Avian Influenza Virus Status and Maternal Antibodies in Nestling White Ibis (Eudocimus albus)

The White Ibis (Eudocimus albus), a nomadic wading bird, has increased its exploitation of urban habitats in South Florida, United States, and has recently established several urban breeding colonies. Certain characteristics of ibis ecology could position them in the natural cycle of the avian influenza virus (AIV). In fact, experimentally infected ibises were shown to be competent hosts for multiple AIV subtypes, and seroconversion to AIV has been documented in adult ibises in natural populations. However, the mechanisms of transmission and the timing of infection are unclear as we have yet to isolate AIV from a free-living ibis. To investigate the age-specific AIV dynamics of ibis, we captured nestlings (n = 115) weekly for 1–4 weeks from urban and natural settings in 2020 and 2021. We collected choanal/cloacal swabs for rRT-PCR and virus isolation, and plasma to screen for maternal AIV antibodies. AIV was not detected in any individual by virus isolation; however, maternal antibodies to AIV were detected in 95% of nestlings, with varying rates of catabolism. These results confirm that nestlings are afforded maternal antibodies from adults at rates reflective of higher adult seroprevalence than previously documented and that nestlings in breeding colonies may have some degree of protection and are unlikely to become infected with AIV.

Irruptive White Ibis breeding is associated with use of freshwater crayfish in the coastal Everglades

As avian reproductive success is generally prey limited, identifying important prey types or sizes and understanding mechanisms governing prey availability are important objectives for avian conservation ecology. Irruptive White Ibis (Eudocimus albus) nesting at coastal colonies in the southern Everglades numbered over 100,000 nests in the 1930s. A century of drainage and altered hydrologic patterns reduced aquatic prey availability and eliminated large nesting events; nesting activity in recent decades has been typically less than 5% of historical peaks. Hydrologic restoration is expected to increase ibis nesting activity, but which prey types will support high nesting effort is less clear. In 2017 and 2018, we collected food boluses from White Ibis chicks at coastal colonies in Everglades National Park. We also monitored regional nesting activity from 1999 to 2018. In 2017, the region had 1,075 nests, typical of the past several decades; but in 2018, there were 30,420 nests, representing the highest recorded nesting activity in 87 yr. Prey composition varied between years; estuarine crabs dominated nestling boluses in 2017, while crayfish and fish were dominant prey in 2018. Crayfish, especially Procambarus alleni, were heavily exploited by ibis early in the 2018 breeding season, while fish were used more at the end. Crayfish abundances in wetlands near the colonies were higher prior to 2018, and more crayfish-producing short-hydroperiod wetlands remained available for ibis foraging in 2018. Our results support previous studies indicating that crayfish are important prey for breeding ibises and suggest that unprecedented, extensive flooding of seasonal wetlands promoted crayfish production and initiated the irruptive breeding in 2018. Our observations indicate that rehydration of the southern Everglades could restore ibis nesting activity at coastal colonies, but further investigations of hydrologic variation, crayfish production, and ibis foraging and nesting activity will be helpful to understand these dynamics and the importance of short-hydroperiod wetlands.

Foraging in Urban Environments Increases Bactericidal Capacity in Plasma and Decreases Corticosterone Concentrations in White Ibises

As humans continue to infringe on natural habitats, more animals are exposed to urbanization and its associated challenges. It is still unclear, however, whether the movement of animals into urban habitats negatively influences the health and/or survival of those animals, however those animals often experience shifts in resource availability, diet composition, and exposure to stimuli that are new and potentially stressful. Recently, white ibises (Eudocimus albus) have become increasingly common in urban habitats where they forage in close proximity to humans and even interact with them, collecting food handouts. We hypothesized that foraging in urban habitats would negatively impact measures of health, impair innate immunity, trigger elevated concentrations of corticosterone, and depress physiological responses to stressors in white ibises. We found that plasma from birds captured from urban sites had higher bactericidal capacity against Escherichia coli than those captured in natural sites. Additionally, adults captured in urban habitats had a significantly lower baseline corticosterone concentrations during the post-breeding season, and corticosterone responses to a handling challenge were lower for birds captured from urban sites during year 2 of the study. These results indicate that exposure to urban habitats impacts ibis health, though in the opposite direction of what was predicted.

Distribución y abundancia de las Aves Marinas residentes y migratorias en El Estero de la Comuna El Real, Provincia de Santa Elena

El estero de la Comuna El Real en la Provincia de Santa Elena – Ecuador, es utilizado como un sitio de descanso y alimentación por varias especies de aves marinas. El estudio permitió conocer la distribución y abundancia de las aves marinas residentes y migratorias mediante 35 monitoreos durante los meses de noviembre, diciembre del 2014 y enero del 2015. Se registraron 12 especies de aves con un total de 62020 ind., Fregata magnificens; 816 ind., Himantopus mexicanus; 182 ind., Anas bahamensis; 119 ind., Nictanassa violácea; 66 ind., Egretta thula; 57 ind., Actitis maculariu; 29 ind., Pelecanus occidentalis; 20 ind., Ardea alba; 15 ind., Platalea ajaja; 14 ind., Pelecanus thagus; 6 ind., Jacana jacana; 1 ind., Eudocimus albus. Los Índices de Simpson, Shannon Wiener y Pielou para noviembre 0,0344; 0,11; 0,0458, diciembre 0,04195; 0,132; 0,0573 y enero 0,04711; 0,1444; 0,0581, demostraron que el lugar de estudio es un hábitat poco diverso en cuanto a variedad de especies pero abundante para una sola especie de la familia Fregatidae cuyas agrupaciones fueron georreferenciadas a lo largo de las riberas del estero El Real. AbstractThe estuary of the El Real Commune in the Province of Santa Elena - Ecuador, is used as a resting and feeding site for several species of seabirds. The study allowed to know the distribution and abundance of resident and migratory seabirds through 35 monitoring during the months of November, December, 2014 and January, 2015. There were 12 species of birds with a total of 62020 ind., Fregata magnificens; 816 ind., Himantopus mexicanus; 182 ind., Anas bahamensis; 119 ind., Nictanassa violacea; 66 ind., Egretta thula; 57 ind., Actitis maculariu; 29 ind., Pelecanus occidentalis; 20 ind., Ardea alba; 15 ind., Platalea ajaja; 14 ind., Pelecanus thagus; 6 ind., Jacana jacana; 1 ind., Eudocimus albus. The Simpson, Shannon Wiener and Pielou Indexes for November 0.0344; 0.11; 0.0458, December 0.04195; 0.132; 0.0573 and January 0.04711; 0.1444; 0.0581, showed that the study site is a habitat that is not diverse in variety of species but abundant for a single species of the Fregatidae family whose groupings were georeferenced along the shores of the El Real estuary.Keywords: Sea birds, distribution, abundance, habitat, georeferencing.

Presencia y abundancia de aves que se reproducen en islas de la bahía de Mazatlán, Sinaloa, México

Registramos la presencia y abundancia de aves, así como el hábitat y temporalidad de la reproducción de especies en las islas Pájaros, Venados, Lobos, Hermano Norte y Hermano Sur, ubicadas en la bahía de Mazatlán. Realizamos siete recorridos entre noviembre de 2014 y mayo de 2015; además contábamos con información colectada en mayo de 2004. Observamos un total de 59 especies de aves, de las cuales 15 fueron reproductoras: Dendrocygna autumnalis (pijije ala blanca), Phaethon aethereus (rabijunco pico rojo), Sula leucogaster (bobo café), Pelecanus occidentalis (pelícano café), Ardea herodias (garza morena), Ardea alba (garza blanca), Egretta thula (garza pie dorado), Bubulcus ibis (garza ganadera), Nycticorax nycticorax (pedrete corona negra), Nyctanassa violacea (pedrete corona clara), Eudocimus albus (ibis blanco), Coragyps atratus (zopilote común), Haematopus palliatus (ostrero americano), Larus heermanni (gaviota ploma) y Falco peregrinus (halcón peregrino). Para P. aethereus y S. leucogaster no había reportes previos de reproducción en estas islas; además, confirmamos la anidación de L. hermanni. La isla Pájaros fue la que albergó el mayor número de especies reproductoras (10 especies). Pelecanus occidentalis fue la especie más abundante con un total de 1 559 individuos, seguido de Fregata magnificens (fragata magnífica) y Sula nebouxii (bobo pata azul) con 1 526 y 1 100 individuos, respectivamente; aunque para estas dos últimas especies no hubo registros de reproducción. Las islas se encuentran bajo protección, pero se requiere realizar monitoreos para establecer el estado y tendencias de las poblaciones de aves, así como los efectos de las perturbaciones por actividades humanas y por las especies introducidas.