Statistical analyses
All analyses were carried out using the statistical package R version
4.0.2 (R Development Core Team 2020). Data were tested for normality and
homogeneity of variance using the Shapiro-Wilk normality test and
residual plots respectively. Only the number of weavers foraging per
diet per minute deviated from a normal distribution. To model relative
diet preference, we built a generalized linear model with a Poisson
error structure including diet, week, feeding session, sex and their
two-way interactions as explanatory variables for variation in the
number of weavers foraging on each diet per minute. We tested for
differences in GUD between diets using a linear model. Diet, week,
feeding session (time of day), and their two-way interaction terms were
included in the model as explanatory variables for variation in GUD. To
test the effect of diet restriction on body condition, we accounted for
the effects of moult and aviaries on all indices by including moult
status and aviary as predictor variables in the model for each body
condition index. The explanatory power of both moult and aviaries on
variation in all indices were not significant and so were dropped from
all our models. Hence, we built linear models for each body condition
index with diet, week, sex, and their two-way interactions as the main
explanatory variables. For all models, a post hoc test was used to
determine which groups differed significantly from each other.
RESULTS