Parasites of Wild Howlers (Alouatta spp.)

A literature review of howler parasites provides the basis for an overview of the ecological significance of parasite surveys in primates. Within this framework, we have added insights into the interactions between primate hosts and their parasites from a long-term study in Costa Rica. We collected fecal samples from mantled howlers (Alouatta palliata) over a 9-year period (1986–1994 inclusive) and analyzed them for parasite eggs, larvae, cysts, and oocysts. We found many misperceptions inherent in the typical methodology of primate parasite surveys and in the reporting of the findings. Our work in Costa Rica suggests that a snapshot effect occurs with most surveys. A static view does not reflect the dynamic and changing ecological interaction between host and parasite. We describe some problems with parasite data analyses that emphasize the need for long-term longitudinal surveys in wild primate groups.     

Geographic Distribution of Red Howlers (Alouatta seniculus) in Southwestern Brazilian Amazonia, with Notes on Alouatta caraya

We surveyed howler (Alouatta) populations at 36 sites throughout the Brazilian state of Rondônia, in southwestern Amazonia, using quantitative (line transect surveys) and qualitative (interviews) methods. We recorded the red howler (Alouatta seniculus) at only one- third of the sites, and the species was relatively rare at most of them, especially in comparison with sympatric atelids (Ateles chamek and Lagothrix cana). In addition to local discontinuities, Alouatta was absent from a wide area (possibly as much as 100,000 km²) of northern Rondônia, south of the upper Madeira river. This lacuna apparently contradicts the typical association of the species with flooded forest ecosystems, but the ecological factors that may underlie it remain unclear. Competition with sympatric atelids does not appear to be a significant factor anywhere within the study area. Also, there is no evidence to suggest that the distribution patterns are related to recent human colonization of the state. We collected indirect evidence of the presence of a second howler species – Alouatta caraya – at two sites in southern Rondônia, where they are associated with highland savanna habitats and gallery forests in the Guaporé grasslands.     

Spatial and Diurnal Distribution of Loud Calling in Black Howlers (Alouatta pigra)

Loud calling, i.e., howling, is the single most distinctive behavioral attribute of the social system of howler monkeys (Alouatta spp.), yet no general consensus has been established regarding its function. During a 16-mo study, we investigated the degree to which howling bouts varied in duration and spatial and temporal patterns across different social contexts in three groups of black howlers (Alouatta pigra) at Palenque National Park, Mexico, to assess how howling functions in intergroup spacing. We recorded 359 howling bouts, of which 42% were spontaneous with no apparent cause, 28% followed nearby howling without visual contact with the caller(s), 25% were during intergroup encounters, and 5% were during encounters with solitary individuals. The mean duration of howling bouts was 14.8 ± SE 0.6 min. During encounters with neighboring groups or solitary individuals howling bouts lasted significantly longer than spontaneous and reply calls. Spontaneous and reply howling showed a bimodal pattern with a marked concentration around dawn and a second increase of howling in the afternoon. In contrast, howling during encounters with neighboring groups or solitary individuals occurred randomly throughout the day. In addition, howling, irrespective of the context in which it was given, occurred throughout the groups’ home ranges without concentrations in the heavily used core areas or borders of the home ranges. Our findings suggest that loud calling in black howlers functions principally in regularly announcing the occupancy of an area, and is concentrated in the morning when sound propagation is optimal.     

Using Acoustics to Determine Eelgrass Bed Distribution and to Assess the Seasonal Variation of Ecosystem Service

Eelgrass beds are an important source of primary production in coastal ecosystems. Understanding seasonal variation in the abundance and distribution of eelgrass is important for conservation, and the objectives of this study were to 1) monitor seasonal variation in eelgrass beds using an acoustic monitoring method (Quantitative echo sounder) and 2) broadly quantify the carbon circulation function. We obtained acoustic data of eelgrass beds in coastal areas north and east of Ikunojima Island. Surveys were conducted nine times over the 3-year period from 2011 to 2013 in order to monitor seasonal variation. Acoustic data were obtained and used to estimate the spatial distribution of eelgrass by geostatistical methods. To determine supporting services, we determined carbon sink and carbon fixation by eelgrass beds using data from the National Research Institute of Fisheries and Environment of Inland Sea (2011). The height and distribution of eelgrass beds were at a maximum in May and at a minimum in November of each year. Distribution trends were different between the north and east areas. Supporting services showed the same patterns throughout the year. The area of distribution was considered to be coincident with the life history of eelgrass. Distribution differed by area and changed yearly due to the effects of bottom characteristics and wind direction. Quantifying the supporting services of eelgrass beds was shown to be useful for managing the conservation of coastal ecosystems.     

Responses to Deforestation in a Group of Mantled Howlers (Alouatta palliata) in Costa Rica

To evaluate the effects of partial deforestation of the home range of a group of free-ranging howlers on Hacienda La Pacifica, Costa Rica, we compared activity patterns, social interactions, daily travel lengths, group sizes and migration patterns before, during, and after habitat destruction. Immediate responses were a decrease in social interactions and increase in start to travel. Long-term responses included an increase in feeding time and longer daily path length. The long-term responses were associated with the adjustment to a new home range which was longer and narrower, with the patchiest resources at the furthest end points. Group size decreased due to a significant decrease in adult males and females and a significant increase in infant deaths between the predeforestation period and the deforestation/postdeforestation periods. Significant increase in adult female deaths/emigration continues, though emigration of immatures remains unchanged. Reduced group size could be due to reduced resources or disturbed migration routes throughout the farm due to the construction of a major canal system.     

Using Tournament Angler Data to Rapidly Assess the Invasion Status of Alien Sport Fishes (Micropterus spp.) in Southern Africa

Fishes are one of the most commonly introduced aquatic taxa worldwide, and invasive fish species pose threats to biodiversity and ecosystem function in recipient waters. Considerable research efforts have focused on predicting the invasibility of different fish taxa; however, accurate records detailing the establishment and spread of invasive fishes are lacking for large numbers of fish around the globe. In response to these data limitations, a low-cost method of cataloging and quantifying the temporal and spatial status of fish invasions was explored. Specifically, angler catch data derived from competitive bass angling tournaments was used to document the distribution of 66 non-native populations of black bass (Micropterus spp.) in southern Africa. Additionally, catch data from standardized tournament events were used to assess the abundance and growth of non-native bass populations in southern Africa relative to their native distribution (southern and eastern United States). Differences in metrics of catch per unit effort (average number of fish retained per angler per day), daily bag weights (the average weight of fish retained per angler), and average fish weight were assessed using catch data from 14,890 angler days of tournament fishing (11,045 days from South Africa and Zimbabwe; 3,845 days from the United States). No significant differences were found between catch rates, average daily bag weight, or the average fish weight between countries, suggesting that bass populations in southern Africa reach comparable sizes and numbers relative to waters in their native distribution. Given the minimal cost associated with data collection (i.e. records are collected by tournament organizers), the standardized nature of the events, and consistent bias (i.e. selection for the biggest fish in a population), the use of angler catch data represents a novel approach to infer the status and distribution of invasive sport fish.     

Individual Winter Movement Strategies in Two Species of Murre (Uria spp.) in the Northwest Atlantic

Individual wintering strategies and patterns of winter site fidelity in successive years are highly variable among seabird species. Yet, an understanding of consistency in timing of movements and the degree of site fidelity is essential for assessing how seabird populations might be influenced by, and respond to, changing conditions on wintering grounds. To explore annual variation in migratory movements and wintering areas, we applied bird-borne geolocators on Thick-billed Murres (Uria lomvia, n = 19) and Common Murres (U. aalge, n = 20) from 5 colonies in the Northwest Atlantic for 2–4 consecutive years. Thick-billed Murres ranged widely and among-individual wintering strategies were highly variable, whereas most Common Murres wintered relatively near their colonies, with among-individual variation represented more by the relative use of inshore vs. offshore habitat. Within individuals, some aspects of the wintering strategy were more repeatable than others: colony arrival and departure dates were more consistent by individual Common than Thick-billed Murres, while the sizes of home ranges (95% utilization distributions) and distances travelled to wintering area were more repeatable for both species. In consecutive years, individual home ranges overlapped from 0–64% (Thick-billed Murres) and 0–95% (Common Murres); and the winter centroids were just 239 km and 169 km apart (respectively). Over the 3–4 year timescale of our study, individuals employed either fixed or flexible wintering strategies; although most birds showed high winter site fidelity, some shifted core ranges after 2 or 3 years. The capacity among seabird species for a combination of fidelity and flexibility, in which individuals may choose from a range of alternative strategies, deserves further, longer term attention.     

Relation of Intergroup Variation in Allogrooming to Group Social Structure and Ectoparasite Loads in Red Howlers (Alouatta seniculus)

We compare the allogrooming behavior of 5 troops (average size = 8.2) of red howlers (Alouatta seniculus) from the Venezuelan Llanos with that of other A. seniculus and Alouatta spp. of the genus. In 126.9 observation hr, we recorded 118 allogrooming events, with an average bout length of 109 sec. Females groomed more frequently than males did, but as groomees there is no significant differences between sexes. Adult males groomed adult females mostly in a sexual context (before copulation). Allogrooming rates differ significantly among groups. There are also significant differences among members of the same troop both as groomers and groomees, which we explain in the context of the social behavior and history of each troop. There is no significant correlation between weight of the groomee and duration of the grooming bout. However, the examination of grooming rates and ectoparasite load suggests that allogrooming may have hygienic consequences. Differences in allogrooming rates among species of Alouatta are related to differences in group kin structure and patterns of female competition, in particular, coalition formation. We conclude that the social structure and the degree of relatedness among individuals within a group (or among individuals in a population in interpopulation comparisons) is a more important determinant of allogrooming rate than body size or group size. Our results emphasize the importance of considering intergroup and interpopulational variation in behavior.     

The Causes and Evolutionary Consequences of Mixed Singing in Two Hybridizing Songbird Species (Luscinia spp.)

Bird song plays an important role in the establishment and maintenance of prezygotic reproductive barriers. When two closely related species come into secondary contact, song convergence caused by acquisition of heterospecific songs into the birds’ repertoires is often observed. The proximate mechanisms responsible for such mixed singing, and its effect on the speciation process, are poorly understood. We used a combination of genetic and bioacoustic analyses to test whether mixed singing observed in the secondary contact zone of two passerine birds, the Thrush Nightingale (Luscinia luscinia) and the Common Nightingale (L. megarhynchos), is caused by introgressive hybridization. We analysed song recordings of both species from allopatric and sympatric populations together with genotype data from one mitochondrial and seven nuclear loci. Semi-automated comparisons of our recordings with an extensive catalogue of Common Nightingale song types confirmed that most of the analysed sympatric Thrush Nightingale males were ‘mixed singers’ that use heterospecific song types in their repertoires. None of these ‘mixed singers’ possessed any alleles introgressed from the Common Nightingale, suggesting that they were not backcross hybrids. We also analysed songs of five individuals with intermediate phenotype, which were identified as F₁ hybrids between the Thrush Nightingale female and the Common Nightingale male by genetic analysis. Songs of three of these hybrids corresponded to the paternal species (Common Nightingale) but the remaining two sung a mixed song. Our results suggest that although hybridization might increase the tendency for learning songs from both parental species, interspecific cultural transmission is the major proximate mechanism explaining the occurrence of mixed singers among the sympatric Thrush Nightingales. We also provide evidence that mixed singing does not substantially increase the rate of interspecific hybridization and discuss the possible adaptive value of this phenomenon in nightingales.     

Distribution, diversity and environmental adaptation of highland papayas (Vasconcellea spp.) in tropical and subtropical America

Vasconcellea species, often referred to as highland papayas, consist of a group of fruit species that are closely related to the common papaya (Carica papaya). The genus deserves special attention as a number of species show potential as raw material in the tropical fruit industry, fresh or in processed products, or as genetic resources in papaya breeding programs. Some species show a very restricted distribution and are included in the IUCN Red List. This study on Vasconcellea distribution and diversity compiled collection data from five Vasconcellea projects and retrieved data from 62 herbaria, resulting in a total of 1,553 georeferenced collection sites, in 16 countries, including all 21 currently known Vasconcellea species. Spatial analysis of species richness clearly shows that Ecuador, Colombia and Peru are areas of high Vasconcellea diversity. Combination of species occurrence data with climatic data delimitates the potential distribution of each species and allows the modeling of potential richness at continent level. Based on these modeled richness maps, Ecuador appears to be the country with the highest potential Vasconcellea diversity. Despite differences in sampling densities, its neighboring countries, Peru and Colombia, possess high modeled species richness as well. A combination of observed richness maps and modeled potential richness maps makes it possible to identify important collection gaps. A Principal Component Analysis (PCA) of climate data at the collection sites allows us to define climatic preferences and adaptability of the different Vasconcellea species and to compare them with those of the common papaya.     

Factors Influencing the Reproductive Success of Female Black Howlers (<Emphasis Type="Italic">Alouatta pigra</Emphasis>)

Measuring reproductive success is necessary to determine an organism's fitness, and thus, to address evolutionary processes. In this study we determined the effects of social, ecological, and individual attributes on the reproductive success of black howlers (Alouatta pigra) measured through infant survival and interbirth intervals (IBIs). From 2006 to 2012 we studied 29 black howler (A. pigra) females living in 11 groups in Campeche (Mexico), and recorded 82 births. We recorded group size and composition and the sex of infants during weekly surveys. We calculated a food availability index based on rainfall levels and on the size of preferred food resources. Daughters had a 30 % higher probability of surviving than sons, and the survival of the latter was positively related to food availability. IBI decreased when the first infant in the interval died, and when considering only IBIs in which the first infant survived, IBIs were longer following the birth of a daughter. These results suggest that, even if the production of daughters reduces reproductive output due to longer IBIs, female black howlers may still accrue higher reproductive success through their daughters due to differences between sexes in survival.     

The Effect of Hurricane Iris on the Food Supply of Black Howlers (Alouatta pigra) in Southern Belize1

Hurricanes frequently affect the forests of South and Central America; however, few studies have quantified their effects to forest structure, especially when concentrating on the food supply of an animal population. Hurricane Iris made landfall in Southern Belize on 8 October 2001, severely damaging a 52 hectare site where the behavioral ecology of a population of Central American Black Howlers (Alouatta pigra) had been under study for 2.5 yr. The hurricane resulted in a mortality rate of 35 percent for major food trees, which was primarily attributed to uprooting, snapping, and major delimbing. This damage accounted for 97 percent of the food tree loss between the two sample periods. Tree species differences were found in both the percentage loss and category of damage to food trees. Trees of different heights also experienced different percentage loss and levels of damage; subcanopy and emergent trees experienced higher loss than canopy trees, and subcanopy trees were frequently uprooted. This was partially attributed to a lack of buttressing on these subcanopy trees. Buttressing was found to decrease the frequency of uprooting. Tree size was the only factor that did not influence either damage or death. Trees from which fruit were eaten by black howlers died more than twice as often as did trees eaten for leaves.     

北美东部8种温带树种向北分布的限制气候因子

利用分布于北美东部的 8种温带落叶树种为研究材料 ,应用反映热量和降水状况的 11个变量为气候指标 ,用标准差分析方法分析了这 8个树种的分布北界与气候因子之间的关系。结果表明 ,在所使用的气候指标中 ,同一树种不同地点的温暖指数或年生物温度的标准差最小 ,说明积温是限制这些树种向北分布的主要气候因子 ;温暖指数和寒冷指数随着年降水量的增大而减小 ,寒冷指数随着年较差的增加而增加 ,温暖指数随着水热综合指数的增加表现出减小的趋势。表明 ,除了生长季节的积温之外 ,降水和大陆性等气候条件对温带树种向北分布也起着重要作用     

北美东部8种温带树种向北分布的限制气候因子

利用分布于北美东部的8种温带落叶树种为研究材料,应用反映热量和降水状况的11个变量为气候指标,用标准差分析方法分析了这8个树种的分布北界与气候因子之间的关系.结果表明,在所使用的气候指标中,同一树种不同地点的温暖指数或年生物温度的标准差最小,说明积温是限制这些树种向北分布的主要气候因子;温暖指数和寒冷指数随着年降水量的增大而减小,寒冷指数随着年较差的增加而增加,温暖指数随着水热综合指数的增加表现出减小的趋势.表明,除了生长季节的积温之外,降水和大陆性等气候条件对温带树种向北分布也起着重要作用.     

Geographical distribution of the black howler (Alouatta pigra) in Central America

The geographic range of the black howler,Alouatta pigra in Mexico, Guatemala, and Belize was investigated by travelling through and visiting 65 locations within or close to the expected range. The existence of the species was noted through first hand observations or was documented by talking with residents and knowledgeable people in the area. Observations were made on captive animals as well. All sites and probable sites ofA. pigra were noted to be under 1,300 ft in altitude and in areas with a mean annual temperature above 25°C and a mean annual rainfall over 1,000 mm per year. This area coincides with tropical rain forest areas, including both tropical evergreen and semievergreen rain forests.A. pigra was most plentiful in riverine areas which showed flooding for some part of the year. Two areas of possible sympatry withA. palliata were noted. In all cases, the troop sizes ofA. pigra were extremely small, under ten individuals, and infants could easily be sexed, in contrast toA. palliata which is known to occur in troops of 15–18 and is difficult to sex at an early age. Finally, a very gross method for population estimation from searching time emerged from the study.     

Influence of Two Plant Species (Flax and Tomato) on the Distribution of Nitrogen Dissimilative Abilities within Fluorescent Pseudomonas spp

The distribution of nitrogen-dissimilative abilities among 317 isolates of fluorescent pseudomonads was studied. These strains were isolated from an uncultivated soil and from the rhizosphere, rhizoplane, and root tissue of two plant species (flax and tomato) cultivated on this same soil. The isolates were distributed into two species, Pseudomonas fluorescens (45.1%) and Pseudomonas putida (40.4%), plus an intermediate type (14.5%). P. fluorescens was the species with the greatest proportion of isolates in the root compartments and the greatest proportion of dissimilatory and denitrifying strains. According to their ability to dissimilate nitrogen, the isolates have been distributed into nondissimilatory and dissimilatory strains, nitrate reducers and true denitrifiers with or without N(inf2)O reductase. The proportion of dissimilatory isolates was significantly enhanced in the compartments affected by flax and tomato roots (55% in uncultivated soil and 90 and 82% in the root tissue of flax and tomato, respectively). Among these strains, the proportion of denitrifiers gradually and significantly increased in the root vicinity of tomato (44, 68, 75, and 94% in uncultivated soil, rhizosphere, rhizoplane, and root tissue, respectively) and was higher in the flax rhizoplane (66%) than in the uncultivated soil. A higher proportion of N(inf2)O reducers was also found in the root compartments. This result was particularly clear for tomato. It is hypothesized that denitrification could be a selective advantage for the denitrifiers in the root environment and that this process could contribute to modify the specific composition of the bacterial communities in the rhizosphere.     

Methods for Studying the Ecological Physiology of Feeding in Free-Ranging Howlers (Alouatta palliata) at La Pacifica, Costa Rica

We lack a general understanding of how primates perform physiologically during feeding to cope with the challenges of their natural environments. We here discuss several methods for studying the ecological physiology of feeding in mantled howlers (Alouatta palliata) at La Pacifica, Costa Rica. Our initial physiological effort focuses on recording electromyographic activity (EMG) from the jaw muscles in free-ranging howlers while they feed in their natural forest habitat. We integrate these EMG data with measurements of food material properties, dental wear rates, as well as spatial analyses of resource use and food distribution. Future work will focus on incorporating physiological measures of bone deformation, i.e., bone strain; temperatures; food nutritional data; and hormonal analyses. Collectively, these efforts will help us to better understand the challenges that howlers face in their environment and the physiological mechanisms they employ during feeding. Our initial efforts provide a proof of concept demonstrating the methodological feasibility of studying the physiology of feeding in free-ranging primates. Although howlers offer certain advantages to in vivo field research, many of the approaches described here can be applied to other primates in natural habitats. By collecting physiological data simultaneously with ecological and behavioral data, we will promote a more synthetic understanding of primate feeding and its evolutionary history.