Ranging behavior and the potential for territoriality in pair‐living titi monkeys (Plecturocebus discolor)

Abstract

Patterns of ranging behavior and space use are key for evaluating current ideas about the evolution and maintenance of pair-living and sexual monogamy as they provide insights into the dispersion of females, the potential for territoriality, and whether males are limited to defending an area that can support only one female and her offspring. We examined ranging behavior and space use to evaluate the potential for territoriality in five groups of red titi monkeys (Plecturocebus discolor) during a 10-year study in Ecuadorian Amazonia. Mean home range size, calculated using a time-sensitive local convex hull estimation procedure, was 4.0 ± 1.4 ha.Annual home ranges of neighboring groups overlapped, on average, 0%-7%. Mean daily path length was 670 ± 194 m, resulting in defendability indices of 2.2-3.6 across groups. Groups visited, on average, 4 of 12 sections of their home range border area per day, but that was not more often than would be expected by chance, and intergroup encounters were infrequent. We did not find evidence of active monitoring for intruders in border areas, in that groups did not travel either faster or slower when at the border than when in central areas of their range. The absence of overt monitoring might be compensated for by engaging in loud calls, which the study groups did throughout their home ranges; these calls may serve as an advertisement of occupancy and a deterrent to intruding conspecifics. Our finding that red titis have a high potential for territoriality is consistent with several of the main hypotheses proposed to explain pair-living in mammals.daily path length, home range overlap, intergroup encounters, loud calls, monitoring behavior, site fidelity | INTRODUCTIONA pair-living social organization and sexually monogamous mating system have been reported in a relatively small number of mammalian taxa and are most prevalent among canids, rodents, and primates (Lukas & Clutton-Brock, 2013). Understanding the selective pressures that have led to pair-living and sexual monogamy (i.e., a male and a female maintain an exclusive mating relationship during at least one reproductive season) in mammals remains challenging

Seasonal behavioral patterns of the Caquetá titi monkey (Plecturocebus caquetensis)

“…obs). A 16 study on P. discolor in Yasuni (Ecuador) shows home range (1.7 -6.4 ha) and core area (0.8 -3.3 ha) sizes similar to our results (Van Belle et al 2020). In addition, a study on the influence of resource distribution and ranging patterns in Aotus azarae (Fernandez-D 2016) suggests that during the lean season or in bottleneck conditions, the monkeys have access to similar resources irrespective to the size of their home ranges or core areas, because these areas offer the minimum nutritional requirements in the dry season.…”

Coordinated Singing in Coppery Titi Monkeys (Plecturocebus cupreus): Resource or Mate Defense?

“…Our study groups sang throughout their home ranges proportional to its use. The same pattern was observed in four other titi monkey species, P. discolor (Van Belle et al, 2021), Plecturocebus modestus and Plecturocebus olallae (Martinez and Wallace, 2017), and Callicebus personatus (Price and Piedade, 2001). This suggests that intergroup spacing mechanism of titi monkeys involves regular advertisement of the occupancy of the entire home range, as shown also in indris, Indri indri (Bonadonna et al, 2020) and black howler monkeys, Alouatta caraya (da Cunha and Byrne, 2006;Van Belle et al, 2013).…”

Linking glucocorticoid variations to monthly and daily behavior in a wild endangered neotropical primate

“…Controlling for temporal variations linked to the predictive homeostasis, our models revealed that, while none of the included variables had an effect on daily fGMs in MDSP, intergroup encounters sparked a short‐term increase in fGM levels in the black lion tamarin group of Guareí. In primates, intergroup encounters are a recurrent outcome of competition over resources and territory, often accompanied by aggressive agonistic behaviors and vocalizations (Van Belle et al, 2021; Cooksey et al, 2020; Cooper et al, 2004; Koch et al, 2016). Although encounters are stressful, energetically costly, and are thus expected to elicit a physiological response, research on this topic is equivocal.…”