RAS results

Dipper is a RAS priority species.
There are currently eight
active Dipper projects. 

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, 194 RAS projects were active in 2022 and of these 180 were able to run. While most of the RAS analysis could be undertaken, there were several species that we were unable to produce trends for, either because no projects ran last year, some ran but with effort much reduced from normal, or because not enough active projects ran to produce comparable data.

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 2022 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 2022

Species Number of projects contributing to the survival trend Number of projects active in 2022 Number of projects new in 2022 Survival Trend Quality
Mute Swan 4 6 1 Moderate
Greylag Goose 1 0 0 Uncertain
Eider 5 2 0 Uncertain
Fulmar 0 1 0 -
Manx Shearwater 2 0 0 Good
Storm Petrel 5 2 0 Good
Shag 4 2 0 Uncertain
Avocet 1 1 0 Uncertain
Ringed Plover 1 1 1 Good
Little Ringed Plover 1 0 0 Uncertain
Common Sandpiper 3 1 0 Moderate
Curlew 0 1 1 -
Puffin 2 2 0 Good
Razorbill 4 3 0 Good
Guillemot 4 4 0 Good
Little Tern 1 1 1 Uncertain
Common Tern 1 1 0 Uncertain
Arctic Tern 1 1 0 Moderate
Kittiwake 8 8 0 Good
Black-headed Gull 2 0 0 Moderate
Herring Gull 1 1 0 Moderate
Great Black-backed Gull 1 1 0 Moderate
Lesser Black-backed Gull 3 1 0 Moderate
Rock Dove 0 1 1 -
Woodpigeon 1 1 0 Uncertain
Collared Dove 2 1 0 Uncertain
Barn Owl 4 4 0 Good
Little Owl 1 1 0 Good
Tawny Owl 1 1 0 Moderate
Swift 3 1 0 Uncertain
Peregrine 1 1 0 Moderate
Jackdaw 5 5 1 Good
Chough 0 1 0 -
Rook 1 2 0 Moderate
Blue Tit 2 2 1 Uncertain
Great Tit 4 2 0 Moderate
Willow Tit 0 0 0 -
Marsh Tit 4 5 0 Uncertain
Bearded Tit 3 1 0 Moderate
Sand Martin 23 10 2 Good
Swallow 8 2 0 Good
House Martin 6 1 0 Moderate
Wood Warbler 2 1 0 Uncertain
Willow Warbler 3 1 0 Moderate
Blackcap 1 0 0 Uncertain
Garden Warbler 1 1 0 Uncertain
Whitethroat 2 1 0 Moderate
Sedge Warbler 3 2 0 Moderate
Reed Warbler 11 8 0 Good
Starling 17 23 2 Good
Dipper 8 6 0 Good
Blackbird 3 0 0 Moderate
Robin 2 2 0 Moderate
Nightingale 2 2 0 Moderate
Pied Flycatcher 30 20 2 Good
Redstart 0 0 0 -
Whinchat 1 1 0 Moderate
Stonechat 3 2 0 Moderate
Wheatear 5 3 0 Moderate
Dunnock 2 1 0 Uncertain
House Sparrow 20 17 0 Good
Tree Sparrow 4 3 0 Moderate
Tree Pipit 2 3 0 Moderate
Chaffinch 3 0 0 Good
Hawfinch 3 3 0 Moderate
Bullfinch 5 2 0 Moderate
Greenfinch 1 0 0 Moderate
Linnet 2 1 0 Good
Twite 2 1 0 Good
Siskin 8 8 3 Moderate
Reed Bunting 1 1 0 Uncertain
Total 271 195 16 -

Mean survival and re-encounter rates by species

Survival Re–encounter
Species Duration of project F M Single sex F M Single sex
Mute Swan 2013-2022 - - 66 - - 59
Greylag Goose 2003–2015 - - 79 - - 48
Eider 1998–2022 86 - - 40 - -
Manx Shearwater 1994–2015 - - 92 - - 19
Storm Petrel 1998–2021 - - 78 - - 21
Shag 1998–2022 88 86 - 23 24 -
Avocet 2012-2022 - - 79 - - 80
Ringed Plover 2000–2009 73 62 - 88 91 -
Little Ringed Plover 2000–2021 54 71 - 40 42 -
Common Sandpiper 1977–2022 67 64 - 67 64 -
Puffin 2008–2021 - - 91 - - 12
Razorbill 1981–2022 - - 89 - - 16
Guillemot 1981–2022 - - 81 - - 23
Arctic Tern 2013-2022 - - 86 - - 76
Kittiwake 2000–2022 - - 83 - - 30
Herring Gull 2012-2022 - - 88 - - 57
Great Black-backed Gull 2015-2022 - - 84 - - 53
Black–headed Gull 2009–2017 - - 73 - - 49
Lesser Black–backed Gull 2003–2022 - - 83 - - 42
Woodpigeon 2012–2022 - - 59 - - 49
Collared Dove 2012–2022 53 48 - 30 23 -
Barn Owl 1997–2022 67 67 - 46 28 -
Little Owl 2006–2022 72 - - 76 - -
Tawny Owl 2006–2020 82 77 - 62 59 -
Swift 2002–2019 - - 74 - - 23
Peregrine 2004–2022 86 86 - 78 73 -
Jackdaw 2006–2022 81 72 - 42 37 -
Blue Tit 2001–2022 63 50 - 33 48 -
Great Tit 1999–2022 60 56 - 44 34 -
Marsh Tit 2003–2022 - - 48 - - 70
Bearded Tit 2002–2022 30 42 - 35 30 -
Sand Martin 1990–2022 30 34 - 39 33 -
Swallow 1998–2022 37 42 - 71 52 -
House Martin 1994–2022 32 30 - 34 51 -
Wood Warbler 2003–2022 23 33 - 55 52 -
Willow Warbler 1994–2019 47 48 - 41 56 -
Blackcap 2013–2018 30 38 - 16 16 -
Garden Warbler 2011–2022 27 48 - 44 39 -
Whitethroat 2015-2022 42 42 - 32 29 -
Sedge warbler 2014-2022 26 38 - 40 48 -
Reed Warbler 1981–2022 48 46 - 27 33 -
Starling 2005–2022 52 53 - 44 42 -
Dipper 2002–2022 52 50 - 68 63 -
Blackbird 1998–2019 52 58 - 57 58 -
Robin 1974–2022 38 45 - 46 45 -
Nightingale 2011–2022 47 54 - 34 54 -
Pied Flycatcher 1980–2022 41 43 - 65 54 -
Whinchat 2011–2022 29 42 - 72 83 -
Stonechat 2002–2022 24 29 - 61 80 -
Wheatear 1998–2022 52 52 - 63 64 -
Dunnock 1998–2022 39 38 - 72 59 -
House Sparrow 2003–2022 42 45 - 57 58 -
Tree Sparrow 2007–2022 33 24 - 31 16 -
Tree Pipit 2011–2022 - - 48 - - 58
Chaffinch 1998–2015 63 68 - 36 38 -
Hawfinch 2011–2022 66 67 - 35 43 -
Bullfinch 1999–2022 38 40 - 53 59 -
Greenfinch 1999–2012 39 35 - 36 38 -
Linnet 2003–2022 27 34 - 51 49 -
Twite 2007–2022 34 35 - 69 71 -
Siskin 2004–2022 36 35 - 12 16 -
Reed Bunting 2014-2022 43 44 - 53 69 -
Yellowhammer 2007–2017 - - - - - -

Species specific results

Select a species from the drop-down list and click on the graph to enlarge.

One project contributes to the national trend and is considered to be Moderate. The trend fluctuates over the short period of time that this trend has been calculated and was stable until a drop in survival in 2020 and 2021. The confidence limits broaden for last year, showing less confidence in the trend that year. The overall narrow confidence limits show that the project is getting a good number of re-sightings from the ringer and staff on the reserve by reading the colour rings on these birds.



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