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Table 2 The optimal future survey sample sizes calculated based on analysis of the degree of statistical independence achieved for each of 10 large-bodied waterbird species in each year from 2016 to 2019

From: Organising a juvenile ratio monitoring programme for 10 key waterbird species in the Yangtze River floodplain: analysis and proposals

Species 2016 2017 2018 2019 2016–2019
Age ratio Survey sample (IH) Age ratio Survey sample (IH) Age ratio Survey sample (IH) Age ratio Survey sample (IH) Optimal future survey sample
Swan Goose 0.133 1153 0.096 868 0.108 963 0.175 1444 2761
Lesser White-fronted Goose 0.344 2257 0.060 564 0.090 819 0.113 1002 826
Siberian Crane 0.178 1463 0.039 375 0.146 1247 0.173 1431 1129
Hooded Crane 0.257 1909 0.169 1404 0.231 1776 0.252 1885 1744
White-naped Crane 0.243 1839 0.125 1094 0.188 1527 0.253 1890 1588
Greater White-fronted Goose 0.164 1371 0.122 1071 0.138 1190 0.187 1520 6364
Greylag Goose 0.259 1919 0.104 900 0.170 1411 0.220 1716 1312
Bean Goose 0.180 1476 0.104 900 0.150 1275 0.140 1204 8955
Bewick’s Swan 0.240 1824 0.125 1056 0.200 1600 0.250 1875 5844
Common Crane 0.190 1539 0.135 1204 0.180 1476 0.240 1824 1511
  1. By then applying the overall sqrt_sum_Weight of each species (see “Methods” section, values derived from Additional file 1: Table S11), we can generate a value for the optimal future survey sample size to generate robust species juvenile ratios. IH means the independence hypothesis