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Table 1 Summary and parameterization of non-linear models (GAM, five- and six-parameter Double-Richards models) testing the temporal variation of numbers of the Shelduck wintering at Sabkha Djendli in northeastern Algeria

From: Are diurnal time-budgets and activity patterns density-dependent in the Shelduck (Tadorna tadorna) wintering in Algeria? An analysis across multiple temporal scales

Parametric coefficients Estimate Std. error t-value p value Sig.
Generalized additive model ‘GAM’ (AIC = 363.2)
 Intercept 505 33.26 15.18 < 0.001 ***
 Smooth term Edf Ref.df F p-value Sig.
 s(10-day period) 6.75 7.86 19.88 < 0.001 ***
Five-parameter Double-Richards model (AIC = 368.4)
 Asym 1733.8639 557.45 3.11 0.005 **
 K 0.5746 0.23 2.52 0.019 *
 Infl 8.5598 0.65 13.20 < 0.001 ***
 RAsym − 1758.0238 635.49 − 2.77 0.011 *
 RM 1.9059 1.39 1.37 0.184 ns
Six-parameter Double-Richards model (AIC = 366.1)
 Asym 1139.0003 221.26 5.15 < 0.001 ***
 K 1.0588 0.51 2.10 0.048 *
 Infl 8.0153 0.51 15.85 < 0.001 ***
 RAsym − 1470.3866 791.61 − 1.86 0.077 ns
 Rk 0.3309 0.25 1.33 0.197 ns
 Ri 22.0231 2.55 8.64 < 0.001 ***
  1. Asym, K, Infl, RAsym, RM, Rk and Ri are parameters of the positive–negative Richards model, see subsection: modelling temporal changes of wintering numbers
  2. AIC Akaike information criterion, Sig. statistical significance
  3. *** p < 0.001, ** p < 0.01, * p ≤ 0.05, nsp > 0.05