Shorebirds

It is well established that once birds have laid their eggs they sometimes incubate non-egg objects. However, reports of birds incubating solely non-egg objects (without prior manipulation by researchers) are rare. Here we report on our observation of a Long-billed Dowitcher Limnodromus scolopaceus incubating a clutch composed entirely of mammalian bones. To our knowledge, this is the first report on (a) incubation of foreign objects in Scolopacidae, (b) incubation of a ‘clutch’ composed entirely of bones, and (c) incubation of foreign objects in a nest atypical for this species in both construction and nest habitat. We discuss possible explanations for this presumably maladaptive behaviour.

Se presentan los resultados del Censo Neotropical de Aves Acuáticas de Venezuela (CNAAV) realizado durante el 2018. El censo se realizó del 03 al 18 de febrero y del 07 al 22 de julio. Se contó con la participación de 31 censistas que visitaron 31 localidades de nueve estados. Se registraron 52 especies residentes, nueve especies residentes con poblaciones migratorias y 21 especies migratorias neárticas, para un total de 93.422 individuos (16.057 en febrero y 77.365 en julio) pertenecientes a 22 familias y nueve órdenes. Como en años anteriores, las especies más abundantes fueron la cotúa (Phalacrocorax brasilianus) y el flamenco (Phoenicopterus ruber). Cuando se compararon estas abundancias con años anteriores se observó una tendencia a la disminución. Entre las especies migratorias, las más abundantes fueron el playerito semipalmeado (Calidris pusilla), el playerito menudo (C. minutilla) y el playero acollarado (Charadrius semipalmatus). Resalta el avistamiento de la gaviota dorsinegra menor (Larus fuscus), previamente reportada solo una vez en el CNAAV. En cuanto a las localidades, Produsal (ahora llamada Salina Solar Los Olivitos, Sitio Internacional de la RHRAP), fue la que presentó mayor abundancia de aves en febrero; para julio lo fue el Refugio de Fauna Silvestre y Reserva de Pesca de los Olivitos, ambas en el estado Zulia. La localidad con mayor riqueza en febrero fue el Sector Adícora (Falcón), mientras que en julio fue la Bahía El Saco en la Isla de Coche. *English version* Neotropical Waterbird Census in Venezuela 2018 / This paper shows the 2018 Venezuelan Neotropical Waterbird Census (CNAAV) results. Surveys were conducted from February 03 to 18 and from July 07 to 22. Survey participants were 16 volunteers that visited 31 localities in nine states. A total of 52 resident species were recorded, as well as nine resident species with migratory populations and 21 Nearctic migrants, accounting 93,422 individuals (16,057 in February; 77,365 in July), belonging to 22 families and nine orders. As in previous years, the most abundant species were the Neotropical Cormorant (Phalacrocorax brasilianus) and the American Flamingo (Phoenicopterus ruber). When their abundances were compared to previous years, a decreasing tendency was noted. From migratory species, the most abundant were the Semipalmated Sandpiper (Calidris pusilla), the Least Sandpiper (C. minutilla), and the Semipalmated Plover (Charadrius semipalmatus). Sighting of the Lesser Black-backed Gull fuscus is noteworthy, reported only once in previous CNAAV. About localities, Produsal (now called Salina Solar Los Olivitos, a focal site of Western Hemisphere Shorebird Reserve Network) harbored the greatest abundance of birds in February, and Refugio de Fauna Silvestre y Reserva de Pesca Ciénaga de los Olivitos in July, both in Zulia state. The locality with the highest richness was Adícora Sector (Falcón) in February, and El Saco Bay on Coche island in July.

Red Knots Calidris canutus roselaari occur along the Pacific coast of the Americas and may use as few as four stopover or staging sites during spring migration. There are key information gaps regarding this population’s status and non-breeding distribution because of its localized distribution during migration, relatively small population size (estimated population of 17,000) and a poor understanding of the location of major overwintering sites. Based on resightings of marked birds, we assessed migratory connectivity of Red Knots along the Pacific coast. Knots captured and marked at two sites in NW Mexico have been observed at several locations, including migration areas in coastal Washington and the Yukon-Kuskokwim Delta in W Alaska and breeding areas in NW Alaska. The greatest connectivity was between Guerrero Negro/Ojo de Liebre and Golfo de Santa Clara, Mexico, and during northbound migration, between those two sites and coastal Washington, USA. Much less is known about the sout...

""Aim: Conservation managers designate significant areas for shorebirds based on imperfect data. Significant wetlands for migratory shorebirds have usually been identified on the basis of whether they exceed certain thresholds, defined either by total abundance (usually 20,000 waterbirds) or percentage of a population (usually 1.0%). We evaluate the performance of existing criteria and determine if lowering thresholds would improve shorebird conservation without adding unreasonable numbers of significant sites.

Location: Australia.

Methods: We evaluated the best available data, which is used by managers to designate significant areas, to describe the effect of lowering thresholds on the number of significant sites identified and the number of shorebirds these sites support using a range of thresholds in existing criteria. We also investigated factors which may explain interspecific differences evident when lowering thresholds.

Results: When the threshold for total abundance was lowered from 20,000 to 2000 shorebirds, an additional 45 shorebird areas, holding 65% more shorebirds, were identified. When thresholds for the percentage of a population criterion were lowered from 1.0 to 0.1%, an additional 86 shorebird areas were identified which held 29% more shorebirds. The proportion of a species population counted within wetlands identified as significant by the application of criteria varied widely between species. The percentage of population criterion always identified a network of areas that included more individuals of each species than the total abundance criterion at all threshold levels tested. The percentage of species populations found in networks of significant areas showed greater increase as thresholds were lowered for species that were abundant, widespread and well represented at existing thresholds.

Main conclusions: Our results suggest lowering thresholds will substantially increase the number of shorebirds in identified significant areas. However, some species will remain under-represented, partly because of interspecific differences in distribution and inadequate sampling of some shorebird habitats."""

Shorebirds (Charadriiformes) undergo rapid migrations with potential for long-distance dispersal (LDD) of plants. We studied the frequency of endozoochory by shorebirds in different parts of Europe covering a broad latitudinal range and different seasons. We assessed whether plants dispersed conformed to morphological dispersal syndromes. A total of 409 excreta samples (271 faeces and 138 pellets) were collected from redshank Tringa totanus, black-winged stilt Himantopus himantopus, pied avocet Recurvirostra avosetta, northern lapwing Vanellus vanellus, Eurasian curlew Numenius arquata and black-tailed godwit Limosa limosa in southwest Spain, northwest England, southern Ireland and Iceland in 2005 and 2016, and intact seeds were extracted and identified. Godwits were sampled just before or after migratory movements between England and Iceland. The germinability of seeds was tested. Intact diaspores were recovered from all bird species and study areas, and were present in 13% of samples overall. Thirteen plant families were represented, including Charophyceae and 26 angiosperm taxa. Only four species had an 'endozoochory syndrome'. Four alien species were recorded. Ellenberg values classified three species as aquatic and 20 as terrestrial. Overall, 89% of seeds were from terrestrial plants, and 11% from aquatic plants. Average seed length was higher in redshank pellets than in their faeces. Six species were germinated, none of which had an endozoochory syndrome. Seeds were recorded during spring and autumn migration. Plant species recorded have broad latitudinal ranges consistent with LDD via shorebirds. Crucially, morphological syndromes do not adequately predict LDD potential, and more empirical work is required to identify which plants are dispersed by shorebirds. Incorporating endozoochory by shorebirds and other migratory waterbirds into plant distribution models would allow us to better understand the natural processes that facilitated colonization of oceanic islands, or to improve predictions of how plants will respond to climate change, or how alien species spread.

The Numeniini is a tribe of 13 wader species (Scolopacidae, Charadriiformes) of which seven are Near Threatened or globally threatened, including two Critically Endangered. To help inform conservation management and policy responses, we present the results of an expert assessment of the threats that members of this taxonomic group face across migratory flyways. Most threats are increasing in intensity, particularly in non-breeding areas, where habitat loss resulting from residential and commercial development, aquaculture, mining, transport, disturbance, problematic invasive species, pollution and climate change were regarded as having the greatest detrimental impact. Fewer threats (mining, disturbance, problematic native species and climate change) were identified as widely affecting breeding areas. Numeniini populations face the greatest number of non-breeding threats in the East Asian-Australasian Flyway, especially those associated with coastal reclamation; related threats were also identified across the Central and Atlantic Americas, and East Atlantic flyways. Threats on the breeding grounds were greatest in Central and Atlantic Americas, East Atlantic and West Asian flyways. Three priority actions were associated with monitoring and research: to monitor breeding population trends (which for species breeding in remote areas may best be achieved through surveys at key non-breeding sites), to deploy tracking technologies to identify migratory connectivity, and to monitor land-cover change across breeding and non-breeding areas. Two priority actions were focused on conservation and policy responses: to identify and effectively protect key non-breeding sites across all flyways (particularly in the East Asian-Australasian Flyway), and to implement successful conservation interventions at a sufficient scale across human-dominated landscapes for species' recovery to be achieved. If implemented urgently, these measures in combination have the potential to alter the current population declines of many Numeniini species and provide a template for the conservation of other groups of threatened species.

RESUMEN. Con el objetivo de evaluar los patrones de comportamiento del playero arenero Calidris alba (Scolopacidae), se realizaron observaciones entre el mes de agosto y septiembre de 2019 en el Humedal Costero Poza de la Arenilla (Callao, Perú). Cada sesión de observación tuvo una duración de 600 segundos (10 min.), con un tiempo total de observación de 40,200 segundos, aplicándose la técnica del "muestreo focal". Se identificaron 58 tipos de comportamiento agrupados en ocho categorías. Las cuatro principales categorías de comportamientos con relación al tiempo total de observación fueron: descanso (37 %), locomoción (26 %), acicalamiento (13 %) y forrajeo (11 %); otras categorías representan el 13 %. Además, con relación al tiempo total de observación priman cuatro comportamientos: descanso con pico entre las alas (15 %), descanso (13 %), corretear (13 %) y caminar (9 %). El conocimiento de los patrones de comportamiento de C. alba permite obtener información

Background: Geolocators are useful for tracking movements of long-distance migrants, but potential negative effects on birds have not been well studied. We tested for effects of geolocators (0.8–2.0 g total, representing 0.1– 3.9 % of mean body mass) on 16 species of migratory shorebirds, including five species with 2–4 subspecies each for a total of 23 study taxa. Study species spanned a range of body sizes (26–1091 g) and eight genera, and were tagged at 23 breeding and eight nonbreeding sites. We compared breeding performance and return rates of birds with geolocators to control groups while controlling for potential confounding variables. Results: We detected negative effects of tags for three small-bodied species. Geolocators reduced annual return rates for two of 23 taxa: by 63 % for semipalmated sandpipers and by 43 % for the arcticola subspecies of dunlin. High resighting effort for geolocator birds could have masked additional negative effects. Geolocators were more likely to negatively affect return rates if the total mass of geolocators and color markers was 2.5–5.8 % of body mass than if tags were 0.3–2.3 % of body mass. Carrying a geolocator reduced nest success by 42 % for semipalmated sandpipers and tripled the probability of partial clutch failure in semipalmated and western sandpipers. Geolocators mounted perpendicular to the leg on a flag had stronger negative effects on nest success than geolocators mounted parallel to the leg on a band. However, parallel-band geolocators were more likely to reduce return rates and cause injuries to the leg. No effects of geolocators were found on breeding movements or changes in body mass. Among-site variation in geolocator effect size was high, suggesting that local factors were important.

La mayoría de las aves playeras migratorias hacen uso de los humedales principalmente como zonas de alimentación; estos sitios están sujetos a diversas amenazas debido a que en ellos convergen varios intereses humanos. El noroeste de México es una región que presenta gran abundancia de aves playeras y forma parte del corredor migratorio del Pacífico; sin embargo, aún no se cuenta con información sistemática que proporcione las bases para identificar y priorizar los hábitats aptos para la alimentación de estas aves y que brinde herramientas para desarrollar estrategias de manejo. Debido a la extensión y complejidad de estos hábitats, las imágenes de satélite son una herramienta útil para ubicarlos y caracterizarlos. En este trabajo, describimos un marco metodológico para desarrollar modelos espaciales como herramienta para identificar humedales potenciales para la alimentación de aves playeras migratorias mediante el análisis de imágenes satelitales Landsat TM, sistemas de información geográfica y métricas de paisaje. Nuestros resultados muestran diferencias consistentes en la configuración espacial de los sitios identificados en la Península de Baja California y el macizo continental. Asimismo, muestran que los sitios continentales presentan una mayor conectividad y extensión, mientras que los sitios peninsulares presentan menor extensión y mayor aislamiento. Discutimos que los aspectos que contribuyen al grado de importancia de un sitio como zona de alimentación para estas aves son su extensión, el grado de agrupamiento de los parches de sustrato húmedo dentro en cada zona y la distancia entre zonas. Palabras clave: imágenes Landsat, SIG, humedales, métricas de paisaje, índice de humedad.