Modifiers matching warbler:

• common,
• migrant,
• breeding,

Simple categories matching migrant:

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