Behavioural Thermoregulation in a Small Neotropical Primate

Abstract

The maintenance of body temperature in endothermic animals imposes considerable metabolic costs that vary with air temperature fluctuations. To minimise these costs, endotherms can adopt certain behaviours to adjust the pattern of heat transfer between their bodies and the environment. In this study, we evaluated whether a small Neotropical primate, the blackfronted titi monkey (Callicebus nigrifrons), living in a seasonal environment can use behavioural mechanisms to cope with fluctuations in the air temperature. We monitored the air temperature and the titi monkeys' behaviour over 1 yr. When the animals were inactive, we recorded the microhabitat used, the huddling between individuals and the body postures adopted. The monkeys primarily responded to air temperature fluctuations through microhabitat selection: they spent more time in sunny places and used higher strata of forest under lower temperatures. Moreover, they used sunny microhabitats during the first hour of their active period after colder nights. The monkeys did not huddle or change body postures in response to air temperature fluctuations. Huddling behaviour seemed to be primarily influenced by social interactions, and body postures were more energy conserving, regardless of temperature. Titi monkeys, however, used more energy-conserving postures and huddling behaviour under cloudy conditions than sunny conditions, suggesting that these behaviours may be important when they are unable to thermoregulate by microhabitat selection. We concluded that fluctuations in air temperature can promote significant changes in the behaviour of titi monkeys and can impose important restrictions on mammals' activities, even in tropical regions.

Thyroid hormone fluctuations indicate a thermoregulatory function in both a tropical (Alouatta palliata) and seasonally cold‐habitat (Macaca fuscata) primate

“…Our findings lend support to the hypothesis that thyroid hormone fluctuations are consistent with a thermoregulatory function in both tropical howlers and seasonally cold‐habitat Japanese macaques. This physiological link corroborates a growing body of behavioral evidence suggesting that tropical primates face greater cool thermoregulatory pressures than previously thought (Gestich, Caselli, & Setz, ; Takemoto, ; Thompson et al, , ). The finding that thyroid hormone increases during the cooler season and decreases in the warmer season for both mantled howlers and Japanese macaques suggests that animals seasonally adjust energy expenditure, which could have wide‐ranging implications for how we interpret commonly collected data such as food choice and activity patterns.…”

Measuring Microhabitat Temperature in Arboreal Primates: A Comparison of On-Animal and Stationary Approaches

“…While some of this may be selection by the animals, it may also be an artifact of our finding that temperatures increase with vertical height in the forest. This conclusion is behaviorally supported by data from a range of primates [chimpanzees (Pan troglodytes), titi monkeys (Callicebus nigrifrons), and red colobus monkeys (Piliocolobus badius)] documenting that animals spend more time in higher forest strata during cool periods and vice versa (Clutton-Brock 1973;Gestich et al 2014;Takemoto 2004). This further supports the idea that temperatures measured closer to the ground (i.e., at researcher height) do not accurately represent the individual's immediate thermal environment.…”

Behavioral adjustments and support use of François' langur in limestone habitat in Fusui, China: Implications for behavioral thermoregulation

“…For instance, when T a is high, primates reduce their daily travel distance (McLester, Brown, Stewart, & Piel, 2019), spend more time resting in the shade ( Callithrix jacchus : Abreu, De la Fuente, Schiel, & Souto, 2016; Fuente, Souto, Sampaio, & Schiel, 2014; Colobus polykomos : Dasilva, 1992; Papio cynocephalus: Stelzner, 1988), and stay in cooler microhabitats (e.g., caves) during the day ( Pan troglodytes verus : Pruetz, 2007; A. palliate : Thompson et al, 2016). On the other hand, when T a is low, primates respond by adopting alternative behaviors: They may change social relationships (increasing physical contact with others) within their group to benefit their thermal competences (McFarland et al, 2015), adjust nest architecture to increase thermoregulation (Stewart, Piel, Azkarate, & Pruetz, 2018), preferentially use heat‐conserving postures in sunny areas or stay under direct sunlight ( Alouatta caraya: Bicca‐Marques & Calegaro‐Marques, 1998; Callicebus nigrifrons: Gestich, Caselli, & Setz, 2014; P. cynocephalus: Stelzner & Hausfater, 1986), form huddles ( Macaca fuscata: Ogawa & Wada, 2011; Ueno & Nakamichi, 2018), select warmer microhabitats during the day ( A. palliate: Thompson et al, 2016), or remain for longer in caves ( P. hamadryas ursinus: Barrett, Gaynor, Rendall, Mitchell, & Henzi, 2004). As summarized by Dunbar, Korstjens, and Lehmann (2009), primates actively avoid thermal stress (e.g., avoid being exposed to environments with T a s that are too high or too low) through various behavioral adjustments.…”