78 4. Results 4.1 Intra-annual female connectivity Out of the 30 nesting females equipped with a satellite tag during this study, only 20 were analyzed (n = 9 in the RP area and n = 11 in the GLS area), since the remaining 10 initiated their migration back to their foraging grounds less than 24 hours after the tag was deployed. All individuals considered, the tracking survey covers 537 days of observation and 37 complete nesting cycles considering the two weeks inter-nesting interval temporality. Each tagged individual’s movements were recorded over a mean duration of 26.9 ± 14.0, n = 20 days before migration initiation, covering 1.9 ± 1.0, n = 20 complete nesting cycles (Table 6 SI Appendix). Individual distribution ranges varied between a minimum of 16.1 km2 and a maximum of 1678.7 km2. The mean individual distribution range size was 278.9 km2 ± 372.8, n = 20, with a strong spatial heterogeneity as it was significantly smaller for individuals tagged in the RP than in the GLS (112.8 km2 ± 139.4, n = 9 and 414.8 km2 ± 450.9, n = 11 respectively, Mann-Whitney U test, W = 17, P < 0.05). Combining all individuals tagged in the same nesting area, distribution sizes ranged from 2721.2 km2 for the RP area to 3417.6 km2 for the GLS area (Figure 19-A, B). These resulted in two distinct and strictly non-overlapping distribution areas (Figure 19-C). No nesting area shift was detected during this study (Nm and Δ were null across all individuals). 4.2 Inter-annual female connectivity The RP dataset comprises 569 tagged females since monitoring initiation in 2006. Over the targeted 2016-17 to 2022-23 period, 368 new individuals have been identified and a mean 68.1 ± 11.8, n = 7 encountered females is reported annually (Bardet 2023). An additional 15 females were recorded in the GLS nesting area, with an annual mean of 2.1 ± 1.9, n = 7 females encountered (Table 7 SI Appendix). Overall, a significant difference in the observed proportion of recaptured individuals is detected between the two areas (Chi-square test, X22 = 9.2876, P < 0.05). An average of 57.0% ± 10.5, n = 7 of all individuals encountered in the RP area being recaptured from previous years, whereas all individuals in the GLS area were encountered for the first time and therefore identified as captured. No tagged individuals have ever been encountered in both the RP and the GLS areas over the study period.
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