Oecologia

Birds infected with the malaria-causing parasite Plasmodium comprise a popular model in evolutionary ecology, yet Plasmodiums impact on host survival and reproduction remains unclear in wild bird populations where Plasmodium is historically endemic. Recent research in endemic host populations shows that Plasmodium reduces survival in juveniles, but not adults. Additional research is needed to understand 1) age-based variation in the impact of Plasmodium on host reproduction, and 2) sex-based variation in the impact of Plasmodium on survival and reproduction. To this end, we leveraged a long-term dataset from a dark-eyed junco (Junco hyemalis carolinensis) population with a high prevalence of Plasmodium. Juvenile males had lower probability of Plasmodium infection than juvenile females, indicating either elevated resistance or mortality in young males before the juvenile stage. Second year females had a lower probability of infection than females of other age classes, which suggests elevated mortality in infected yearling females after their first breeding season. Model comparison did not identify a direct relationship between Plasmodium infection and adult return (a proxy of survival), yet surprisingly, females paired with infected males in the previous breeding season had a higher probability of return. There was no relationship between Plasmodium infection and juvenile return, but returners with relatively higher parasite loads as juveniles had shorter lifespans than those without juvenile infections. Among adults, Plasmodium infection did not predict fledging success or fledgling number. However, returning juncos with relatively heavier bodies and higher parasite loads as juveniles had an increased probability of breeding in their first adult year. Combined with the shorter lifespans observed in infected juveniles, this suggests a terminal investment strategy for juncos contracting Plasmodium early in life. Our results indicate that the impact of Plasmodium on host fitness likely varies by host age at first infection and may exacerbate physiologically stressful life stages.

While interspecific variation in seed dispersal, a critical ecosystem process in tropical forests, is relatively well-studied, intraspecific variation as a consequence of differences in body size, foraging behaviours, and ranging patterns among age-sex categories within a species is relatively understudied. Among vertebrates, primates play a critical role in seed dispersal and exhibit behavioural differences between age and sex categories, making them a suitable study system for intraspecific variation in seed dispersal. Lion-tailed macaques Macaca silenus, an endemic and predominantly frugivorous primate species in the Western Ghats Biodiversity Hotspot, provide an excellent model for such studies. We examined the influence of age and sex on 1) the diversity and 2) the quantity of native and non-native fruits consumed, 3) the number of seeds dispersed, 4) seed dispersal distance, and 5) seed deposition substrates in lion-tailed macaques. We conducted over 375 hours of focal animal watches, distributed evenly across adult males, females, and subadults. Our findings showed that subadults consumed a higher diversity of native and non-native fruits than females and males. They dispersed fewer Ficus seeds than females. We found differences in the proportions of non-native fruits in the diets of different age- sex categories. Males consumed more Coffea liberica, whereas females and subadults fed on Coffea and Lantana. We found weak evidence suggesting that males were more likely to disperse Ficus seeds on trees, which are suitable substrates for Ficus establishment. Our study highlights that age and sex significantly influence seed dispersal patterns of native and non- native species by an endemic, frugivorous primate species with potential influence on recruitment.

Hosts can differ in parasite susceptibility across individuals, populations, and species. Genetic variation can influence parasite susceptibility by affecting host resistance to parasitism. For example, genetic variation among related individuals, such as within broods of offspring, might be a key factor influencing within-brood resistance to ectoparasitism. The goal of this study was to determine if within-brood variation of eastern bluebirds (Sialia sialis) affects susceptibility to ectoparasitic blowflies (Protocalliphora sialia). To address the goal, we conducted a partial cross-fostering study for which half of the nestlings were cross-fostered (experimental) or not (control). Nestling physiology (i.e., glucose, hemoglobin, and parasite-specific IgY antibody levels), morphometrics (i.e., mass, tarsus length, bill length, and first primary feather), survival, nestling status (resident versus fostered), and sex were characterized. We also quantified parasite abundance, life stage, and pupal size. We found that experimental nests had fewer parasites and more larvae than pupae compared to control nests, which suggest that within-brood genetic variation affects parasite abundance. However, this effect was driven by the sex ratio with the experimental nests, with female-biased nests having fewer parasites than male-biased nests. Treatment did not affect nestling morphometrics, physiology, or survival at the nest level. Within experimental nests, resident females had significantly higher hemoglobin levels when compared to fostered females. Resident and fostered males and fostered females had significantly higher glucose levels than resident females. Together, these results suggest that resident females were fed upon less than fostered females and may have been less stressed than males and fostered females. Overall, our study demonstrates the importance of considering within-brood variation and nestling sex in understanding host-parasite interactions.

Interspecific territoriality is a prevalent form of interference competition among animals. However, the connections between hybridization, climate, and interspecies territorial aggression in tropical regions remain largely unexplored. Here, we investigated territorial aggression in two hybridizing tropical bird species, C. z. brevirostris and C. f. pallescens, in western Ecuador using playback experiments. We tested three hypotheses: 1) hybridizing species exhibit comparable intra- and inter-specific territorial aggression; 2) asymmetrical aggression driven by C. z. brevirostris dominance determines gene flow patterns; and 3) precipitation influences territorial aggression. Supporting hypothesis 1, the admixed C. f. pallescens North showed no difference in intra-vs inter-specific aggression. However, the non-admixed C. f. pallescens South exhibited greater inter-specific aggression, providing partial support for hypothesis 1. Contrary to hypothesis 2, C. f. pallescens South displayed significantly higher aggression than C. z. brevirostris and C. f. pallescens North. Furthermore, precipitation models outperformed null models, supporting hypothesis 3 that precipitation influences Campylorhynchus territorial aggression. Collectively, these findings suggest hybridization can stabilize coexistence via territoriality, and precipitation strongly affects aggression, potentially through resource availability. Unexpectedly, C. z. brevirostris dominance did not appear to drive asymmetric introgression between species, warranting further investigation into the underlying mechanisms. Complex factors shape territorial aggression in tropical birds, including genetic admixture, group size, latitude, and climate. This study highlights the need for additional research elucidating the relationships between hybridization, territoriality, and environmental stressors in tropical avian communities. We discuss possible mechanisms explaining the detected effects of precipitation on aggression and the lack of C. z. brevirostris dominance in determining introgression patterns.

Prospecting is an understudied yet pivotal information-gathering process often preceding natal dispersal. While prospecting may enable individuals to optimise dispersal outcomes and obtain high quality territories, it is also likely to incur costs stemming from energy expenditure and predation risks. This trade-off may drive individual differences in prospecting effort. We tested for evidence of costs of prospecting behaviour in a wild population of Florida scrub-jays, Aphelocoma coerulescens, which prospect as nonbreeding helpers. Using random sampling across all helpers, we compared prospecting effort--approximated by frequency, distance, and activity level--with body mass changes and oxidative stress levels. We tested if prospecting incurred costs and if early-life body condition predicted subsequent prospecting effort. Prospecting frequency was positively linked to oxidative damage but not to any loss in body mass during the breeding season, suggesting that extra-territorial movement costs manifest unevenly. Early-stage body condition did not affect subsequent prospecting effort across a large set of helpers, but early-stage body condition and morphometric measures did correlate with subsequent oxidative status of those sampled. Our results suggest that prospecting movement carries some physiological costs, perhaps contributing to individual differences in prospecting. This research highlights how body condition plays a role in trade-offs between information gathering movement and physiological costs of movement itself, ultimately providing insight on the evolution of prospecting in social species. HIGHLIGHTSO_LIProspecting prior to breeding enables informed dispersal but incurs cost C_LIO_LIWe tested whether prospecting by nonbreeding Florida scrub-jays results in physiological costs or varies with initial condition C_LIO_LIWe measured oxidative status using assays testing antioxidant capacity and oxidative damage C_LIO_LIFrequent prospecting was linked to subsequent oxidative damage C_LIO_LIEarly-stage body condition and wing length affected subsequent oxidative status C_LI

Cooperatively breeding species frequently live in family groups of related individuals, with helpers delaying their own reproduction and participating in alloparental care, predator vigilance, and territory defense. It remains challenging to disentangle the roles of the indirect fitness benefits of helping kin and the potential direct fitness benefits helpers receive in the evolution of cooperative breeding. While many studies test for associations between helper relatedness and helping effort, few estimate the realized fitness consequences of helping in relation to these factors. Understanding these fitness outcomes elucidates the selective forces that maintain helping behavior, whether through inclusive fitness gains by helping related individuals or as a means of gaining access to later direct fitness benefits. Using 29 years of extensive demographic data from a closely monitored population of Florida scrub-jays (Aphelocoma coerulescens), we quantified the effect of helpers on breeder survival, offspring survival, and nestling production and how these effects depend on relatedness and sex of helpers. We found that female breeder survival was significantly greater when more helpers were present and that offspring survival was greater when more male helpers were present on small territories. Neither effect of helpers depended on the relatedness between helpers and the individuals they helped. Our results suggest that helping behavior is highly context-dependent and varies based on the potential impact of helping and the direct fitness benefits helpers receive.

Abiotic and biotic factors are known to be key in limiting the geographical distribution of species. However, our understanding on the influence of habitat heterogeneity on ecological interactions and behavior in tropical animals is limited. We studied groups of Acorn Woodpeckers (Melanerpes formicivorus flavigula) in urban and rural areas in northern South America to understand how habitat and resource requirements (food storage structures) influences patterns of distribution across the Aburra Valley, in the northern area of the Central Andes of Colombia. Using focal observations of 10 different groups over nearly a two-year period, we estimated territory size, habitat use, and described the use and presence of granaries. We found that territory size, tree diversity, and the use of granaries varied among groups. Accordingly, Acorn Woodpeckers use a wide variety of tree species to make cavities, to feed and to build granaries for social interactions. Our study supports the hypothesis that Acorn Woodpeckers do not rely on the Colombian Oak (Quercus humboldtii Bonpl.) for feeding, nesting or foraging in the Aburra Valley, and that the construction of granaries to store food is present in urban populations, despite the lack of strong seasonal changes in tropical areas. We suggest that the distribution of the Acorn Woodpecker in our study area is strongly associated with one particular species of tree, Albizia carbonaria Britton, and the behavior of granaries construction might be hardwired in this species for the maintenance and cohesion of family groups.

Reduced competition or facilitation between kin relative to nonkin can improve plant performance, particularly under resource-limited conditions. Understanding whether kin interactions differ between invasive and native species may provide insights into the mechanisms underlying the persistence and spread of invasive species, particularly for species that spread clonally. To explore this, we conducted a greenhouse experiment using the invasive Alternanthera philoxeroides and its native congener A. sessilis in China. For both species, we grew central plants without or with neighbors, and for the latter we had three intraspecific neighbor kinship treatments (kin only, nonkin only, and both kin and nonkin [mixed] neighbors). To test whether kinship effects are affected by resource limitation, we grew the plants under two watering conditions (well-watered and drought-stressed). Our findings revealed that at both the group (i.e., pot-level) and individual levels, invasive plants had a higher biomass production and experienced a less negative relative neighbor effect in kin groups than in nonkin groups, while these patterns were reversed in the native species. Although aboveground architecture of central plants did not differ significantly between kin and nonkin neighbors in either species, neighbor plants of the invasive species produced fewer nodes in kin groups than in nonkin groups, while the reverse was true for the native species. These patterns were not affected by the watering treatment. Together, these results indicate that while the native plants has stronger kin competition, the invasive species has reduced kin competition. Such reduced competition among kin in the invasive Alternanthera philoxeroides may enhance its population dominance and facilitate its spread.

Breeding pairs of American Crows (Corvus brachyrhynchos) in Stillwater, OK, lived with 0-10 auxil-iaries in territories distributed throughout public, campus, commercial, and residential areas. Unpaired crows moved easily among groups throughout the year, but commonly did so during the two months or so preceding the onset of nesting across the population, and the week or so preceding hatching within groups. In 2001 and 2002, pre-hatch group size ranged from 2-10 (mean = 4.5 in both years), and auxiliaries included a male sibling, social and genetic offspring, step-offspring, half-siblings, and unrelated immigrants of both sexes, ranging in age from 1 to at least five years old. Twenty nine percent of pre-hatch auxiliaries dispersed out of groups at hatch-ing (for half, only temporarily), including all females unrelated to female breeders. Post-hatch group size ranged from 2-6, with means of 3.7 in both years, and the post-hatch auxiliary popula-tion differed in composition from the pre-hatch population: whereas post-hatch male auxiliaries included a sibling, half siblings, and unrelated immigrants in addition to social and genetic sons, all post-hatch female auxiliaries were the social and genetic daughters of female breeders, and all but one (the same individual in both years) were also the social and genetic daughters of male breeders. Crows in Stillwater delayed breeding for one or more years beyond sexual maturity, despite the availability of space and members of the opposite sex. Individual dispersal decisions by unpaired crows, and the behavior of paired territory owners, did not follow patterns described for other cooperative breeders. We found little support for extant theories regarding the formation, com-position, and maintenance of avian groups, and discuss aspects of the lives of crows that may have contributed to the complex and benign nature of this populations society. How to Cite: Caffrey, C. and C. C. Peterson. 2015. Group composition and dynamics in American Crows: insights into an unusual cooperative breeder. Friesen Press.

How closely related species co-exist, especially under conditions of resource limitation remains an intriguing problem in ecology. Having to share space and resources, such species are expected to have evolved a variety of behavioural mechanisms to reduce competition. Understanding such adaptation could also provide clues to designing effective conservation strategies for these species. In this chapter, I examine the niche partitioning and co-existence of three congeneric species, the rhesus macaque Macaca mulatta, northern pig-tailed macaque Macaca leonina and stump-tailed macaque Macaca arctoides, in a fragment of less than 20 km2, the Hollongapar Gibbon Sanctuary, which still harbours a significant proportion of original species pool. An intensive observational study was conducted on two troops each of the three species over a period of 23 months from March 2008 to January 2010. We examined niche partitioning among the macaques along two major axes--space and food. Our results found significant interspecific differences among macaques in their utilisation of both horizontal and vertical space, as well as in their utilisation of food resources. The differential utilisation of space and food has enabled the continued co-existence of the three macaque species in this fragment. At the fragment level and over proximate time scales, our results explain why primates, particularly the three species of macaques, are able to thrive even after being isolated for over one hundred years. Ecological and behavioural insights gleaned from this fragment will help us understand and promote the co-existence of primates in other habitat fragments of the Upper Brahmaputra Valley.

Animals spend a significant amount of time roosting. Therefore, understanding roosting patterns and the processes that influence roosting behaviour and roost site choice is essential. Hornbills exhibit interesting roosting patterns with some species roosting communally in large flocks. They are important seed dispersers and patterns of roost site use can have a significant influence on seed dispersal distributions and thereby on plant recruitment. We documented roost site use by four Great Hornbills (Buceros bicornis) and one Wreathed Hornbill (Rhyticeros undulatus) at a site in north-east India using GPS telemetry. We examined the influence of riverine habitats, nests and foraging range on roost selection. We determined the proportion of seeds that hornbills disperse at roosts and the dispersal distances of seeds dispersed at roosts from the source trees. Through telemetry, we found that roosts of Great Hornbills were generally in forested habitats. Our telemetry data showed that Wreathed Hornbill roosts were close to the river. These results were corroborated by observational data from roost sites where we had regular detections of relatively large flocks of Wreathed Hornbills and occasionally Great Hornbills. The roost sites were not close to the nest sites and were generally within the 95% kernel density diurnal activity ranges. Hornbills dispersed a small proportion of seeds at roost sites. Seeds dispersed at roost sites had almost twice the dispersal distances compared to those dispersed at non-roost sites. This study highlights variation in roost site pattern across individual hornbills and its implications for seed dispersal.

Plant fitness is shaped by interactions with insect mutualists and antagonists. Vegetative (leaf) herbivory often results in increased allocation of resources to defense in order to deter further damage. This allocation to defense can reduce floral or reproductive allocation. Reductions in floral allocation can have negative effects on pollinator attraction and therefore decrease plant fitness. However, defense-induced changes in reproductive tissues may also be protective against antagonistic fruit-feeding insects (frugivores). This may have important implications for plant fitness when plants experience multiple types of insect damage, but the potential protective effect of herbivory against frugivory is not well-understood. In this study, we tested the prediction that herbivory mediates interactions between plants and their antagonistic frugivores. In the greenhouse, we manipulated vegetative induction in Physalis pubescens (Solanaceae) and measured the effects on plant fitness via changes in floral and fruit allocation, herbivore resistance in the next generation, and deterrence of an antagonistic frugivore (Chloridea virescens (Lepidoptera)). Vegetative induction in P. pubescens enhanced plant resistance to Chloridea virescens frugivores with minimal negative effects on plant reproductive traits. Vegetative induction reduced C. virescens larval growth rate on fruits. Chloridea virescens also avoided induced plants for larval fruit feeding and oviposition. While leaf induction reduced flower size, induction did not negatively affect fruit size, seed set, or seed germination. Furthermore, offspring of induced plants showed increased resistance to Manduca sexta leaf herbivory. These findings indicate that herbivore-induced resistance may benefit plant fitness when plants are under simultaneous pressure from herbivores and frugivores.

In a large and ever-growing number of animal species, it is now appreciated that females use colors as a visual signal in a range of social interactions, including both courtship and territorial aggression. Yet, it remains unclear whether female color phenotypes and/or aggressive behaviors are correlated with any attributes of their mates phenotype. For example, we might expect species in which males contribute more to parental care or territorial defense to have more colorful or aggressive females. On the other hand, within species, we might expect those females mated to higher quality males to be more colorful or aggressive than those mated to lower quality males. To begin to address these possibilities, we conducted a preliminary study in two sister taxa of fairywren (Maluridae) with distinct life-history strategies and plumage dichromatism: white-shouldered fairywrens (Malurus alboscapulatus moretoni) in tropical Papua New Guinea, a species in which both males and females have ornamented plumage and jointly defend territories year-round, and red-backed fairywrens (M. melanocephalus melanocephalus) in temperate Australia, a sexually dichromatic species with ornamented males and unornamented females. At the between species level, we predicted white-shouldered fairywren females would be more aggressive in same-sex interactions than red-backed fairywrens, as both white-shouldered males contribute to year-round territorial defense, whereas territories break-down during non-breeding in red-backed fairywrens. Further, we predicted that, within species, females mated to males of higher quality would be more aggressive in simulated same-sex encounters. Between species, female white-shouldered fairywrens were more aggressive on average than female red-backed fairywrens as predicted. Within both species, indices of male quality were not related to female aggression (although there was a non-significant tendency for more aggressive female white-shouldered fairywren to have heavier mates with longer tails). These results point to a need for additional research exploring relationships between life history, female plumage, and female aggressive behaviors in a wider range of species.

O_LISocioecological theory attributes variation in social organization of female-bonded species to differences in within- and between-group competition, shaped by food distribution. Strong between-group contests are expected over large, monopolisable resources, and are not generally expected in species that feed on low quality resources distributed across large, undefended home ranges. Within groups, frequent contests are expected over discrete feeding sites but not over low-quality, dispersed resources. C_LIO_LIWe report on the first tests of socioecological theory, largely unexplored in non-primate species, in female Asian elephants. Asian elephants show graminivory, overlapping home ranges, and high fission-fusion dynamics, traits that are thought to be associated with infrequent contests. C_LIO_LIWe studied agonistic interactions within and between female elephant clans with respect to food distribution, food abundance, and competitor density effects of group size and clan density, in a grassland habitat around the Kabini backwaters, southern India. C_LIO_LIWe found that the Kabini grassland had three times the grass biomass as adjacent forests, and between-clan encounters were considerably higher than that known from a neighbouring forest. Individual-level agonism was also more frequent between clans than within clans. Thus, the food-rich habitat patch probably enabled strong between-clan contest competition under graminivory. Moreover, the rate of between-clan encounters increased when more clans were present, and the duration of encounters was positively related to grass biomass at the contested sites. Despite fission-fusion dynamics, within-clan agonism was also somewhat frequent, but not influenced by food distribution, in contradiction to classic socioecological predictions, possibly because of intensified competition due to high density. Interestingly, within-clan agonism increased with female group size until intermediate group sizes, suggesting that the tension between within-group and between-group competition might govern group size, since larger groups are advantageous in this strong between-clan contest regime. C_LIO_LIOur findings refine the current understanding of female elephant socioecology. Despite predominant graminivory and fission-fusion dynamics, within-group agonism can be frequent, especially when large groups face ecological constraints at high density. Further, frequent between-group contests may arise despite graminivory and non-territoriality when food becomes patchy and density is high. These changes may be effected by anthropogenic alteration of habitats. C_LI

The relative abundance patterns of tropical trees have been of interest since the expeditions of Alfred Russel Wallace, but little is known about how differences in relative abundance relate to reproductive patterns. Flowering is resource-dependent and fitness differences as well as differences in the quality of the abiotic and biotic neighborhood may contribute to the variation in reproductive status responsible for population-level flowering patterns. This variation determines the density and distance between flowering conspecifics and may alter relative abundance extremes among species during reproduction, factors known to influence pollination success. We collected flowering status data for a guild of twenty-three co-occurring tree species that flower in the understory of the Korup Forest Dynamics Plot in Cameroon. We examined how the occurrence and location of reproductive events were related to spatial patterns of adult abundance, focal tree size, neighborhood crowding, and habitat, while accounting for the influence of shared ancestry. Across species, the probability of flowering was higher for individuals of rarer species and for larger individuals but was unrelated to neighborhood crowding or habitat differences. Relative abundance extremes were reduced when only flowering individuals were considered, leading to a negative relationship between plot abundance and flowering probability at the species level that was not structured by shared ancestry. Spatially, flowering conspecifics tended to be overdispersed relative to all adult conspecifics. Rare species are predicted to suffer Allee effects or reduced fitness due to the difficulty of finding mates at low densities and frequencies. Here, however, rare species appear to maximize the size of their mate pool, compared to abundant species. If this partial leveling of the playing field during reproduction is typical, it has consequences for our understanding of biodiversity maintenance and species coexistence in tropical forests.

O_LISpecies with diverse parental care patterns often exhibit flexibility in response to environmental changes. Such changes can influence parental care decisions by altering the trade-offs between current and future reproduction. While previous studies have revealed correlations between specific social and ecological factors and parental care patterns, the joint effects of multiple factors could be rather complex and may result in different outcomes within and across populations, and between sexes. C_LIO_LIIn this study, we revealed parental care systems and their seasonal variations across three geographic populations in a polygamous species, the Chinese penduline tits (Remiz consobrinus), by monitoring breeding events over years. To investigate how local conditions (including social and ecological conditions) correlate with sex-specific parental care patterns, we compared breeding phenology and local conditions (including season length, mating opportunity and reproductive success) across the populations. C_LIO_LIStriking population differences in parental care strategies are found in this species: biparental care predominated in one population, whereas female-only care was more common in the other two. Our analyses reveal that, despite a large difference in season length, the time of egg-laying peaked similarly across the three populations. Female penduline tits determined the breeding phenology, which varies male mating opportunities dramatically over the season. For all populations, male Chinese penduline tits were more likely to desert the clutch when male mating opportunities were high. In contrast, females consistently provided care, regardless of variation in female mating opportunities. C_LIO_LIWe also found that fitness costs on the current brood resulting from offspring desertion differed across populations. This desertion cost on brood fitness matters more than achieving a high reproductive reward in driving the emergence of uniparental care, contrary to the theory that uniparental care only occurs when single parents can efficiently raise nestlings alone. C_LIO_LIOur study demonstrates that similar parental care patterns across populations could result from different underlying factor interactions and highlights the consistent sex-specific responses to local conditions in parental care. C_LI

The effects of conspecific densities on dispersal have been well documented. However, while positive and negative density-dependent dispersal based on conspecific densities are often shown to be the result of intraspecific competition or facilitation respectively, the effects of heterospecific densities on dispersal are examined far less frequently. This despite the potential for the analogous processes of interspecific competition and heterospecific attraction to influence dispersal. Here we use 51 years of live-trapping data on deer mouse (Peromsycus maniculatus), eastern chipmunk (Tamias striatus), red-backed vole (Myodes gapperi), and jumping mice (Napaeozapus insignis and Zapus hudsonius) to examine the effects of both conspecific and heterospecific densities on dispersal frequency. In terms of conspecific densities, jumping mice were more likely to disperse from areas of low conspecific densities, while red-backed voles and chipmunks did not respond to conspecific densities in their dispersal frequencies. When considering interspecific density effects, while there were no statistically clear effects of density on dispersal frequency, the effects of chipmunk and jumping mice densities on dispersal by red-backed vole were greater than the effects of conspecific densities, with voles more likely to disperse from areas of high chipmunk densities and low jumping mice densities. Likewise, the effect of chipmunk densities on dispersal by jumping mice was greater than the conspecific density effect. Conspecific densities clearly can affect dispersal by two of these four species, but the effects of heterospecific densities on dispersal frequency are less clear. Based on effect sizes it appears that there is potential for heterospecific effects on dispersal by some species in the community, but future experimental work could elucidate the strength and causes of these relationships.

O_LIAge- and sex-specific survival estimates are crucial to understanding important life-history characteristics and variation in these estimates can be a key driver of population dynamics. When estimating survival using Cormack-Jolly-Seber (CJS) models and capture-recapture data, emigration is typically assumed to have a negligible effect on estimates such that apparent survival is indistinguishable from true survival. Consequently, especially for populations or age classes with high dispersal rates, apparent survival estimates are often biased low and temporal patterns in survival might be masked when site fidelity varies temporally. C_LIO_LIWe used 9 years of annual mark-recapture data to estimate age-, sex-, and time-specific apparent survival of Humboldts flying squirrels (Glaucomys oregonensis) and Townsends chipmunks (Neotamias townsendii). For Humboldts flying squirrels, these estimates support a small body of research investigating potential variation of survival among age and sex classes, but age- and sex-specific survival has not been evaluated for Townsends chipmunks. We also quantified the effects of age- and sex-specific emigration on confounded estimates of apparent survival. C_LIO_LIOur estimates of juvenile flying squirrel survival were high relative to other small mammal species and estimates for both species were variable among years. We found survival differed moderately among age and sex classes for Humboldts flying squirrels, but little among age and sex classes for Townsends chipmunks, and that the degree to which emigration confounded apparent survival estimates varied substantially among years. Without correcting for emigration, apparent survival estimates were lower and temporal variation was obscured, particularly for male Humboldts flying squirrels and female Townsends chipmunks. C_LIO_LIOur results demonstrate that emigration can influence commonly used estimates of apparent survival. Unadjusted estimates confounded the interpretation of differences in survival between age and sex classes and masked potential temporal patterns in survival because the magnitude of adjustment varied among years. We conclude that apparent survival estimators are robust during some time periods; however, when emigration rates vary in time the effects of emigration should be carefully considered and accounted for, especially in comparative studies and those with policy and conservation implications. C_LI

In group-living mammals, reproductive success can be attributed to both resident and non-resident males. However, the reproductive success of non-resident males has rarely been investigated at an individual level. As male reproductive success is highly skewed towards specific males, often the most dominant males, the percentage of similar-aged paternal siblings within groups is expected to increase. However, the extent to which each male contributes to the production of cohorts of paternal siblings remains unclear. Here we examined the paternity of 46 offspring born over five consecutive years in a group of Japanese macaques Macaca fuscata on Shodoshima Island. We quantitatively assessed paternity success for males, including both resident and non-resident males, and the percentages of paternal sibling dyads in the same age cohorts produced by those males. Non-resident males sired neither higher nor lower percentage of offspring compared to resident males, indicating that various males, including non-resident males, usually partake in the within-group breeding of macaque groups. These are possibly because female preference of mating partners can change over time. Subadult males had a lower percentage of paternity success, which may be because females may not prefer the physically immature subadult males. Various males, including non-resident males, contributed to the creation of paternal sibling in the same age cohort. The overall results suggest that not only resident but also non-resident males play an important role in shaping within-group kin structures. Future studies are required to examine how paternal siblings interact with each other.

During the nestling stage of breeding seasons in Stillwater, OK, pairs of American Crows (Corvus brachyrhynchos brachyrhynchos) lived alone or in groups of variable composition; auxiliaries included individuals that had delayed dispersal, immigrated into groups, or returned to natal territories after having lived elsewhere. Most, but not all, auxiliaries contributed to feeding nestlings, and their contributions varied considerably. On average, breeders fed nestlings at greater rates than did auxiliaries, and female breeders spent more time at nests than did other group members. Breeders compensated for auxiliary contributions by reducing their own; this and breeder responses to the disappearance of auxiliary feeding group members provide evidence that these long-lived, iteroparous animals were managing energy budgets so as to maximize fitness over the long term. Female breeders in larger groups spent more time at nests than did those in smaller groups, but not for expected reasons and not to any reproductive benefit. A few female auxiliaries spent increasing amounts of time at nests as nestlings aged. No other measured phenotypic characteristic of individuals was found to explain any of the wide variation in the patterns of nestling care exhibited by members of our population.