Effects of Climate-Induced Changes in Parasitism, Predation and Predator-Predator Interactions on Reproduction and Survival of an Arctic Marine Bird

A detailed understanding of the processes and interactions within biological communities is needed to describe and predict the biological consequences of climate change. Global warming may affect biological communities at specific sites through changes in the species composition that follow changes in range, or through altered food web interactions caused by changes in phenology or behaviour. We describe the demographic consequences for a colonial nesting seabird, the Thick-billed Murre (Uria lomvia), of exceptionally intense mosquito parasitism and predation by polar bears in a particular year. Increases in mosquito parasitism and bear predation are changes in behaviour rather than changes in range, and both caused unusual adult mortality and reproductive failure in Thick-billed Murres. In the case of adult mortality, the effects of predation and parasitism were complementary, whereas in the case of reproductive failure, most birds affected by parasitism would in any case have subsequently lost their eggs to bear predation. The mosquito and bear activities had the secondary result of redirecting the attention of gulls and foxes, the usual predators of murre eggs, towards scavenging carcasses and preying on eggs exposed by birds deserting their ledges. This diversion reduced the impact of gulls and foxes on the murres and altered the spatial configuration of predation risk. Our observations emphasize the difficulty faced by ecologists in predicting the consequences of global warming even for simple and relatively well-studied ecosystems. Moreover, the net effect of combined parasitism and predation was much greater than reported previously, reducing overall colony productivity by 20% and increasing adult mortality by 20%. If this effect happens every year, it will have population consequences.Il y a lieu de bien comprendre les processus et les interactions qui se produisent au sein des communautés biologiques afin d’être en mesure de décrire et de prévoir les conséquences biologiques du changement climatique. Le réchauffement climatique peut avoir des incidences sur les communautés biologiques de sites spécifiques en ce sens que la composition des espèces peut être modifiée en raison de changements caractérisant le parcours naturel ou en encore, en raison d’interactions altérées à l’échelle du réseau alimentaire attribuables à des changements de phénologie ou de comportement. Nous décrivons les conséquences démographiques relatives à un oiseau de mer colonial en nidification, soit le guillemot de Brünnich (Uria lomvia), de même que les conséquences du parasitisme exceptionnellement intense des moustiques et de la prédation par les ours polaires au cours d’une année donnée. L’intensification du parasitisme des moustiques de même que la prédation par les ours correspondent à des changements de comportement plutôt qu’à des changements de parcours, et ces deux facteurs ont causé une mortalité inhabituellement élevée chez les adultes ainsi qu’une infécondité chez le guillemot de Brünnich. En matière de mortalité chez les adultes, les effets de la prédation et du parasitisme étaient complémentaires, tandis qu’en matière d’infécondité, la plupart des oiseaux touchés par le parasitisme auraient tout de même fini par perdre leurs oeufs en raison de la prédation par les ours. L’activité des moustiques et des ours a eu pour résultat secondaire de réorienter l’attention des goélands et des renards, qui sont les prédateurs habituels des oeufs de guillemot, vers la charogne des carcasses et la prédation des oeufs exposés par les oiseaux qui désertaient leurs corniches. Cette diversion a eu pour effet d’atténuer l’incidence des goélands et des renards sur les guillemots, en plus de modifier la configuration spatiale du risque de prédation. Nos observations font ressortir la difficulté à laquelle font face les écologistes en matière de prévision des conséquences du réchauffement climatique, même dans le cas d’écosystèmes simples et relativement bien étudiés. Par ailleurs, l’effet final du parasitisme et de la prédation mis ensemble était beaucoup plus grand que ce qui n’avait déjà été signalé, ce qui a eu pour effet de réduire la productivité générale de la colonie de 20 pour cent et d’accroître le taux de mortalité chez les adultes dans une mesure de 20 pour cent. Si cet effet se répétait chaque année, il aurait des conséquences sur la population

Aerial Surveys Do Not Reliably Survey Boreal-nesting Shorebirds

Aerial surveys have been used as a method for surveying boreal-nesting shorebirds, which breed in difficult-to-access terrain; however, the fraction of breeding birds observed from the air is unknown. We investigated rates of detection by conducting simultaneous air and ground surveys for shorebirds at three sites in the boreal forest of the Northwest Territories, Canada, in 2007. Helicopter surveys included both pond-based surveys where the helicopter flew around the perimeter of each wetland and transect-based surveys where observers recorded birds seen on line transects. Ground surveys involved intensive observation, territory mapping and nest searching in 5 km2 of plots over a period of 5-6 weeks. Shorebird densities observed from the helicopter were highest near large bodies of water. No shorebirds were observed over closed forest despite breeding densities on ground surveys being highest in closed forest. Detection rates were very low, varied among species and aerial survey types, and were inconsistent over time. Ground-based observations showed that the shorebirds often did not flush in response to the helicopter passing overhead. Owing to poor rates of detection, we conclude that helicopter surveys are not an appropriate method for surveying breeding shorebirds in boreal habitats, but may have some utility for monitoring birds' use of stop-over locations

Arctic Cod (Boreogadus saida) as Prey: Fish Length-Energetics Relationships in the Beaufort Sea and Hudson Bay

Although Arctic cod (Boreogadus saida) is widely recognized as an important trophic link to top predators in Arctic marine ecosystems, the challenges of conducting fieldwork in the Arctic make this species difficult to study. We establish some basic relationships to improve prey energetics modeling when only in-field parameters (e.g., fork length) can be measured. We investigated the intraspecific relationships among energy density, fork length, mass, and water content for Arctic cod captured by Black Guillemots and Thick-billed Murres at two sites (Western Beaufort and Hudson Bay). Dry energy density was similar between sites (21.6 – 22.2 kJ g-1) and increased with fork length (Dry EDkJ/g = 0.028 (± 0.01) • Fork Lengthmm + 18.12 (± 1.33). Even though fish lost some water as they were transported to the nest by avian predators, wet energy density also increased with fork length. We suggest that environmental conditions had a similar effect on growth at these two locations although they occur in very different oceanographic regimes. Arctic cod, especially large cod, is one of the most energy-rich prey species in the Arctic. Our results highlight the importance of this valuable prey to Arctic ecosystems and the utility of using seabirds opportunistically as samplers of the marine environment.Même si la morue polaire (Boreogadus saida) est grandement reconnue comme un lien trophique important pour les prédateurs situés en bout de chaîne des écosystèmes marins de l’Arctique, cette espèce est difficile à étudier en raison des défis inhérents à la réalisation de travaux sur le terrain dans l’Arctique. Nous établissons des relations de base afin d’améliorer la modélisation de la valeur énergétique des proies lorsque seuls des paramètres sur le terrain (comme la longueur à la fourche) peuvent être mesurés. Nous avons étudié les relations intraspécifiques qui existent entre la densité d’énergie, la longueur à la fourche, la masse et la teneur en eau de la morue polaire capturée par le guillemot à miroir et le guillemot de Brünnich à deux sites (ouest de Beaufort et baie d’Hudson). La densité d’énergie sèche était semblable entre les sites (21,6 – 22,2 kJ g-1) et augmentait en fonction de la longueur à la fourche (DE sèche EDkJ/g = 0,028 (± 0,01) • longueur à la fourchemm + 18,12(± 1,33). Même si les poissons perdaient de l’eau pendant le transport jusqu’au nid par les oiseaux prédateurs, la densité d’énergie humide augmentait également en fonction de la longueur à la fourche. Nous suggérons que les conditions environnementales avaient un effet similaire sur la croissance à ces deux sites même s’ils se trouvent dans des régimes océanographiques très différents. La morue polaire, surtout celle de grande taille, est l’une des espèces proies les plus riches en énergie de l’Arctique. Nos résultats mettent en évidence l’importance de cette précieuse proie pour les écosystèmes de l’Arctique et l’utilité de se servir des oiseaux de mer de manière opportuniste en guise d’échantillonneurs de l’environnement marin

Thyroid hormones correlate with resting metabolic rate, not daily energy expenditure, in two charadriiform seabirds

K. Woo, M. Le Vaillant, T. van Nus, and especially A. Wesphal, J. Schultner and I. Dorresteijn, assisted with field work, often under unpleasant conditions. K. Wauthier was instrumental in wrestling the gamma counter into submission. P. Redman and C. Hambly conducted the isotopic analyses. K. Scott and K. Campbell provided the FoxBox. K.H.E. benefited from a Natural Sciences and Engineering Research Council (NSERC) Vanier Scholarship, Association of Canadian Universities for Northern Studies Garfield Weston Northern Studies Award and the Arctic Institute of North America Jennifer Robinson Scholarship. Research support came from Bird Studies Canada/Society of Canadian Ornithologists James Baillie Award, Animal Behavior Society Research Grant, American Ornithologists’ Union Research Grant, Frank Chapman Research Grant, the Waterbird Society Nisbet Grant and NSERC Discovery Grants to J.F.H. and W.G.A. Any use of trade names is for descriptive purposes only and does not imply endorsement by the US Government.Peer reviewedPublisher PD

Counting calories in cormorants : dynamic body acceleration predicts daily energy expenditure measured in pelagic cormorants

The doubly-labelled water assays and accelerometers were paid for by the authors. Funding to reach Middleton Island was supported through the Animal Behaviour Society Research Grant and the Northern Scientific Training Program of Indigenous and Northern Affairs Canada.Peer reviewedPublisher PD

Inbreeding effects on immune response in free-living song sparrows (Melospiza melodia)

The consequences of inbreeding for host immunity to parasitic infection have broad implications for the evolutionary and dynamical impacts of parasites on populations where inbreeding occurs. To rigorously assess the magnitude and the prevalence of inbreeding effects on immunity, multiple components of host immune response should be related to inbreeding coefficient (f) in free-living individuals. We used a pedigreed, free-living population of song sparrows (Melospiza melodia) to test whether individual responses to widely used experimental immune challenges varied consistently with f. The patagial swelling response to phytohaemagglutinin declined markedly with f in both females and males in both 2002 and 2003, although overall inbreeding depression was greater in males. The primary antibody response to tetanus toxoid declined with f in females but not in males in both 2004 and 2005. Primary antibody responses to diphtheria toxoid were low but tended to decline with f in 2004. Overall inbreeding depression did not solely reflect particularly strong immune responses in outbred offspring of immigrant–native pairings or weak responses in highly inbred individuals. These data indicate substantial and apparently sex-specific inbreeding effects on immune response, implying that inbred hosts may be relatively susceptible to parasitic infection to differing degrees in males and females

Central-place Foraging in an Arctic Seabird Provides Evidence for Storer-Ashmole's Halo

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Diagnóstico situacional Hospital Gaspar García Laviana- Rivas y Ernesto Sequeira- Región Autónoma Atlántico Sur. Nicaragua. Año 2004.

Estudio de tipo descriptivo de corte transversal, en los Hospitales Ernesto Sequeira de la Región Autónoma del Atlántico Sur y Gaspar García Laviana de Rivas durante el año 2004. Se encontró que en ambos Hospitales brindan atención general, de prioridad Materno-Infantil, ubicados en las cabeceras de los departamentos; pertenecen al Segundo nivel de atención, con un nivel de complejidad básico, de referencias departamental para los centros de salud, cuyo propietario es el Ministerio de Salud. Con poblaciones objetivos mayores de 175,000 habitantes donde el 65% de las personas son niños o mujeres en edad de procrear. La cartera de servicios que ofertan ambos hospitales es acorde a su complejidad en las que se encuentran las cuatro especialidades básicas Medicina Interna, Cirugía General, Pediatría y Gineco obstetricia y los servicios de apoyo tales como: Farmacia, Radiología, Laboratorio así como en su estructura física cuenta con consultorios para consulta externa, emergencia, quirófanos, salas de parto y camas censables. El número de recursos humanos en cada hospital es mayor a 300 personas, donde el 55 al 60% es asistencial. En los recursos financieros el 80% del presupuesto proviene de fondo fiscal y el mayor gasto es en el pago de recursos humanos. El equipamiento asistencial de los hospitales se encuentra desfasado y obsoleto, entre el 20 al 40% en regular y muy mal estado y tienen más de un año de estar sin funcionamiento y no han sido reparados. El modelo de gestión de ambos hospitales es tradicional, sin implementación de herramientas gerenciales, ni toma de decisiones. La producción de servicios es baja en relación a su capacidad instalada

Human Vault Nanoparticle Targeted Delivery of Antiretroviral Drugs to Inhibit Human Immunodeficiency Virus Type 1 Infection.

"Vaults" are ubiquitously expressed endogenous ribonucleoprotein nanoparticles with potential utility for targeted drug delivery. Here, we show that recombinant human vault nanoparticles are readily engulfed by certain key human peripheral blood mononuclear cells (PBMC), predominately dendritic cells, monocytes/macrophages, and activated T cells. As these cell types are the primary targets for human immunodeficiency virus type 1 (HIV-1) infection, we examined the utility of recombinant human vaults for targeted delivery of antiretroviral drugs. We chemically modified three different antiretroviral drugs, zidovudine, tenofovir, and elvitegravir, for direct conjugation to vaults. Tested in infection assays, drug-conjugated vaults inhibited HIV-1 infection of PBMC with equivalent activity to free drugs, indicating vault delivery and drug release in the cytoplasm of HIV-1-susceptible cells. The ability to deliver functional drugs via vault nanoparticle conjugates suggests their potential utility for targeted drug delivery against HIV-1

Limited heat tolerance in a cold-adapted seabird: Implications of a warming Arctic

The Arctic is warming at approximately twice the global rate, with welldocumented indirect effects on wildlife. However, few studies have examined the direct effects of warming temperatures on Arctic wildlife, leaving the importance of heat stress unclear. Here, we assessed the direct effects of increasing air temperatures on the physiology of thick-billed murres (Uria lomvia), an Arctic seabird with reported mortalities due to heat stress while nesting on sun-exposed cliffs.We used flow-through respirometry to measure the response of body temperature, resting metabolic rate, evaporative water loss and evaporative cooling efficiency (the ratio of evaporative heat loss to metabolic heat production) in murres while experimentally increasing air temperature. Murres had limited heat tolerance, exhibiting: (1) a low maximum body temperature (43.3°C); (2) a moderate increase in resting metabolic rate relative that within their thermoneutral zone (1.57 times); (3) a small increase in evaporative water loss rate relative that within their thermoneutral zone (1.26 times); and (4) a low maximum evaporative cooling efficiency (0.33). Moreover, evaporative cooling efficiency decreased with increasing air temperature, suggesting murres were producing heat at a faster rate than they were dissipating it. Larger murres also had a higher rate of increase in resting metabolic rate and a lower rate of increase in evaporative water loss than smaller murres; therefore, evaporative cooling efficiency declined with increasing body mass. As a coldadapted bird, murres\u27 limited heat tolerance likely explains their mortality on warm days. Direct effects of overheating on Arctic wildlife may be an important but under-reported impact of climate change