Saving wetlands for wildlife & people
Saving wetlands for wildlife & people
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Species/Populations All goose and swan populations are monitored. History Field-based age assessments were initiated in the 1940s, initially for European White-fronted Geese. This was extended to most other populations between the 1960s and 1980s. Aims To determine the annual reproductive success of each goose or swan population. Coverage Mostly carried out at wintering and autumn stop-over sites. Frequency Annual. Methods Age assessments of geese and swans comprise two measures of annual reproductive success (or productivity): the proportion of young (first-winter) birds in non-breeding flocks, and the average brood size. Due to differences in plumage characteristics, swans and geese in their first winter are usually easily separated from adult birds, at least for part of the non-breeding season. In many swans and geese, young birds remain in family units with their parents throughout their first winter, and thus it is also possible to measure the number of young produced by successful breeding pairs. The timing of migration and post-juvenile moult differs between species, meaning that the time period in which data can be collected also varies between species (see table below). Plumage differences also vary between species, and are more subtle for some species than others, meaning that the level of experience required by the observer is greater. Survey periods for Age Assessments
Results Please refer to individual species accounts for information on the annual reproductive success of goose and swan populations. Getting involved The skill level required to conduct age assessments varies considerably with the species concerned, and most age assessments are conducted by a small network of experienced observers. The main exception to this is for Dark-bellied Brent Goose, where an extensive network of observers collects data throughout the UK wintering range. If you would like to participate in age assessments, please contact the Species Monitoring Unit . Resources Count forms Guidance notes Field ageing guide
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Wildfowl & Wetlands Trust
Slimbridge, Gloucestershire GL2 7BT
T: +44 (0) 1453 891900 E: enquiries@wwt.org.uk
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