2. INTEGRATED POPULATION MONITORING (IPM)

2.1 Monitoring Strategy

The IPM Programme is focused on the formulation of population models which combine data on the numbers, productivity and survival rates of a wide range of breeding bird species with appropriate environmental data to fulfil the following objectives:

1. To establish thresholds for changes in population size, reproduction and survival that will be used to notify conservation bodies of requirements for further research or conservation action.
2. To identify the stage of the life cycle at which changes are taking place.
3. To provide data that will assist in identifying the causes of changes.
4. To distinguish changes induced by human activities from natural population fluctuations.

The programme brings together data from several long-running BTO schemes, as shown in the diagram below. Although it covers the majority of breeding bird species in the UK, it excludes certain groups because they are well covered by other programmes: the JNCC’s Seabird Monitoring Programme, Rare Breeding Birds Panel and the Wetland Bird Survey (see section 7 below).

2.2 Integrated Reporting and Alert Limits

The results of the BTO’s IPM Programme are brought together in a series of reports called: Breeding Birds in the Wider Countryside: their conservation status (Crick et al. 1997, 1998). These reports are designed to be working documents for use by conservation practitioners as ready reference guides to the current changes in status of breeding birds in the UK. One hundred and six species are covered by the reports. The status of each species is summarised on a single page in a way that allows conservationists to see all the relevant information at a glance. In addition to a brief summary of the main results, we provide a graph of population trends over the past 25 years from one of the census schemes, tables of percentage changes in population size over 25 years and changes in breeding performance from NRS and CES schemes, together with one or two interesting graphs of significant trends from CES and NRS.

A major function of the monitoring programme is to alert JNCC and Country Agencies to severe or developing declines in the status of any bird species. Alerts are issued at two levels. High BTO Alerts are issued for species that have shown a decline in abundance of at least 50% over the past 25 years, or for species which have shown a sufficiently large fall in breeding performance or survival that population size is likely to be severely affected. Medium BTO Alerts, for species which have shown a decline in abundance of 25-49% over the past 25 years, or for species which have shown a statistically significant decline in breeding performance or survival.

In the most recent report (Crick et al. 1998), 20 species were given High BTO Alerts: Grey Partridge, Snipe, Woodcock, Redshank, Turtle Dove, Lesser Spotted Woodpecker, Skylark, Tree Pipit, Song Thrush, Grasshopper Warbler, Goldcrest, Spotted Flycatcher, Willow Tit, House Sparrow, Tree Sparrow, Redpoll, Bullfinch, Yellowhammer, Reed Bunting, Corn Bunting. A further 20 species were given Medium BTO Alerts: Red-throated Diver, Moorhen, Lapwing, Curlew, Tawny Owl, Kingfisher, Meadow Pipit, Yellow Wagtail, Grey Wagtail, Pied Wagtail, Dunnock, Blackbird, Mistle Thrush, Willow Warbler, Marsh Tit, Raven, Starling, Greenfinch, Linnet, Twite.

The system of BTO Alerts used in these reports is simple and straightforward. This has benefits in terms of understandability. A more sophisticated system of alerts has been developed by Marchant et al. (1997) in which between-year changes in population size are smoothed and then trends are measured as the differences in population size measured over five, 10 and 25 year periods. Over the past year, a series of discussion meetings and workshops have been held, involving statisticians and conservationists, to reach consensus on the best way forward for the development of alert systems. These were held under the auspices of the BTO/JNCC and the WeBS partnerships. Alert systems to detect declines in breeding performance or survival rates will take longer to develop because they will need to address the possible impact of any decline on population size by making reasonable assumptions about a species’ life history.

2.3 Government Indicators

In 1998 the UK government published a series of indicators of sustainable development (DETR 1988). These indicators covered 13 topics including economic growth, health, education, air pollution, and water quality. The indicator for wildlife was chosen to be population changes of wild birds, which drew heavily upon data from the Common Birds Census. The second report Quality of Life Counts (DETR 1999) showed that declines in farmland birds (35%) was one of only four headline indicators that was moving significantly away from meeting government objectives. BTO data are shown here to be of fundamental importance in monitoring the "health" of the UK environment.

Key References

Baillie, S.R. (1990). Integrated population monitoring of breeding birds in Britain and Ireland. Ibis, 132: 151-166.

Baillie, S.R. (1991). Monitoring terrestrial breeding bird populations. In: Monitoring for Conservation and Ecology (ed. F.B. Goldsmith), pp. 112-132. Chapman & Hall, London.

Crick, H.Q.P., Baillie, S.R., Balmer, D.E., Bashford, R.I., Dudley, C., Glue, D.E., Gregory, R.D., Marchant, J.H., Peach, W.J. & Wilson, A.M. (1997). Breeding Birds in the Wider Countryside: their conservation status (1971-1995). BTO Research Report No. 187. BTO, Thetford.

Crick, H.Q.P., Baillie, S.R., Balmer, D.E., Bashford, R.I., Beaven, L.P., Dudley, C., Glue, D.E., Gregory, R.D., Marchant, J.H., Peach, W.J. & Wilson, A.M. (1998). Breeding Birds in the Wider Countryside: their conservation status (1972-1996). BTO Research Report No. 198. BTO, Thetford.
DETR (1998). Sustainability Counts. DETR, London.

DETR (1999). Quality of Life Counts: Indicators for a Strategy for Sustainable Development for the United Kingdom. DETR, London.

Greenwood, J.J.D., Baillie, S.R., Crick, H.Q.P., Marchant, J.H. & Peach, W.J. (1993). Integrated population monitoring: detecting the effects of diverse changes. In: Birds as Monitors of Environmental Change (ed. R.W. Furness & J.J.D. Greenwood), pp. 267-342. Chapman & Hall, London.

Marchant, J.H., Wilson, A.M., Chamberlain, D.E., Gregory, R.D. & Baillie, S.R. (1997). Opportunistic Bird Species - Enhancements for the Monitoring of Populations. BTO Research Report No. 176. BTO, Thetford.

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