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Frequently
Asked Questions
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1. What
is the aim of the WeBS Alerts System?
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2. How
are species selected for the Alerts assessment for a given site?
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3. Are
Alerts generated for all cited or listed species in a designated site?
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4 What
is the purpose of the Biological Filter?
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5. Are
Alerts based on numbers of birds at passage times as well as during
the winter?
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6. Are
Alerts generated only from WeBS Core Count data?
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7. Why
can't I find Alerts for all of the species in my area or on my designated
site?
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8. Why are the Alerts based only on data from 25 year ago to the present, given that good older data exist?
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9. Isn't
it a useful indication of site condition to have Alerts for all species
on a site and not just those that are cited features for a particular
designation?
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10. Can
I use the Alerts for Common Standards Monitoring of features on designated
sites?
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11. An
Alert has been triggered for a species on my site but my experience
is that its numbers have not declined. Why?
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12. So
I've got an Alert - now what?
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12. How
do I download the Alerts report?
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14. How
can I give feedback to WeBS on this report?
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15. How do I cite this report?
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16. I
have read all the FAQs and the methods chapter of the report but still
have unanswered questions about Alerts, what can I do?
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1. What is
the aim of the WeBS Alerts System?
The WeBS Alerts System has
been developed to provide a standardised method of measuring and
reporting on changes in wintering waterbird numbers at different
temporal and spatial scales using Wetland Bird Survey (WeBS) data.
Alerts are triggered for populations that have undergone major
declines and are intended to help identify where research into
causes of decline may be needed and inform conservation management.
National Alerts are generated for species (or specific populations
of a species) using data from across the WeBS site network, either
at the UK level or individual country level. These Alerts provide
some context for understanding finer scale changes in numbers.
Site Alerts are generated for selected species at individual designated
sites, including Special Protection Areas (SPAs) and Sites of
Special Scientific Interest (SSSIs), whose boundaries overlap
those of WeBS count sites. Regional trends are also given to facilitate
the interpretation of site-level changes for any given species.
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2. How are species selected
for the Alerts assessment for a given site?
For site-based Alerts a filter,
the Conservation Concern Filter, has been used to prioritise the
species for which Alerts status has been assessed; this filter relates
to whether a species is a cited or listed feature in the designated
site in question.
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| 3.
Are Alerts generated for all cited or listed species in a designated
site?
No. Some of the main reasons are:
The WeBS Alerts System uses winter counts, so only those species
that are cited or listed for their wintering numbers will be assessed.
In some cases a species may be a cited or listed feature in a designated
site, but occurs there only sporadically, for example during severe
weather. This type of data is unsuitable for the trend analysis
upon which the Alerts are based.
Some species may have only recently colonised a site and so there
may be too few data for an Alerts assessment.
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| 4.
What is the purpose of the Biological
Filter?
This has been developed to allow
absolute changes in numbers to be assessed and interpreted in the
context of a species' population dynamics and demographics. For
example, a short-term, major change in numbers of a long-lived species
that is relatively site faithful and whose population typically
fluctuates little may be of greater concern than such a change in
a short-lived highly mobile species.
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| 5.
Are Alerts based on numbers of birds at passage times as well as during
the winter?
The data used for the WeBS Alerts
System are from the months in which peak winter numbers occur nationally.
For the majority of species this is December to February, but for
some it is September to March. See Table 2.1 for full details of
months used for the Alerts analysis for each species.
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| 6.
Are Alerts generated only from WeBS Core Count data?
Alerts reporting until now has been based solely on WeBS Core Counts. Long-term data from other surveys, such as the national goose surveys, have not been available. We intend to include data from the national goose surveys in subsequent reports.
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| 7.
Why can't I find Alerts for all of the species in my area or on my
designated site?
Not all species are sufficiently
well monitored by WeBS (such that numbers are recorded only sporadically
or are unlikely to be representative) to be included in this analysis
and so have been excluded. In addition, species that are not cited
or listed features in individual designated sites have been excluded
by the Conservation Filter.
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| 8.
Why are the Alerts based only on data from 25 year ago to the present, given that good older data exist?
Although good older data exists for some sites it is not available for many. We want to be consistent across site as far as is practical. Time-frames of 5, 10 and 25 years have been chosen to represent short-, medium- and long-term Alerts. While it would be feasible to generate Alerts over longer time-frames (e.g. an all-time Alert) for some sites, until these have become functionally different to the 25 year long-term time-frame there is little advantage to be gained from doing so. The need for longer Alert periods will remain under review.
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| 9.
Isn't it a useful indication of site condition to have Alerts for
all species on a site and not just those that are cited features for
a particular designation?
Trends for other species on a site
may be useful for assessing the overall condition of habitats on
a site, but the conservation objectives, and hence management approach,
for a designated site are specifically for the cited features. Because
it takes so long to interpret Alerts the cited features are prioritised.
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| 10.
Can I use the Alerts for Common Standards Monitoring of features on
designated sites?
Yes. The Alerts have been developed
to aid in monitoring features on designated sites as well as providing
contextual information for interpreting changes in site numbers
at regional and national scales. The Common Standards Monitoring
(CSM) Guidance provides more information and will help you decide
whether the Alerts information is relevant for the feature you are
assessing, or whether you will need additional data. The CSM Guidance
also gives advice on how to use the Alerts information.
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| 11.
An Alert has been triggered for a species on my site but my experience
is that its numbers have not declined. Why?
One explanation might be that you
are thinking in terms of peak numbers. WeBS Alerts are based on
the trend in the average of counts during the winter period - for
most species Alerts are based on counts from several months. It
might be that while the peak numbers have remained stable, or even
increased, the total number of 'bird-months', i.e. the sum of counts
from several months, and hence the average has declined.
Another explanation might be that the seasonal usage of the site
by the species does not coincide well with the months used for calculating
trends for the species in question. Alerts are generated based on the same data used for national indices.
Thus, they use counts from those months in which peak numbers occur
at a national level (see Table 2.1 for a list of months used for
each species), but these months may not always coincide with the
peak use of a particular site by a species.
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| 12.
So I've got an Alert - now what?
An Alert is there to do just that
- to 'alert' you to an apparent change in numbers. Whether this
is a real cause for concern then needs to be investigated further,
for example, to discount the possibility of a numeric artefact,
or to assess if it simply reflects a regional/national trend. Further
investigation of possible causes of declines may then be warranted.
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| 13.
How do I download the Alerts report?
When printed, the entire report exceeds 1500
pages and in its electronic form exceeds 65Mb making it unsuitable for downloading in its
complete form for most users. Furthermore, most users are probably only interested in accounts for a subset of sites
from their own region or the national accounts. For ease, each section of the report can be downloaded as a separate portable
document format (pdf) file, as can each separate country or site account. If you require the complete report but it is not practical
for you to download it, it can be provided at cost on CD or, in exceptional circumstances, as hardcopy. For further information,
including prices, e-mail
.
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| 14.
How can I give feedback to WeBS on this report?
Constructive comments on the report
are welcomed and we will feed these into our annual review of the
scope and content of the WeBS Alerts Report. If you have any comments
please download and use the WeBS Alerts QUESTIONNAIRE
for this purpose and e-mail it to .
Please include the word 'questionnaire' in the e-mail subject header.
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| 15.
How do I cite this report?
Maclean, I.M.D. & Austin, G.E. (2008) WeBS Alerts 2004/2005 (Release 2):
Changes in numbers of wintering waterbirds in the United Kingdom, its Constituent Countries, Special Protection Areas (SPAs)
and Sites of Special Scientific Interest (SSSIs). BTO Research Report No. 492 to the WeBS partnership. BTO, Thetford.
Available: http://www.bto.org/webs/alerts/alerts/index.htm.
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| 16.
I have read all the FAQs and the methods chapter of the report but
still have unanswered questions about Alerts, what can I do?
In the first instance please e-mail
.
Please state the problem you have as concisely as possible and include
the words 'alerts query' in the e-mail subject header.
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