Degrees of Breeding Evidence and Survey Activity
Degrees of breeding evidence
Degree of breeding evidence in a given grid has been expressed using
indices from 1 to 8. Indices 6–8 have been divided into sub-indices. The same
indices with the same definitions were used also in the first and second breeding
A. Breeding unlikely (index 1)
- 1. Species detected in the grid during the breeding season, but almost
certainly does not breed there. This class includes e.g. birds that have
stopped for several days during migration or that are clearly non-breeders.
Birds detected in migration flight or at a short stop are not included.
B. Possible breeding (indices 2–3)
- 2 . A solitary bird detected once (e.g. a singing male) in suitable breeding
habitat, and breeding of the species in the grid is possible. The site has
been visited only once or the bird has been observed only once despite multiple
- 3 . A pair detected once in a suitable breeding habitat, and breeding of
the species in the grid is possible.
C. Probable breeding (indices 4–6, subindices 61–66)
- 4 . A singing or a displaying male observed at the same site in different
- 5 . A female or a pair observed at the same site in different days .
- 6 . A bird or a pair observed
- 61: visiting frequently at the probable nest,
- 62: building a nest,
- 63: giving alarm calls because of proximity to nest or brood,
- 64: displaying broken wing -act, or
- 65: attacking the observer.
- 66: Nest found with fresh nest material or remains of food; no direct
evidence of eggs or young found.
D. Confirmed breeding (indices 7–8, subindices 71-75 ja 81-82)
- 7 . Indirect evidence of verified breeding detected :
- 71: nest found with signs indicating that is has been used in the same
year (eggs or egg remains, or remains of nestlings)
- 72: a bird seen entering or coming out from the nest in a way that suggests
breeding (eggs or nestlings not seen)
- 73: fledglings or young detected so that they can be assumed to have
hatched within the grid
- 74: a parent carrying food to nestlings or faeces of nestlings away from
the nest (it is likely that the nest was located in the grid)
- 75: an incubating bird seen in the nest.
- 8 . Direct evidence of a verified breeding detected:
- 81: begging or other calls of nestlings heard from the nest
- 82: a nest found with eggs or nestlings.
Survey activity of each grid has been calculated as a weighed sum
of degrees of breeding evidence for each species detected in the grid. Species
with confirmed breeding were given score 3, probable breeding resulted in score
2 and possible breeding resulted in score1. Thus, survey activity of a given
grid is influenced by both number of species and degree of breeding evidence
of each species. For example, a combination of 15 confirmed breeding species,
10 probable breeding species and 12 possible breeding species will result in
survey activity of 77.
The survey activity was classified into six categories: 0 = no observations
in the grid, 1 = only occasional observations, 2 = the grid was fairly-well
surveyed, 3 = the grid was satisfactorily surveyed, 4 = the grid was well-surveyed
and 5 = the grid was thoroughly surveyed. These categories are used on the
atlas maps to illustrate the survey efficiency. Lower and upper limits of weighed
sums of degrees of breeding evidence have been determined for each category.
In general, the limit values are lower in the north because the number of potential
breeding species is lower there. Further, also the amount of land area has
been taken into account when determining lower and upper category limits.