Capture efficiency of torrent ducks by the active mist‐net method

Abstract

We report on the use and efficiency of an active mist-net method for capturing 3 subspecies of torrent ducks (Merganetta armata), a territorial and specialized South American waterfowl, in fast-moving rivers of the Andes Mountains. As an active process, the execution of this methodology required the presence of a well-trained, 3-person team. During the austral winter and spring between 2010 and 2014, we captured 372 torrent ducks in 410 capture events on 8 different rivers in Colombia (n ¼ 1), Peru (n ¼ 5), and Argentina (n ¼ 2). Each captured torrent duck was banded and 38 opportunistic recaptures events were obtained using the same methodology in the same territories. We deployed the mist nets across fast-moving deep rivers, along elevational gradients (680-4,200 m). Males were more easily captured than females, because of their greater tendency to fly. Our data validated this capture method for torrent ducks, as we succeeded in capturing individuals of the 3 subspecies in different habitats at different elevations and latitudes. To avoid animal mortality, we recommend application of this method only when 3 minimal conditions are met: 1) each field crew has !3 people; 2) all of the crew members have hand-radios to enable continuous communication; and 3) each crew member has received prior training (e.g., installation, inspection, manipulation, and removal of the mist net, bird extraction, and familiarity with the behavior of the torrent ducks). Ó 2017 The Wildlife Society.

Down Feather Structure Varies Between Low- and High-Altitude Torrent Ducks (MerganettaArmata) in the Andes

“…Torrent Ducks ( Merganetta armata ) are specialized riverine ducks that inhabit many of the rivers along the Andes from Venezuela to Tierra del Fuego (Fjeldså and Krabbe 1990). This species is characterized as a small bodied (350-550g; Alza et al 2017) diving forager that feeds primarily on aquatic insects by gleaning the surface of submerged boulders (Cerón 2010). M. armata form monogamous pairs and both sexes cooperate in the defense an approximate 1–2 kilometer stretch of river where they remain year round (Moffet 1970).…”

Old divergence and restricted gene flow between torrent duck (Merganetta armata) subspecies in the Central and Southern Andes

“…Blood samples were collected from 156 captured and released torrent ducks, during the 2010-2011 dry seasons, from two rivers in the western and eastern slopes of the Central Andes of Peru (Chillón River, n = 57 and Pachachaca River, n = 49; Table 1 and Figure 1b,c), and two rivers in the eastern slope of the southern Andes of Argentina (Arroyo Grande River, n = 32 and Malargüe River, n = 18; Table 1; Figure 1b,c). Each river was surveyed along an altitudinal transect (maximum range, 900-4,000 m) using an active mist net method by which torrent ducks were driven to nets (Alza et al, 2017). Blood samples (3 ml of whole blood per individual) were stored in liquid N 2 in the field before being placed in long-term storage at −80°C.…”

“…We hypothesize that these results are likely due to three nonmutually exclusive hypotheses: (1) Strong territoriality and breeding site fidelity in adults increase the similarity of the individuals within a river, (2) geographic (e.g., watershed boundary, high mountain ranges) or climatic barriers (e.g., large deserts) isolate rivers preventing the dispersal of the individuals, and driving an independent evolution of each riverine population by genetic drift, and (3) individual dispersal capacity (i.e., frequency and distance) describes an isolation-by-distance pattern that in short distance dispersal resembles a metapopulation model. For example, the year-round territorial behavior, the long-term pair bonds, and the strong site fidelity in adult torrent ducks, as mentioned in the first hypothesis, can prevent gene flow among rivers, but also contribute to the similarity of the individuals of a growing population in vacant or improved habitat, and thus increase the relatedness within each riverine population and develop an "extended family" (Alza et al, 2017;Cardona & Kattan, 2010;Eldridge, 1986;Hartl & Clark, 2007;Pernollet, Estades, & Pavez, 2012). Additionally, as referred in the second hypothesis, torrential river systems inside watersheds are analogous to islands (islands on mountain slopes) that isolate and sustain populations and communities (Black, 1997;Naiman, Magnuson, McKnight, Stanford, & Karr, 1995;Omernik & Bailey, 1997;Sullivan, Watzin, & Keeton, 2007), similarly observed in lakes (Barbour & Brown, 1974), marshes (Brown & Dinsmore, 1988), caves (Culver, Holsinger, & Baroody, 1973), mountaintops (Nores, 1995), or woodlots (Holland, 1978).…”

“…In the rivers occupied by torrent ducks, the adults show a high breeding site fidelity (Alza et al, 2017;Cardona & Kattan, 2010) to territories that reportedly range from 0.7 to 2 km during the breeding season (Cerón & Trejo, 2009;Colina, 2010;Eldridge, 1986;Johnsgard, 2010;Moffet, 1970;Naranjo & Ávila, 2003;Ubeda, Cerón, & Trejo, 2007). However, immature and adult individuals have been reported moving away from rivers likely searching for new habitats (i.e., four opportunistic records of male-biased dispersal ;Cerón & Capllonch, 2016).…”

Sobre la importancia de la certificación internacional para los anilladores de aves en Perú

“…Posteriormente, en el 2010 y durante el desarrollo de la cuarta conferencia del WHBBN en Brasil, se anunció la creación del Programa de Anillamiento CORBIDI (PAC) (Moreno et al 2011). En asociación con Porzana Ltd. y The Wetland Trust y con el financiamiento del Acta para la Conservación de las Aves Migratorias Neotropicales del Servicio de Pesca y Vida Silvestre de los Estados Unidos (NMBCA-USFWS), COR-BIDI logró obtener anillos y equipo que permitieron impulsar diversas investigaciones usando el anillamiento como herramienta para el monitoreo de aves silvestres en el Perú (Nolazco & Roper 2014, Tavera et al 2016, Díaz & Dimming 2017, Alza et al 2017, Guevara-Torres et al 2017, Díaz et al 2018. Se han realizado, además, simposios, disertación de tesis (Díaz 2015, Mandujano-Collantes 2016, Chumpitaz-Trujillo 2018, Antezana 2019, talleres y cursos de anillado, con el fin de promover el uso y resaltar la importancia del anillamiento para el estudio de aves silvestres.…”