Table 1.
Summary of the significance of terms included in statistical models (see Methods) explaining the number of gulls at the different feeding grounds. s(Time), time of day (15 min) as a smooth term; s(Time : week), time of day on weekdays as a smooth term; s(Time : weekend), time of day on weekend days as a smooth term; df, degrees of freedom; edf, estimated degrees of freedom for the smooth term. Estimates (with standard error) are given for the terms in the final best-fit model except for the categorical variables with more than two levels, which can be found in the Supporting Information Appendix S1.
| Model | Response | Explanatory | df | χ 2 | P | β-coefficients ± se/edf |
|---|---|---|---|---|---|---|
| Park | Number of gulls (at time of count) | Number of people (continuous) | 1 | 13.9 | < 0.001*** | −0.135 ± 0.004 |
| s(Time) | 6.51 | 46.94 | < 0.001*** | 5.41 | ||
| School | Number of gulls (at time of count) | Number of people (continuous) | 1 | 11.84 | < 0.001*** | 0.0055 ± 0.001 |
| Food (factor) | 1 | 7.84 | 0.005** | 0.340 ± 0.135 | ||
| Number of people: Day of the week | 1 | 4.76 | 0.029* | −0.057 ± 0.008 | ||
| s(Time) | 7.08 | 120 | < 0.001*** | 5.915 | ||
| Waste centre | Number of gulls (at time of count) | Day of the week (factor) | 1 | 241.5 | < 0.001*** | −0.917 ± 0.189 |
| s(Time) | 5.55 | 31.768 | < 0.001*** | 4.715 | ||
| s(Time : weekday) | 4.85 | 15.695 | 0.023* | 4.086 | ||
| s(Time : weekend) | 11.92 | 1.799 | 0.509 | 1.468 | ||
| Waste centre | Percentage on pile (at time of count) | Day of the week (factor) | 1 | 14.745 | < 0.001*** | 0.323 ± 0.109 |
| Waste-related activity level (factor) | 3 | 1601.00 | < 0.001*** | |||
| Time since waste unload (factor) | 6 | 241.58 | < 0.001*** |
P < 0.1. ***P < 0.001. **P < 0.01. *P < 0.05.