• Annual variation in breeding success and changes in population density of Cacajao calvus ucayalii in the Lago Preto Conservation Concession, Peru

      Bowler, Mark; Barton, C.; McCann-Wood, S.; Puertas, P.; Bodmer, R.; Veiga, Liza M.; Barnett, Adrian A.; Ferrari, Stephen F.; Norconk, Marilyn A. (Cambridge University PressCambridge, 2013)
    • Communities and uacaris: conservation initiatives in Brazil and Peru

      Bowler, Mark; Valsecchi, João; Queiroz, Helder L.; Bodmer, Richard; Puertas, Pablo; Veiga, Liza M.; Barnett, Adrian A.; Ferrari, Stephen F.; Norconk, Marilyn A. (Cambridge University PressCambridge, 2013)
    • Ecology and behavior of uacaris (genus Cacajao)

      Barnett, Adrian A.; Bowler, Mark; Bezerra, Bruna M.; Defler, Thomas R.; Veiga, Liza M.; Barnett, Adrian A.; Ferrari, Stephen F.; Norconk, Marilyn A. (Cambridge University PressCambridge, 2013)
    • Functional morphology of the female genital organs in the Peruvian red uakari monkey (Cacajao calvus ucayalii)

      Mayor, Pedro; Bowler, Mark; López-Plana, Carlos (2013)
      Functional morphology may provide important information that could improve methodologies for the diagnosis of the reproductive phase of females, and develop assisted breeding techniques for wildlife. This study examined features of genital organs in 19 Peruvian red uakari monkey (Cacajao calvus ucayalii) females in different reproductive stages, collected from wild animals hunted for food by rural communities in the North-eastern Peruvian Amazon, in order to provide knowledge on the reproductive physiology of this species …
    • Geographic comparison of plant genera used in frugivory among the pitheciids Cacajao, Callicebus, Chiropotes, and Pithecia

      Boyle, Sarah A.; Thompson, Cynthia L.; Deluycker, Anneke; Alvarez, Silvia J.; Alvim, Thiago H.G.; Aquino, Rolando; Bezerra, Bruna M.; Boubli, Jean P.; Bowler, Mark; Caselli, Christini Barbosa; et al. (2016)
      Pitheciids are known for their frugivorous diets, but there has been no broad-scale comparison of fruit genera used by these primates that range across five geographic regions in South America. We compiled 31 fruit lists from data collected from 18 species (three Cacajao, six Callicebus, five Chiropotes, and four Pithecia) at 26 study sites in six countries. Together, these lists contained 455 plant genera from 96 families. We predicted that 1) closely related Chiropotes and Cacajao would demonstrate the greatest similarity in fruit lists; 2) pitheciids living in closer geographic proximity would have greater similarities in fruit lists; and 3) fruit genus richness would be lower in lists from forest fragments than continuous forests. Fruit genus richness was greatest for the composite Chiropotes list, even though Pithecia had the greatest overall sampling effort. We also found that the Callicebus composite fruit list had lower similarity scores in comparison with the composite food lists of the other three genera (both within and between geographic areas). Chiropotes and Pithecia showed strongest similarities in fruit lists, followed by sister taxa Chiropotes and Cacajao. Overall, pitheciids in closer proximity had more similarities in their fruit list, and this pattern was evident in the fruit lists for both Callicebus and Chiropotes. There was no difference in the number of fruit genera used by pitheciids in habitat fragments and continuous forest. Our findings demonstrate that pitheciids use a variety of fruit genera, but phylogenetic and geographic patterns in fruit use are not consistent across all pitheciid genera. This study represents the most extensive examination of pitheciid fruit consumption to date, but future research is needed to investigate the extent to which the trends in fruit genus richness noted here are attributable to habitat differences among study sites, differences in feeding ecology, or a combination of both. Am. J. Primatol. 78:493–506, 2016. © 2015 Wiley Periodicals, Inc.
    • Highly polymorphic colour vision in a New World monkey with red facial skin, the bald uakari Cacajao calvus

      Corso, Josmael; Bowler, Mark; Heymann, Eckhard W.; Roos, Christian; Mundy, Nicholas I. (2016)
      Colour vision is highly variable in New World monkeys (NWMs). Evidence for the adaptive basis of colour vision in this group has largely centred on environmental features such as foraging benefits for differently coloured foods or predator detection, whereas selection on colour vision for sociosexual communication is an alternative hypothesis that has received little attention. The colour vision of uakaris (Cacajao) is of particular interest because these monkeys have the most dramatic red facial skin of any primate, as well as a unique fission/fusion social system and a specialist diet of seeds. Here, we investigate colour vision in a wild population of the bald uakari, C. calvus, by genotyping the X-linked opsin locus. We document the presence of a polymorphic colour vision system with an unprecedented number of functional alleles (six), including a novel allele with a predicted maximum spectral sensitivity of 555 nm. This supports the presence of strong balancing selection on different alleles at this locus. We consider different hypotheses to explain this selection. One possibility is that trichromacy functions in sexual selection, enabling females to choose high-quality males on the basis of red facial coloration. In support of this, there is some evidence that health affects facial coloration in uakaris, as well as a high prevalence of blood-borne parasitism in wild uakari populations. Alternatively, the low proportion of heterozygous female trichromats in the population may indicate selection on different dichromatic phenotypes, which might be related to cryptic food coloration. We have uncovered unexpected diversity in the last major lineage of NWMs to be assayed for colour vision, which will provide an interesting system to dissect adaptation of polymorphic trichromacy.
    • Intestinal helminths in wild Peruvian red uakari monkeys (Cacajao calvus ucayalii) in the northeastern Peruvian Amazon

      Conga, David F.; Bowler, Mark; Tantalean, Manuel; Montes, Daniel; Serra-Freire, Nicolau Maués; Mayor, Pedro (2014)
      …We examined 36 fecal samples from Peruvian red uakari monkeys (Cacajao calvus ucayalii ) collected from wild animals in the northeastern Peruvian Amazon. Samples were positive for helminth infection. Nematodes egg: Strongyloididae, Trypanoxyuris sp., Spirurid, and a cestode egg were identified.
    • Low birthrates and high levels of female reproductive inactivity may characterize the reproductive biology of wild Peruvian red uakaris (Cacajao calvus ucayalii)

      Mayor, Pedro; Bowler, Mark (2015)
      ...We collected reproductive organs from wild uakari monkeys hunted for subsistence by indigenous hunters and examined them for embryos or fetuses. We extrapolated birth dates to test for breeding seasonality and calculated birthrates....
    • Male-male affiliation and cooperation characterize the social behavior of the large-bodied pitheciids, Chiropotes and Cacajao: A review

      Gregory, Tremaine; Bowler, Mark (2016)
      …In this review of recent studies of male-male social interactions in Chiropotes and Cacajao, we posit that the ability to maintain large groups in these genera may be related to the affiliative and perhaps coalitionary relationships between males, who may or may not be related. Affiliative male-male relationships may allow for monopolization of groups of females and facilitate group cohesion by reducing intragroup aggression; however data on male-male interactions with identified individuals will be required to determine patterns of affiliation, while genetic studies may be the most practical way of determining dispersal patterns for these genera….
    • Morphology of the oxyurid nematodes Trypanoxyuris (T.) cacajao n. sp. and T. (T.) ucayalii n. sp. from the red uakari monkey Cacajao calvus ucayalii in the Peruvian Amazon

      Conga, D. F.; Giese, E. G.; Serra-Freire, N. M.; Bowler, Mark; Mayor, P. (2016)
      Cacajao calvus ucayalii (Thomas, 1928) (Primates: Pitheciidae), a subspecies endemic to the Peruvian Amazon, occurs in patchy and sometimes isolated populations in north-eastern Peru and is in a vulnerable situation, mainly due to habitat loss and hunting. This rareness and remote distribution means that, until now, parasitical studies have been limited. Based on optical and scanning electron microscopy of specimens of both sexes, we report two new species of Trypanoxyuris pinworms occurring in the large intestine of the Peruvian red uakari, namely Trypanoxyuris (Trypanoxyuris) cacajao and Trypanoxyuris (Trypanoxyuris) ucayalii. ...
    • Proximate causes of the red face of the bald uakari monkey (Cacajao calvus)

      Mayor, P.; Mamani, J.; Montes, D.; González-Crespo, C.; Sebastián, M. A.; Bowler, Mark (2015)
      In social species, such as primates, facial appearances transmit a variety of social signals. Although it is suggested that the intense red colour of the face of the bald uakari monkey might be an indicator of health, this hypothesis still has not been verified. This study describes the histological structure of the skin of the face in the bald uakari, compared with other non-red neotropical primates, to better understand the maintenance of its colour. The facial skin of the bald uakari monkey is characterized by a thinner epidermis, absence of melanin pigments and a high density of vascular capillaries that spread below the epidermis. These vascular capillaries are larger and more tortuous than in other neotropical primates. The skin of the face of the bald uakari monkey allows a direct external assessment of haematological status, suggesting that the colour of the face would be an honest indicator of health, but could also signal sexual or behavioural states.