• Declining species

• New alerts

• Positive changes

• Reduced breeding success

• Increased breeding success

• Early nesting

Declining species

Best trend estimates over the longest available time period (usually 36 years) provide alerts to rapid declines of 50% or greater 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 (PSOB) list (Gregory et al. 2002).

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 have long-term data only 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 ten species trigger alerts as a result of long-term declines of between 25% and 50% over periods of 25 to 36 years. These are Red-legged Partridge, Kestrel, Lapwing, Redshank, Common Sandpiper, Meadow Pipit, Dunnock, Mistle Thrush, Lesser Whitethroat and Reed Bunting. Most of these species are already on the PSOB list on account of their population declines.

Recent alerts

In the 2005 report, we draw special attention to the alerts for three species that have recently crossed the 50% decline threshold. These are Yellow Wagtail (-67%), Willow Warbler (-60%) and Cuckoo (-57%). These may be candidates for future addition to the red section of the PSOB list.

We also identify two species that may become candidates to join the amber list due to declines of between 25% and 50%. These are Common Sandpiper (-28% over 28 years) and Lesser Whitethroat (-29% over 25 years). Red-legged Partridge also falls within this decline category
(-46% over 25 years) but would not be a candidate for amber listing because it is an introduced species.

Positive changes

Few of those species that have declined previously show evidence of improvements in status. Song Thrush numbers have increased by 23% over the last ten years but even after this recovery they show a 51% decline over the last 36 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 Kestrel 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 may now be recovering). Additionally BBS data indicate recent increases for Snipe and Grasshopper Warbler but we lack good annual monitoring data on longer-term changes in these species.

Sixteen species have more than doubled over the longest time period for which data are available (usually 36 years). These are Mute Swan, Canada Goose, Shelduck, Mallard, Oystercatcher, Sparrowhawk, Buzzard, Stock Dove, Collared Dove, Woodpigeon, Green Woodpecker, Great Spotted Woodpecker, Nuthatch, Blackcap, Magpie, Carrion Crow.