Modifiers matching visa:

• permanent,
• temporary,
• migrant,
• valid,
• resident,

Simple categories matching migrant:

• warbler,
• bird,
• sandpiper,
• group,
• population,
• organization,
• passerine,
• visa,
• songbird,
• language,
• fish,
• insectivore,
• labourer,
• thrush,
• worker,
• waterbird,
• finch,
• shorebird,
• sparrow,