Modifiers matching insectivore:

• mammalian,
• terrestrial,
• smaller,
• native,
• small,
• migrant,
• nocturnal,
• flying,
• avian,

Simple categories matching migrant:

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