Figure 1. Variation in preference for fat-enriched food (as opposed to preference for anthocyanin-enriched food) between blackcaps with different levels of multiple status of infection by haemosporidian parasites. Preference estimates with 95% confidence intervals represent the probability (expressed as a percentage) that feeding-oriented behaviours are directed to fat-enriched food, controlling for residual body mass and year. The horizontal dashed line set at 50% indicates the absence of preference for either food choice. Dots are observations of single feeding-oriented behaviours, which therefore take values of 0% if directed to anthocyanin-enriched food and 100% if directed to fat-enriched food, jittered to reduce overlapping. The identity of individuals expressing these behaviours has been controlled as a random factor in the model.

Table 1. GLMMs that analyze variation in food preference as a function of ecological condition (residual mass and parasite infection), controlling for the fixed effect of year, and including individual differences as a random factor. Significant results are highlighted in bold. Different models (in columns) with parasite infection quantified as the multiple infection status or the intensity of the infection were tested.