Data from: Senescence of maternal effects: aging influences egg quality and rearing capacities of a long-lived bird

Senescence could depress prenatal and postnatal capacities of mothers to
invest in offspring. Longitudinal observations on the blue-footed booby
(Sula Nebouxii) revealed a quadratic effect of female age on fledgling
production and cohorts differences in rate of reproductive decline. By
swapping clutches between females of different ages, we tested whether
reproductive senescence is due to decline in egg quality or capacity to
care. As laying mothers aged, egg size, ulna length of 5-days old chicks,
and ulna growth of second chicks up to age 30-days declined; and as
rearing mothers aged, ulna growth and cellular mediated immune response of
second chicks diminished. Oddly, the number of fledglings produced by
senescent females (> 11 years) was greater rearing offspring of
middle-aged females (8-11 years) than offspring of senescent or young
females. Thus, senescence reduced egg quality and rearing capacities, and
reproductive success of senescent mothers depended on prenatal effects
associated with the age of the laying mother. Reproductive senescence of
boobies may involve constraints on resources allocated to reproduction as
well as adaptive adjustment of provision and care according to offspring
value, implying that negative effects of senescence on offspring survival
can be ameliorated by plasticity in post-laying or postnatal care.