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Species Groups - BirdTrends 2023

This page summarises the data as used in the latest version of the Bird Trends Explorer.

Summary of time series

The current Bird Trends Explorer contains 63,713 graph data points across 4,263 individual time series spanning 329 species (including populations). The number of species covered by each metric is shown in the table below.

You can also download the BirdTrends 2023 Summary Stats as a PDF and see the Key Findings for BirdTrends 2023 on this complementary page.


Metric type Metric Source scheme No. species
Population abundance Long-term trend (1994–) BBS 113
Population abundance Long-term trend (1998–) along linear waterways WBBS 76
Population abundance Long-term trend (1970s–) along linear waterways WBS-WBBS 25
Population abundance Long-term trend (1960s–) CBC-BBS 72
Population abundance Long-term trend (RBBP) RBBP abundance 2
Population abundance Long-term trend at heronries Heronries Census 1
Population abundance Long-term trend at colonies SMP colony counts 18
Population abundance Adult abundance (CES) CES abundance 23
Distribution Range size Birdatlas range size 329
Breeding performance Long-term trend at colonies SMP productivity 19
Breeding performance Clutch size NRS clutch size 90
Breeding performance Brood size NRS brood size 79
Breeding performance Egg-stage nest failure rate NRS egg-stage nest failure rate 90
Breeding performance Chick-stage nest failure rate NRS chick-stage nest failure rate 79
Breeding performance Fledglings per breeding attempt NRS productivity 79
Breeding performance Whole-season productivity (CES) CES productivity 23
Survival and mortality Adult survival (recoveries) Ringing survival 18
Survival and mortality Adult survival (RAS) RAS survival 24
Timing of life cycle events Timing of breeding NRS laying date 90
Timing of life cycle events Onset of primary moult Ringing moult timing 1

Metric type Metric UK England Scotland Wales NI
Population abundance Long-term trend (1994–) 111 108 65 58 35
Population abundance Long-term trend (1998–) along linear waterways 76 70 15 0 0
Population abundance Long-term trend (1970s–) along linear waterways 25 0 0 0 0
Population abundance Long-term trend (1960s–) 51 70 0 0 0
Population abundance Long-term trend (RBBP) 2 1 2 2 2
Population abundance Long-term trend at heronries 1 1 1 1 0
Population abundance Long-term trend at colonies 18 0 0 0 0
Breeding performance Long-term trend at colonies 18 7 18 4 0
Distribution Range size 329 318 297 288 237
Breeding performance Clutch size 90 0 0 0 0
Breeding performance Brood size 79 0 0 0 0
Breeding performance Egg-stage nest failure rate 90 0 0 0 0
Breeding performance Chick-stage nest failure rate 79 0 0 0 0
Breeding performance Fledglings per breeding attempt 79 0 0 0 0
Timing of life cycle events Timing of breeding 90 0 0 0 0
Timing of life cycle events Onset of primary moult 1 0 0 0 0


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