Table 2.
Summary of the effects of the feeding regime on community structure measures and individual species abundances at urban study properties in northern Auckland, New Zealand
| Species/measure | Evidence of feeding regime effect | Comparison of pattern between experimental periods (between feeding and nonfeeding groups) | Ratio of multiplicative factors* (F/NF) | t | P |
| Overall community structure responses | |||||
| Overall species richness | No | During/before | 0.21† | 0.58 | 0.56 |
| During/after | −0.10† | −0.28 | 0.78 | ||
| Introduced species richness | Yes | During/before | 0.66† | 2.42 | 0.015 |
| During/after | 0.09† | 0.32 | 0.75 | ||
| Native species richness | Yes | During/before | −0.45† | −2.07 | 0.039 |
| During/after | −0.19† | −0.86 | 0.39 | ||
| Overall abundance | Yes | During/before | 1.68 | 7.42 | <0.0001 |
| During/after | 1.69 | 7.80 | <0.0001 | ||
| Individual responses: Introduced species | |||||
| House sparrow (Passer domesticus) | Yes | During/before | 2.36 | 6.10 | <0.0001 |
| During/after | 2.93 | 9.13 | <0.0001 | ||
| Common myna (Acridotheres tristis) | No | During/before | 1.72† | 1.36 | 0.18 |
| During/after | 1.23† | 0.52 | 0.60 | ||
| Eurasian blackbird (Turdus merula) | No | During/before | 1.33 | 1.81 | 0.07 |
| During/after | 1.16 | 1.27 | 0.20 | ||
| Spotted dove (Streptopelia chinensis) | Yes | During/before | 6.61 | 7.52 | <0.0001 |
| During/after | 3.44 | 5.24 | <0.0001 | ||
| European starling (Sturnus vulgaris) | Yes | During/before | 1.96 | 2.04 | 0.042 |
| During/after | 1.09 | 0.35 | 0.72 | ||
| Song thrush (Turdus philomelos) | Yes | During/before | 0.80 | −0.58 | 0.56 |
| During/after | 0.58 | −1.98 | 0.049 | ||
| Eastern rosella (Platycercus eximius) | No | During/before | 0.71 | −0.66 | 0.51 |
| During/after | 0.94 | −0.17 | 0.86 | ||
| Chaffinch (Fringilla coelebs) | No | During/before | 0.23 | −1.18 | 0.24 |
| During/after | 1.01 | 0.01 | 0.99 | ||
| Individual responses: Native species | |||||
| Silvereye (Zosterops lateralis) | No | During/before | 1.17 | 0.86 | 0.39 |
| During/after | 1.10 | 0.51 | 0.61 | ||
| Tūī (Prosthemadera novaeseelandiae) | No | During/before | 0.82 | −0.93 | 0.35 |
| During/after | 1.03 | 0.14 | 0.89 | ||
| Grey warbler (Gerygone igata) | Yes | During/before | 0.43 | −2.54 | 0.011 |
| During/after | 0.90 | −0.31 | 0.76 | ||
| New Zealand fantail (Rhipidura fuliginosa) | No | During/before | 0.75 | −0.49 | 0.62 |
| During/after | 0.61 | −0.88 | 0.38 | ||
Significance tests for the relevant interaction terms (experimental group × experimental period) from GLMM results are presented, assessing whether patterns of change between experimental periods (before, during, or after the feeding regime) differ between experimental groups (feeding or nonfeeding). The ratio of multiplicative factors is the change from one period to the next in the feeding group compared with the nonfeeding group. Significant effects are highlighted in boldface. Species are listed by mean overall abundance (highest first).
A ratio of 1 indicates that the change from one period to the next was the same for both the feeding and the nonfeeding groups. A ratio of 2 indicates that change from one period to the next was two times higher in the feeding group. A ratio of 0.5 indicates that change from one period to the next was 0.5× that of the nonfeeding group.
These measures are interpreted in terms of a difference in the difference in means (period 1 – period 2; feeding – nonfeeding), rather than a ratio of multiplicative factors, as these measures were modeled using a normal distribution.