Assessing the effectiveness of foraging radius models for seabird distributions using biotelemetry and survey data

Relatively simple foraging radius models have the potential to generate predictive distributions for a large number of species rapidly, thus providing a cost-effective alternative to large-scale surveys or complex modelling approaches. Their effectiveness, however, remains largely untested. Here we compare foraging radius distribution models for all breeding seabirds in Ireland, to distributions of empirical data collected from tracking studies and aerial surveys. At the local/colony level, we compared foraging radius distributions to GPS tracking data from seabirds with short (Atlantic puffin Fratercula arctica, and razorbill Alca torda) and long (Manx shearwater Puffinus puffinus, and European storm-petrel Hydrobates pelagicus) foraging ranges. At the regional/national level, we compared foraging radius distributions to extensive aerial surveys conducted over a two-year period. Foraging radius distributions were significantly positively correlated with tracking data for all species except Manx shearwater. Correlations between foraging radius distributions and aerial survey data were also significant, but generally weaker than those for tracking data. Correlations between foraging radius distributions and aerial survey data were benchmarked against generalised additive models (GAMs) of the aerial survey data that included a range of environmental covariates. While GAM distributions had slightly higher correlations with aerial survey data, the results highlight that the foraging radius approach can be a useful and pragmatic approach for assessing breeding distributions for many seabird species. The approach is likely to have acceptable utility in complex, temporally variable ecosystems and when logistic and financial resources are limited.     

Unraveling the complex maternal history of Southern African Khoisan populations

The Khoisan populations of southern Africa are known to harbor some of the deepest‐rooting lineages of human mtDNA; however, their relationships are as yet poorly understood. Here, we report the results of analyses of complete mtDNA genome sequences from nearly 700 individuals representing 26 populations of southern Africa who speak diverse Khoisan and Bantu languages. Our data reveal a multilayered history of the indigenous populations of southern Africa, who are likely to be the result of admixture of different genetic substrates, such as resident forager populations and pre‐Bantu pastoralists from East Africa. We find high levels of genetic differentiation of the Khoisan populations, which can be explained by the effect of drift together with a partial uxorilocal/multilocal residence pattern. Furthermore, there is evidence of extensive contact, not only between geographically proximate groups, but also across wider areas. The results of this contact, which may have played a role in the diffusion of common cultural and linguistic features, are especially evident in the Khoisan populations of the central Kalahari. Am J Phys Anthropol 153:435–448, 2014. © 2013 Wiley Periodicals, Inc.     

Leadership solves collective action problems in small-scale societies

Observation of leadership in small-scale societies offers unique insights into the evolution of human collective action and the origins of sociopolitical complexity. Using behavioural data from the Tsimane forager-horticulturalists of Bolivia and Nyangatom nomadic pastoralists of Ethiopia, we evaluate the traits of leaders and the contexts in which leadership becomes more institutional. We find that leaders tend to have more capital, in the form of age-related knowledge, body size or social connections. These attributes can reduce the costs leaders incur and increase the efficacy of leadership. Leadership becomes more institutional in domains of collective action, such as resolution of intragroup conflict, where collective action failure threatens group integrity. Together these data support the hypothesis that leadership is an important means by which collective action problems are overcome in small-scale societies.     

Influence of environmental and colony factors on the initial commodity choice of foragers of the stingless bee Plebeia tobagoensis (Hymenoptera, Meliponini)

Novice foragers of social bees have to decide what food commodity to collect when they start foraging for the first time. In this decision making process two types of factors are involved: internal factors (the response threshold) and external factors (environmental and colony conditions). In this study we will focus on the importance of two external factors, pollen storage level and information from experienced foragers about food availability in the field, on the initial commodity choice of foragers of the stingless bee species Plebeia tobagoensis. We also studied the effect of the initial choice of individuals on their subsequent foraging career. This study was performed in a closed greenhouse compartment, where food availability and colony condition could be controlled. Information on food availability in the field from experienced foragers and pollen storage level both greatly influenced the initial commodity choice of individuals, with more choices for the commodity communicated by experienced foragers or lacking in storage. The initial choice of foragers is of importance for their future foraging career, although a substantial proportion of foragers did switch between food commodities. Because of the ability of novice foragers to become flexibly distributed over foraging tasks, social bees are able to react to changes in their environment without directly having to decrease foraging effort devoted to other foraging tasks. This, in combination with individual flexibility during foraging careers makes it possible for colonies of P. tobagoensis to forage efficiently in an ever-changing environment. Received 7 November 2005; revised 12 January 2006; accepted 16 February 2006.     

Life in the slow lane revisited: ontogenetic separation between chimpanzees and humans

This study investigates the evolution of human growth by analyzing differences in body mass growth trajectories among three populations: the Ache of eastern Paraguay, the US (NHANES, 1999-2000), and captive chimpanzees. The relative growth statistic "A" from the mammalian growth law is allowed to vary with age and proves useful for comparing growth across different ages, populations, and species. We demonstrate ontogenetic separation between chimpanzees and humans, and show that interspecific differences are robust to variable environmental conditions. The human pattern of slow growth during the lengthened period from weaning to the beginning of the adolescent growth spurt is found among the Ache (low energy availability and high disease load) and also in the US (high energy availability and low disease load). The human growth pattern contrasts with that of the chimpanzee, where absolute growth rates and relative "A" values are faster and less prolonged. We suggest that selection has acted to decrease human growth rates to allow more time for increased cognitive development with lower body-maintenance costs.     

Activity of salivary glands in secreting honey‐elaborating enzymes in two subspecies of honeybee (Apis mellifera L)

The activity of invertase, glucose oxidase and amylase in the cephalic (post‐cerebral) and thoracic salivary glands is determined in Egyptian and Carniolan honeybees (Apis mellifera L). For this purpose, three ages of worker bees are selected for enzyme assays. The results show that the three target enzymes are detected in the two glands during the three worker ages, except invertase, which cannot be detected in the cephalic gland of newly emerged bees of both subspecies. In both glands, the secretion of invertase is highest, followed by amylase and then glucose oxidase. In Carniolan bees, invertase secretion of the cephalic and thoracic glands increases gradually with age. In Egyptian bees, invertase increases with age only in the cephalic gland, whereas, in the thoracic gland, the highest secretion activity is detected in 10–15‐day‐old bees. The highest amounts of glucose oxidase and amylase in the cephalic gland are detected in newly emerged individuals of both Egyptian and Carniolan bees. In the thoracic gland, however, the highest activity of both enzymes is recorded only in newly emerged Egyptian bees. The results are discussed in the light of bee management and biological aspects of the two subspecies.     

Ant- and termite-eating in Australian mammals and lizards: a comparison

Abstract Relative abundance is one factor that influences selection of prey by insectivorous mammals and lizards. Ants and termites are extremely abundant over most of inland Australia. Their patterns of abundance are also broadly similar across climatic gradients, being most and least abundant in seasonally arid (tropic and sub-tropic) and temperate mesic regions, respectively. All else being equal (e. g. mechanisms of prey defence, palat-ability, availability), animals that eat many termites should also eat many (adult) ants. The present study asks three questions: (i) What is the diversity of specialized ant-eaters (>50% volume)?; (ii) Does specialization vary with climate?; and (iii) Are ants and termites eaten in broadly similar proportions (using an earlier study on termites). Of the mammals, only the echidna (Tachyglossus aculeatus) in mesic regions, and probably the marsupial mole (Notoryctes typhlops) in the arid zone and the striped possum (Dactylopsila trivirgata) in mesic regions are ant-specialized. Ant-specialization in mammals shows no pattern with regard to climate. Of the lizards, only four agamid lizards are ant-specialized: Moloch horridus (arid, semi-arid), Ctenophorus fordi (arid, semi-arid), Ctenophorus isolepis (arid) and Ctenophorus maculatus (arid). Specialization on ants by lizards is greatest in the arid zone (4 spp.); no lizard species were found to be ant-specialists in mesic regions. In the arid and semi-arid zone, two mammals each specialize on termites and one on ants; in mesic regions, two mammals specialize on ants and one on termites. Specialized insectivorous mammals thus demonstrate no marked preference for either termites or ants. Lizards, in contrast, are markedly termite-specialized (4 ant-specialist spp., 16 termite-specialist spp.), and specialization is greatest in the arid zone (16 spp.). Greater specialization on termites than on (adult) ants in lizards is explained with reference to differences in prey defence and palatability between ants and termites. Consumption of ant brood (eggs, larvae, pupae) appears to be associated with a fossorial foraging mode (the marsupial mole N. typhlops; spp. of Aprasia lizards; spp. of blindsnakes Ramphotyphlops).     

Changing Patterns of Infant Mortality and Maternal Fertility among Pumé Foragers and Horticulturalists

National census data show that the modern demographic transition—the recent trend toward declining mortality and fertility—is well underway in most countries. A different picture emerges when data from small-scale societies in unindustrialized parts of the world are considered. Many of these small-scale societies are also adapting to rapid changes in their subsistence economies. In this article, we examine the relationship between the pace of acculturation, infant mortality, and fertility levels among Pumé foragers and horticulturalists, two related groups of native South Americans. During the earliest stages of acculturation, Pumé horticulturalists experience not only a rapid drop in infant mortality but also a rise in birth rates. An anthropological view of demographic transitions provides important insight into how small-scale societies are affected by exposure to the labor market economy and has practical applications to effective development initiatives and public health policies.     

Infant and child diet in Neolithic hunter-fisher-gatherers from Cis-Baikal, Siberia: intra-long bone stable nitrogen and carbon isotope ratios

Analysis of stable nitrogen and carbon isotopes (δ(15) N and δ(13) C) from subadults and adults allows for assessment of age-related dietary changes, including breastfeeding and weaning, and adoption of an adult diet. In one of the first studies of hunter-fisher-gatherer subadults from Eurasia, three Neolithic (8,800-5,200 calBP) mortuary sites from southwestern Siberia are analyzed to evaluate hypothesized differences in weaning age between Early versus Late Neolithic groups. An intra-individual sampling methodology is used to compare bone formed at different ages. Collagen samples (n = 143) from three different growth areas of long bones-the proximal metaphysis, diaphysis, and distal metaphysis-were obtained from 49 subadults aged birth to 10 years. In infants (birth to 3 years, n = 23) contrasting the δ(15) N values of the metaphysis, which contains newer bone, to the δ(15) N values of the diaphysis, which contains older bone, permits a more precise determination of breastfeeding-weaning status. In Early and Late Neolithic groups breast milk was the major protein source until the age of 2-3 years. However, there are differences in the age of weaning completion and duration: Early Neolithic groups weaned their infants at a later age and over a shorter amount of time. Differences may have affected infant morbidity and mortality, and female fecundity and inter-birth intervals. Stable isotope values in older subadults (4-10 years, n = 26) do not differ from adults suggesting the absence of age-based food allocation.