Age effects on Nazca booby foraging performance are largely constant across variation in the marine environment: Results from a 5-year study in Galápagos

Foraging outcomes dictate the nutritional resources available to an organism and may vary with intrinsic factors, like age. Thus, understanding how age affects foraging performance, alone or in interaction with extrinsic factors (like environmental quality), improves our understanding of aging processes in the wild. We examined how foraging traits, measured across five breeding seasons, change with age, environmental variation, and their interaction in Nazca boobies (Sula granti), a pelagic seabird in Galápagos. We evaluated the hypotheses that (1) foraging performance is better in middle-aged birds than in young ones, and that (2) foraging performance is better in middle-aged birds than in old ones. Furthermore, favorable environmental conditions will either (3) attenuate age differences in foraging performance (by relieving constraints on young, inexperienced and old, senescent age classes), or (4) accentuate age differences (if middle-aged birds can exploit abundant resources better than other age classes can). Incubating birds tagged with GPS loggers (N = 815) provided data on foraging performance (e.g., total distance traveled, mass gained) to evaluate interactions between age and environmental variation (e.g., sea surface temperature). Poor environmental conditions associated with the cool phase of the El Niño-Southern Oscillation increased foraging effort, including foraging distance and duration, for example. Across age classes, foraging boobies responded similarly to environmental variation except for female mass gain rate: age-related declines in mass gain rate were reduced under favorable environmental conditions. Birds of different ages also searched in somewhat distinct areas in the poor conditions of 2016, but not in other years. In several foraging traits, including foraging duration and distance, female boobies showed predicted early-life improvement and late-life decline, following the established pattern for reproductive traits in this species. Thus, deficits in resource acquisition (this study) may contribute to the poor survival and reproductive outcomes previously observed in old Nazca boobies, particularly in females.

Global COVID-19 lockdown highlights humans as both threats and custodians of the environment

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus, initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness.

Densidad y uso de hábitat de la pava caucana (Penelope perspicax) en los Farallones de Cali, Colombia

La pava caucana (Penelope perspicax) es un ave endémica de las laderas del valle geográfico del río Cauca en Colombia, considerada en peligro de extinción. La pérdida de hábitat y la cacería han sido sus principales amenazas, lo que ha generado la reducción y aislamiento de sus poblaciones. El objetivo de este estudio fue determinar la densidad poblacional en una localidad en los Farallones de Cali y desarrollar modelos de ocupación, para evaluar factores que expliquen el uso de hábitat de la especie. Obtuvimos una densidad de 9 ind.km-2, el valor más bajo de los estimados disponibles para la especie; además, encontramos una relación estrecha entre el área de cobertura boscosa y el uso del hábitat de la especie. Los resultados indican la necesidad de conservar los remanentes de bosque y mantener la conectividad, ya que a pesar de que la especie puede utilizar gran variedad de hábitats, la probabilidad de uso aumenta en relación a las áreas disponibles de bosque. Recomendamos que se aumenten los esfuerzos de muestreo en este núcleo poblacional, asegurando variabilidad temporal y espacial, con el fin de contar con mejor información para su manejo en este núcleo.

Aves del departamento del Valle del Cauca, Colombia

La avifauna del departamento del Valle del Cauca, Colombia, ha sido uno de los grupos biológicos mejor estudiados en Colombia desde finales del siglo XIX. Producto de estos ejercicios de compilación de información, los estimados de la riqueza de especies varían entre 818 y 1025 especies. Recopilamos información de registros de aves de diferentes fuentes y obtuvimos un listado de 989 especies de aves confirmadas para el departamento y 13 especies que fueron catalogadas como potencialmente presentes. Documentamos ocho especies introducidas que no tienen registros publicados o son anecdóticos en Colombia. Futuras expediciones o investigaciones deberían enfocarse en llenar los vacíos de información de aves que se concentran en el cañón del río Garrapatas, y el área al sur de Buenaventura y la cordillera Central.

Variación poblacional de tres especies de piqueros (Suliformes: Sulidae) en isla Gorgona, Pacífico colombiano, según la temperatura del mar

Introducción: La alteración de la temperatura del ambiente pelágico puede repercutir en la variación poblacional de los consumidores tope como las aves marinas. Objetivo: Evaluar la respuesta poblacional de tres especies de piqueros en isla Gorgona (Pacífico colombiano) con respecto a la variabilidad local y regional de las condiciones de temperatura superficial del mar (TSM). Métodos: Se analizaron las tendencias mensuales de la abundancia de Sula leucogaster, Sula nebouxii y Sula variegata en relación a la variación de la TSM en el área de influencia de Gorgona, la región de San José en la costa del Perú y la región Niño 1+2. Resultados: La mayor correlación positiva se presentó entre S. nebouxii y S. variegata con la TSM de la región Niño 1+2, con un desfase de cuatro y cinco meses, respectivamente. Este desfase temporal posiblemente corresponde al tiempo que demora su migración entre la costa peruana y Gorgona. En contraste, la abundancia de S. leucogaster disminuyó al aumentar la TSM mensual de Gorgona. Conclusiones: Es probable que las tendencias descritas estén relacionadas con la disminución de la productividad y disponibilidad de presas asociadas con temperaturas más cálidas en estas áreas. Se sugiere que la TSM puede influir sobre las tendencias de abundancia de los tres piqueros, y su continuo monitoreo permitirá mejorar el conocimiento sobre la variación natural de estas poblaciones.

Comparative phylogeography of brown (Sula leucogaster) and red-footed boobies (S. sula): the influence of physical barriers and habitat preference on gene flow in pelagic seabirds

To test the hypothesis that both physical and ecological barriers to gene flow drive population differentiation in tropical seabirds, we surveyed mitochondrial control region variation in 242 brown boobies (Sula leucogaster), which prefer inshore habitat, and 271 red-footed boobies (S. sula), which prefer pelagic habitat. To determine the relative influence of isolation and gene flow on population structure, we used both traditional methods and a recently developed statistical method based on coalescent theory and Bayesian inference (Isolation with Migration). We found that global population genetic structure was high in both species, and that female-mediated gene flow among ocean basins apparently has been restricted by major physical barriers including the Isthmus of Panama, and the periodic emergence of the Sunda and Sahul Shelves in Southeast Asia. In contrast, the evolutionary history of populations within ocean basins differed markedly between the two species. In brown boobies, we found high levels of population genetic differentiation and limited gene flow among colonies, even at spatial scales as small as 500km. Although red-footed booby colonies were also genetically differentiated within ocean basins, coalescent analyses indicated that populations have either diverged in the face of ongoing gene flow, or diverged without gene flow but recently made secondary contact. Regardless, gene flow among red-footed booby populations was higher than among brown booby populations. We suggest that these contrasting patterns of gene flow within ocean basins may be explained by the different habitat preferences of brown and red-footed boobies.

Western Sandpipers (Calidris Mauri) During the Nonbreeding Season: Spatial Segregation on a Hemispheric Scale

The nonbreeding distribution of Western Sandpipers (Calidris mauri) was documented using 19 data sets from 13 sites along the Pacific and Atlantic coasts of the Americas. Western Sandpipers showed latitudinal segregation with regard to sex and age. Females wintered farther south than males. A “U” shaped pattern was found with respect to age, with juveniles occurring at higher proportions at both the northern and southern ends of the range. Distribution of sexes might be affected by differences in bill length and a latitudinal trend in depth distribution of prey. For age class distribution, two different life-history tactics of juveniles might exist that are related to the higher cost of feather wear for juveniles compared to adults. Most juveniles complete three long-distance migrations on one set of flight feathers whereas adults complete two. Juveniles may winter either far north, thereby reducing feather wear induced by ultraviolet light, migration, or both, or far south and spend the summer on the nonbreeding area.