Table 1. Summary of population characteristics of Norway rats for comparison between seasons in Salvador, Brazil.
| Characteristic | Season | |||
|---|---|---|---|---|
| n | Rainy | n | Dry | |
| No. of rats (percentage) | 459 (57.9) | 334 (42.1) | ||
| Male | 233 (50.8) | 167 (50) | ||
| Female | 226 (49.2) | 167 (50) | ||
| Mean (SE) mass (g): | ||||
| Males | 233 | 306.8 (7.5) | 167 | 291.4 (8.6) |
| Females | 226 | 282.9 (7.4)* | 167 | 245.5 (8.4) |
| Mean (SE) age (days) | ||||
| Males | 233 | 86 (3) | 167 | 83 (3) |
| Females | 226 | 81 (3)* | 167 | 70 (3) |
| Mean (SE) Scaled mass index | ||||
| Males | 233 | 245 (4) | 167 | 280 (5)* |
| Females | 225 | 248 (4) | 167 | 274 (6)* |
| No. of sexually active males (percentage) | 228 | 191 (83.8) | 166 | 135 (81.3) |
| No. pregnant rats (percentage)† | 119 | 60 (50.4) | 91 | 46 (50.5) |
| Median (1Q–3Q) of embryos | 57 | 10 (9–12) | 46 | 10 (8–12) |
| Mean (SE) of embryos | 57 | 10.3 (0.3) | 46 | 9.9 (0.5) |
| No. of lactating (percentage) rats† | 120 | 41 (34.2) | 92 | 35 (38) |
| Pregnant | 11 (26.8) | 12 (34.3) | ||
| Trap success (1Q–3Q) | 15 | 13 (10.1–15.7) | 12 | 11.9 (10.9–13) |
SE, standard error; 1Q, first quartile; 3Q, third quartile;
†, considering only sexually active females;
*, P < 0.05.