The pathogenesis of a North American H5N2 clade 2.3.4.4 group A highly pathogenic avian influenza virus in surf scoters (Melanitta perspicillata)

Background Aquatic waterfowl, particularly those in the order Anseriformes and Charadriiformes, are the ecological reservoir of avian influenza viruses (AIVs). Dabbling ducks play a recognized role in the maintenance and transmission of AIVs. Furthermore, the pathogenesis of highly pathogenic AIV (HPAIV) in dabbling ducks is well characterized. In contrast, the role of diving ducks in HPAIV maintenance and transmission remains unclear. In this study, the pathogenesis of a North American A/Goose/1/Guangdong/96-lineage clade 2.3.4.4 group A H5N2 HPAIV, A/Northern pintail/Washington/40964/2014, in diving sea ducks (surf scoters, Melanitta perspicillata) was characterized. Results Intrachoanal inoculation of surf scoters with A/Northern pintail/Washington/40964/2014 (H5N2) HPAIV induced mild transient clinical disease whilst concomitantly shedding high virus titers for up to 10 days post-inoculation (dpi), particularly from the oropharyngeal route. Virus shedding, albeit at low levels, continued to be detected up to 14 dpi. Two aged ducks that succumbed to HPAIV infection had pathological evidence for co-infection with duck enteritis virus, which was confirmed by molecular approaches. Abundant HPAIV antigen was observed in visceral and central nervous system organs and was associated with histopathological lesions. Conclusions Collectively, surf scoters, are susceptible to HPAIV infection and excrete high titers of HPAIV from the respiratory and cloacal tracts whilst being asymptomatic. The susceptibility of diving sea ducks to H5 HPAIV highlights the need for additional research and surveillance to further understand the contribution of diving ducks to HPAIV ecology.

Interacting effects of latitude, mass, age, and sex on winter survival of Surf Scoters (Melanitta perspicillata): implications for differential migration

We quantified variation in winter survival of Surf Scoters (Melanitta perspicillata (L., 1758)) across nearly 30° of latitude on the Pacific coast of North America to evaluate potential effects on winter distributions, including observed differential distributions of age and sex classes. We monitored fates of 297 radio-marked Surf Scoters at three study sites: (1) near the northern periphery of their wintering range in southeast Alaska, USA, (2) the range core in British Columbia, Canada, and (3) the southern periphery in Baja California, Mexico. We detected 34 mortalities and determined that survival averaged lower at the range peripheries than in the range core, was lower during mid-winter than during late winter at all sites, and was positively correlated with body mass within locations. Although neither age nor sex class had direct effects, mass effects led to differential survival patterns among classes. When simultaneously incorporating these interacting influences, adult males of mean mass for their location had highest survival at the northern range periphery in Alaska, whereas adult females and juveniles had higher survival at the range core and the southern periphery. Our observations help to explain patterns of differential migration and distribution reported for this species and highlight seasonal periods (mid-winter) and locations (range peripheries) of elevated levels of mortality for demographically important age–sex classes (adult females).

Registros nuevos y notables de aves en el AICA Humedales de Alvarado, Veracruz

A partir del trabajo de campo realizado entre marzo de 2003 y enero de 2015 en los humedales de Alvarado (HA), reunimos aquíobservaciones de 10 especies de aves encontradas fuera de sus intervalos típicos de distribución o de las que, a pesar de estarpotencialmente presentes en ha, carecen o cuentan con pocos registros en el Área de Importancia para la Conservación de lasAves (AICA). Registramos por primera vez para esta área al colimbo mayor (Gavia immer) y al bobo enmascarado (Sula dactylatra);por segunda ocasión a la negreta nuca blanca (Melanitta perspicillata), la gaviota de Bonaparte (Chroicocephalus philadelphia),al reyezuelo de rojo (Regulus calendula) y al chipe de pradera (Setophaga discolor). Presentamos observaciones adicionales delmielero pata roja (Cyanerpes cyaneus) y de la tángara escarlata (Piranga olivacea), especies raras en el área; así como del jilguerodominico (Spinus psaltria) y la tórtola turca (Streptopelia decaocto), las cuales recientemente han expandido su distribución. Estosregistros pueden atribuirse a diferentes causas: conducta migratoria, fenómenos meteorológicos, introducción humana, modificacionesde hábitat e incremento del esfuerzo de observación.