Maternal condition and maternal investment during lactation in mantled howler monkeys

Abstract

These results converge with previous theoretical and empirical studies on this topic and contribute to the growing evidence that nonhuman primate mothers allocate maternal care based on their current condition to maximize lifetime reproductive success.

Energetic constraints on the reproduction of female mantled howlers

“…A total of 22 mantled howler monkeys live in this ca. 100‐ha evergreen forest (Dias et al, , ). At the onset of the study, three females had infants, whose ages were estimated on the basis of morphology and behavior (Balcells & Veà, ).…”

“…Each month we sampled each group for a mean (±SD) of 10 ± 3 days and classified females in one of three reproductive states: lactating (i.e., females with an associated immature of 0–20 months: Balcells and Veà ()); gestating (i.e., females in the period encompassing the day before parturition to 186 days back from that date, which corresponds to the duration of pregnancy in this species: SD = 6 days, Glander ()); or cycling (neither lactating nor gestating). Lactating females were further classified in lactation categories according to the age of their immatures: early lactation, when immatures were 0 to <4 months; mid lactation, when immatures were 4–<15 months; late lactation, when immatures were 15–20 months (Dias et al, ). The occurrence of conception was inferred by counting back 186 days from birth dates.…”

“…The fourth was lactation stage, as maternal condition varies through lactation (e.g., Emery Thompson et al, ). In A. palliata , maternal physical condition is the lowest at early and late lactation, compared with mid lactation (Dias, Cano‐Huertes, Coyohua‐Fuentes, Chavira‐Ramírez, Canales‐Espinosa & Rangel‐Negrín, ). Therefore, we expected that conception occurred when females were not lactating, and if they were lactating, were in mid lactation, had high thyroid hormone levels, a demonstrated proxy for energy acquisition in this species (Dias et al, ; Wasser et al, ), and had low glucocorticoid levels.…”

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

“…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). Given that in this species maternal behavior varies through lactation (e.g., Dias, Coyohua‐Fuentes, Canales‐Espinosa, Chavira‐Ramírez, & Rangel‐Negrín, 2018), it remains to be determined whether leadership patterns in lactating females vary according to infant age through the examination of a larger sample of females.…”

Factors influencing infant sex ratio in howler monkeys (Alouatta spp.): A literature review and analysis

“…Given that sex allocation is proximately affected by maternal physical condition (Cameron et al, ; Gutiérrez‐Adán et al, ; Rangel‐Negrín, Coyohua‐Fuentes, Canales‐Espinosa, et al, ; Ryan et al, ), we reviewed the literature to assess variation in infant sex ratio relative to maternal condition in howler monkeys. As there are very few data on the physical condition of female howler monkeys (Cano‐Huertes et al, ; Dias et al, ; Rangel‐Negrín, Coyohua‐Fuentes, Chavira‐Ramírez, Canales‐Espinosa, & Dias, ), we indexed maternal condition by annual rainfall and the potential for resource competition. In tropical forests, rainfall levels are positively correlated with habitat productivity such that where rainfall is higher, net primary productivity, plant biomass, and plant species diversity are higher (e.g., Lewis et al, ; Malhi et al, ; Quesada et al, ; Ter Steege et al, ; Toledo et al, ).…”