ObjectivesInfant handling describes cases in which youngsters are temporarily removed from the ca... more ObjectivesInfant handling describes cases in which youngsters are temporarily removed from the care of their mothers and “taken care of” (held, carried, etc.) by other conspecifics. Handlers may gain indirect fitness benefits from these actions and can practice mothering skills, thereby improving the odds of survival of their own infants. Great apes are notable for displaying little infant handling. Apart from anecdotal observations, no published data exist on infant handling in wild mountain gorillas. We tested two of the most pertinent explanations (“kin selection” and “learning to mother”) in a wild population of mountain gorillas in Rwanda. We predicted that (a) nulliparous females would exhibit infant handling (i.e., carrying) more than parous females and (b) maternal kin would exhibit more infant handling than nonkin.MethodsWe collated 8 years of data on infant carrying behavior collected in 13 groups monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center.Res...
When family resources are limited, as in much of Timor-Leste (Mendoca 2002), the allocation of fo... more When family resources are limited, as in much of Timor-Leste (Mendoca 2002), the allocation of food between adults and children and among children can be crucial to child growth (Crooks et al 2007, Haaga and Mason 1987). We examine variation in household characteristics including resources available (e.g. wage labour, house materials, education etc), place of residency (town or hamlet) and family composition, and relate these variables to child growth in the Ossu area of Viqueque District. Because resources are acquired through labour and are consumed by family members, the age and perhaps sex composition of families may influence both resource accumulation and consumption (Pelto et al 1991). From 1975 to 1999, the people of Timor-Leste suffered food shortages, foreign occupation, warfare, civil disturbances and political upheaval on a background of general poverty. Today, a sizeable proportion of the population (41%) survive on less than 88 cents per day (AUSAID 2011). Rural Timore...
Subsistence and economic activities undertaken by households in the context of transition from su... more Subsistence and economic activities undertaken by households in the context of transition from subsistence farming to cash economies are sometimes seen as substitutable with only minimal reference to the households themselves. We use data from in-depth interviews of 190 householders in Ossu (mountains) and Natarbora (coastal plains), Timor-Leste, to query relationships of family composition, resource strategies, and their relationships to children’s growth. Principal component analyses of six household composition variables reveal “grandparent and fostered-in children”, “two generational households with numerous adults and children”, and “smaller households with few adults and fostered-out children”, explaining 72% of the variance. A similar procedure with 11 resource variables produced four components explaining 56% of resource variance. Households with grandparents have a pension income and engage in large animal husbandry, and are associated with better standardized BMI for resid...
Competition for food is often a cost associated with living in a group, and can occur in an indir... more Competition for food is often a cost associated with living in a group, and can occur in an indirect (scramble) or direct (contest) form. We investigated feeding competition in a supergroup of Rwenzori black-and-white colobus monkeys (Colobus angolensis ruwenzorii) in Rwanda, with the aim of establishing whether freedom from scramble competition allows these monkeys to form supergroups. We used the patch depletion method, measuring intake rate coupled with movement rate, to assess if food patches become depleted over the occupancy period. Resource depletion was evident when the colobus fed on young leaves, but not when feeding on mature leaves. Scramble competition was inferred from a negative correlation between group size and change in intake rate over patch occupancy. Between-group contest competition was inferred from displacement from patches. Although feeding competition exists for select resources, limited competition for mature leaves may enable Rwenzori colobus to live in a...
The decrease in numbers of Ospreys (Pandion haliaetus) that coincided with the use of chlorinated... more The decrease in numbers of Ospreys (Pandion haliaetus) that coincided with the use of chlorinated hydrocarbon pesticides aroused interest in determining their population sizes and productivity in North America (e.g., Henny and Wight 1969, Henny and Ogden 1970, Henny 1975, Henny and Noltemeier 1975, Wiemeyer et al. 1975, Roberts and Lind 1977). Many populations along the east coast of the United States have been monitored for the past 15 years (Henny and Ogden 1970). These populations consist of migratory Ospreys that spend the winter in Central and South America (Henny and Van Velzen 1972). Within North America, non-migratory populations of Ospreys are currently found in southern Florida (Ogden 1975, 1977) and in Baja California, along the coast of Sonora, and throughout the Gulf of California islands, Mexico (Friedman et al. 1950). Prior to 1930, the Baja California population extended into southern California (Kenyon 1947, Jones and Diamond 1976). A recent aerial survey of the Baja California and Gulf of California regions resulted in an estimated population of 810 + 55 pairs of Ospreys (Henny and Anderson 1979). This paper reports the results of an investigation of the phenology of reproduction and productivity of a portion of this population during 1977 and 1978.
Primates display broad diversity in their social organization. The social groups of a few primate... more Primates display broad diversity in their social organization. The social groups of a few primate species are organized in a multilevel fashion, with large groups composed of multiple, core one‐male units (OMUs). A characteristic of multilevel societies is that the higher levels can include hundreds of individuals. The Rwenzori black‐and‐white colobus (Colobus angolensis ruwenzorii) in the montane forests of Rwanda form supergroups and have been suspected to exhibit multilevel social organization. Here we present the first data on the “anatomy” of a supergroup numbering 500+ individuals. We identified subgroups within the supergroup based on progression data, extracting the social network structure from the time‐stamped spatiotemporal distribution of passing individuals identified to age–sex class, and selecting an optimal time window for each network using the two‐step approach developed by Uddin, Choudhury, Farhad, and Rahman (2017). We detail the existence of core units—multi‐male units (MMUs) with a mean of 1.7 adult males and 3.1 adult females, as well as OMUs, all‐female units and bachelor units composed of adult and sub‐adult males. More than two‐thirds of units are MMUs. These grouping patterns conform to a multilevel society with predominantly multi‐male core units, a social system that has recently also been described for a population of the same taxon in Uganda. Individual identification will be required to corroborate these interpretations.
ObjectivesInfant handling describes cases in which youngsters are temporarily removed from the ca... more ObjectivesInfant handling describes cases in which youngsters are temporarily removed from the care of their mothers and “taken care of” (held, carried, etc.) by other conspecifics. Handlers may gain indirect fitness benefits from these actions and can practice mothering skills, thereby improving the odds of survival of their own infants. Great apes are notable for displaying little infant handling. Apart from anecdotal observations, no published data exist on infant handling in wild mountain gorillas. We tested two of the most pertinent explanations (“kin selection” and “learning to mother”) in a wild population of mountain gorillas in Rwanda. We predicted that (a) nulliparous females would exhibit infant handling (i.e., carrying) more than parous females and (b) maternal kin would exhibit more infant handling than nonkin.MethodsWe collated 8 years of data on infant carrying behavior collected in 13 groups monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center.Res...
When family resources are limited, as in much of Timor-Leste (Mendoca 2002), the allocation of fo... more When family resources are limited, as in much of Timor-Leste (Mendoca 2002), the allocation of food between adults and children and among children can be crucial to child growth (Crooks et al 2007, Haaga and Mason 1987). We examine variation in household characteristics including resources available (e.g. wage labour, house materials, education etc), place of residency (town or hamlet) and family composition, and relate these variables to child growth in the Ossu area of Viqueque District. Because resources are acquired through labour and are consumed by family members, the age and perhaps sex composition of families may influence both resource accumulation and consumption (Pelto et al 1991). From 1975 to 1999, the people of Timor-Leste suffered food shortages, foreign occupation, warfare, civil disturbances and political upheaval on a background of general poverty. Today, a sizeable proportion of the population (41%) survive on less than 88 cents per day (AUSAID 2011). Rural Timore...
Subsistence and economic activities undertaken by households in the context of transition from su... more Subsistence and economic activities undertaken by households in the context of transition from subsistence farming to cash economies are sometimes seen as substitutable with only minimal reference to the households themselves. We use data from in-depth interviews of 190 householders in Ossu (mountains) and Natarbora (coastal plains), Timor-Leste, to query relationships of family composition, resource strategies, and their relationships to children’s growth. Principal component analyses of six household composition variables reveal “grandparent and fostered-in children”, “two generational households with numerous adults and children”, and “smaller households with few adults and fostered-out children”, explaining 72% of the variance. A similar procedure with 11 resource variables produced four components explaining 56% of resource variance. Households with grandparents have a pension income and engage in large animal husbandry, and are associated with better standardized BMI for resid...
Competition for food is often a cost associated with living in a group, and can occur in an indir... more Competition for food is often a cost associated with living in a group, and can occur in an indirect (scramble) or direct (contest) form. We investigated feeding competition in a supergroup of Rwenzori black-and-white colobus monkeys (Colobus angolensis ruwenzorii) in Rwanda, with the aim of establishing whether freedom from scramble competition allows these monkeys to form supergroups. We used the patch depletion method, measuring intake rate coupled with movement rate, to assess if food patches become depleted over the occupancy period. Resource depletion was evident when the colobus fed on young leaves, but not when feeding on mature leaves. Scramble competition was inferred from a negative correlation between group size and change in intake rate over patch occupancy. Between-group contest competition was inferred from displacement from patches. Although feeding competition exists for select resources, limited competition for mature leaves may enable Rwenzori colobus to live in a...
The decrease in numbers of Ospreys (Pandion haliaetus) that coincided with the use of chlorinated... more The decrease in numbers of Ospreys (Pandion haliaetus) that coincided with the use of chlorinated hydrocarbon pesticides aroused interest in determining their population sizes and productivity in North America (e.g., Henny and Wight 1969, Henny and Ogden 1970, Henny 1975, Henny and Noltemeier 1975, Wiemeyer et al. 1975, Roberts and Lind 1977). Many populations along the east coast of the United States have been monitored for the past 15 years (Henny and Ogden 1970). These populations consist of migratory Ospreys that spend the winter in Central and South America (Henny and Van Velzen 1972). Within North America, non-migratory populations of Ospreys are currently found in southern Florida (Ogden 1975, 1977) and in Baja California, along the coast of Sonora, and throughout the Gulf of California islands, Mexico (Friedman et al. 1950). Prior to 1930, the Baja California population extended into southern California (Kenyon 1947, Jones and Diamond 1976). A recent aerial survey of the Baja California and Gulf of California regions resulted in an estimated population of 810 + 55 pairs of Ospreys (Henny and Anderson 1979). This paper reports the results of an investigation of the phenology of reproduction and productivity of a portion of this population during 1977 and 1978.
Primates display broad diversity in their social organization. The social groups of a few primate... more Primates display broad diversity in their social organization. The social groups of a few primate species are organized in a multilevel fashion, with large groups composed of multiple, core one‐male units (OMUs). A characteristic of multilevel societies is that the higher levels can include hundreds of individuals. The Rwenzori black‐and‐white colobus (Colobus angolensis ruwenzorii) in the montane forests of Rwanda form supergroups and have been suspected to exhibit multilevel social organization. Here we present the first data on the “anatomy” of a supergroup numbering 500+ individuals. We identified subgroups within the supergroup based on progression data, extracting the social network structure from the time‐stamped spatiotemporal distribution of passing individuals identified to age–sex class, and selecting an optimal time window for each network using the two‐step approach developed by Uddin, Choudhury, Farhad, and Rahman (2017). We detail the existence of core units—multi‐male units (MMUs) with a mean of 1.7 adult males and 3.1 adult females, as well as OMUs, all‐female units and bachelor units composed of adult and sub‐adult males. More than two‐thirds of units are MMUs. These grouping patterns conform to a multilevel society with predominantly multi‐male core units, a social system that has recently also been described for a population of the same taxon in Uganda. Individual identification will be required to corroborate these interpretations.
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