The effects of lactation and infant care on adult energy budgets in wild siamangs (Symphalangus syndactylus)

Abstract

In mammals with biparental care of offspring, males and females may bear substantial energetic costs of reproduction. Adult strategies to reduce energetic stress include changes in activity patterns, reduced basal metabolic rates, and storage of energy prior to a reproductive attempt. I quantified patterns of behavior in five groups of wild siamangs (Symphalangus syndactylus) to detect periods of high energetic investment by adults and to examine the relationships between infant care and adult activity patterns. For females, the estimated costs of lactation peaked at around infant age 4-6 months and were low by infant age 1 year, whereas the estimated costs of infant-carrying peaked between ages 7 and 12 months, and approached zero by age 16 months. There was a transition from primarily female to male care in the second year of life in some groups. Females spent significantly less time feeding during lactation than during the later stages of infant care, suggesting that female siamangs do not use increased food intake to offset the costs of lactation. Female feeding time was highest between infant ages 16 and 21 months, a period of relatively low female investment in the current offspring that coincided with the period of highest male investment in infant care. This suggests that male care may reduce the costs of infant care for females in the later stages of a reproductive attempt. The female energy gain resulting from male care was likely invested in somatic maintenance and future reproduction, rather than the current offspring.

Alloparenting is associated with reduced maternal lactation effort and faster weaning in wild chimpanzees

“…marmosets and tamarins, Callitrichidae  [14]; siamangs, Sy. syndactylus  [31,32]; black-and-white ruffed lemurs, V. variegata  [27]). Even though we did not find that receipt of alloparenting was positively correlated with the amount of time that mothers spent feeding, those mothers whose infants were handled more could still have benefited because they could forage more efficiently and thereby increase their net energy gain when they were not encumbered by infants and/or because they expend less energy on carrying young [6,10,12,15,31,32].…”

“…vervets, Chlorocebus pygerythrus  [11]; siamangs, Symphalangus syndactylus  [31,32]; black-and-white ruffed lemurs, V. variegata  [27]). While alloparenting frequencies, types of interactions and the individuals involved are well documented in many primate taxa, the adaptive value of alloparenting remains understudied and unresolved [8,33].…”

Sex differences in leadership during group movement in mantled howler monkeys (Alouatta palliata)

“…Lactating females led group movements to feeding trees less frequently that gestating females. This may be associated with the observed trend of lactating primate females to spend, compared to females in other reproductive states, a lower proportion of time moving and feeding but more time resting or in vigilance ( Alouatta pigra : Dias, Rangel‐Negrín & Canales‐Espinosa, 2011; Symphalangus syndactylus : Lappan, 2009; Papio hamadryas ursinus : Barrett, Halliday, & Henzi, 2006). Increased resting time may operate as an efficient strategy to store and save energy (Dasilva, 1992; Dunbar & Sharman, 1984), which is required for milk production and maternal care (Emery Thompson, 2013).…”

Diet predicts milk composition in primates

“…We consider this explanation plausible 262 and potentially testable with inter-or intraspecific data on travel distance, activity 263 budgets, food selection, and maternal mass depletion. Primate mothers appear to 264 employ multiple strategies to meet the costs of lactation by increasing gross energy 265 intake, reducing expenditures, or temporarily relying on stored reserves (cercopithecoids: 266 Altmann & Samuels, 1992;Altmann, 1983;Dunbar & Dunbar, 1988;Koenig et al, 1997;267 Barrett et al, 2006), (hominoids: Murray et al, 2009Bates & Byrne, 2009;Pontzer & 268 Wrangham, 2006;Lappan, 2009), (platyrrhines: Guedes et al, 2008;Rose, 1994;Boinski, 269 1988;Miller et al, 2006;Nievergelt & Martin, 1999;Tardif, 1994), (strepsirhines: Saito, 270 1988;Vasey, 2005;Sauther, 1994).…”