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

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

Species	2016		2017		2018		2019		2016–2019
Species	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

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

ISSN: 2053-7166