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Help on species accounts |
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3.
Help on species accounts
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on the availability of data (all species are not covered by each scheme), each
account usually consists of the following: |
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| 1)
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Conservation
Listings: the conservation status of the species is graded with reference
to the JNCC/Country Agency Conservation Importance List (JNCC
1996) as follows: |
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Table
1: |
IUCN globally
threatened species. These species require monitoring of populations and the preparation
of International Species Action Plans to ensure effective conservation. |
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Table
2: |
Uncommon and,
rapidly or historically, declining British breeding birds. These species require
monitoring of populations and the preparation of Species Action Plans to ensure
their effective conservation. |
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Table
3: |
Rapidly declining,
but common British breeding birds. For these species the JNCC and Country Agencies
will, in collaboration with Non-Governmental Organisations, investigate causes
of decline and consider their conservation requirements and, where appropriate,
prepare Species Action Plans to ensure effective conservation. |
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Table
4: |
Species listed
as moderately declining, historically declining but common, internationally important,
localised or 'threatened in Europe' British breeding birds. These species require
monitoring of populations and, where appropriate, the preparation of Species Action
Plans to ensure effective conservation. |
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Unlisted:
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Other British
breeding birds. |
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Species are
also categorised with reference to the Birds of Conservation Concern listing (Gibbons
et al. 1996) as follows: |
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Red: |
generally
equivalent to Tables 1, 2 & 3 of the JNCC list. |
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Amber:
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generally equivalent
to Table 4. |
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Green: |
generally equivalent to
unlisted.
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The main reason
for listing as Red or Amber is provided in parentheses as follows: |
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- >50% Population decline
(generally from CBC data)
- >50% Distribution decline
(generally from the New Breeding Atlas, Gibbons
et al. 1993)
- 25-49% Population decline
(generally from the New Breeding Atlas, Gibbons
et al. 1993)
- 25-49% Distribution decline
(generally from the New Breeding Atlas, Gibbons
et al. 1993)
- Historical decline (in
UK between 1800-1995, assessed by literature review)
- Important breeding and/or
wintering population (>20% of European population in UK or >50% of UK population
in just 1-10 sites)
- European Status (species
with unfavourable conservation status in Europe
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The UK Biodiversity
Steering Group produced three lists of species of conservation concern (Anon.
1995) that have since been rationalised to two lists (Anon.
1998). These are indicated as follows: |
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Biodiversity
Steering Group Priority Species List:
species which are globally threatened or rapidly declining in the UK (i.e. by
at least 50% in the last 25 years); and for which costed Action Plans have been
prepared (previously the "short" and "middle" lists) |
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Biodiversity
Steering Group Conservation Concern List:
this includes species on the Priority List but also species for which UK has >25%
of the world or appropriate biogeographical population; species for which numbers
or range have declined between 25 and 49% over the last 25 years; species which
are found in <15 10-km squares in the UK; and species listed in international
or national conservation legislation. |
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| 2) |
Long
term trend: This summarises the trend in population size over the past
31 years from CBC or shorter for WBS and CES. The terms mean the following: |
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- Rapid decline: >50%
(and statistically significant) population decline from CBC, WBS or CES.
- Moderate decline:
25-49% (and statistically significant) population decline from CBC, WBS or CES.
- Shallow decline:
<25% (but statistically significant) population decline from CBC, WBS or CES.
- Decline: derived
from other data sources or when statistical significance is unknown.
- Probable decline:
as "decline" but the information is not as certain - see the status
summary for reasons.
- Possible decline:
as "decline" but the information is less certain than "probable
decline" but it is still most likely that there has been a decline - see
the status summary for reasons.
- Stable/Fluctuating,
with no long-term trend: where the confidence limits of the decline encompass
0 (or no overall change).
- Uncertain: where
the information from two monitoring schemes indicate conflicting trends or if
the schemes are unrepresentative of the species' UK population.
- Unknown: no information
on the UK population trend is available.
- Increase/Probable Increase/Possible
Increase: data from other sources, see "decline" above.
- Shallow increase:
10-49% population increase, where the lower confidence limit is >0 (but see
Alerts, Section 2.7), measured by CBC, WBS or
CES.
- Moderate increase:
50-99% population increase, where the lower confidence limit is >0 (but see
Alerts, Section 2.7), measured by CBC, WBS or
CES.
- Rapid increase:
>100% population increase, where the lower confidence limit is >0 (but see
Alerts, Section 2.7), measured by CBC, WBS or
CES.
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| 3) |
Status
summary: this provides a brief summary of the trends detailed for the
species and indicates why such changes might have occurred with reference to published
information when available. |
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| 4) |
Population
trends graphs: the first of these shows the changes in abundance for that
species over the period from 1966-1999, as measured by the Common Birds Census.
For some species, the Waterways Bird Survey, Constant Effort Sites scheme or Breeding
Bird Survey provides the most representative trend and is shown. After the following
table, graphs are presented to show trends in other habitats and regions from
the other monitoring schemes. Details about how the graphs are calculated are
provided in the Methods (Section 2)
for each scheme. For CBC and WBS, the graphs show a smoothed line (blue) and its
85% confidence limits (green); for CES, Heronries Census and BBS, annual estimates
are shown (blue) together with their 85% or 95% (BBS) confidence limits (green),
and for the first two schemes a smoothed line (red). |
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| 5) |
Population
trends table: this provides details of percentage changes in population
size over the past 31 years (or a shorter period, depending on the availability
of data), 25 years, 10 years and 5 years. It lists the period of years concerned,
the average (mean) number of census plots which contained the species in each
year and the upper and lower confidence intervals ("limits") for a population
decline. The Alert column indicates whether a statistically significant population
decline over the period is greater than (or equal to) 50% (>50) or between 25
and 49% (>25) (see Alerts, Section 2.7 for further
details). The comment column lists any caveats that must be considered when interpreting
the changes. The caveats are: |
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- Small sample: for
CBC, WBS and CES data, a mean sample size of less than 20 census plots was available;
for BBS data, a mean sample of <50 plots was available
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- Unrepresentative?:
the CBC data may not be representative of the population as a whole either because
the average abundance of a species in 10-km squares containing CBC plots was less
than that in other 10-km squares of the species' distribution in the UK (as measured
from New Breeding Atlas data (Gibbons
et al. 1993)), or where
average abundances could not be calculated, expert opinion judged that CBC data
may not be representative
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| 6) |
Productivity
trends table: this provides details of changes in productivity over the
past 30 years (or a shorter period, depending on the availability of data). It
lists the period of years concerned, the mean annual sample, the type of trend,
if the trend is significant then the predicted values (from the smoothed trend)
for the first and last years and their difference is listed, and the existence
of any caveats that must be considered when interpreting the data. The caveat
"small sample" is given when the mean number of records per year is
between 10-30 for the Nest Record Scheme, or when the mean number of CES plots
was <20 per year. |
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| 7)
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Productivity
graphs: graphs of changes recorded by the Constant Effort Sites Scheme
or Nest Record Scheme illustrate significant trends in population size or productivity.
For NRS data, annual means (averages) are provided with error bars to denote ±1
standard error either side of the mean (in green); regression lines (in black)
and the upper and lower 95% confidence intervals of these lines (in blue) are
also shown. For CES data, the annual values are plotted (blue) with their 85%
confidence intervals (green) and a smoothed line (red) is put through these points
(see Section 2.5 for details). |
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