Using Citizen Science and Field Surveys to Document the Introduction, Establishment, and Rapid Spread of the Bare-Eyed Pigeon, Patagioenas corensis, on the Island of Saint-Martin, West Indies.

Early reporting of the introduction and establishment of exotic species is of paramount importance for successful management. Here, we report the introduction and rapid spread of the Bare-eyed Pigeon, Patagioenas corensis, on the binational island of Saint-Martin, the West Indies. This range-restricted species naturally occurs in arid coastal areas of Columbia and Venezuela and nearby islands. Its introduction on Saint-Martin represents an expansion of about 1000 km beyond its established native range. Using observations recorded in eBird and results from a recent field survey, we show that since its introduction, most probably between late 2012 and early 2013, the species has expanded fast in Saint-Martin and has recently broadened its habitat to include anthropized, built areas. The expansion of Bare-eyed Pigeon on Saint-Martin and the neighboring Leeward Islands, possibly facilitated by climate change in the future, could be a threat to both native columbid species and other bird species through competition for resources. We therefore recommend that local authorities and stakeholders rapidly eradicate the species or at least prevent its further spread on Saint-Martin, possibly though listing it as a game species, while it is still possible to do so.

Integrating eDNA metabarcoding and citizen science enhances avian ecological research.

Research Highlight: Bourbour et al., 2024. Feeding en route: Prey availability and traits influence prey selection by an avian predator on migration. Journal of Animal Ecology. Diet selection plays a key role in the eco-evolutionary dynamics of animals, exhibiting substantial variability across species, environments and seasons. The complex interplay between movement capability, hunting strategies, habitat use, prey traits and availability shapes the foraging patterns of avian predators. However, detailed information on how these birds exploit their extensive territories remains limited. In this study, Bourbour et al. utilised a novel integration of eDNA metabarcoding and citizen science to explore predator-prey interactions between migrating sharp-shinned hawks (Accipiter striatus) and an ephemeral avian prey community along North America's Pacific flyway. The research identified 1396 detections from the diet (65 species) of 588 migrating sharp-shinned hawks. Hawks' diet composition correlated with prey abundance indices sourced from the eBird database throughout the migration season, highlighting the significant impact of prey availability-shaped by migration tendency, flocking behaviour, and habitat-on raptor-songbird interactions. Notably, the study also found significant differences in prey size between male and female hawks, indicating that sexual dimorphism has led to diverse foraging strategies during migration. These findings underscore the potential of combining eDNA metabarcoding with citizen science to deepen our understanding of the foraging ecology of highly mobile and wide-ranging birds, as well as to monitor complex and vast ecosystems.

Bicolored Hawk, Accipiter bicolor in Guayaquil city (Western Ecuador): new preys-species records and citizen science urban records

Accipiter bicolor is a widely distributed Neotropical raptor but knowledge about its ecology is poor, particularly in urban areas. In this work, we document the presence of A. bicolor in the city of Guayaquil and in nearby forested areas, in addition, we provide new records on its diet and discuss possible foraging strategies in synanthropic environments. Also, reports of this species are considered on citizen science platforms. Accipiter bicolor was observed consuming an individual of Columbina bluckeyi and another of Artibeus fraterculus; near a colony of this species of bat. Finally, we found 59 records of A. bicolor between 2007 and 2022 for Guayaquil and its surrounding areas, 14 records were in urban habitats. Observations in different urban and peri-urban habitats are discussed, as well as their feeding habits.

Accipiter bicolor es una rapaz Neotropical ampliamente distribuida pero el conocimiento sobre su ecología es escaso en particular en zonas urbanas. En este trabajo, documentamos la presencia de A. bicolor en la ciudad de Guayaquil y en áreas boscosas cercanas, además, proveemos nuevos registros sobre su dieta y discutimos posibles estrategias de forrajeo en ambientes sinantrópicas. También, se consideran reportes de esta especie en plataformas de ciencia ciudadana. Accipiter bicolor fue observada consumiendo un individuo de Columbina bluckeyi y otro de Artibeus fraterculus; cerca de una colonia de esta especie de murciélago. Finalmente, se encontraron 59 registros de A. bicolor entre el 2007 y 2022 para Guayaquil y sus áreas circundantes, 14 registros fueron en hábitat urbanos. Se discute las observaciones en diferentes hábitats urbanos y periurbanos, así como sus hábitos de alimenticios.

Integrating data types to estimate spatial patterns of avian migration across the Western Hemisphere.

For many avian species, spatial migration patterns remain largely undescribed, especially across hemispheric extents. Recent advancements in tracking technologies and high-resolution species distribution models (i.e., eBird Status and Trends products) provide new insights into migratory bird movements and offer a promising opportunity for integrating independent data sources to describe avian migration. Here, we present a three-stage modeling framework for estimating spatial patterns of avian migration. First, we integrate tracking and band re-encounter data to quantify migratory connectivity, defined as the relative proportions of individuals migrating between breeding and nonbreeding regions. Next, we use estimated connectivity proportions along with eBird occurrence probabilities to produce probabilistic least-cost path (LCP) indices. In a final step, we use generalized additive mixed models (GAMMs) both to evaluate the ability of LCP indices to accurately predict (i.e., as a covariate) observed locations derived from tracking and band re-encounter data sets versus pseudo-absence locations during migratory periods and to create a fully integrated (i.e., eBird occurrence, LCP, and tracking/band re-encounter data) spatial prediction index for mapping species-specific seasonal migrations. To illustrate this approach, we apply this framework to describe seasonal migrations of 12 bird species across the Western Hemisphere during pre- and postbreeding migratory periods (i.e., spring and fall, respectively). We found that including LCP indices with eBird occurrence in GAMMs generally improved the ability to accurately predict observed migratory locations compared to models with eBird occurrence alone. Using three performance metrics, the eBird + LCP model demonstrated equivalent or superior fit relative to the eBird-only model for 22 of 24 species-season GAMMs. In particular, the integrated index filled in spatial gaps for species with over-water movements and those that migrated over land where there were few eBird sightings and, thus, low predictive ability of eBird occurrence probabilities (e.g., Amazonian rainforest in South America). This methodology of combining individual-based seasonal movement data with temporally dynamic species distribution models provides a comprehensive approach to integrating multiple data types to describe broad-scale spatial patterns of animal movement. Further development and customization of this approach will continue to advance knowledge about the full annual cycle and conservation of migratory birds.

Differential reporting of biodiversity in two citizen science platforms during COVID-19 lockdown in Colombia.

The COVID-19 pandemic highlighted the potential of using data from long-term citizen science projects to answer questions about the impacts of unexpected events on biodiversity. We evaluate the suitability of data from the citizen science platforms iNaturalist and eBird to describe the effects of the "anthropause" on biodiversity observation in Colombia. We compared record distribution according to human footprint, sampling behaviors, overall and conservation priority species composition during the strictest phase of the COVID-19 lockdown in 2020 to the same periods in 2015-2019. Overall participation in both platforms during the lockdown was high when compared to previous years, but records were concentrated on highly-transformed regions, had lower sampling efforts, and fewer species were recorded. For eBird, species composition was similar to that observed in previous years, and records of species of conservation concern declined in proportion to the decrease in overall species richness across samples. For iNaturalist, the species pool sampled each year remained too dissimilar for comparisons. Once differences in observer behaviors are accounted for, data from these platforms can be used in unplanned comparisons of relatively common species, in regions with high levels of human transformation, and at narrowly defined geographical contexts. To increase the potential of citizen science to monitor rarer species, more natural areas, or be used in large-scale analyses, we need to build and strengthen more diverse networks of observers that can further promote decentralization, democratization, and cost-effectiveness in biodiversity research.

Citizen science data reveals the cryptic migration of the common potoo Nyctibius griseus in Brazil

The Common Potoo Nyctibius griseus is abundant, charismatic and generally considered to be sedentary across its range. Using citizen science data from eBird and WikiAves, we demonstrate that the Common Potoo may be a partial migrant whose breeding populations depart southeastern Brazil, Uruguay and northern Argentina in May to August during the region’s austral winter. MaxEnt models revealed that spatio‐temporal shifts in Common Potoo distributions were driven by seasonal changes in temperature and precipitation. We examined potential seasonal detection biases by restricting our analysis to daytime observations and testing for seasonally dependent shifts in distribution for two nocturnal non‐migratory species. Our results provide the first evidence of migration for any member of the family Nyctibiidae. Our approach exposes the potential value that WikiAves data offer towards elucidating seasonal movements of South American birds.

Holding steady: Little change in intensity or timing of bird migration over the Gulf of Mexico.

Quantifying the timing and intensity of migratory movements is imperative for understanding impacts of changing landscapes and climates on migratory bird populations. Billions of birds migrate in the Western Hemisphere, but accurately estimating the population size of one migratory species, let alone hundreds, presents numerous obstacles. Here, we quantify the timing, intensity, and distribution of bird migration through one of the largest migration corridors in the Western Hemisphere, the Gulf of Mexico (the Gulf). We further assess whether there have been changes in migration timing or intensity through the Gulf. To achieve this, we integrate citizen science (eBird) observations with 21 years of weather surveillance radar data (1995-2015). We predicted no change in migration timing and a decline in migration intensity across the time series. We estimate that an average of 2.1 billion birds pass through this region each spring en route to Nearctic breeding grounds. Annually, half of these individuals pass through the region in just 18 days, between April 19 and May 7. The western region of the Gulf showed a mean rate of passage 5.4 times higher than the central and eastern regions. We did not detect an overall change in the annual numbers of migrants (2007-2015) or the annual timing of peak migration (1995-2015). However, we found that the earliest seasonal movements through the region occurred significantly earlier over time (1.6 days decade-1 ). Additionally, body mass and migration distance explained the magnitude of phenological changes, with the most rapid advances occurring with an assemblage of larger-bodied shorter-distance migrants. Our results provide baseline information that can be used to advance our understanding of the developing implications of climate change, urbanization, and energy development for migratory bird populations in North America.

Navigating north: how body mass and winds shape avian flight behaviours across a North American migratory flyway.

The migratory patterns of birds have been the focus of ecologists for millennia. What behavioural traits underlie these remarkably consistent movements? Addressing this question is central to advancing our understanding of migratory flight strategies and requires the integration of information across levels of biological organisation, e.g. species to communities. Here, we combine species-specific observations from the eBird citizen-science database with observations aggregated from weather surveillance radars during spring migration in central North America. Our results confirm a core prediction of migration theory at an unprecedented national scale: body mass predicts variation in flight strategies across latitudes, with larger-bodied species flying faster and compensating more for wind drift. We also find evidence that migrants travelling northward earlier in the spring increasingly compensate for wind drift at higher latitudes. This integration of information across biological scales provides new insight into patterns and determinants of broad-scale flight strategies of migratory birds.

Global change and the distributional dynamics of migratory bird populations wintering in Central America.

Understanding the susceptibility of highly mobile taxa such as migratory birds to global change requires information on geographic patterns of occurrence across the annual cycle. Neotropical migrants that breed in North America and winter in Central America occur in high concentrations on their non-breeding grounds where they spend the majority of the year and where habitat loss has been associated with population declines. Here, we use eBird data to model weekly patterns of abundance and occurrence for 21 forest passerine species that winter in Central America. We estimate species' distributional dynamics across the annual cycle, which we use to determine how species are currently associated with public protected areas and projected changes in climate and land-use. The effects of global change on the non-breeding grounds is characterized by decreasing precipitation, especially during the summer, and the conversion of forest to cropland, grassland, or peri-urban. The effects of global change on the breeding grounds are characterized by increasing winter precipitation, higher temperatures, and the conversion of forest to peri-urban. During spring and autumn migration, species are projected to encounter higher temperatures, forests that have been converted to peri-urban, and increased precipitation during spring migration. Based on current distributional dynamics, susceptibility to global change is characterized by the loss of forested habitats on the non-breeding grounds, warming temperatures during migration and on the breeding grounds, and declining summer rainfall on the non-breeding grounds. Public protected areas with low and medium protection status are more prevalent on the non-breeding grounds, suggesting that management opportunities currently exist to mitigate near-term non-breeding habitat losses. These efforts would affect more individuals of more species during a longer period of the annual cycle, which may create additional opportunities for species to respond to changes in habitat or phenology that are likely to develop under climate change.

ANOTACIONES SOBRE LOS REGISTROS DEL VIREO VERDEAMARILLO (Vireo flavoviridis: Vireonidae) EN LA SABANA DE BOGOTÁ, CUNDINAMARCA (COLOMBIA) / Notes of Records about Yellow-Green Vireo (Vireo flavoviridis: Vireonidae) at the Sabana de Bogotá, Cundinamarca (Colombia)

El vireo verdeamarillo (Vireo flavoviridis) es una especie de ave migratoria que no cuenta con registros en literatura dentro del departamento de Cundinamarca. Adicionalmente, la distribución conocida de V. flavoridis en Colombia solo incluye localidades por debajo de 1500 msnm. Dos individuos de V. flavoviridis fueron vistos a 2600 msnm en el campus de Bogotá de la Universidad Nacional de Colombia, dentro de la Sabana de Bogotá del departamento de Cundinamarca en 2011. Posterior a consulta en colecciones y reportes de observadores de aves, encontramos 18 registros no publicados de la especie para el departamento de Cundinamarca por encima de 2500 msnm. Diez registros fueron a partir de colecciones científicas (Instituto de Ciencias Naturales de la Universidad Nacional de Colombia, Colección de Vertebrados (Ornitología) de la Universidad de los Andes y colección del Instituto de Investigación en Recursos Biológicos Alexander von Humboldt), y los otros ocho por reportes de observadores de aves. El primer registro fue en 1964, pero la mayoría de registros corresponden al período entre 2008 y 2013. Consideramos que V. flavoviridis ha pasado desapercibido en Cundinamarca por las similitudes morfológicas con el vireo ojirrojo (V. olivaceus). Además, la falta de revisión de colecciones científicas y un inconstante depósito de especímenes en ellas, genera un vacío de información sobre la distribución de la biodiversidad. Al parecer, V. flavoviridis puede ser más común de lo que se espera por encima de 1500 m durante migración, como ocurre para el departamento de Cundinamarca.

The Yellow-green Vireo (Vireo flavoviridis) is migrant bird specie, previously non reported to Cundinamarca Department. Distribution known in Colombia only includes localities below 1500 masl. Two individuals of the Yellow-green Vireo were observed at 2600 masl in the Universidad Nacional de Colombia Bogotá Campus, at the Sabana de Bogotá in Cundinamarca Department in 2011. In addition, we found 18 unpublished records for this species in the Cundinamarca Department above 2500 masl. Ten records were museum specimens (Instituto de Ciencias Naturales de la Universidad Nacional de Colombia, Vertebrate collection (Ornitology) Universidad de los Andes and Instituto de Investigación en Recursos Biológicos Alexander von Humboldt Museum), and the other eight were birdwatching records. The oldest record was in 1964, but the great majority of records were collected between 2008 and 2013. We consider that the Yellow-green Vireo has been unnoticed in the Cundinamarca Department because of its morphological similarities with the Red-eye Vireo (V. olivaceus). Furthermore, the lack of review of scientific collections, and the deposition of specimens discontinuous there, make gap information about biodiversity distribution. Apparently, Yellow-green Vireo could be more common than expected above 1500 m during its migration, such as it was observed in at Cundinamarca Department.