Data from: Food supplementation fails to reveal a trade-off between incubation and self-maintenance in female house wrens

Incubating birds must allocate their time and energy between maintaining egg temperature and obtaining enough food to meet their own metabolic demands. We tested the hypothesis that female house wrens (Troglodytes aedon) face a trade-off between incubation and self-maintenance by providing females with supplemental food during incubation. We predicted that food supplementation would increase the amount of time females devoted to incubating their eggs, lower their baseline plasma corticosterone levels (a measure of chronic stress), and increase their body mass, haematocrit (a measure of anaemia), and reproductive success relative to control females. As predicted, food-supplemented females spent a greater proportion of time incubating their eggs than control females. Contrary to expectation, however, there was no evidence that food supplementation significantly influenced female baseline plasma corticosterone levels, body mass, haematocrit, or reproductive success. However, females with high levels of corticosterone at the beginning of incubation were more likely to abandon their nesting attempt after capture than females with low levels. Corticosterone significantly increased between the early incubation and early nestling stages of the breeding cycle in all females. These results suggest that although food supplementation results in a modest increase in incubation effort, it does not lead to significantly lower levels of chronic stress as reflected in lower baseline corticosterone levels. We conclude that female house wrens that begin the incubation period with low levels of plasma corticosterone can easily meet their own nutritional needs while incubating their eggs, and that any trade-off between incubation and self-feeding does not influence female reproductive success under the conditions at the time of our study

Lothery et al raw data and key

The raw data are contained in sheet one. There is a key in the second sheet of the spreadsheet to explain column names

Repeated measures ANOVA of female baseline plasma corticosterone (ng/mL ± SE).

<p>Values in graph are from back-transformed least-squares means.</p

Bivariate means (±SE) of incubation constancy and mean off-bout length in experimentally supplemented and control female house wrens.

<p>Significant MANOVA effects are as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0106260#pone-0106260-t001" target="_blank">Table 1</a>.</p

MANCOVA of the effect of food supplementation and clutch-initiation date on mean incubation constancy, mean on-bout length, mean off-bout length, and number of bouts per hour.

<p>MANCOVA of the effect of food supplementation and clutch-initiation date on mean incubation constancy, mean on-bout length, mean off-bout length, and number of bouts per hour.</p

Average daily temperature (A), rainfall (B), and number of fledglings produced per egg laid (C) during May of the ten years preceding the study (2001–2010, open circles) and May of the year of the study (2011; filled circle).

<p>Average daily temperature (A), rainfall (B), and number of fledglings produced per egg laid (C) during May of the ten years preceding the study (2001–2010, open circles) and May of the year of the study (2011; filled circle).</p