Fig 1.
Research questions and predicted results for our hypotheses about temperature effects on wild barn swallow nestling mass before fledging.
Feeding level refers to the average nest-level feeding rate assessed at three points in time across nestling development.
Fig 2.
An overview of the study design indicating the types of data collected across the nestling period at three time points in wild barn swallows in Boulder County, CO.
Fig 3.
Conceptual graphs displaying hypothesized causal relationships investigated in each of our three questions.
The explanatory and response variables have black boxes, while confounders and precision covariates have gray boxes. Arrows represent hypothesized relationships. An arrow pointing directly into the middle of another arrow represents effect modification.
Fig 4.
Temperature effects in early and late development on the mass of 11–13-day-old nestlings.
Predicted relationships of minimum temperature (A), maximum temperature (B), and temperature variability (C) and nestling mass from separate linear mixed models for each developmental stage—in early (‘Early’, n = 106) development, from hatch through day five, and late (‘Late’, n = 106) development, from day six to final measures at 11-13 days post-hatch. Model predictions are displayed as lines, and raw data are displayed as points. Colors, line types, and shapes correspond to the developmental stage.
Fig 5.
Temperature effects on the mass of 11–13-day-old nestlings that are the smallest in their brood versus other nestlings.
Predicted relationships of minimum temperature (A), maximum temperature (B), and temperature variability (interquartile range) (C) across the nestling period and nestling mass from linear mixed models, stratified by relative nestling size—the smallest nestling (‘Smallest’, n = 31) and all other nestlings (‘Other’, n = 72)—at days 8–9 post-hatch. Model predictions are displayed as lines, and raw data are displayed as points. Colors, line types, and shapes correspond to the relative nestling size. Because relative nestling size was determined at days 8–9 and some nestlings did not survive to final measures on days 11–13 (n = 2 nestlings that died between days 8–9 and 11–13), only ‘Smallest’ or ‘Other’ nestling points are present for some nests.
Fig 6.
Temperature effects on the mass of 11–13-day-old nestlings at nests receiving low or high parental feeding.
Predicted relationships of minimum temperature (A), maximum temperature (B), and temperature variability (interquartile range) (C) across the nestling period and nestling mass from linear mixed models, stratified by two levels of parent feeding—low (‘Low’, n = 51) and high (‘High’, n = 55). Model predictions are displayed as lines, and raw data are displayed as points. Colors, line types, and shapes correspond to the level of parent feeding.