(see handbook for full description & use suggestions)
PO Category - possible breeding evidence
Species (male or female) observed in its breeding season in suitable nesting habitat, with no other indication of breeding noted.
PR Category - probable breeding evidence
Pair observed in suitable nesting habitat during its breeding season.
Permanent territory presumed through either defense (e.g. chasing of other birds) or song at same location on at least 2 occasions 7 days or more apart.
Courtship behavior or copulation. Not used for waterfowl, shorebirds, and diurnal raptors.
Visiting probable nest site.
Agitated behavior or anxiety calls from adult.
Nest building by wrens or excavation of holes by woodpeckers.
CO Category - confirmed evidence of breeding
Nest building by any species except wrens and woodpeckers.
Distraction display or injury feigning.
Used nests or egg shells found. Must be carefully identified, if they are to be accepted.
Recently fledged young (of altricial species) incapable of sustained flight or downy young (of precocial species) restricted to the natal area by dependance on adults or limited mobility.
Adults entering or leaving a nest site in circumstances indicating occupied nest. To be used for nests which are too high (e.g. the tops of trees) or enclosed (e.g. chimneys) for the contents to be seen.
Adults with fecal sac or food for young.
Nest with egg(s) or adult sitting on nest.
Nest with young or downy young of waterfowl, quail, waders, etc.