Modifiers matching warbler:

• breeding,
• migrant,
• common,

Simple categories matching migrant:

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