b1_indicator_analysis_steps.Rmd
The following steps were used in the 2021 analysis of both breeding and wintering seabird abundance counts, as part of the B1 indicator.
Analysis guidelines are documented in OSPAR CEMP Guidelines. Common Indicator: Marine Bird Abundance (B1) (Agreement 2016-09) word document downloaded from CEMP website (OSPAR’s Coordinated Environmental Monitoring Programme).
Restrict abundance counts to year ranges
Breeding | Non-breeding | |
---|---|---|
Im: North Barents Sea | 1991 - 2020 | |
In: South Barents Sea | 1991 - 2020 | 1991 - 2020 |
Io: Norwegian Sea | 1991 - 2020 | 1991 - 2020 |
I: Arctic Waters | 1991 - 2020 | 1991 - 2020 |
IIa: Northeast coast of Britain | 1991 - 2019 | 1991 - 2020 |
IIb: West coast of Norway | 1991 - 2020 | 1991 - 2020 |
IIc: Skagerrak/Kattegat area | 1991 - 2020 | 1991 - 2020 |
IId: Southern North Sea |
1991 - 2019 1991 - 2017 (20 species1) |
1991 - 2020 1991 - 2016 (39 species2) |
IIe: The Channel | 1991 - 2019 | 1991 - 2020 |
IIf: North coast of Scotland and the Northern Isles | 1991 - 2019 | 1991 - 2020 |
II: Greater North Sea |
1991 - 2019 1991 - 2017 (20 species1) |
1991 - 2020 1991 - 2016 (39 species2) |
III: Celtic Seas | 1991 - 2019 | 1991 - 2020 |
IV: Bay of Biscay and Iberian Coast | 1991 - 2016 | |
V: Wider Atlantic | 2010 - 2020 |
Set the baseline count
Either
Calculate the relative abundance values for each year by dividing the years abundance count by the predicted baseline abundance count.
Calculate the six year rolling relative abundance geometric means, ignoring missing years. Handle zero year counts by adding one to all the year counts with the six year period and removing one from the resulting geometric mean. For example
2020: take the geometric mean of relative abundance values 2020, 2019, 2018, 2017, 2016, 2015
2019: take the geometric mean of relative abundance values 2019, 2018, 2017, 2016, 2015, 2014
Plot both the yearly relative abundance values with six year rolling relative abundance geometric mean line for each species in each region and birds subdivision.
Take the latest six year geometric mean relative abundance values as the assessment value for the species in each region and subdivision, using this assessment value to create the four colours of the traffic–light table plot.
above upper threshold if greater than 1.3 (dark green)
above threshold if greater than or equal to 0.7 for species laying more than one egg or 0.8 for species laying one egg. (green)
below threshold if less than 0.7 for species laying more than one egg or 0.8 for species laying one egg. (red)
incomplete information (grey)
Compare the latest threshold status with the 2014 threshold status displaying status change with arrows in the traffic-light table plot.
vertical thick arrow pointing down for latest change from above upper threshold to below species threshold.
vertical thin arrow pointing down for either latest change from above upper threshold to between threshold or between thresholds to below species threshold.
vertical thin arrow pointing up for either latest change from below species threshold to between thresholds or between thresholds to above upper threshold.
vertical thick arrow pointing up for latest change below threshold to above upper threshold.
Use the species six year rolling relative abundance geometric means to calculate the yearly proportion that are above the threshold values of 0.7 for species laying more than one egg and 0.8 for species that lay one egg for the following groups
all species within OSPAR regions I, II, III
all breeding species within OSPAR regions, I, II, III, IV
all non-breeding species with OSPAR regions I, II, III
all breeding, breeding surface feeders, breeding water column feeders, all non-breeding, non-breeding wader feeders for OSPAR Region I
all breeding, breeding surface feeders, breeding water column feeders, all non-breeding, non-breeding wader feeders for OSPAR Region II
all breeding, breeding surface feeders, breeding water column feeders, all non-breeding, non-breeding wader feeders for OSPAR Region III
all breeding, breeding surface feeders, breeding water column feeders, all non-breeding, non-breeding wader feeders for OSPAR Region IV
Use the species latest six year relative abundance geometric mean assessment value to calculate the percentage of species within each functional group, within each region, that is greater than or equal to 0.7 for species laying more than one egg or 0.8 for species laying one egg.
For breeding counts OSPAR regions I, II, III, IV and birds subdivisions Im, In, Io, IIa, IIb, IIc, IId, IIe, IIf
breeding species across all functional groups
breeding wading feeder species
breeding surface feeder species
breeding water column feeder species
breeding benthic feeder species
breeding grazing feeder species
For non-breeding counts OSPAR regions I, II, III and birds subdivisions In, Io, IIa, IIb, IIc, IId, IIe, IIf
non-breeding species across all functional groups
non-breeding wading feeder species
non-breeding surface feeder species
non-breeding water column feeder species
non-breeding benthic feeder species
non-breeding grazing feeder species