7. Maternal energy budgets
We calculated yearly maternal energy budgets by subtracting energy content of all clutches/litters (of fresh eggs) from energy budget of non-reproductive females:
\(V_{m}=E_{m0}+E_{m}-\sum_{i=1}^{n}E_{e}\) [Function 2]
where n was the reproductive frequency (number of clutches/litters) through a year, Em0 was the initial energy storage of mother, Em was the summed energy budget of mother from the first to the last hour of the year, Ee was the energy content of a clutch of fresh eggs.
Because viviparous mothers carry their embryos longer than do oviparous mothers (an additional 2/3 of development), and experience metabolic increment due to pregnancy during this period, we subtract this increased metabolic cost from viviparous yearly maternal energy budgets (Table S1). We average all results across 1980-2000 and 2080-2100 respectively as results for the past and the future.