Elizabeth Forys

Black Skimmers (Rynchops niger) are sexually monochromatic seabirds that are dimorphic in size. Although most dimorphic seabird adults can be accurately sexed using non-invasive techniques, determining the sex of pre-fledglings is more challenging. Schew and Collins (1990) developed an equation to estimate chick age from wing chord and used body mass of chicks ≥ 24 days old to evaluate the sex of skimmers in California; however, this was not verified on known-sexed individuals. Our objective was to assess the accuracy of their methodology on banded skimmer chicks from southwest Florida whose sexes were confirmed during adulthood. Out of 32 skimmers, Schew and Collins' (1990) method only classified 44% of males and 81% of females correctly. While males on average were larger than females, there was considerable overlap between the sexes when measurements of body mass, culmen and tarsus length were plotted against wing chord. It appears our Florida chicks grow slower than those in the California study and do not asymptote until after they are flight capable. As Black Skimmer populations decline, further research is needed to determine the most effective chick sexing method as knowledge of survival rates of pre-fledglings by sex will be critical for evaluating management efforts.

Simple SummaryThis research studied three species of imperiled shorebirds—Piping Plover, Snowy Plover, and Wilson’s Plover—that are similar in appearance and share habitats outside the breeding season. Researchers counted the number of these birds on a barrier island in Southwest Florida and examined how tide and wind affected their abundance and foraging behavior. They found that all three species were more likely to be found on the mudflats during lower tides and on the beach during higher tides. All of the feeding observed was on the mudflat, but one of the species, Wilson’s Plovers, was never observed feeding during the study. The high densities of these plover species are likely due to the mudflat habitat that provides more food, a beach habitat that provides a relatively safe location to roost, and the location of the barrier island, which is surrounded by other good places to forage and rest. While each species used the barrier island’s habitats slightly differently, the high densities of all three species present an opportunity to have a large conservation impact by protecting this dynamic area.AbstractPiping Plover (Charadrius melodus), Snowy Plover (Charadrius nivosus), and Wilson’s Plover (Charadrius wilsonia) are imperiled species that overlap in both their range and habitat outside the breeding season. The purpose of this research was to document the abundance of these species at a barrier island in Southwest Florida, USA, and to examine the influence of tide and wind on both their abundance and foraging. We walked ~700 m surveys through tidal mudflat and adjacent beach semiweekly at 0730–1030 from 24 September 2021–4 March 2022. During these 38 surveys, Piping Plovers were the most abundant of the three species, and the average number counted was 34 (SD 17.3) compared with 11 (SD 6.3) Snowy Plovers and 14 (SD 14.1) Wilson’s Plovers. All of the species were more likely to be found on the mudflats during low tides and the beach during high tides. Our findings suggest the high densities of Piping, Snowy, and Wilson’s Plover are due to a mudflat habitat that provides high availability of prey, a beach habitat that provides a relatively safe location to roost, and the context of the barrier island, which is surrounded by other suitable habitats. While each species used the barrier island’s habitats slightly differently, the high densities of all three species present an opportunity to have a large conservation impact by protecting this dynamic area.

Abstract Sound management of coastal bird populations depends on detailed knowledge of where individuals move after dispersal from their natal colonies. This study tracked the movement of Black Skimmer (Rynchops niger niger) chicks after they fledged from two important colonies on the Gulf of Mexico (in Pinellas and Collier counties of southern Florida, USA). A total of 35 flight-capable chicks approximately 3 weeks old were fitted with digitally-encoded VHF “nanotags” during July–August of the 2017 and 2018 breeding seasons. Chicks were followed with manual telemetry, automated tracking via the Motus Network, and systematic band resighting. Nanotags stayed attached for a mean minimum of 21 days, and chicks remained at their natal colony for a minimum of 24 days after being tagged. Only 10% of tags were deemed to be detected by Motus towers and all of those detections were dismissed as false positives. Band resightings demonstrated exchange of fledglings between colonies, with the furthest known movement being 370 km from St. Pete Beach to Key West. This paper documents inter-colony movement of skimmer chicks, shares lessons about the use of automated telemetry, and helps to frame questions for future research about regional movement patterns to support conservation of this colonial waterbird. Keywords breeding, Caribbean, colonial waterbird, dispersal, Florida, Motus, Rynchopinae, Rynchops niger Resumen Conocimientos obtenidos a partir de los intentos de rastrear el movimiento de volantones de Rynchops niger en el sur del Golfo de México con telemetría automatizada y reavistamiento de anillos • El manejo adecuado de las poblaciones de aves costeras depende del conocimiento detallado de los lugares a los que se desplazan los individuos tras la dispersión desde sus colonias de origen. En este estudio se realizó un seguimiento de los movimientos de los pichones de Rynchops niger niger después de que abandonaron dos colonias importantes en el Golfo de México (en los condados de Pinellas y Collier, en el sur de Florida, EE. UU.). Durante julio y agosto de las temporadas reproductivas de 2017 y 2018, un total de 35 pichones capaces de volar, de aproximadamente 3 semanas de edad, fueron equipados con "nanoetiquetas" VHF codificadas digitalmente. Los pichones fueron seguidos con telemetría manual, seguimiento automatizado a través de la red Motus y reavista- miento sistemático de anillos. Las nanoetiquetas permanecieron adheridas durante una media mínima de 21 días, y los pichones permanecieron en su colonia natal durante un mínimo de 24 días después de haber sido marcados. Sólo el 10% de las marcas fueron detectadas por las torres Motus y todas esas detecciones fueron descartadas como falsos positivos. Los reavistamientos de anillos demostraron el intercambio de volantones entre colonias, siendo el movimiento más lejano conocido de 370 km, desde St. Pete Beach hasta Cayo Hueso. Este artículo documenta el movimiento de pichones de esta especie entre colonias, comparte lecciones sobre el uso de la telemetría automatizada y ayuda a formular preguntas para futuras investigaciones sobre patrones de movimiento regional para apoyar la conservación de esta ave acuática colonial. Palabras clave ave acuática colonial, Caribe, cría, dispersión, Florida, Motus, Rynchopinae, Rynchops niger Résumé Aperçu des essais de suivi des déplacements de jeunes Becs-en-ciseaux noirs (Rynchops niger) après l’envol dans le sud du golfe du Mexique par télémétrie automatisée et lecture de bagues • Une bonne gestion des populations d’oiseaux côtiers dépend de la connaissance détaillée des lieux vers lesquels les individus se dispersent après avoir quitté leur colonie natale. Cette étude a permis le suivi des déplacements de jeunes Becs-en-ciseaux noirs (Rynchops niger niger) après leur envol de deux importantes colonies du golfe du Mexique (dans les comtés de Pinellas et Collier, au sud de la Floride, aux États-Unis). Au total, 35 jeunes volants, âgés d’environ 3 semaines, ont été équipés de « nanoémetteurs » VHF codés numériquement, au cours de la saison de reproduction, en juillet-août 2017 et 2018. Ils ont été suivis par télémétrie manuelle, par suivi automatisé via le réseau Motus et par relecture systématique des bagues. Les nanoémetteurs sont restés fixés au moins 21 jours en moyenne, et les jeunes sont restés dans leur colonie d’origine au moins 24 jours après avoir été marqués. Seulement 10 % des émetteurs ont été détectés par les stations Motus et toutes ces détections ont été considérées comme de faux positifs. Les lectures de bagues ont démontré l’échange de jeunes entre les colonies, le plus long déplacement connu étant de 370 km de St Pete Beach à Key West. Cet article présente des données sur les déplacements de jeunes Bec-en-ciseaux entre les colonies, partage des enseignements tirés de l’utilisation de la télémétrie automatisée, et aide à formuler des questions pour les recherches futures sur les modèles de déplacements régionaux visant à soutenir la conservation de cet oiseau d’eau colonial. Mots clés Caraïbes, dispersion, Floride, Motus, oiseau d’eau colonial, reproduction, Rynchopinae, Rynchops niger

Understanding dispersal patterns in a species provides important evolutionary and ecological knowledge. Dispersal decreases inbreeding, which can greatly influence a species’ genetic diversity and conservation status. We examined natal dispersal sex differences in a southwest Florida population of Black Skimmers (Rynchops niger) by collecting band resighting data from 86 (57 males, 29 females) skimmers during the 2017–2022 breeding seasons. We examined sex biases in the proportion of natal dispersers and the distances traveled from their natal colonies. The majority of skimmers dispersed (72% of females, 61% of males), however, no statistically significant difference was found between the proportion or distance traveled between the sexes. As beach habitat becomes fragmented by development and sea level rise, the ability of both sexes to disperse may benefit both Black Skimmer genetics and demographics in a changing world.

Extreme weather events, particularly heavy rainfall, are occurring at greater frequency with climate change. Although adverse human health effects from heavy rainfall are often publicized, impacts to free-ranging wildlife populations are less well known. We first summarize documented associations of heavy rainfall on wildlife health. We then report a novel investigation of a salmonellosis outbreak in a colony of black skimmers (Rynchops niger) in Florida, USA. During June-September 2016, heavy rainfall resulted in the discharge of millions of gallons of untreated wastewater into the Tampa Bay system, contaminating the water body, where adult skimmers foraged. At least 48 fledglings died, comprising 39% of the colony's nesting season's offspring. Of eight examined deceased birds from the colony, six had a systemic salmonellosis infection. Isolates were identified as Salmonella enterica serotype Typhimurium. Their pulsed-field gel electrophoresis patterns were identical to each other and matched those from several human Salmonella sp. infections. Differences among whole-genome sequences were negligible. These findings and the outbreak's epidemic curve suggest propagated transmission occurred within the colony. A multidisciplinary and One Health approach is recommended to mitigate any adverse effects of climate change-driven stochastic events, especially when they place already imperiled wildlife at further risk.

Infanticide, which is the killing of dependent offspring, occurs in many species of colonial seabirds. Most infanticide attempts are made when chicks wander outside their parents' territories and are more likely to occur when the colony experiences a disturbance or food is limited. Our objective was to determine the rate of infanticide at three Black Skimmer Rynchops niger colonies located on highly urbanized beaches in Pinellas County, Florida, USA. Infanticide occurred 42 times during 3 223 hours of monitoring (0.013 attempts per hour) over four breeding seasons (2018-2021). More than one third of the infanticide attempts occurred after a disturbance, and most of the attackers were not the chick's parents. However, in 10 attempts, parents were observed killing or attempting to kill their own chicks, and these attacks were primarily at a colony experiencing high stress due to coyote Canis latrans predation. We recommend reducing disturbance through a robust bird stewardship program and targeted predator management to reduce infanticide at Black Skimmer colonies in human-dominated ecosystems.