Modifiers matching passerine:

• interesting,
• migrant,
• exotic,
• small,
• upland,
• smaller,
• insectivorous,
• passerine,
• european,
• breeding,

Simple categories matching breeding:

• predator,
• bird,
• facility,
• animal,
• trait,
• seabird,
• wildfowl,
• shorebird,
• livestock,
• organization,
• duck,
• method,
• mammal,
• songbird,
• news,
• vertebrate,
• characteristic,
• system,
• waterbird,
• pet,
• cattle,
• season,
• creature,
• rodent,
• passerine,
• raptor,
• warbler,
• farm,
• structure,
• waterfowl,
• information,
• poultry,
• antelope,