Table 2.
Categorical variables tested for significance, including the number of categories within each variable (Cat) and a list of the possible designations (except taxonomic categories).
| Variable | Cat | Description and source |
|---|---|---|
| Order | 8 | Bird order (Remsen et al., 2012) |
| Family | 24 | Bird family (Remsen et al., 2012) |
| Genus | 53 | Bird genus (Remsen et al., 2012) |
| Species | 59 | Bird species (Remsen et al., 2012) |
| Diet specific | 11 | Specific dietary specialization: nectar, generalist, insect, seed, arthropod, fruit, insect/fruit, fruit/insect, nectar/insect, arthropod/vertebrates, fruit/nectar/insects (C. Sanchez, pers. com.) |
| Diet broad | 3 | Broad dietary specialization: plant material, animal material, both |
| Diet B&O | 4 | Broad dietary specialization assigned by Bennett and Owens (2002): frugivore, nectarivore, insectivore, omnivore |
| Habitat | 5 | General habitat assigned by Bennett and Owens (2002): woodland, forest, forest/grassland, forest/grassland/scrub, all habitats |
| Foraging strata | 9 | Foraging strata assigned by Stotz et al. (1996): canopy, midstory, understory, terrestrial, under/midstory, midstory/canopy, terrestrial/understory, terrestrial/midcanopy, understory/canopy |
| Locality | 12 | Sampling locality (see Figure 1): Tirimbina, Londres, Los Charcos, Piedras Blancas, Golfo Dulce, El Copal, Janirvan, Tuba Creek, San Jorge II, La Selva, Veragua, Santa Juana |
| Country | 2 | Country of sampling: Costa Rica, Peru |
| NSEW | 6 | Relative location of sampling locality: north-east Costa Rica, midwest Costa Rica, southwest Costa Rica, middle Costa Rica, mideast Costa Rica, Peru |
| Elevation | 13 | Elevation of sampling locality: 65, 75, 80, 110, 170, 200, 250, 260, 325, 400, 415, 430, and 1050 m |
| Sex | 3 | Sex of the bird: male, female, unknown |
| Age | 14 | Percent of skull ossification (a proxy for age of bird): 0, 3, 5, 10, 15, 20, 25, 50, 70, 75, 90, 95, 100, unknown |
| Stomach contents | 12 | Contents of stomach at time of collection: insects, seeds, fruit, plant material, seeds/insects, insects/pollen, fruit/insects, insects/plants, seeds/plants, fruit/insects/seeds, empty, unknown |
| Phyla richness | 10 | Number of bacterial phyla identified in the gut microbiota fingerprint: 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 |
| Species richness | 5 | Which fifth the number of 97% OTUs identified in a gut microbiota fingerprint belongs to: 20%ile, 40%ile, 60%ile, 80%ile, 100%ile |