RAS aims to generate annual survival rate estimates for adult birds, focusing primarily on species not encountered in large numbers during standard mist netting activities such as CES.
In total, 167 RAS projects were active in 2025. Data from historical projects and active projects that have been running successfully for five or more years are included in the analyses of the national results presented here.
The RAS analyses generate two parameters: survival rates and re-encounter rates. The survival rates indicate the proportion of birds that survive and return to the site to breed each year, while the re-encounter rates provide a measure of the probability of a bird’s presence being detected should it have survived and returned; the higher the re-encounter rate, the more precise the survival estimate.
The table and graphs below present the mean re-encounter rates, survival rates and survival trends for all species for which we have sufficient data to produce a trend. For more information about the RAS results, please see the Explanatory Notes pages.
Summary results
The summary table of active and historical RAS projects shows, for each species, how many projects ran in 2025 and how many projects contributed to each trend. It is apparent from these data that some species, e.g. Pied Flycatcher, House Sparrow, lend themselves well to RAS and uptake has been very high. Priority species for future RAS recruitment are those for which established studies are producing reliable survival trends but currently only at a few sites; these include Barn Owl, Dipper, Mute Swan, Starling, Swallow and Tree Sparrow.
The other table below summarises the mean survival and re-encounter rates by species. Re-encounter rates may be heavily influenced by methodology and several general patterns are apparent:
- Species that are caught on or near nests/nestboxes, such as Dipper, Barn Owl and Pied Flycatcher, tend to exhibit higher re-encounter rates for females as they spend more time incubating and brooding the contents than the males do.
- Species caught using tape lures, e.g. Willow Warbler, Sedge Warbler, tend to exhibit higher re-encounter rates for males.
- Colony nesters, such as seabirds and Sand Martins, tend to have lower re-encounter rates as it is much harder to systematically target individual birds.
While not summarised in this table, re-encounter rates are also generally higher in studies using colour rings, e.g. Bearded Tit, Kittiwake, Shag and Wood Warbler, but this is obviously dependent on resighting effort.
Summary of active and historical RAS projects in 2025
Species | Number of projects contributing to the survival trend | Number of projects active in 2025 | Number of projects new in 2025 | Survival Trend Quality |
Arctic Tern | 1 | 1 | 0 | Moderate |
Avocet | 1 | 0 | 0 | Uncertain |
Barn Owl | 4 | 3 | 0 | Good |
Bearded Tit | 3 | 1 | 0 | Moderate |
Blue Tit | 3 | 1 | 0 | Uncertain |
Bullfinch | 5 | 1 | 0 | Good |
Chough | 1 | 0 | 0 | Good |
Collared Dove | 2 | 1 | 0 | Uncertain |
Common Sandpiper | 3 | 0 | 0 | Moderate |
Common Tern | 1 | 1 | 0 | Uncertain |
Dipper | 9 | 4 | 1 | Good |
Dunnock | 2 | 1 | 0 | Uncertain |
Eider | 5 | 1 | 0 | Uncertain |
Fulmar | 1 | 1 | 0 | Uncertain |
Garden Warbler | 1 | 1 | 1 | Uncertain |
| Great Black-backed Gull | 1 | 1 | 0 | Moderate |
Great Tit | 4 | 2 | 0 | Uncertain |
Greylag Goose | 0 | 1 | 0 | - |
Guillemot | 5 | 3 | 0 | Good |
Hawfinch | 3 | 2 | 0 | Moderate |
Herring Gull | 1 | 1 | 0 | Good |
Hooded Crow | 0 | 1 | 0 | - |
House Martin | 6 | 0 | 0 | Moderate |
House Sparrow | 23 | 9 | 0 | Good |
Jackdaw | 5 | 4 | 0 | Good |
Kittiwake | 10 | 6 | 0 | Good |
Lesser Black-backed Gull | 3 | 1 | 0 | Good |
Linnet | 2 | 2 | 0 | Good |
Little Owl | 1 | 1 | 0 | Moderate |
Little Ringed Plover | 1 | 0 | 0 | Uncertain |
Little Tern | 1 | 1 | 0 | Uncertain |
Manx Shearwater | 1 | 1 | 1 | Good |
Marsh Tit | 5 | 3 | 0 | Uncertain |
Mute Swan | 5 | 4 | 0 | Good |
Nightingale | 2 | 1 | 0 | Moderate |
Peregrine | 1 | 1 | 0 | Moderate |
Pied Flycatcher | 33 | 18 | 1 | Good |
Puffin | 3 | 4 | 2 | Moderate |
Razorbill | 4 | 3 | 0 | Good |
Reed Bunting | 1 | 1 | 0 | Moderate |
Reed Warbler | 13 | 11 | 0 | Good |
Ringed Plover | 1 | 1 | 0 | Good |
Robin | 2 | 2 | 0 | Moderate |
Rock Dove | 0 | 1 | 0 | - |
Rock Pipit | 0 | 1 | 1 | - |
Rook | 2 | 1 | 0 | Moderate |
Roseate Tern | 0 | 1 | 0 | - |
Sand Martin | 25 | 9 | 1 | Good |
Sandwich Tern | 0 | 0 | 0 | - |
Sedge Warbler | 3 | 2 | 0 | Moderate |
Shag | 4 | 3 | 0 | Uncertain |
Siskin | 8 | 4 | 0 | Good |
Starling | 22 | 22 | 2 | Good |
Stonechat | 3 | 2 | 0 | Moderate |
Storm Petrel | 5 | 2 | 0 | Moderate |
Swallow | 8 | 1 | 0 | Good |
Swift | 3 | 3 | 1 | Uncertain |
Tawny Owl | 1 | 1 | 0 | Moderate |
Tree Pipit | 2 | 3 | 0 | Moderate |
Tree Sparrow | 4 | 2 | 0 | Moderate |
Twite | 2 | 0 | 0 | Good |
Wheatear | 6 | 3 | 0 | Good |
Whinchat | 1 | 1 | 1 | Moderate |
Whitethroat | 2 | 1 | 0 | Moderate |
Wood Warbler | 1 | 1 | 0 | Uncertain |
Woodpigeon | 1 | 1 | 0 | Moderate |
Total | 282 | 167 | 12 |
|
Mean survival and re-encounter rates by species
Survival rate | Re-encounter rate | ||||
| Species | Duration of project | Female | Male | Single sex |
|
| Arctic Tern | 2013–2025 | - | - | 82% | 73% |
| Avocet | 2011–2024 | - | - | 79% | 78% |
| Barn Owl | 1997–2025 | 67% | 67% | - | 41% |
| Bearded Tit | 2002–2025 | 30% | 42% | - | 35% |
| Blue Tit | 2001–2025 | 58% | 47% | - | 50% |
| Bullfinch | 1999–2025 | 38% | 40% | - | 53% |
| Chough | 2018–2023 | 90% | 79% | - | 78% |
| Collared Dove | 2012–2025 | 56% | 48% | - | 25% |
| Common Sandpiper | 1977–2023 | 67% | 64% | - | 63% |
| Common Tern | 2016–2025 | - | - | 79% | 32% |
| Dipper | 2002–2025 | 50% | 48% | - | 66% |
| Dunnock | 1998–2025 | 41% | 38% | - | 63% |
| Eider | 1998–2025 | - | - | 87% | 41% |
| Fulmar | 2020–2025 | - | - | 69% | 32% |
| Garden Warbler | 2011–2022 | 27% | 48% | - | 42% |
| Great Black-backed Gull | 2015–2025 | - | - | 84% | 56% |
| Great Tit | 1999–2025 | 59% | 55% | - | 40% |
| Guillemot | 1981–2025 | - | - | 84% | 23% |
| Hawfinch | 2011–2025 | 66% | 67% | - | 34% |
| Herring Gull | 2012–2025 | - | - | 88% | 59% |
| House Martin | 1994–2024 | 32% | 29% | - | 42% |
| House Sparrow | 2003–2025 | 42% | 45% | - | 58% |
| Jackdaw | 2006–2025 | 80% | 71% | - | 45% |
| Kittiwake | 2000–2025 | - | - | 80% | 53% |
| Lesser Black–backed Gull | 2003–2025 | - | - | 83% | 44% |
| Linnet | 2003–2025 | 27% | 35% | - | 49% |
| Little Owl | 2006–2024 | - | - | 71% | 77% |
| Little Ringed Plover | 2000–2021 | 54% | 71% | - | 41% |
| Little Tern | 2017–2023 | - | - | 94% | 73% |
| Manx Shearwater | 2014–2025 | - | - | 90% | 65% |
| Marsh Tit | 2003–2025 | 64% | 49% | - | 68% |
| Mute Swan | 2013–2025 | - | - | 68% | 61% |
| Nightingale | 2011–2025 | 46% | 57% | - | 43% |
| Peregrine | 2004–2025 | 83% | 83% | - | 77% |
| Pied Flycatcher | 1980–2025 | 41% | 44% | - | 60% |
| Puffin | 2008–2025 | - | - | 90% | 39% |
| Razorbill | 1981–2025 | - | - | 88% | 14% |
| Reed Bunting | 2014–2025 | 42% | 50% | - | 58% |
| Reed Warbler | 1981–2025 | 46% | 45% | - | 31% |
| Robin | 1974–2025 | 39% | 45% | - | 44% |
| Rook | 2017–2025 | 77% | 85% | - | 46% |
| Sand Martin | 1990–2025 | 30% | 34% | - | 37% |
| Sedge warbler | 2014–2025 | 28% | 36% | - | 41% |
| Shag | 1998–2025 | 88% | 86% | - | 40% |
| Siskin | 2004–2025 | 47% | 47% | - | 14% |
| Starling | 2005–2025 | 49% | 51% | - | 43% |
| Stonechat | 2002–2025 | 26% | 31% | - | 63% |
| Storm Petrel | 1998–2025 | - | - | 80% | 20% |
| Swallow | 1998–2025 | 37% | 41% | - | 61% |
| Tawny Owl | 2006–2025 | 82% | 76% | - | 56% |
| Tree Pipit | 2011–2025 | - | - | 46% | 60% |
| Tree Sparrow | 2007–2025 | 32% | 25% | - | 23% |
| Twite | 2007–2022 | 34% | 35% | - | 70% |
| Wheatear | 1998–2025 | 49% | 51% | - | 68% |
| Whinchat | 2011–2022 | 29% | 42% | - | 78% |
| Whitethroat | 2015–2025 | 40% | 39% | - | 35% |
| Wood Warbler | 2011–2025 | 21% | 34% | - | 67% |
| Woodpigeon | 2012–2025 | - | - | 61% | 57% |
Species specific results
Select a species from the drop-down list.
For more information about how to interpret the data shown on the RAS results graphs, please see the RAS Results Explanatory Notes.