Redhead (Aythya americana)

Woodin, Marc C.; Michot, Thomas C.

doi:10.2173/bna.695

Cited by 9 publications

(8 citation statements)

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“…The association with croplandwoodland likely captures the high abundances in the aspen parkland. Like Canvasback, Redheads prefer deeper, more open water bodies (Woodin and Michot 2002), and they are more abundant in the parklands, despite a reported association with nonforested wetlands ).…”

Section: Variablementioning

confidence: 90%

Models to predict the distribution and abundance of breeding ducks in Canada

Barker¹,

Cumming²,

Darveau³

2014

ACE

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ABSTRACT. Detailed knowledge of waterfowl abundance and distribution across Canada is lacking, which limits our ability to effectively conserve and manage their populations. We used 15 years of data from an aerial transect survey to model the abundance of 17 species or species groups of ducks within southern and boreal Canada. We included 78 climatic, hydrological, and landscape variables in Boosted Regression Tree models, allowing flexible response curves and multiway interactions among variables. We assessed predictive performance of the models using four metrics and calculated uncertainty as the coefficient of variation of predictions across 20 replicate models. Maps of predicted relative abundance were generated from resulting models, and they largely match spatial patterns evident in the transect data. We observed two main distribution patterns: a concentrated prairie-parkland distribution and a more dispersed pan-Canadian distribution. These patterns were congruent with the relative importance of predictor variables and model evaluation statistics among the two groups of distributions. Most species had a hydrological variable as the most important predictor, although the specific hydrological variable differed somewhat among species. In some cases, important variables had clear ecological interpretations, but in some instances, e.g., topographic roughness, they may simply reflect chance correlations between species distributions and environmental variables identified by the model-building process. Given the performance of our models, we suggest that the resulting prediction maps can be used in future research and to guide conservation activities, particularly within the bounds of the survey area. Des modèles pour prédire la répartition et l'abondance des canards nichant au CanadaRÉSUMÉ. Le manque de connaissances détaillées sur l'abondance et la répartition des espèces de sauvagine dans l'ensemble du Canada limite notre capacité à conserver et à gérer leurs populations de façon efficace. Au moyen de 15 années de données provenant d'inventaires aériens réalisés par transects, nous avons modélisé l'abondance de 17 espèces ou groupes d'espèces de canards dans les parties méridionale et boréale du Canada. Nous avons inclus 78 variables relatives au climat, à l'hydrologie et au paysage dans des modèles amplifiés d'arbres de régression, pour lesquels des courbes de réponse flexibles et les interactions multidimensionnelles entre les variables ont pu être examinées. Nous avons évalué la capacité de prédiction des modèles à l'aide de quatre paramètres et avons estimé l'incertitude en calculant le coefficient de variation des prédictions d'un jeu de 20 répétitions de modèles. Des cartes de l'abondance relative prédite ont été produites à partir des modèles et elles correspondent bien au profil spatial des données récoltées dans les transects. Nous avons observé deux tendances principales dans la répartition : l'une centrée sur les Prairies et les forêts-parcs, l'autre plus dispersée à la grandeur du Canada. Ces ten...

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Section: Variablementioning

confidence: 90%

Models to predict the distribution and abundance of breeding ducks in Canada

Barker¹,

Cumming²,

Darveau³

2014

ACE

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“…This suggests at first that rhizomes in shallow beds of shoalgrass may have become depleted (Mitchell et al, 1994), making foraging at deeper sites relatively more profitable by late winter. By March, however, when most redheads have departed the winter range (Woodin & Michot, 2002), diving and tipping had reverted to levels first observed in early winter, and dipping remained low.…”

Section: Discussionmentioning

confidence: 88%

“…Redheads observed gleaning were seen feeding frequently in association with other dipping, tipping, or diving birds, usually other redheads or lesser scaup, Aythya affinis (Eyton). Presumably, the gleaning birds were exhibiting cooperative feeding on shoalgrass rhizomes brought to the surface by other foraging birds (Woodin & Michot, 2002).…”

Section: Discussionmentioning

confidence: 99%

“…Foraging flocks of redheads prefer shallow water (often only 12-30 cm deep), where the most commonly observed feeding behaviors are dipping and tipping (Mitchell, 1992;Mitchell et al, 1992). While redheads often forage by diving (Woodin & Michot, 2002), this is an energetically costly means of acquiring food (Lovvorn & Jones, 1991). Diving tufted ducks, Aythya fuligula (L.), for example, showed an average output of mechanical power nearly an order of magnitude greater (1.349 watt) than swimming tufted ducks (0.182 watt) (data from Stephenson et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

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Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

Woodin

Michot

2006

Hydrobiologia

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Redheads, Aythya americana, concentrate in large numbers annually in traditional wintering areas along the western and northern rim of the Gulf of Mexico. Two of these areas are the Laguna Madre of Texas and Chandeleur Sound of Louisiana. We collected data on 54,340 activities from 103 redhead flocks in Texas and 51,650 activities from 57 redhead flocks in Louisiana. Males and females fed similarly, differing neither in levels of feeding (percent of all birds in flock that were feeding) (p>0.90) nor in percentages of birds feeding by diving, tipping, dipping, or gleaning from the surface (p>0.10). The foraging level of redheads in the upper Laguna Madre region was relatively constant throughout two winters. Foraging of redheads in early winter in Louisiana was significantly greater than redhead foraging in the upper Laguna Madre, but by late winter, foraging by redheads in Louisiana had declined to the same level as that shown by redheads foraging in the upper Laguna Madre. The overall foraging level of redheads from Chandeleur Sound was greater (41%) than that of redheads in the upper Laguna Madre (26%), yet it was quite similar to the 46% foraging level reported for redheads from the lower Laguna Madre. Redheads in the upper Laguna Madre region of Texas fed more by diving than did those in the Chandeleur Sound and the lower Laguna Madre. Diving increased in frequency in late winter. Greater reliance by redheads on diving in January and February indicates that the birds altered their foraging to feed in deeper water, suggesting that the large concentrations of redheads staging at this time for spring migration may have displaced some birds to alternative foraging sites. Our results imply that the most likely period for food resources to become limiting for wintering redheads is when they are staging in late winter.

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“…The lower Texas coast is the most important wintering area for the redhead (Aythya americana), where up to 80% of the continent's population winters (Weller 1964, Michot 2000, Woodin and Michot 2002. During winter, redheads feed primarily on shoalgrass (Halodule wrightii) rhizomes in the Laguna Madre, a large ($1,500 km 2 ), hypersaline lagoon (Cornelius 1977, Michot et al 2008, Tunnel 2002.…”

mentioning

confidence: 99%

Impacts of wind turbines on redheads in the Laguna Madre

2018

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Freshwater ponds adjacent to the Laguna Madre along the lower Texas coast provide an important and heavily used source of fresh water for the redhead (Aythya americana) throughout winter. A 267‐turbine wind farm was constructed within the core wintering area of the redhead on a private ranch along the western coast of the Laguna Madre, in 2010. Our objective was to investigate the effects of this wind farm on the habitat and potential displacement of redheads and their use of coastal ponds along the lower Texas coast. We conducted weekly aerial surveys to monitor coastal pond use by wintering redheads from mid‐October through mid‐March during pre‐construction (2000–2003) and post‐construction (2012–2014) of the wind farm. Pond availability and Palmer Drought Severity Index (PDSI) within the wind farm were significantly correlated during pre‐construction (n = 16, R2 = 0.53, P = 0.035) and post‐construction (n = 11, R2 = 0.64, P = 0.003). However, the number of ponds available at each PDSI level within the wind farm decreased during post‐construction (paired t = 3.2, n = 5, P = 0.033). The average number of redheads detected per survey on coastal ponds within the wind farm decreased by 77% from pre‐construction to post‐construction. Redhead abundance on ponds across the entire Laguna Madre increased by an average of 3.26 times between pre‐construction and post‐construction, partly due to increases in the continental redhead population. It appears that the wind farm has altered the use of coastal ponds by redheads during winter. Future wind farm placement along the lower Texas coast should consider coastal pond distribution and the dynamics of redhead use between coastal ponds and foraging areas in the Laguna Madre. © 2018 The Wildlife Society.

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Redhead (Aythya americana)

Cited by 9 publications

References 0 publications

Models to predict the distribution and abundance of breeding ducks in Canada

Models to predict the distribution and abundance of breeding ducks in Canada

Foraging behavior of redheads (Aythya americana) wintering in Texas and Louisiana

Impacts of wind turbines on redheads in the Laguna Madre

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