Birds of Two Oceans? Trans-Andean and Divergent Migration of Black Skimmers (Rynchops niger cinerascens) from the Peruvian Amazon

We are grateful for assistance from John Terborgh, Antonio Guerra Rosas, Marcos Maguiña, Inés Nole, John Takekawa, Lisa Ferguson, Juan Kapeshi, Nikanor Kapeshi, Cathy Bykowsky, Chi (Tim) Lam, Scott Robinson, Fabrice Schmitt, and Cesar Flores. Alex Jahn, Ugo Mellone, Sergio Lambertucci and one anonymous reviewer provided comments that helped improve the manuscript.Seasonal flooding compels some birds that breed in aquatic habitats in Amazonia to undertake annual migrations, yet we know little about how the complex landscape of the Amazon region is used seasonally by these species. The possibility of trans-Andes migration for Amazonian breeding birds has largely been discounted given the high geographic barrier posed by the Andean Cordillera and the desert habitat along much of the Pacific Coast. Here we demonstrate a trans-Andes route for Black Skimmers (Rynchops niger cinerascens) breeding on the Manu River (in the lowlands of Manu National Park, Perú), as well as divergent movement patterns both regionally and across the continent. Of eight skimmers tracked with satellite telemetry, three provided data on their outbound migrations, with two crossing the high Peruvian Andes to the Pacific. A third traveled over 1800 km to the southeast before transmissions ended in eastern Paraguay. One of the two trans-Andean migrants demonstrated a full round-trip migration back to its tagging location after traveling down the Pacific Coast from latitude 9° South to latitude 37° S, spending the austral summer in the Gulf of Arauco, Chile. This is the first documentation of a trans-Andes migration observed for any bird breeding in lowland Amazonia. To our knowledge, this research also documents the first example of a tropical-breeding waterbird migrating out of the tropics to spend the non-breeding season in the temperate summer, this being the reverse pattern with respect to seasonality for austral migrants in general.Yeshttp://www.plosone.org/static/editorial#pee

Ground-nesting birds in a changing climate: case studies of proximate behavioral mechanisms used by skimmers and terns to address seasonal variation in resources

Understanding how species will adapt to anthropogenic climate change is one of the greatest challenges for ecologists and evolutionary biologists. For organisms with low dispersal abilities, rapid adaptation will often be critical for survival. Some species, primarily microorganisms and invertebrates with short generation times, might be able to adapt to changing environmental conditions or evolve in response to climate change. For species with longer generation times, the unusual rate and extent of anthropogenic alterations of the environment may exceed the capacity of mechanisms that populations have evolved to deal with environmental change. It has been posited that behavioral plasticity can reduce exposure to selective pressures and shield population from climate extremes. For this dissertation, I focus upon behavioral mechanisms that are used by individuals and populations to mitigate selective influences upon reproduction. Specifically, the chapters in this dissertation focus on dietary plasticity, alteration in parental reproductive strategies, and seasonal alteration in migration strategies. Combined, the three chapters provide support that phenotypic plasticity in behavior can be an important mechanism used address varying selective pressures in changing environments for longer lived species such as the Black Skimmer and Gull-billed Tern. For dietary generalists, having a degree of opportunism is valuable in changing climates where food resources are vulnerable to changing climactic conditions. Having the ability to alter parental investment, in the form of nest attendance and offspring provisioning can influence offspring survival by accelerating the advancement of offspring to the next developmental stage. And by adjusting migration strategies, individuals can control investment in time and energy allocation which thereby influences both reproduction and individual survival

Long-distance movements of Black Skimmers tagged in Manu National Park, Perú, 2012–2014.

<p>Tracks of 8 skimmers tagged in Manu National Park with arrows denoting received locations and direction of travel. Pacific coast stopovers used by Manuel (orange track) for >48 h noted with green stars. Created with ESRI ArcGIS 10.2.2 software. Basemap data sources include: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community.</p

Regional movements of Black Skimmers from Manu National Park.

<p>Movements during the breeding season in the region of our two tagging sites: 1) the Cocha Cashu Biological Station (EBCC); and 2) Playa Garza, on the Manu River. Created with ESRI ArcGIS 10.2.2 software. Basemap data sources include: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community.</p

Trans-Andes migration routes used by two Manu Black Skimmers.

<p>Routes of Manuel (orange) and Vicky (pink) depict the varied routes used for the 3 Andean crossings tracked for two skimmers. Created with ESRI ArcGIS 10.2.2 software. Basemap data sources include: DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community.</p

Biparental incubation behaviour under temperature extremes in sandbank nesting black skimmers

Abstract Birds nesting on riverine beaches are exposed to large temperature fluctuations, while changing water levels pose flooding risks. We used miniature temperature loggers (iButtons®) placed in nests and on the beach surface combined with time‐lapse photography to study incubation behaviour in the black skimmer (Rynchops niger) on the Manu River, Peru. Since the species exhibits sexual size dimorphism, we could identify partner switches in images and the contribution to incubation effort by each pair member. Results of the study documented that nest temperature was less affected by ambient temperature and fluctuated less than the surroundings. Despite shorter incubation bouts at midday, black skimmers maintained a close to constant presence at the nest by more frequent nest exchanges. In fact, while female black skimmers generally incubated more and for longer than males, pairs shared incubation most consistently during the hottest part of the day. Incubation probability decreased around dusk, a peak foraging time for the species and a time when beach temperature overlapped with nest temperature. A biparental incubation strategy across the diel cycle appears to allow black skimmers breeding at the Manu River to incubate in challenging thermal conditions, but further studies are needed to determine proximity to thermal limits