-
[show abstract]
[hide abstract]
ABSTRACT: Male Colobus vellerosus are the main participants in intergroup encounters, and lead incursions in neighboring groups during which they attack infants.
Extragroup copulations, all-male groups, and male takeover occur in the species. Here, we provide additional information on
behaviors associated with male reproductive competition in Colobus vellerosus. We examined 1 resident male loud calling and participation in intergroup encounters in relation to a takeover. We also report
a second case of takeover that led to the death of the former resident male and the death of 2 male infants, presumably as
a result of aggression from the all-male group. The new resident male wounded the third infant of the group, which apparently
died after its mother abandoned it. During the period characterized by the attacks on the infant and after its disappearance,
females initiated and participated in loud call bouts with the new resident male. We examine the possible functions of female
loud calling, and suggest that in this context, it might force the resident male to call along to indicate his presence.
International Journal of Primatology 04/2012; 28(3):627-636. · 1.54 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Examination of the characteristics and locations of sleeping sites helps to document the social and ecological pressures acting on animals. We investigated sleeping tree choice for four groups of Colobus vellerosus, an arboreal folivore, on 298 nights at the Boabeng-Fiema Monkey Sanctuary, Ghana using five non-mutually exclusive hypotheses: predation avoidance, access to food, range and resource defense, thermoregulation, and a null hypothesis of random selection. C. vellerosus utilized 31 tree species as sleeping sites and the species used differed per group depending on their availability. Groups used multiple sleeping sites and minimized their travel costs by selecting trees near feeding areas. The percentage that a food species was fed upon annually was correlated with the use of that species as a sleeping tree. Ninety percent of the sleeping trees were in a phenophase with colobus food items. Entire groups slept in non-food trees on only one night. These data strongly support the access to food hypothesis. Range and resource defense was also important to sleeping site choice. Groups slept in exclusively used areas of their home range more often than expected, but when other groups were spotted on the edge of the core area, focal groups approached the intruders, behaved aggressively, and slept close to them, seemingly to prevent an incursion into their core range. However, by sleeping high in the canopy, in large, emergent trees with dense foliage, positioning themselves away from the main trunk on medium-sized branches, and by showing low rates of site reuse, C. vellerosus also appeared to be avoiding predation in their sleeping site choices. Groups left their sleep sites later after cooler nights but did not show behavioral thermoregulation, such as huddling. This study suggests that access to food, range and resource defense, and predation avoidance were more important considerations in sleeping site selection than thermoregulation for ursine colobus.
Primates 02/2012; 53(3):287-96. · 1.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Dispersal is male-biased in ursine colobus monkeys (Colobus vellerosus), although female dispersal also occurs (Teichroeb et al., 2009). Here we describe the process of male dispersal and its connection with between-group encounters (BGEs, N = 444) and male incursions (when males left their group and approached within 50 m of another group; N = 128) at the Boabeng-Fiema Monkey Sanctuary in central Ghana. Through BGEs and incursions, particularly those with non-aggressive interactions between individuals in different groups (BGEs, N = 17; incursions, N = 4), males could probably assess other groups for dispersal opportunities. There was a trend for males to perform incursions more frequently before emigrating voluntarily than involuntarily. Incursions were often performed towards the group that the male eventually transferred to. Incursions by alpha males were temporally shorter and more aggressive than those by non-alpha males. We suggest that non-alpha males used incursions to assess other groups for breeding or dispersal opportunities, whereas alpha males performed incursions mainly to convey information about their quality to neighbouring males and females. Male emigrations/disappearances (natal N = 20, secondary N = 43, unknown N = 9) and immigrations (N = 62) were recorded for seven groups during ten years (2000- 2010). Alpha males always emigrated involuntarily. Parallel emigration and immigration occurred. Males often immigrated into groups with a more favourable adult male/adult female ratio and improved their rank, both of which likely increased their mating opportunities. The most fitting ultimate explanation for both natal and secondary male dispersal in this population was the intrasexual competition for mates hypothesis, as males of all ages appeared to emigrate to improve their reproductive opportunities.
Behaviour 06/2011; 148(7):765-793. · 1.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Male agonistic displays may allow males to assess competitors, females to assess mates, or could be directed at cycling females to sexually coerce them. We analysed the display output of 26 male ursine colobus monkeys (Colobus vellerosus) in four groups over 13-mo at the Boabeng-Fiema Monkey Sanctuary, Ghana. Display indices (including three behaviours, loud calls, stiff-legs, and jump-displays) were calculated for males in each group. Males vary in their expression of these behaviours suggesting they are sexually selected signals. We investigated the target of displays and whether display indices varied in relation to male dominance rank, eviction of other males, copulation rate, and proceptive behaviours received from females, to assess the primary function of these behaviours. Male displays decreased in vigour over time and were targeted to other groups and males. High-ranking males displayed more than low-ranking males. Alpha male display indices correlated with the number of other males evicted from the group. Display rates were generally higher when cycling females were present in the group. However, neither male display index nor rank correlated with copulation rates. Alpha and non-alpha males gave cycling females equal rates of sexual solicitations; likewise cycling females showed no difference in the rates of proceptive behaviours directed towards alpha and non-alpha males. Females mated promiscuously and did not seem to base mating decisions on male display output, although data on female hormones is needed to determine if they mate with strongly displaying males more in the periovulatory period. The male–male competition hypothesis received the greatest support, with some support for the female mate choice hypothesis. Although behaviours that appeared sexually coercive were observed, the function of male displays did not seem to be sexual coercion. Displays were rarely directed at females and males that displayed more did not have greater mating success.
Ethology 03/2010; 116(4):366 - 380. · 2.01 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Parasite richness and prevalence in wild animals can be used as indicators of population and ecosystem health. In this study, the gastrointestinal parasites of ursine colobus monkeys (Colobus vellerosus) at the Boabeng-Fiema Monkey Sanctuary (BFMS), Ghana, were investigated. BFMS is a sacred grove where monkeys and humans have long lived in relatively peaceful proximity. Fecal samples (n = 109) were collected opportunistically from >27 adult and subadult males in six bisexual groups and one all-male band from July 2004 to August 2005. Using fecal floatation, we detected three protozoans (two Entamoeba sp., Isospora sp.), five nematodes (Ascaris sp., Enterobius sp., Trichuris sp., two strongyle sp.), and one digenean trematode. Using fluorescein labeled antibodies, we detected an additional protozoan (Giardia sp.), and with PCR techniques, we characterized this as G. duodenalis Assemblage B and also identified a protistan (Blastocystis sp., subtype 2). The most prevalent parasite species were G. duodenalis and Trichuris sp. Parasites were more prevalent in the long wet season than the long dry. Parasite prevalence did not vary by age, and average parasite richness did not differ by rank for males whose status remained unchanged. However, males that changed rank tended to show higher average parasite richness when they were lower ranked. Individuals that spent more time near human settlements had a higher prevalence of Isospora sp. that morphologically resembled the human species I. belli. The presence of this parasite and G. duodenalis Assemblage B indicates possible anthropozoonotic and/or zoonotic transmission between humans and colobus monkeys at this site.
American Journal of Physical Anthropology 05/2009; 140(3):498-507. · 2.82 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Under the dispersal/foraging efficiency model, colobines are predicted to be 'indifferent mothers', neither facilitating philopatry for their daughters nor evicting them from the natal home range because food competition is thought to be slight. We observed six groups of Colobus vellerosus at the Boabeng-Fiema Monkey Sanctuary in Ghana (2000-2007) and recorded changes in female composition caused by observed (N = 11) and inferred (N = 12) emigrations and immigrations (N = 3). We also observed 14 immigration attempts. Most emigrating females were subadult and nulliparous. Parallel emigration was frequent. Resident females behaved aggressively to immigrating females and immigration attempts were rarely successful. Voluntary female emigration (N = 10) occurred mostly when male group membership was unstable or in association with the immigration of all-male bands. Involuntary emigrations (N = 13) associated with increased female-female aggression occurred in the two largest groups, where parous females targeted nulliparous maturing females. Larger groups tended to lose females and female immigration was successful only in the study group with the lowest number of females. Females appear to emigrate to reduce infanticide threat although feeding competition is reduced in smaller groups as well. C. vellerosus at BFMS are better described as 'incomplete suppressors'.
Behaviour 03/2009; 146(4-5):551-582. · 1.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: For group-living mammals, the ecological-constraints model predicts that within-group feeding competition will increase as group size increases, necessitating more daily travel to find food and thereby constraining group size. It provides a useful tool for detecting scramble competition any time it is difficult to determine whether or not food is limiting. We tested the ecological-constraints model on highly folivorous ursine colobus monkeys (Colobus vellerosus) at the Boabeng-Fiema Monkey Sanctuary in Ghana. Three differently sized groups were followed for 13 months and two others were followed for 6 months each in 2004-2005 using focal-animal sampling and ranging scans; ecological plots and phenology surveys were used to determine home-range quality and food availability. There was relatively little difference in home-range quality, monthly food availability, diet, adult female ingestion rates, and rate of travel within food patches between the groups. However, home-range size, day-range length, and percent of time spent feeding all increased with group size. We performed a single large test of the ecological-constraints model by combining several separate Spearman correlations, each testing different predictions under the model, using Fisher's log-likelihood method. It showed that the ecological-constraints model was supported in this study; scramble competition in this population is manifesting in increased ranging and time spent feeding. How costly this increased energy expenditure is for individuals in larger groups remains to be determined.
American Journal of Primatology 10/2008; 71(1):49-59. · 2.22 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: During a 13-month study period on four groups of Colobus vellerosus at the Boabeng-Fiema Monkey Sanctuary in Ghana, we recorded all instances of male aggression to infants and mothers with infants using focal-animal and ad libitum sampling. Resident males did not attack infants, whereas new immigrant males who became high-ranking and those that immigrated as part of an all-male band did. During this period, three cases of confirmed infanticide, one case of likely infanticide, and three suspected infanticides were attributed to new males. Not all new alpha males attacked infants; however, after a takeover in Group B2, the new alpha male did not attack an eight-week old infant. Some resident males aided females in infant defence but were not successful. These new cases and previously reported cases of infanticide seem to best-fit predictions of the sexual selection hypothesis. Infant attacks were performed by seemingly unrelated males who gained mating access to mothers after their infants died. Loss of a previous infant shortened the inter-birth intervals of females (N = 6). Male infants may have been targeted preferentially at this site, which would support the 'eliminate a future sexual rival' hypothesis, although more cases are needed to reach a firm conclusion.
Behaviour 05/2008; 145(6):727-755. · 1.57 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Male testosterone (T) levels are thought to be linked with the mating system, degree of parental care, and male-male aggression in reproductive contexts (The 'challenge hypothesis'; Wingfield et al., 1990). In many species though, T increases associated with mating behavior cannot be separated from those associated with male-male aggression. We tested the challenge hypothesis on aseasonally breeding ursine colobus (Colobus vellerosus), where male-male competition is intense outside of mating contexts. Fecal samples (N=109) were collected from >27 subadult and adult males in seven groups during 13-months of research in Ghana in 2004-2005. Fecal T (fT) levels were determined by enzyme immunosorbant assays. Behavioral data was collected using focal-animal and ad libitum sampling. The number of receptive females in each group did not positively correlate with male fT. There was a trend for adult males to have higher fT than subadult males; however there was no effect of rank on fT. The level of male-male aggression experienced was positively correlated with fT and individual males showed higher mean fT during 'challenge' than during 'non-challenge' periods. The number of male incursions experienced positively correlated with fT whereas the number of between-group encounters did not. Males attempt to gain reproductive opportunities during incursions, thus these results support the 'challenge hypothesis' in C. vellerosus. Outside of mating contexts, higher male fT levels are associated with increased aggression. Male parental investment in the form of infant defense was associated with increased fT, rather than the decline expected from other forms of paternal care.
Hormones and Behavior 04/2008; 54(3):417-23. · 3.87 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This study describes natal attraction and infant handling in wild ursine colobus (Colobus vellerosus). Focal animal samples were collected from five infants of 1-16 weeks of age (mean: 14.5 focal hours per infant). Group members may be attracted to an infant, but unable to handle it because of resistance from the mother. We thus measured natal attraction independently from infant handling by the number of interactive approaches received. The youngest infants were most attractive. Immature females were attracted to and handled infants more than other group members. Mothers were tolerant of most handling attempts and infant-directed aggression was rare. A sixth infant was attacked by members of an all-male band, which allowed us to record the expression of natal attraction and infant handling in the context of an acute threat of infanticide. This infant was carried by non-mothers less frequently than the other infants, and its mother resisted handling attempts more often.
American Journal of Primatology 02/2008; 70(1):101-5. · 2.22 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The ability to recognize individuals is a prerequisite for analyzing social relationships. We marked five adult and subadult Colobus vellerosus (three in 2002, and two in 2003) at the Boabeng Fiema Monkey Sanctuary, Ghana, to assess the feasibility of dye-marking black-and-white colobus, describe their reactions, and compare some of their behaviors with those of unmarked individuals. We used Nyanzol-D, a nontoxic black dye sprayed on the white tail (or white thigh) of the animal with a spray gun or a tree sprayer. Reactions to the marking procedure ranged from moving away and staring at the observer, without interruption in feeding (in one subject), to fleeing about 5 m away (in four subjects). In 234 hr of ad libitum observations (in 2002 and 2003), marks were scratched or otherwise were the object of attention from the bearer or other individuals on only one occasion. In 2002 we collected 22 hr of observations on the three marked monkeys and some unmarked monkeys in 10-min focal samples. Neither the marked nor the unmarked animals attended to the marks during focal samples. Marked and unmarked individuals displayed similar rates of displacement activities (autogrooming, scratching, and yawning). The proportion of scans with at least one near neighbor varied between marked and unmarked subjects, but the direction of the difference was not the same between males and females. The only aggression observed was displacements, and only in one comparison (out of four) did a difference emerge: the marked subadult male received more displacements than the unmarked males. Overall, marked and unmarked individuals did not differ consistently in our measures. Examination of the potential effects of marking should continue, since changes in pelage coloration may have longer-term social effects in species that rely largely on vision.
American Journal of Primatology 03/2005; 65(2):197-203. · 2.22 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Group size influences foraging efficiency in several primates. We examined the activity budgets of 3 groups of Geoffroy's pied colobus (Colobus vellerosus) at the Boabeng-Fiema Monkey Sanctuary in Ghana to determine whether larger group size induces scramble competition. We studied 2 groups (B1; N = 7-8 and WW; N = 31-33) occupying slightly overlapping home ranges from August to November 2000. We observed the third group, B2 (N = 15-16), comprising B1 and 7 male invaders in the same home range as B1 from August to November 2001. By comparing groups belonging to the same population and occupying sligthly overlapping or similar home ranges, we were able to control, to a certain extent, for differences in food distribution. We recorded a total of 3353 scans, yielding 14,886 activity records, over 73 days. As with other black-and-white colobus, resting was their most common activity (59%). Intergroup comparisons suggest that time spent feeding, resting and moving did not vary in relation to group size. However, intragroup comparisons between the sexes show that females in the large group spent more time feeding than males did, whereas this was not the case in the small group, which suggests that scramble competition may be occurring among female Colobus vellerosus at BFMS. It is also possible that this may be due to greater nutritional requirements because of a higher proportion of infants in the large group. In fact, the proportion is quite similar between the two groups, lending support to the idea that females in the two groups had comparable nutritional demands due to lactation. This suggests that increased feeding in females in the large group was partly an effect of scramble competition. Group size and group composition also influenced the frequency of social behavior. There was more grooming in the large group, and it was performed mostly by females. The distribution of activities throughout the day was similar to the pattern reported for other black-and-white colobus.
International Journal of Primatology 07/2003; 24(4):743-758. · 1.54 Impact Factor
