Table 1. Abundance estimation models of Crocodylus moreletii in Calakmul using three different N-mixture model approaches (Poisson, Negative Binomial—NB and Zero Inflated Poisson—ZIP).
Models were fitted with different combinations of waterbody perimeter as covariate of abundance (λ) and vegetation cover (Low, Moderate, High) and water level (Dry, Drying, Stable, Full) as categorical co-variables of detection (p). The models highlighted in bold exhibited the lowest AIC values amongst all possible N-mixture combinations.
| Model structure | Model covariates | AIC | (–) LogLike | ΔAIC | AIC weight |
|---|---|---|---|---|---|
| Poisson | p (Water + Veg), λ (Perimeter + Gsp) | 473 | 218 | 0 | >0.99 |
| p (Water), λ (Perimeter + Gsp) | 493 | 230 | 20 | <0.01 | |
| p (Water + Veg), λ (Gsp) | 524 | 245 | 51 | <0.01 | |
| p (Water), λ (Gsp) | 543 | 256 | 70 | <0.01 | |
| p (Veg), λ (Perimeter + Gsp) | 680 | 325 | 207 | <0.01 | |
| p (Water + Veg), λ (Perimeter) | 737 | 360 | 264 | <0.01 | |
| p (Veg), λ (Gsp) | 747 | 359 | 274 | <0.01 | |
| p (Water), λ (Perimeter) | 765 | 376 | 291 | <0.01 | |
| p (.), λ (Perimeter + Gsp) | 902 | 438 | 429 | <0.01 | |
| p (.), λ (Gsp) | 968 | 472 | 495 | <0.01 | |
| p (Veg), λ (Perimeter) | 1,012 | 501 | 539 | <0.01 | |
| p (Water + Veg), λ (.) | 1,058 | 522 | 585 | <0.01 | |
| p (Water), λ (.) | 1,094 | 542 | 612 | <0.01 | |
| p (.), λ (Perimeter) | 1,282 | 638 | 809 | <0.01 | |
| p (Veg), λ (.) | 1,446 | 719 | 973 | <0.01 | |
| p (.), λ (.) | 1,710 | 853 | 1,237 | <0.01 | |
| NB | p (Water + Veg), λ (Perimeter + Gsp) | 416 | 189 | 0 | 0.56 |
| p (Water), λ (Perimeter + Gsp) | 417 | 191 | 1 | 0.43 | |
| p (Water + Veg), λ (Gsp) | 427 | 195 | 10 | <0.01 | |
| p (Water), λ (Gsp) | 427 | 197 | 10 | <0.01 | |
| p (Water + Veg), λ (Perimeter) | 434 | 208 | 18 | <0.01 | |
| p (Water), λ (Perimeter) | 434 | 210 | 18 | <0.01 | |
| p (Water), λ (.) | 439 | 213 | 23 | <0.01 | |
| p (Water + Veg), λ (.) | 440 | 212 | 24 | <0.01 | |
| p (Veg), λ (Perimeter + Gsp) | 603 | 285 | 186 | <0.01 | |
| p (Veg), λ (Gsp) | 614 | 292 | 197 | <0.01 | |
| p (Veg), λ (Perimeter) | 626 | 307 | 209 | <0.01 | |
| p (Veg), λ (.) | 633 | 311 | 216 | <0.01 | |
| p (.), λ (Perimeter + Gsp) | 728 | 350 | 311 | <0.01 | |
| p (.), λ (Gsp) | 737 | 355 | 320 | <0.01 | |
| p (.), λ (Perimeter) | 748 | 370 | 331 | <0.01 | |
| p (.), λ (.) | 742 | 373 | 335 | <0.01 | |
| ZIP | p (Water + Veg), λ (Perimeter + Gsp) | 448 | 205 | 0 | >0.99 |
| p (Water), λ (Perimeter + Gsp) | 459 | 212 | 11 | <0.01 | |
| p (Water + Veg), λ (Gsp) | 483 | 223 | 35 | <0.01 | |
| p (Water), λ (Gsp) | 491 | 229 | 42 | <0.01 | |
| p (Water + Veg), λ (Perimeter) | 601 | 291 | 153 | <0.01 | |
| p (Water), λ (Perimeter) | 613 | 299 | 165 | <0.01 | |
| p (Veg), λ (Perimeter + Gsp) | 649 | 308 | 201 | <0.01 | |
| p (Veg), λ (Gsp) | 699 | 334 | 251 | <0.01 | |
| p (Water + Veg), λ (.) | 790 | 387 | 341 | <0.01 | |
| p (Water), λ (.) | 797 | 392 | 349 | <0.01 | |
| p (Veg), λ (Perimeter) | 820 | 404 | 371 | <0.01 | |
| p (.), λ (Perimeter + Gsp) | 859 | 415 | 411 | <0.01 | |
| p (.), λ (Gsp) | 905 | 439 | 456 | <0.01 | |
| p (.), λ (Perimeter) | 1,040 | 516 | 592 | <0.01 | |
| p (Veg), λ (.) | 1,066 | 528 | 617 | <0.01 | |
| p (.), λ (.) | 1,268 | 631 | 819 | <0.01 |