NOTES ON THE DISTRIBUTION, REPRODUCTION AND DISPLAY OF THE ANDEAN TORRENT DUCK MERGANETTA ARMATA

McCracken³

2017

Preprint

Feathers are one of the defining characteristics of birds and serve a critical role in thermal insulation and physical protection against the environment. Feather structure is known to vary among individuals, and it has been suggested that populations exposed to different environmental conditions may exhibit different patterns in feather structure. We examined both down and contour feathers from two populations of male Torrent Ducks (Merganetta armata) from Lima, Peru, including one high-altitude population from the Chancay-Huaral River at approximately 3500 meters (m) elevation and one low-altitude population from the Chillón River at approximately 1500 m. Down feather structure differed significantly between the two populations. Ducks from the high-altitude population had longer, denser down compared with low-altitude individuals. Contour feather structure varied greatly among individuals but showed no significant difference between populations. These results suggest that the innermost, insulative layer of plumage (the down), may have developed in response to lower ambient temperatures at high elevations. The lack of observable differences in the contour feathers may be due to the general constraints of the waterproofing capability of this outer plumage layer.ResumenEl plumaje es una característica que define a las aves y cumple roles críticos en el aislamiento térmico y protección física del ambiente. Se sabe que la estructura de las plumas varía ente individuos, y se ha sugerido que poblaciones expuestas a diferentes condiciones ambientales pueden exhibir diferentes patrones en la estructura de las plumas. En este estudio se examinaron tanto el plumón como las plumas de contorno de machos adultos del Pato de los Torrentes (Merganetta armata) de dos poblaciones, una en el río Chancay-Huaral a 3,500 msnm y otra en el río Chillón a 1,500 msnm, ubicadas en Lima, Perú. La estructura de los plumones difiere significativamente entre las dos poblaciones. Los patos de la población a grandes elevaciones tienen plumones largos, y densos comparados con los individuos de las partes bajas. La estructura de las plumas de contorno varía ampliamente entre individuos pero no muestra diferencias significativas entre poblaciones. Estos resultados sugieren que las diferencias entre las capas interiores de aislamiento del plumaje (plumón), haberse desarrollado como respuesta en ambientes de bajas temperaturas a grandes elevaciones. En cambio la falta de detectables diferencias en las plumas de contorno puede ser debido a la constante selección en la capacidad impermeable de la capa de plumas exteriores.

Section: Discussionmentioning

confidence: 99%

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

Cheek

McCracken³

2017

Preprint

“…Historical and current field records show that two dry Andean regions serve as a disjunction between the distribution ranges of M. a. leucogenis and M. a. armata, probably due to the lack or extreme seasonality of torrential rivers in these regions (Conover, 1943;eBird, 2016;Fjeldså & Krabbe, 1990;Johnsgard, 2010;Johnson, 1963). One of these regions is located in the junction ( (Blisniuk, Stern, Chamberlain, Idleman, & Zeitler, 2005;Hartley, 2003;Rabassa, Coronato, & Martínez, 2011;Rabassa, Coronato, & Salemme, 2005;Zachos, Pagani, Sloan, Thomas, & Billups, 2001), the Arid Diagonal is defined by its dry climate and absence of glaciers, a defining feature dividing the Central Andes from Southern Andes and Patagonia ( Figure 1c; and Burniard, 1982;Seltzer, 1990).…”

Section: South American Arid or Dry Diagonalmentioning

confidence: 99%

“…Previous studies have reported seasonal altitudinal movements of torrent ducks, and these movements can be influenced by reproductive season, food availability, variation in the streamflow, and winter conditions, especially in the Southern Andes (Johnsgard, 1966;Johnson, 1963;Pernollet et al, 2012;Ramírez, Botero, & Kattan, 2014). Also during our banding activities in the Chillón River, we recovered two individuals that had moved at least 4 km along the river.…”

Section: Population Structure Among Rivers "Extended Family" Withimentioning

confidence: 99%

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

Lavretsky

Peters

et al. 2019

Ecology and Evolution

Aim To investigate the structure and rate of gene flow among populations of habitat‐specialized species to understand the ecological and evolutionary processes underpinning their population dynamics and historical demography, including speciation and extinction. Location Peruvian and Argentine Andes. Taxon Two subspecies of torrent duck (Merganetta armata). Methods We sampled 156 individuals in Peru (M. a. leucogenis; Chillón River, n = 57 and Pachachaca River, n = 49) and Argentina (M. a. armata; Arroyo Grande River, n = 33 and Malargüe River, n = 17), and sequenced the mitochondrial DNA (mtDNA) control region to conduct coarse and fine‐scale demographic analyses of population structure. Additionally, to test for differences between subspecies, and across genetic markers with distinct inheritance patterns, a subset of individuals (Peru, n = 10 and Argentina, n = 9) was subjected to partial genome resequencing, obtaining 4,027 autosomal and 189 Z‐linked double‐digest restriction‐associated DNA sequences. Results Haplotype and nucleotide diversities were higher in Peru than Argentina across all markers. Peruvian and Argentine subspecies showed concordant species‐level differences (ΦST mtDNA = 0.82; ΦST autosomal = 0.30; ΦST Z chromosome = 0.45), including no shared mtDNA haplotypes. Demographic parameters estimated for mtDNA using IM and IMa2 analyses, and for autosomal markers using ∂a∂i (isolation‐with‐migration model), supported an old divergence (mtDNA = 600,000 years before present (ybp), 95% HPD range = 1.2 Mya to 200,000 ybp; and autosomal ∂a∂i = 782,490 ybp), between the two subspecies, characteristic of deeply diverged lineages. The populations were well‐differentiated in Argentina but moderately differentiated in Peru, with low unidirectional gene flow in each country. Main conclusions We suggest that the South American Arid Diagonal was preexisting and remains a current phylogeographic barrier between the ranges of the two torrent duck subspecies, and the adult territoriality and breeding site fidelity to the rivers define their population structure.

“…In South America, 3 subspecies of the torrent duck ( Merganetta armata ) inhabit many of the rivers in the west and the east slopes along the Andes Mountains from northwestern Venezuela to southern Chile and Argentina (Conover ). These ducks are small‐bodied diving ducks (350–550 g) that feed primarily on benthic macro‐invertebrates (Johnson , Alvarez et al ) and nest in cliffs, rocks, and tree cavities adjacent to the rivers (Conover , Johnson , Moffet ). Torrent ducks are one of the most difficult species to capture alive for study purposes because of their avoidance behavior and the torrential rivers they inhabit (Johnsgard , Cardona and Kattan ).…”

mentioning

confidence: 99%

“…Their natural environment consists mostly of fast‐flowing water, which may be extremely difficult to cross, and in some areas, delimited by inaccessible thick riverine vegetation. However, strong territorial and philopatric behaviors throughout their elevational and latitudinal distribution facilitate the capture and recapture of individuals (Johnson , Johnsgard ).…”

mentioning

confidence: 99%

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

Bautista²,

Smith

et al. 2017

Wildl. Soc. Bull.

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.