| Abstrakt: |
This is the 76th annual report of the British Trust for Ornithology's Ringing Scheme, covering work carried out and data processed in 2012. Demographic integrated population monitoring has been the focus of the Scheme priorities in recent years and models that integrate ringing and nest record data and abundance trends were built for ten species for which sufficient data were available. Population drivers vary between species but they can be split between changes in breeding success, survival, or both. Multi-brooded species exhibited more seasonal variation in reproductive output than single-brooded species. In particular, migratory species showed a seasonal decrease in fledgling output, as do single-brooded species while residents generally showed a seasonal increase in productivity. Constant Effort Site (CES) data showed long-term (1984–2011) declines in four long-distance migrants and five resident species. However, four species (two short-distance migrants and two residents) have increased over the same period. Productivity of migrants monitored by CES was poor in 2012: seven of the eight species showed significant reductions in productivity compared to the five-year average and had the lowest productivity since CES began in 1983. Breeding performance of resident birds was low in 2012, with juvenile:adult ratios significantly lower than those calculated over the preceding five years for 10 of the 16 species. The number of CE sites increased in 2012, with data submitted for 125 sites, the highest total for a decade. The number of active RAS projects increased to 163 in 2012, with 21 new projects, eight of which involved RAS target species. In 2012 the total number of birds ringed (970,957) was the second highest recorded, and included 408,225 first-year birds, 377,199 adults (birds in their second calendar year or older), 23,772 unaged birds and 161,761 nestlings. In addition, there were 249,551 recaptures of ringed birds at or near the ringing site. The reduction in numbers ringed compared to 2012 was probably the result of the record wet weather that most of Britain & Ireland experienced in spring and summer 2012. A total of 18,693 BTO-ringed birds were recovered in 2012, which was lower than in 2011 but higher than in any previous year. This is the result of an increased number of birds ringed in the past 10 years, an increasing number of colour-ringed and tagged birds and subsequent resightings, more ringers within the Ringing Scheme, efforts to increase reports from members of the public of both metal and colour-ringed birds and an improvement in the way recoveries are processed. Recoveries of 22 BTO-ringed and 11 foreign-ringed individual birds that have extended our knowledge of movement of the species or constitute a new longevity record are presented. In total 44,895 nest records were submitted in 2012, the highest annual submission since the scheme began. Of these, 81% originated from England, 9% from Wales and 9% from Scotland, the remaining 1% divided equally between Northern Ireland and the Republic of Ireland. Submissions from England, Scotland and Northern Ireland have all risen by similar proportions since 2007 (18–22%), while those from Wales have increased by 34% over the same period. Long-term annual productivity trends have been calculated for three additional species. Long-term productivity trends were significant for 40 of the 72 species monitored and nine of these trends were negative, indicating a decline in breeding success over time. [ABSTRACT FROM AUTHOR] |
