Nested species assemblages as a tool to detect sensitivity to forest fragmentation: the case of cloud forest birds

In an ecological community, groups of species may or may not have a nested structure. Furthermore, any nested structure detected could have several causes, each of which would have to be identified, since they may have important theoretical and management implications. In this paper, I assessed the nested structure of bird communities using cloud forest fragments in eastern Mexico to identify bird species and groups of species sensitive to cloud forest fragmentation. Sensitive species were expected to have a nested arrangement highly correlated with forest fragmentation intensity. Analysis identified the following groups of birds as showing a nested structure highly correlated with cloud forest fragmentation: birds with a body mass between 100 and 300 g and larger than 600 g, some trophic behavioural guilds (terrestrial granivore, terrestrial granivore–frugivore, understory granivore–frugivore, arboreal granivore–frugivore, gleaning terrestrial insectivore, gleaning understory insectivore, cliff gleaning insectivore, nocturnal aerial insectivore, diurnal raptor, nocturnal raptor, terrestrial omnivore, scavenger), forest interior and generalist birds, species restricted to cloud forest, and threatened species. This study shows that the analysis of the nested species assemblage can be considered a useful tool to identify species sensitivity to ecological or landscape patterns and processes, in this case, species or groups of species affected by a fragmented landscape pattern.     

Evolution of angiosperm seed disperser mutualisms: the timing of origins and their consequences for coevolutionary interactions between angiosperms and frugivores

The origins of interactions between angiosperms and fruit‐eating seed dispersers have attracted much attention following a seminal paper on this topic by Tiffney (1984). This review synthesizes evidence pertaining to key events during the evolution of angiosperm–frugivore interactions and suggests some implications of this evidence for interpretations of angiosperm–frugivore coevolution. The most important conclusions are: (i) the diversification of angiosperm seed size and fleshy fruits commenced around 80 million years ago (Mya). The diversity of seed sizes, fruit sizes and fruit types peaked in the Eocene around 55 to 50 Mya. During this first phase of the interaction, angiosperms and animals evolving frugivory expanded into niche space not previously utilized by these groups, as frugivores and previously not existing fruit traits appeared. From the Eocene until the present, angiosperm–frugivore interactions have occurred within a broad frame of existing niche space, as defined by fruit traits and frugivory, motivating a separation of the angiosperm–frugivore interactions into two phases, before and after the peak in the early Eocene. (ii) The extinct multituberculates were probably the most important frugivores during the early radiation phase of angiosperm seeds and fleshy fruits. Primates and rodents are likely to have been important in the latter part of this first phase. (iii) Flying frugivores, birds and bats, evolved during the second phase, mainly during the Oligocene and Miocene, thus exploiting an existing diversity of fleshy fruits. (iv) A drastic climate shift around the Eocene–Oligocene boundary (around 34 Mya) resulted in more semi‐open woodland vegetation, creating patchily occurring food resources for frugivores. This promoted evolution of a ‘flying frugivore niche’ exploited by birds and bats. In particular, passerines became a dominant frugivore group worldwide. (v) Fleshy fruits evolved at numerous occasions in many angiosperm families, and many of the originations of fleshy fruits occurred well after the peak in the early Eocene. (vi) During periods associated with environmental change altering coevolutionary networks and opening of niche space, reciprocal coevolution may result in strong directional selection formative for both fruit and frugivore evolution. Further evidence is needed to test this hypothesis. Based on the abundance of plant lineages with various forms of fleshy fruits, and the diversity of frugivores, it is suggested that periods of rapid coevolution in angiosperms and frugivores occurred numerous times during the 80 million years of angiosperm–frugivore evolution.     

The putative niche requirements and landscape dynamics of Microstegium vimineum: an invasive Asian grass

The theoretical foundations of population and community ecology stress the importance of identifying crucial niche requirements and life history stages of invasive species and, in doing so, give insight into research and management. We focus on Microstegium vimineum, an invasive grass which is causing marked changes in the structure and function of US forests. We describe M. vimineum’s life history and habitat characteristics, infer its niche requirements and synthesize this information in the context of population dynamics and management. Based on the results synthesized here, M. vimineum’s crucial niche requirements appear to be light (reproductive output), soil moisture (reproductive output, seedling recruitment) and aboveground coverage by leaf-litter and competing species (seedling recruitment and survival). These data suggest a source-sink dynamic might allow M. vimineum to disperse and thrive along sunny, and sometimes wet, edge habitats and, in turn, these populations might act as source populations for adjacent shady forest habitats. By evaluating M. vimineum in the context of its stage-specific requirements, we highlight potential weaknesses in its life history that provide strategies for effective management.     

Tracing the Origin of Dietary Protein in Tropical Dry Forest Birds1

Fundamental to our understanding of the ecology of animal communities in the tropics is knowledge of the effect of seasonal changes in the abundance of food sources in consumer diets. We determined stable‐isotope composition (¹³C/¹²C and ¹⁵N/¹⁴N) in whole blood of 14 resident avian species in a tropical dry forest to quantify the origin of their assimilated protein. We used a probabilistic approach (IsoSource) to estimate the relative contribution of C₃ plants, CAM‐C₄ plants, C₃ insects, and CAM‐C₄ insects during the dry and rainy seasons. IsoSource iteratively creates each possible combination of source contribution and produces a distribution of all feasible combinations that adequately predict the observed isotopic signature of the consumer. Granivore–frugivores and granivore–frugivore–insectivores were modeled as predominantly dependent upon plants whereas insectivorous birds were modeled to derive protein almost exclusively from insects. Between these extremes there were several species using mixed diets such as insectivore–frugivores or insectivore–granivores. In most species, virtually all assimilated food was of C₃ origin with the exception of Ruddy Ground‐Doves (Columbina talpacoti) in which CAM or C₄ plants contributed significantly. Seasonal changes in relative food source contribution were followed in eight species of birds. Of these species, White‐tipped Doves (Leptotila verreauxi), Grayish Saltators (Saltator coerulescens), and Social Flycatchers (Myiozetetes similis) increased their use of insects in the rainy season, in contrast to Great Kiskadees (Pitangus sulphuratus), which decreased their use of insects. Our study suggests that that diverse strategies are used by various avian species to obtain dietary proteins within seasonal habitats.     

不同生境下景宁玉兰灌丛萌株形态及其生殖特征

景宁玉兰是萌生能力很强的灌木树种,为了解不同生境下景宁玉兰萌枝形态及其生殖特征,选择了灌丛(SH)、黄山松林(PTF)、落叶阔叶林(DBF)、杉木林(CLF)和林缘(FE)等5种坡向一致的生境类型,通过典型样地调查,比较分析了5种不同生境下景宁玉兰萌枝数量、大小、高度、枝系、开花及结实等性状。结果表明:(1)景宁玉兰在黄山松林下的分布密度最高,但5种生境下景宁玉兰每丛的萌枝数量没有差异,每丛最大萌枝基径对每丛萌枝数有一定影响,但最大萌枝高度与每丛萌枝数没有关系。在所有调查的景宁玉兰居群中,大于2根以上萌枝的灌丛达82.5%,说明萌生更新在种群繁衍中发挥着重要作用。(2)在落叶阔叶林下的萌枝基径显著小于其他生境(P0.05),黄山松林下一级枝粗度和长度显著小于其他生境(P0.05);灌丛中的总分枝率和逐步分枝率最高,灌丛和林缘生境的逐步分枝率(SBR2:3)高于其他生境。(3)生殖萌枝基径(r=0.320,P0.05)和高度(r=0.349,P0.05)与花量均呈显著正相关关系。杉木林下景宁玉兰生殖萌枝的花量显著高于黄山松林、落叶阔叶林和林缘生境(P0.05)。虽然黄山松林下景宁玉兰萌枝开花率及开花萌枝比例最低,但其果实大小、单果种子粒数及每丛结实率却较高(P0.05),(4)景宁玉兰对环境变化极为敏感,生境类型和海拔对萌枝形态和生殖性状均有一定影响。研究表明,景宁玉兰萌生特征主要受其内在生物学特性所控制,而萌枝形态及生殖特征则与其所处环境条件更为密切。     

Bird Assemblage and Visitation Pattern at Fruiting Elmerrillia tsiampaca (Magnoliaceae) Trees in Papua New Guinea

Most tropical trees produce fleshy fruits that attract frugivores that disperse their seeds. Early demography and distribution for these tree species depend on the effects of frugivores and their behavior. Anthropogenic changes that affect frugivore communities could ultimately result in changes in tree distribution and population demography. We studied the frugivore assemblage at 38 fruiting Elmerrillia tsiampaca, a rain forest canopy tree species in Papua New Guinea. Elmerrillia tsiampaca is an important resource for frugivorous birds at our study site because it produces abundant lipid-rich fruits at a time of low fruit availability. We classified avian frugivores into functional disperser groups and quantified visitation rates and behavior at trees during 56 canopy and 35 ground observation periods. We tested predictions derived from other studies of plant–frugivore interactions with this little-studied frugivore assemblage in an undisturbed rain forest. Elmerrillia tsiampaca fruits were consumed by 26 bird species, but most seeds were removed by eight species. The most important visitors (Columbidae, Paradisaeidae and Rhyticeros plicatus) were of a larger size than predicted based on diaspore size. Columbidae efficiently exploited the structurally protected fruit, which was inconsistent with other studies in New Guinea where structurally protected fruits were predominantly consumed by Paradisaeidae. Birds vulnerable to predation foraged for short time periods, consistent with the hypothesis that predator avoidance enhances seed dispersal. We identified seven functional disperser groups, indicating there is little redundancy in disperser groups among the regular and frequent visitors to this tropical rain forest tree species.     

Characterization of social behavior in the spiny mouse,Acomys cahirinus

While there are many species that are commonly used for the study of mammalian social behavior, there remains a need for lab-suitable organisms that are appropriate for examining sociality specifically in non-reproductive contexts (i.e., social behavior not in the context of mating or parenting). The spiny mouse, Acomys cahirinus, is a cooperatively breeding rodent that lives in large groups and is a species that holds great potential for studying a wide range of social behaviors in reproductive and non-reproductive contexts. Here, we characterize the basic social behaviors in male and female A. cahirinus to obtain a foundation for future study. We tested adult A. cahirinus in social approach, social preference, social interaction, social recognition, and group size preference paradigms. Regardless of sex, novelty, or familiarity, we found that both males and females rapidly approach conspecifics demonstrating high social boldness. Additionally, both sexes are significantly more prosocial than aggressive when freely interacting with conspecifics. However, we observed effects of sex on social preferences, such that males exhibit a preference to affiliate with same-sex conspecifics, whereas females exhibit a preference for affiliating with opposite-sex conspecifics. We discuss how this preference may relate to the cooperative breeding system of spiny mice. Lastly, both sexes show a robust preference for affiliating with large over small groups, indicating they may be an ideal species for the study of mammalian gregariousness. These data lay a basic foundation for future studies that seek to assess complex group dynamics and the mechanisms underlying reproductive and non-reproductive social behaviors in a highly social mammal.     

Modeling Developmental Class Provides Insights into Individual Contributions to Infant Survival in Callitrichids

Cooperative breeders live in social groups in which individuals in an age–sex class vary in reproductive development due to reproductive dominance by a few individuals in each group. Among callitrichids, adult males have been implicated in driving group reproductive output, but uneven sampling efforts, the underlying effects of group size, and pseudoreplication at the group and species levels are confounding variables in these analyses. We examined the drivers of group reproductive output in callitrichids by 1) conducting a meta-analysis of published studies of callitrichid group composition; 2) assigning developmental class based on reproductive morphology; and 3) using multivariate modeling to test whether the proportion of individuals of each developmental class predicts the presence and the number of surviving offspring among free-ranging Weddell’s saddleback tamarins (Leontocebus weddelli) and emperor tamarins (Saguinus imperator) in Peru. The meta-analysis revealed that the number of adult females and group size, but not the number of adult males, are significantly correlated with group reproductive output. Statistical models of the new dataset revealed that the proportion of primary breeding males, primary breeding females, and group size predicted whether groups had surviving infants, and that only the proportion of primary breeding females and group size predicted the number of surviving infants. Thus, primary breeding males appear to be necessary for groups to raise any infants, but a higher proportion of primary breeding females and a larger group size increase group reproductive output overall.     

Avian distribution in treefall gaps and understorey of terra firme forest in the lowland Amazon

We compared the bird distributions in the understorey of treefall gaps and sites with intact canopy in Amazonian terra firme forest in Brazil. We compiled 2216 mist-net captures (116 species) in 32 gap and 32 forest sites over 22.3 months. Gap habitats differed from forest habitats in having higher capture rates, total captures, species richness and diversity. Seventeen species showed a significantly different distribution of captures between the two habitats (13 higher in gap and four higher in forest). Gap habitats had higher capture rates for nectarivores, frugivores and insectivores. Among insectivores, capture rates for solitary insectivores and army ant followers did not differ between the two habitats. In contrast, capture rates were higher in gaps for members of mixed-species insectivore flocks and mixed-species insectivore–frugivore flocks. Insectivores, especially members of mixed-species flocks, were the predominant species in gap habitats, where frugivores and nectarivores were relatively uncommon. Although few canopy species were captured in gap or forest habitats, visitors from forest mid-storey constituted 42% of the gap specialist species (0% forest) and 46% of rare gap species (38% forest). Insectivore, and total, captures increased over time, but did so more rapidly in gap than in forest habitats, possibly as a response to gap succession. However, an influx of birds displaced by nearby timber harvest also may have caused these increases. Avian gap-use in Amazonian terra firme forests differs from gap-use elsewhere, partly because of differences in forest characteristics such as stature and soil fertility, indicating that the avian response to gaps is context dependent.     

Behavioral and Endocrine Responses in Male Marmosets to the Establishment of Multimale Breeding Groups: Evidence for Non-monopolizing Facultative Polyandry

Studies of wild callitrichids provide conflicting evidence regarding polyandrous groups. One perspective supports a monopolizing breeding strategy on the part of one male, while the alternative perspective suggests that polyandry does not lead to a breeding monopoly. We tested the hypotheses in male marmosets (Callithrix kuhlii) with 5 polyandrous groups composed of related/familiar males as our attempts to establish polyandrous groups of unrelated/familiar males failed. We monitored male social and sexual behavior and urinary testosterone (T) and cortisol (CORT) across the first 80 days of group formation and contrasted them with similar measures in males housed in monogamous groups. We also examined the same measures across the females' ovulatory cycles for polyandrous males. We found little evidence that males in polyandrous groups exercised a mating monopoly over the female and no evidence for overt competition between polyandrous males. We found 2 behavioral differences: polyandrous males were less often in proximity and copulated more often with the female than monogamous males did. Our findings suggest that the males in newly-formed groups of marmosets do not monopolize breeding and social behavior with the female. This appears to be the case for 3 reasons. First, males may use sperm competition rather than overt competition. Secondly, it may take longer for relationships to develop between the female and the males in polyandrous groups versus in monogamous groups. Thirdly, the cost of infant care is sufficiently high to demand that group members get along when groups are small and reproductive benefits are shared.     

Breeding system of Anemone shikokiana and the influential factors of fruit-setting ratio in different habitats

Anemone shikokiana (Makino) Makino is a rare perennial herb distributed only in China and Japan in restricted patches of two different habitats: the shrubs of mountaintop and the conifer and broadleaf mixed forest. Our data showed that the fruit-setting ratio is much lower in the latter than in the former. Given that the reproductive strategy is very crucial for fruit-setting, to reveal the main reasons that influence the fruit-setting ratio, breeding system must be known. Therefore, firstly, P/O and OCI were analyzed and results showed that breeding system of A. shikokiana was self-compatible and mainly outcrossed. Secondly, controlled pollination tests were carried out showing that neither apomixes nor wind pollination occurred. Further results on the type of the breeding system confirmed that A. shikokiana was self-compatible and mainly outcrossed by insects. Lastly, diameters of flowers and frequency of pollinators in two habitats were compared. Results showed that flowers were bigger and frequency of pollinators were higher in shrubs of mountaintop than those in conifer and broadleaf mixed forest, while numbers of pollens and ovaries had little difference. Thus, the overall analysis of the results indicates that the paucity of insect pollinators is the most important reason for the fruit-setting ratio of A. shikokiana lower in the conifer and broadleaf mixed forest than in the shrubs of mountaintop; however, such an implication needs to be further verified with additional work.     

Male-male competition and repeated evolution of terrestrial breeding in Atlantic Coastal Forest frogs*

Terrestrial breeding is a derived condition in frogs, with multiple transitions from an aquatic ancestor. Shifts in reproductive mode often involve changes in habitat use, and these are typically associated with diversification in body plans, with repeated transitions imposing similar selective pressures. We examine the diversification of reproductive modes, male and female body sizes, and sexual size dimorphism (SSD) in the Neotropical frog genera Cycloramphus and Zachaenus, both endemic to the Atlantic rainforest of Brazil. Species in this clade either breed in rocky streams (saxicolous) or in terrestrial environments, allowing us to investigate reproductive habitat shifts. We constructed a multilocus molecular phylogeny and inferred evolutionary histories of reproductive habitats, body sizes, and SSD. The common ancestor was small, saxicolous, and had low SSD. Terrestrial breeding evolved independently three times and we found a significant association between reproductive habitat and SSD, with shifts to terrestrial breeding evolving in correlation with decreases in male body size, but not female body size. Terrestrial breeding increases the availability of breeding sites and results in concealment of amplexus, egg-laying, and parental care, therefore reducing male-male competition at all stages of reproduction. We conclude that correlated evolution of terrestrial reproduction and small males is due to release from intense male-male competition that is typical of exposed saxicolous breeding.     

Breeding phenology,variation in reproductive effort and offspring size in a tropical population of the woodlouse Porcellionides pruinosus

Summary Most species of woodlice in temperate habitats have discrete breeding seasons. It is hypothesised that breeding synchronises with favourable environmental conditions to maximise offspring growth and survivorship (Willows 1984). We measured the breeding phenology of a species introduced to a tropical environment, primarily to consider the assumption that life histories in the tropics will differ fundamentally from those in temperate habitats. In addition to breeding phenology we considered variation in reproductive effort between individual females and the division of this effort between the size and number of young.A continuous breeding phenology was observed in a synanthropic population of Porcellionides pruinosus within the tropics. Reproductive effort varied between months, showed a weak relationship with female size and was independent of female fecundity. Female sizefecundity relationships varied between samples and when the proportion of reproductive females was high size-fecundity slopes were steeper than at other times. Mean offspring size varied between months and there was a wide range in offspring size within broods. Offspring size was not related to female body mass, reproductive effort or fecundity; consequently brood mass increased linearly with an increase in fecundity. Increased reproductive effort goes into more rather than larger offspring.We propose that the continuous breeding in this population was the result of the constant presence of an environmental cue to reproduction evolved in temperate habitats. Continuous breeding is not necessarily equivocal to high individual reproductive success even though overall population growth may be rapid. However, variation in reproductive effort suggests that individuals respond to current environmental conditions on short time scales.     

Reproductive system,social organization,human disturbance and ecological dominance in native populations of the little fire ant,Wasmannia auropunctata

The invasive ant species Wasmannia auropunctata displays both ecologically dominant and non‐dominant populations within its native range. Three factors could theoretically explain the ecological dominance of some native populations of W. auropunctata: (i) its clonal reproductive system, through demographic and/or adaptive advantages; (ii) its unicolonial social organization, through lower intraspecific and efficient interspecific competition; (iii) the human disturbance of its native range, through the modification of biotic and abiotic environmental conditions. We used microsatellite markers and behavioural tests to uncover the reproductive modes and social organization of dominant and non‐dominant native populations in natural and human‐modified habitats. Microsatellite and mtDNA data indicated that dominant and non‐dominant native populations (supercolonies as determined by aggression tests) of W. auropunctata did not belong to different evolutionary units. We found that the reproductive system and the social organization are neither necessary nor sufficient to explain W. auropunctata ecological dominance. Dominance rather seems to be set off by unknown ecological factors altered by human activities, as all dominant populations were recorded in human‐modified habitats. The clonal reproductive system found in some populations of W. auropunctata may however indirectly contribute to its ecological dominance by allowing the species to expand its environmental niche, through the fixation over time of specific combinations of divergent male and female genotypes. Unicoloniality may rather promote the range expansion of already dominant populations than actually trigger ecological dominance. The W. auropunctata model illustrates the strong impact of human disturbance on species’ ecological features and the adaptive potential of clonal reproductive systems.     

One for all and breeding for one: Cooperation and competition as a tamarin reproductive strategy

In this paper I examine behavioral strategies used by male and female tamarins to increase individual reproductive opportunities while continuing to maintain a high level of group cohesion and social cooperation. Tamarins of the genus Saguinus are characterized by social groups generally composed of more than one adult of each sex, but a breeding system in which only a single female in each group gives birth. The breeding sovereignty of a single dominant female limits the reproductive opportunities of subordinate females as well as the reproductive opportunities of resident adult males.^1-3 Despite extreme variability in year-to-year reproductive success among members of the same social group, field studies indicate that within-group intrasexual aggression and fighting are rare, and that both breeding and nonbreeding individuals expend time and energy cooperatively caring for young, defending productive feeding sites, and assisting in food harvesting activities.^4-11 In fact, Caine¹² has argued that “co-operation, tolerance, and flexibility” are the primary themes of tamarin social interactions (p. 218). A major question that remains unanswered, however, is how such high levels of cooperation could have evolved in a social system characterized by emigration of both adult males and females from the natal group, polyandrous mating, and intense reproductive competition.     

Vertically stratified frugivore community composition and interaction frequency in a liana fruiting across forest strata

Vertical stratification is a key feature of tropical forests and structures plant–frugivore interactions. However, it is unclear whether vertical differences in plant-frugivore interactions are due to differences among strata in plant community composition or inherent preferences of frugivores for specific strata. To test this, we observed fruit removal of a diverse frugivore community on the liana Marcgravia longifolia in a Peruvian rain forest. Unlike most other plants, Marcgravia longifolia produces fruits across forest strata. This enabled us to study effects of vertical stratification on fruit removal without confounding effects of plant species and stratum. We found a high number of visits of a few frugivore species in the understorey and a low number of visits of many different frugivores in the canopy and midstorey. Whereas partial and opportunistic frugivores foraged across strata with differing frequencies, obligate frugivores were only found eating fruits in the higher strata. Avian frugivores foraging in the canopy were mainly large species with pointed wings, whereas under- and midstorey avian foragers were smaller with rounded wings. Our findings suggest a continuous shift in the frugivore community composition along the vertical gradient, from a few generalized frugivores in the understorey to a diverse set of specialized frugivores in the canopy. This shift in the frugivore community leads to correlated, reciprocal changes from specialized to generalized plant-frugivore interactions. Thus, we conclude that vertical niche differentiation between species in tropical forests persists even when food resources are available across strata. This highlights its role for promoting biodiversity and ecosystem functioning.     

Reliability of macaques as seed dispersers

Seed dispersal is an ecological process crucial for forest regeneration and recruitment. To date, most studies on frugivore seed dispersal have used the seed dispersal effectiveness framework and have documented seed-handling mechanisms, dispersal distances and the effect of seed handling on germination. In contrast, there has been no exploration of “disperser reliability” which is essential to determine if a frugivore is an effective disperser only in particular regions/years/seasons or across a range of spatio-temporal scales. In this paper, we propose a practical framework to assess the spatial reliability of frugivores as seed dispersers. We suggest that a frugivore genus would be a reliable disperser of certain plant families/genera if: (a) fruits of these plant families/genera are represented in the diets of most of the species of that frugivore, (b) these are consumed by the frugivore genus across different kinds of habitats, and (c) these fruits feature among the yearly staples and preferred fruits in the diets of the frugivore genus. Using this framework, we reviewed frugivory by the genus Macaca across Asia to assess its spatial reliability as seed dispersers. We found that the macaques dispersed the seeds of 11 plant families and five plant genera including at least 82 species across habitats. Differences in fruit consumption/preference between different groups of macaques were driven by variation in plant community composition across habitats. We posit that it is essential to maintain viable populations of macaques across their range and keep human interventions at a minimum to ensure that they continue to reliably disperse the seeds of a broad range of plant species in the Anthropocene. We further suggest that this framework be used for assessing the spatial reliability of other taxonomic groups as seed dispersers.     

Habitat Use and Ranging Behavior of <Emphasis Type="Italic">Callimico goeldii</Emphasis>

We studied the diet, habitat use, and ranging behavior of 1 group of Callimico goeldii (callimicos) over 12 mo in northwestern Bolivia. The group’s diet was comprised of fungi (39%), fruits (31%), arthropods (14%), exudates (14%), and other matter (2%). Callimicos concentrated their ranging activities in secondary forest (50%), primary forest with dense understory (30%), and bamboo (17%) habitats. The group’s total home range was 114 ha; on average they used 38.4 ha/ mo and had a day range of 925 m. Monthly average day ranges—but not monthly home ranges—increased as frugivory declined, suggesting that subjects foraged on fungi and exudates by rechecking resources within a core area, making their day ranges longer than during months when they concentrated on fruit resources. The callimicos formed polyspecific associations with tamarins (Saguinus labiatus and S. fuscicollis) during 81% of observations. Day ranges increased in months with higher association rates which appears to result from the callimicos using a broader set of habitats when with tamarins than when alone. The ranging pattern of callimicos appears to be influenced primarily by 3 factors: their seasonal shift in diet requires that they forage in a variety of habitats across the year; their depletion of resources causes them to shift their core area over time; and their lack of territorial behavior eliminates the need to patrol boundaries as part of their daily movement. As a result, callimicos differ from many other callitrichids in their low ratio of day range length to home range size.     

Foraging niche shift maintains breeding parameters of a colonial waterbird during range expansion

Relating the effects of foraging niche variation to reproductive dynamics is critical to understand species response to environmental change. We examined foraging niche variations of the slender‐billed gull (Chroicocephalus genei), a nomadic colonial waterbird species during its range expansion along the French Mediterranean coast over a 16‐year period (1998–2013). We investigated whether range expansion was associated with a change in chick diet, breeding success, and chicks body condition. We also examined whether breeding success and chicks body condition were explained by diet and colonial characteristics (number of pairs, laying phenology, habitat, and locality). Diet was characterized using dual‐stable isotopic proxies (δ¹³C and δ¹⁵N) of feather keratin from 331 individuals subsampled from a total of 4,154 chicks ringed and measured at 18 different colonies. δ¹³C decreased and δ¹⁵N increased significantly during range expansion suggesting that chicks were fed from preys of increasing trophic level found in the less salty habitat colonized by the end of the study period. Niche shift occurred without significant change of niche width which did not vary among periods, habitats, or localities either. Breeding success and chick body condition showed no consistent trends over years. Breeding success tended to increase with decreasing δ¹³C at the colony level while there was no relationship between stable isotope signatures and chick body condition. Overall, our results suggest that even if range expansion is associated with foraging niche shift toward the colonization of less salty and more brackish habitats, the shift had marginal effect on the breeding parameters of the Slender‐billed gull. Niche width appears as an asset of this species, which likely explains its ability to rapidly colonize new locations.     

High Conservation Value of Forest Fragments for Plant and Frugivore Communities in a Fragmented Forest Landscape in South Africa

Fragmentation is a major threat factor for plant–frugivore communities in tropical and subtropical forests. Resulting changes in the distribution of traits within these communities, e.g., a loss in large‐bodied frugivores, may lead to strong changes in plant–frugivore interactions in fragmented forests. Yet, we still lack a thorough understanding of the interplay between forest fragmentation, the trait‐composition of communities and resulting plant–frugivore interactions on a community‐scale. In a fragmented South African landscape comprising different forest categories—i.e., continuous natural forest, forest fragments surrounded by natural grassland, and forest fragments surrounded by sugarcane—we investigated the relationship between communities of fruiting plants and their frugivore visitors in response to forest fragmentation, as well as the interactive effects of forest fragmentation and fruit size of the plants on the number of frugivore visitors and their body size. Neither the fruit size of plant nor the body mass of frugivore communities differed between natural forest sites and forest fragments. Moreover, in‐depth analyses of frugivore assemblages visiting plant species revealed no effect of forest category on the number of frugivore visits or their mean body mass. The number of visits and body mass of frugivores were merely determined by the crop and fruit size of the focal plant species. Overall, our results suggest that frugivory of plant species with differently sized fruits was not reduced in forest fragments. Thus, fragments with high fruit availability may be key elements maintaining the functional connectivity of a heterogeneous forest landscape.