Interior Double-crested cormorant reproduction was examined on a large geographical scale to evaluate management actions. Three distinct breeding areas across Ontario were selected. Beginning in 2002, over 11,000 preledged cormorants have been marked. During 2006 and 2007, re-observation of banded birds, colony data such as nest, egg, and chick measurements, and island morphology, were collected. Data revealed no significant regional differences in adult size. However, eggs in eastern Lake Ontario (ELO) were larger than North Channel of Lake Huron (NChan) and Lake of the Woods (LOW). Chicks in ELO throughout development were smaller than NChan and LOW. Number of gulls was correlated inversely to cormorant fledge rate. Survival estimates were <20% for young of the year, but increased to >80% after year 2. Elasticity analysis revealed that a 50% reduction in adult survival combined with 100% fecundity reduction would result in a 42% reduction in population growth.

Double-crested cormorants have steadily increased in the Mississippi Delta. This bird serves as a definitive host for digenetic trematodes, many of which infect fish. To identify these digeneans in cormorants and determine the impact these infections have on wild fish in the Mississippi Delta, two surveys were done. Cormorants were collected for two years in the Mississippi Delta. At necropsy trematodes were collected and identified morphologically and molecularly as: Austrodiplostomum ostrowskiae, Hysteromorpha triloba, Drepanocephalus spathans, Ascocotyle longa and Pseudopsilostoma varium. Additionally, 14 fish species were collected from a Mississippi Delta lake. Fish were examined for parasites and Posthodiplostomum minimum metacercariae were found in multiple organs in 6/14 fish species. The 18S gene sequences of these metacercariae were identical to published P. minimum sequences, whereas the cytochrome oxidase I (COI) sequences matched published COI sequences for Posthodiplostomum sp. 3, 5 and 8, suggesting subspecies of Posthodiplostomum in this fish population.

Wetlands of the Prairie Pothole Region (PPR) provide important breeding habitat for greater than 30 species of waterbirds. Approximately 70% of PPR wetlands have been lost since European settlement and remaining wetlands are subjected to frequent degradation, primarily due to agricultural activities. Horned grebes (Podiceps auritus) are experiencing long-term population declines and are listed as a species of Special Concern in Canada. Because there is virtually no information on the status and trends of pied-billed grebes (Podilymbus podicep) this species is also of considerable conservation concern. Grebes are recorded on the Waterfowl Breeding Population and Habitat Surveys (WBPHS) conducted annually in May by the Canadian Wildlife Service; however, how accurately these counts reflect actual abundance has been unknown. Using a repeated counts method in 2010 and 2011, estimates of detection probabilities averaged 0.48 and 0.18 for horned and pied-billed grebes, respectively. These results suggest that WBPHS ground surveys may be used as an efficient and effective management tool for monitoring horned grebe abundances. However, low detection rates for pied-billed grebes lend little support for including the species in future monitoring efforts using the WBPHS. I recommend that the Canadian Wildlife Service consider implementing standardized ground survey methods to facilitate annual monitoring of horned grebe abundances. Marshbird research has focused primarily on breeding habitat use or selection but has seldom examined how productivity is related to wetland characteristics. Understanding processes that affect distribution patterns and productivity of grebes could provide insights into actions needed to achieve conservation goals. Therefore, occupancy of wetlands by breeding and brood-rearing horned and pied-billed grebes was evaluated on 6-7 study sites (5.8-11.6 km2) in south-central Saskatchewan, 2010 and 2011, and related to wetland and upland habitat features. Wetland occupancy by grebes was influenced by interspecific competition as well as local and landscape-level wetland features. Horned and pied-billed grebes rarely co-occurred on smaller (≤4 ha) semi-permanent and permanent wetlands. At the wetland level, horned grebe occupancy and productivity were highly correlated with the amount of emergent vegetation, whereas wetland area alone was a better predictor of adult pied-billed grebe occupancy and productivity. At a landscape level, the number of semi-permanent, permanent, and artificial wetlands on each study site was an important predictor of breeding and brood-rearing wetland occupancy probability for horned grebes in 2010 and for pied-billed grebes in both years. However, breeding horned grebe occupancy probability and productivity were higher in low wetland density landscapes in 2011. Horned grebes may be opportunistic, exploiting more of the available wetland habitats in low wetland density landscapes during years of above-average water conditions. Conservation initiatives for grebes should consider the roles of wetland-specific and landscape-level features while protecting semi-permanent and permanent wetlands in landscapes characterized by both high and low wetland densities.

Drepanocephalus auritus is a digenetic trematode parasitizing the double-crested cormorant, a piscivorous waterbird often found feeding on catfish aquaculture ponds in Mississippi. The aquatic snail Planorbella trivolvis was the only known intermediate host in Mississippi until a new snail host, Biomphalaria havanensis, was discovered releasing cercariae belonging to North and South American D. auritus haplotypes. In addition, previous work has reported D. auritus metacercariae begin to resolve in channel catfish 7-21 days post-infection. As a result, a 2-year study was undertaken to elucidate the life cycle of D. auritus and identify if channel catfish can serve as a true intermediate host. In year 1, the role of the channel catfish as a true intermediate host was established, as gravid adults were recovered from double-crested cormorants fed parasitized fish. In year 2, each step of the life cycle was completed, and developmental timelines for each life stage were established.

The commercial production of channel catfish (Ictalurus punctatus) is major industry in Mississippi. Infections of channel catfish with the digenetic trematode Bolbophorus damnificus have often been associated with heavy economic losses in the industry. To efficiently control transmission of this trematode, the avian hosts need to be identified. In the first study, two American white pelicans, two double-crested cormorants, two great blue herons, and two great egrets were fed channel catfish infected with B. damnificus metacercariae. The presence of Bolbophorus damnificus ova in pelican feces at three days post infection (dpi) indicated the pelicans had patent infections. Mature B. damnificus were recovered from the intestines of both pelicans at 21 dpi. No B. damnificus infections were observed in the other bird species. In a second study, 33 American white pelicans, 34 double-crested cormorants, 35 great blue herons, and 32 great egrets were collected in the Mississippi Delta. The prevalence of B. damnificus in the American white pelican was 93.9%, with an average of 158 B. damnificus found per bird (range 0-681). Bolbophorus damnificus was not found in any of the other bird species. The results of these two studies confirm that the AWPE is the only proven natural host for B. damnificus. In a third study, two previously undescribed cercariae were found infecting rams-horn snails in commercial catfish ponds. In challenge studies, channel catfish were exposed to both cercariae types. Only one type of cercariae (type I) was infective to channel catfish. The first evidence of type I metacercariae was seen histologically at 14 dpi and grossly at 21 dpi. Development continued until 120 dpi, when both gross examination and histology suggested that the metacercariae were mature. The type I metacercariae appeared to cause little host damage. Molecular analysis of the 18S rRNA gene region indicated that the type I cercariae and metacercariae may be a species of Clinostomum. The data generated in these three studies provides additional information that can be used in the development of efficacious management schemes to control digenetic trematodes infecting commercial catfish.

No description available.

I investigated if constructed wetlands provide breeding habitat for the Horned Grebe (Podiceps auritus) in northwest Alberta. Over two years, I conducted bird surveys of 201 borrow-pits (ponds created during road construction) and 18 natural wetlands and collected data on local habitat and landscape features. For subsets of ponds, I also collected water chemistry and invertebrate data, and conducted stable isotope analysis. Grebes occurred on 36% of borrow-pits and produced chicks on 61% of occupied sites in 2007 and 81% in 2008. Grebes occurred more frequently on larger ponds, with more emergent vegetation, and avoided forested ponds that supported beaver activity. Horned Grebes are generalist foragers that did not select nesting ponds based on food-web structure. Twenty-six other bird species used borrow-pits, with distinct assemblages occurring on agricultural versus forested ponds. My study indicates that wetland construction offers a viable method for creating habitat for Horned Grebes and other species. / Ecology

Production de bois et autres ressources (gibier, champignons,...), conservation de la biodiversité et gestion des paysages, la forêt a suscité de riches débats depuis quelques années, le Grenelle de l'Environnement ayant révélé des intérêts parfois contradictoires. Si le gestionnaire forestier tente de développer autant que possible une gestion multifonctionnelle de ses forêts, il reste dépendant des connaissances fragmentaires sur les interactions dans les écosystèmes forestiers. La politique actuelle, qui vise à concilier la production de bois et la préservation des espèces, repose plus sur des expériences de terrain que sur des études étayées scientifiquement. Les Chiroptères comptent des espèces candidates pour étudier l'influence de la gestion forestière sur la biodiversité : le jour, elles occupent des gîtes arboricoles et, la nuit, elles exploitent des habitats forestiers pour chasser leurs proies, qui dépendent elles-mêmes de micro-habitats forestiers. Pour aider le gestionnaire à mettre en œuvre une stratégie de gestion conservatoire, nous avons étudié l'utilisation des ressources de la forêt par trois espèces : Myotis bechsteinii, Myotis nattereri et Plecotus auritus. La radio-localisation a permis d'identifier des réseaux d'arbres-gîte dont l'occupation varie selon les espèces, leur statut reproducteur et l'implication dans le comportement de fission-fusion des colonies de parturition. Les différentes utilisations des gîtes impliquent une stratégie de gestion propre à chaque espèce, voire à chaque colonie de reproduction. Procurant a priori de potentiels gîtes et proies, le bois mort debout favorise la richesse spécifique des Chiroptères forestiers à partir de 25 m3 à l'hectare, mais une stratification de la végétation pourrait être un objectif de gestion, la réponse des espèces était essentiellement liée à la structure forestière des trouées induites par le bois mort. Ce travail a ensuite nécessité de s'intéresser aux méthodes permettant de comprendre l'utilisation de l'espace par chaque individu (domaine vital) et la façon dont chacun d'eux fréquente ses terrains de chasse (sélection de l'habitat). Compte tenu des limites technologiques, le Kernel semble actuellement la meilleure méthode de représentation et de calcul de surface du domaine vital alors que la K-select a livré des résultats significatifs pour mettre en évidence des facteurs de sélection d'habitat. Les surfaces des domaines vitaux et des centres d'activité varient selon les espèces, Myotis bechsteinii associe de petites surfaces à un comportement territorial, surtout en période d'allaitement. M. nattereri et Plecotus auritus peuvent exploiter de grands espaces sur lesquels ils se limitent à de petits centres d'activité. Les colonies de ces dernières pourront plus facilement se déplacer dans leur domaine vital au gré des itinéraires de gestion mis en œuvre. Les caractéristiques des habitats forestiers utilisés comme terrains de chasse varient selon les espèces, voire le sexe, l'âge et le statut reproducteur des individus, mais toutes trois montrent une forte sélectivité pour les peuplements forestiers présentant un fort encombrement végétal, des gros arbres et une forte structuration du peuplement. Cinq principes de gestion dans un contexte fort de production de bois sont développés en conclusion des résultats avec deux exemples de stratégies de gestion destinée au maintien des Chiroptères. / The forest is the center of many interests that fuel the debates of our society. These debates are particularly exacerbated since the french " Grenelle de l'Environnement " in 2008. Among the various expectations, forest produce wood that is the subject of attentions, both by an increased demand for certain types of trees and by the naturalist world which sees in it one of last refuges for biodiversity in our modified landscapes. Thus, if the forest manager is trying to develop a management that is as much multifunctional as possible, it remains dependent on fragmented knowledge on the link between biodiversity and the forest ecosystem. Despite the establishment of a conservation policy that seeks to balance timber production and species preservation, the way to conduct such a policy is based on concrete field experiences yet scientifically unsubstantiated. Bats are good candidate species to study the response of biodiversity to forest management: they select networks of tree-roosts in which they form breeding colonies composed of several dozen individuals and they exploit forest habitats to hunt their prey, prey which themselves depend on forest microhabitats. However, their study is recent in forest and provides very vague management guidelines. To help managers implement a conservation management strategy, we thus studied the behavior of forest usage by three species of gleaning bats, Myotis bechsteinii, Myotis nattereri and Plecotus auritus. This work required to focus on the methods available to understand the use of space by each individual (home range) and how each individual selects its hunting habitats. We showed that each species had a unique response to available habitats and that the status of individuals (sex, age and reproductive status) intervenes in explaining the selection of tree roosts and hunting grounds. Both compartments are constrained by the availability of suitable habitat, helping to explain the structuring of habitat selection factors and the shape and surface of individual home ranges. Furthermore, the way networks of tree-roost are used partly explains the types of roosts selected. These different results means that it is necessary to lay down specific management strategies for each species, even each breeding colony. Finally, we studied the role of deadwood to explain the presence of bats in forests. We have shown that species richness increased from standing deadwood of 25m3 per hectare, while the response of species to deadwood was mainly restricted to forest habitat structure produced by the gaps resulting from the deadwood patch, favoring particularly edge-foraging species. Some species do however clearly benefit from insects emerging from deadwood. Five recommendations are proposed for the conservation of these species in a context of strong wood production.