Post-Reproductive Pacific Salmon, Oncorhynchus spp., as a Major Nutrient Source for Large Aggregations of Gulls, Larus spp.

On the Pacific coast of North America, the most abundant vertebrate visitors to estuaries and rivers during salmon migration are gulls, yet the utilization of salmon nutrients by these scavengers, and subsequent ecological impacts are not well documented. On two forested watersheds on the central coast of British Columbia, we tracked gull abundance during the spawning period for two consecutive years, and estimated consumption of post-reproductive salmon carcasses and eggs, as well as guano production. At Clatse River, gulls (Larus glaucescens, L. argentatus, L. thayerii, L. californicus, L. canus, L. philadelphia) consumed 13-26% of total salmon carcass biomass and 29-36% of all salmon eggs deposited in the system. At Neekas River, gulls consumed 11-19% of salmon carcass biomass and 7-18% of total salmon eggs. Local guano production over the 60-day period ranged from 600 kg to 1190 kg at Clatse and from 1200 kg to 2100 kg at Neekas River, and was distributed to marine, estuarine, freshwater and riparian habitats. The large aggregations of gulls and subsequent nutrient cycling observed on our study watersheds may represent a once widespread phenomenon that is now largely reduced due to recent declines in salmon populations

Pacific Hagfish, Eptatretus stoutii, Spotted Ratfish, Hydrolagus colliei, and Scavenger Activity on Tethered Carrion in Subtidal Benthic Communities off Western Vancouver Island

The influence of pelagic carrion food falls on marine benthic scavenging communities was investigated at two depths (10 m, 50 m) in Barkley Sound, west Vancouver Island, British Columbia from 12 May to 4 June, 2003. A remotely operated vehicle (ROV) equipped with video cameras was used to monitor anchored carrion (15 kg pig leg) during daylight and darkness. The videos were subsequently analyzed for species diversity, abundance and the intensity of scavenging. At 10 m, Redrock Crab (Cancer productus) and Kelp Greenling (Hexagrammos decagrammus) dominated, while at 50 m, Spot Shrimp (Pandalus platyceros), Spotted Ratfish (Hydrolagus colliei) and Pacific Hagfish (Eptatretus stoutii) were the dominant species, most of which were nocturnal. Hagfish were the major consumers of the carrion and after 23 days, no soft tissues remained at 50 m while 40% remained at 10 m. Within 24 hours of the carrion deployment, two of eleven ratfish succumbed, probably due to the direct clogging effects of hagfish mucus on the respiratory apparatus of the ratfish. These field observations are consistent with laboratory results suggesting high efficacy of hagfish mucus in competitive interactions

Host Patch Traits Have Scale‐Dependent Effects On Diversity In A Stickleback Parasite Metacommunity

Many metacommunities are distributed across habitat patches that are themselves aggregated into groups. Perhaps the clearest example of this nested metacommunity structure comes from multi‐species parasite assemblages, which occupy individual hosts that are aggregated into host populations. At both spatial scales, we expect parasite community diversity in a given patch (either individual host or population) to depend on patch characteristics that affect colonization rates and species sorting. But, are these patch effects consistent across spatial scales? Or, do different processes govern the distribution of parasite community diversity among individual hosts, versus among host patches? To answer these questions, we document the distribution of parasite richness among host individuals and among populations in a metapopulation of threespine stickleback Gasterosteus aculeatus. We find some host traits (host size, gape width) are associated with increased parasite richness at both spatial scales. Other patch characteristics affect parasite richness only among individuals (sex), or among populations (lake size, lake area, elevation and population mean heterozygosity). These results demonstrate that some rules governing parasite richness in this metacommunity are shared across scales, while others are scale‐specific

Range Expansion by Moose into Coastal Temperate Rainforests of British Columbia, Canada

Ranges of species are dynamic and respond to long-term climate change and contemporary effects such as habitat modification. We report here that moose (Alces alces) have recently colonized coastal temperate rainforests of British Columbia, Canada. Contrary to recent publications, field observations of moose and their sign, combined with their occurrence in wolf (Canis lupus) faeces, suggest that moose are now widespread on the coastal mainland and occur on least three islands. Traditional ecological knowledge (information accumulated by aboriginal peoples about their environment) suggests that colonization occurred during the mid 1900s, concomitant with logging of major watersheds that bisect the Coast Mountain Range. Range expansion by moose may have ecological consequences such as alteration of predator– prey dynamics and transmission of disease to native deer (Odocoileus hemionus)

Temporal variation in divergent selection on spine number in threespine stickleback.

Abstract. Short-term temporal cycles in ecological pressures, such as shifts in predation regime, are widespread in nature yet estimates of temporal variation in the direction and intensity of natural selection are few. Previous work on threespine stickleback (Gasterosteus aculeatus) has revealed that dorsal and pelvic spines are a defense against gape-limited predators but may be detrimental against grappling insect predators. In this study, we examined a 15-year database from an endemic population of threespine stickleback to look for evidence of temporal shifts in exposure to these divergent predation regimes and correlated shifts in selection on spine number. For juveniles, we detected selection for increased spine number during winter when gape-limited avian piscivores were most common but selection for decreased spine number during summer when odonate predation was more common. For subadults and adults, which are taken primarily by avian piscivores, we predicted selection should generally be for increased spine number in all seasons. Among 59 comparisons, four selection differentials were significant (Bonferroni corrected) and in the predicted direction. However, there was also substantial variability in remaining differentials, including two examples with strong selection for spine reduction. These reversals were associated with increased tendency of the fish to shift to a benthic niche, as determined from examination of stomach contents. These dietary data suggest that increased encounter rates with odonate predation select for spine reduction. Strong selection on spine number was followed by changes in mean spine number during subsequent years and a standard quantitative genetic formula revealed that spine number has a heritable component. Our results provide evidence of rapid morphological responses to selection from predators and suggest that temporal variation in selection may help maintain variation within populations. Furthermore, our findings indicate that variable selection can be predicted if the agents of selection are known

Faecal-Centric Approaches to Wildlife Ecology and Conservation; Methods, Data and Ethics

Abundant and commonly encountered in the field, wildlife faeces have long attracted scientists. Recent advances in molecular techniques, however, especially when coupled with creative study designs, can now yield a great variety of high quality data. Herein, we review the opportunities and challenges of faecal-centric approaches to address ecological and conservation questions using wolves of coastal British Columbia, Canada, as a case system. We begin by discussing methodological considerations, which should have broad applicability to any wildlife study system. We then summarize the extensive and unique variety of data that has emerged from our ‘facts from faeces’ approach with wolves, which has ranged from descriptive autecology to process-oriented hypothesis-testing to applied conservation management. We conclude by contrasting this non-invasive approach with radio-collaring in an ethics framework. We contend that when the two methods are equally efficacious in answering required research questions, scatology become the only ethical option, a perspective increasingly codified as policy governing research activities

ARTICLE Population, sex, and ontogenetic differences in the procurrent rays of the caudal fin in threespine sticklebacks (Gasterosteus aculeatus)

Abstract: The procurrent rays occur at the leading edge of the caudal fin in bony fishes and are taxonomically variable and possibly important to caudal motion. Using radiographs, as well as stained and cleared specimens, of threespine sticklebacks (Gasterosteus aculeatus L., 1758) from lakes on Haida Gwaii, British Columbia, we examined the extent of individual and population variabilities in these rays. Among 1113 fish from Drizzle Lake, 53% of individuals were dorsoventrally asymmetric in number of rays of which 95% had greater number of rays on the dorsal lobe. On 274 fish, we also quantified dorsal to ventral (D/V) ratios of the width of the most posterior procurrent rays and found ontogenetic shifts with symmetrical D/V ratios in subadults shifting to significant dorsal biases on the larger fish (60-90 mm standard length (SL)). Males have proportionally greater dorsal bias than females of equivalent size in both number and width of procurrent rays. We examined D/V width ratios in 105 stained and cleared specimens from 13 additional allopatric lake populations on Haida Gwaii. Eight populations were symmetrical for width of dorsal and ventral rays, while three populations were ventrally biased and two populations were dorsally biased. D/V ratios were best predicted by positive associations with adult body size and negative associations with total number of gill rakers. Key words: asymmetry, caudal peduncle, Gasterosteus, Haida Gwaii, homocercal tail, intraspecific variation, procurrent rays, stickleback. Résumé : Les rayons procurrents qui se trouvent à la bordure externe de la nageoire caudale chez les poissons osseux présentent des variations taxinomiques et pourraient jouer un rôle important dans le mouvement de la queue. En utilisant des radiographies ainsi que de spécimens colorés et dépigmentés d'épinoches à trois épines (Gasterosteus aculeatus L., 1758) provenant de lacs de l'archipel Haida Gwaii (Colombie-Britannique), nous avons examiné l'ampleur des variabilités de ces rayons à l'échelle individuelle et des populations. Sur 1113 poissons du lac Drizzle, 53 % des individus présentaient une asymétrie dorsoventrale du nombre de rayons, 95 % de ce nombre comptant plus de rayons dans le lobe dorsal que dans le lobe ventral. Nous avons également quantifié les rapports de la largeur dorsale à de la largeur ventrale (D/V) des rayons procurrents les plus postérieurs de 274 poissons et noté des changements ontogénétiques consistant au passage de rapports D/V symétriques chez les subadultes à des biais dorsaux significatifs chez les poissons plus grands (60-90 mm longueur standard (LS)). Les mâles présentent un biais dorsal proportionnellement plus important que les femelles de taille équivalente, tant sur le plan du nombre que de la largeur des rayons procurrents. Nous avons examiné les rapports D/V de la largeur de 105 spécimens colorés et dépigmentés de 13 autres populations de lacs allopatriques d'Haida Gwaii. Huit populations présentaient une symétrie sur le plan de la largeur des rayons dorsaux et ventraux, alors que trois populations présentaient un biais ventral et deux populations présentaient un biais dorsal. Des associations positives avec la taille du corps pour les adultes et négatives avec le nombre total de branchicténies prédisaient le mieux les rapports D/V. [Traduit par la Rédaction

Early Ontogenetic Diet in Gray Wolves, Canis lupus, of Coastal British Columbia

Within populations, different age classes often consume dissimilar resources, and provisioning of juveniles by adults is one mechanism by which this can occur. Although the diet of Gray Wolves (Canis lupus) has been studied extensively, the diet of pups is largely unknown. We examined faeces deposited by altricial pups and adult providers during the first two months following birth at two den sites over two years on the central coast of British Columbia, Canada. Pups and adult wolves consumed similar species, and Black-tailed Deer (Odocoileus hemionus) constituted most of the diet for both age groups. Pup and adult diet, however, diverged. Specifically, adult deer occurred significantly less frequently in the diet of pups than in the diet of adult wolves, which suggests that adults selectively provisioned pups. We speculate that this may relate to adaptive strategies of adult wolves to provide their offspring with food of optimal nutritional value or reduced parasitic burden, and/or logistic factors associated with provisioning such as prey transportability and availability

Early Ontogenetic Diet in Gray Wolves, Canis lupus, of Coastal British Columbia

Within populations, different age classes often consume dissimilar resources, and provisioning of juveniles by adults is one mechanism by which this can occur. Although the diet of Gray Wolves (Canis lupus) has been studied extensively, the diet of pups is largely unknown. We examined faeces deposited by altricial pups and adult providers during the first two months following birth at two den sites over two years on the central coast of British Columbia, Canada. Pups and adult wolves consumed similar species, and Black-tailed Deer (Odocoileus hemionus) constituted most of the diet for both age groups. Pup and adult diet, however, diverged. Specifically, adult deer occurred significantly less frequently in the diet of pups than in the diet of adult wolves, which suggests that adults selectively provisioned pups. We speculate that this may relate to adaptive strategies of adult wolves to provide their offspring with food of optimal nutritional value or reduced parasitic burden, and/or logistic factors associated with provisioning such as prey transportability and availability

Isotopic Niche Differentiation Among Mammals from a Rainforest in Peninsular Malaysia

We performed stable isotope analysis on eight mammalian species: pig-tailed macaque (Macaca nemestrina), long-tailed macaque (M. fascicularis), dusky leaf monkey (Trachypithecus obscurus), brush-tailed porcupine (Atherurus macrourus), wild boar (Sus scrofa), lesser mouse-deer (Tragulus javanicus), greater mouse-deer (T. napu), and barking deer (Muntiacus muntjac), to test the hypothesis that the differences in diet and habitat types among species, guilds and foraging strategies are reflected in the δ15N and δ13C signatures of their tissues. Whereas the isotopic ratios differed among taxa, the four major isotopic groups observed were: mouse-deer species, primate species, brush-tailed porcupine, and wild boar. The brush-tailed porcupine showed the most divergent isotopic signatures, depleted in both δ15N and δ13C, and the wild boar had isotopic signatures enriched in both δ15N and δ13C. Although results are only indicative, the three habitat types occupied by the species were reflected by differences in isotopic signatures, with the ground-dwelling species having the most divergent isotopic values from arboreal and semi-arboreal species. Likewise, among the four different types of dietary lifestyle groups tested, each group showed either significantly different δ15N or δ13C from other groups. Omnivores had the highest isotopic values, and bark-eater/frugivores had the lowest. By increasing the sample sizes both within the species and the number of species in future analyses, this isotopic technique provides opportunity to elucidate the diets of their putative predators in the rainforests of Peninsular Malaysia