BTO Categories of Breeding Evidence


Following list includes all the BTO Categories of Breeding Evidence, as used during field work for the most recent atlas. Not all these codes are applicable to Rooks
Level Code Description
Non-breeding F Flying over
  M Migrant
  U Summering non-breeder
Possibly Breeding H Observed in suitable nesting habitat
  S Singing Male
Probably Breeding P Pair in suitable nesting habitat
  T Permanent Territory (defended over at least 1 week)
  D Courtship and Display
  N Visiting probable nest site
  A Agitated Behaviour
  I Brood patch of Incubating bird (from bird in hand)
  B Nest Building or excavating nest hole
Confirmed Breeding DD Distraction Display or injury feigning
  UN Used nest or eggshells found from this season
  FL Recently fledged young or downy young
  ON Adults entering or leaving nest site in circumstances indicating Occupied Nest
  FF Adult carrying faecal sac or food for young
  NE Nest containing eggs
  NY Nest with young seen or heard
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