|
 | Declining species Best trend estimates over the longest available time period (usually 35 years) provide alerts to rapid declines of greater than 50% for 23 species. These are Grey Partridge, Little Grebe, Woodcock, Turtle Dove, Cuckoo, Lesser Spotted Woodpecker, Skylark, Tree Pipit, Yellow Wagtail, Song Thrush, Whitethroat, Willow Warbler, Spotted Flycatcher, Marsh Tit, Willow Tit, Starling, House Sparrow, Tree Sparrow, Linnet, Lesser Redpoll, Bullfinch, Yellowhammer and Corn Bunting.
Most of these rapidly declining species are already red- or amber-listed on the Population Status of Birds list (Gregory et al. 2002).
The Turtle Dove (left) is one of a number of farmland birds that show rapid declines over the last 35 years
The Whitethroat decline results from the severe crash between 1968 and 1969 linked to conditions on the wintering grounds. The Little Grebe decline should be treated with caution as we only have long-term data from waterways. Lesser Redpoll, Tree Pipit and Woodcock also have limited data. For several of the species listed here long-term trend data are only available for England, where BTO has more volunteers to record information. Different long-term trends could be operating in other parts of the UK.
A further 12 species trigger alerts as a result of long-term declines of between 25% and 49% over periods of 25 to 35 years. These are Red-legged Partridge, Kestrel, Lapwing, Redshank, Common Sandpiper, Meadow Pipit, Grey Wagtail, Dunnock, Mistle Thrush, Lesser Whitethroat, Goldcrest and Reed Bunting. Most of these species are already on the PSOB list on account of their population declines. To help with the BTO's vital conservation work click the image (left)
|
|  | New alerts In the 2004 report, the BTO draw special attention to the alerts for three species that have recently crossed the 50% decline threshold. These are Yellow Wagtail (-67%), Willow Warbler (shown left) (–58%) and Cuckoo (–56%). These may be candidates for future addition to the red section of the Population Status of Birds (PSOB) list.
The BTO also identify two species that may become candidates to join the amber list due to declines of between 25% and 49%. These are Common Sandpiper (-29% over 27 years) and Lesser Whitethroat (-27% over 25 years). Red-legged Partridge also falls within this decline category
(-48% over 25 years) but would not be a candidate for amber listing because it is introduced. To help with the BTO's vital conservation work click the image (left)
|
|  | Positive changes Relatively few species show evidence of improvements in status. Song Thrush numbers have increased by 20% over the last 10 years but even after this recovery they show a 51% decline over the last 35 years.. The 25-year decline measures for Marsh Tit and Reed Bunting are now below 50% as a result of their declines having levelled out in recent years. However, all of these species will need to show further improvements in status if they are to become candidates to leave the red list. For similar reasons Dunnock, Grey Wagtail and Goldcrest could become candidates for removal from the amber list. Overall, most species that have declined show little sign of recovery in the last ten years (only six of the 37 species with long-term declines).
The Song Thrush (shown left) is now showing some signs of population recovery following a large decline
Fourteen species have more than doubled over the longest time period for which data are available (usually 35 years). These are Mute Swan, Mallard, Coot, Oystercatcher, Buzzard, Stock Dove, Collared Dove, Woodpigeon, Green Woodpecker, Great Spotted Woodpecker, Nuthatch, Blackcap, Magpie, Carrion Crow. To help with the BTO's vital conservation work click the image (left)
|
|  | Reduced breeding success There are a number of species for which declines in breeding performance are likely to be driving the population declines (Linnet (SHOWN LEFT) and Lapwing) or helping to inhibit recovery (possibly Reed Bunting). The importance of decreases in individual aspects of breeding performance for declining Yellow Wagtail, Dunnock, Willow Warbler and House Sparrow remain to be determined, as do the implications of the large reductions in CES productivity measures recorded for Song Thrush, Whitethroat and Lesser Redpoll. Many declining species show improving productivity, probably as a consequence of density-dependent processes (there are more resources available to feed the young when population numbers are low. To help with the BTO's vital conservation work click the image (left)
|
| Increased breeding success Increasing breeding performance may be helping to drive population expansion of a number of rapidly increasing species: the predatory Grey Heron, Sparrowhawk and Buzzard; the corvids Jackdaw, Magpie, Carrion Crow and Rook; the seed-eaters Collared Dove and Stock Dove; and the insectivores Pied Wagtail, Robin, Wren, Nuthatch and Great Tit.
|
|  | Early nesting Data from the Nest Record Scheme provide strong evidence of shifts towards earlier laying in a range of species, linked to climate change (Crick et al. 1997, Crick & Sparks 1999). We have now identified 31 species that, on average, are laying up to 26 days earlier than they did 34 years ago. This latest report adds four species to our previous list of earlier layers; Great Tit, Reed Warbler, Wren and Blackbird.(shown left) To help with the BTO's vital conservation work click the image (left) |
|
|
|
