنْ يَذْبَحَ الْمُحْرِمُ الشَّاةَ، وَالْبَقَرَ، وَالْبَعِيرَ، وَالدَّجَاجَ، وَالْبَطَّ الْكَسْكَرِيَّ.
Translation: There is no objection to a person in ihram slaughtering sheep/goats, cattle, camels, chickens, and the domestic Kashkari duck.
These are ordinary domestic stock or fowl and are not treated here as prohibited wild game.
Al-batt al-kaskari specifies a domestic kind of duck. It is not a general license to hunt every wild duck. Other normal rules of valid slaughter remain relevant; this clause addresses the ihram restriction.