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Michel D. Houseman - One of the best experts on this subject based on the ideXlab platform.
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Fossil grebes from the Truckee Formation (Miocene) of Nevada and a new phylogenetic analysis of Podicipediformes (Aves)
Palaeontology, 2013Co-Authors: Daniel T. Ksepka, Amy M. Balanoff, Michael A. Bell, Michel D. HousemanAbstract:Podicipediformes is a cosmopolitan clade of foot-propelled diving birds that, despite inhabiting marine and lacustrine environments, have a poor fossil record. In this contribution, we describe three new grebe fossils from the diatomite beds of the Late Miocene Truckee Formation (10.2 ± 0.2 Ma) of Nevada (USA). Two postcranial skeletons and an associated set of wing elements indicate that at least two distinct grebe species occupied the large, shallow Lake Truckee during the Miocene. Phylogenetic analysis of morphological data supports a basal divergence between a clade uniting the dabchicks (Tachybaptus, Limnodytes, Poliocephalus) and a clade uniting Podilymbus, Rollandia, Podiceps and Aechmophorus. Missing data, combined with a paucity of informative skeletal characters, make it difficult to place the Truckee grebes within either of these major clades. Given the weak projection of the cnemial crests compared with extant grebes, it also remains plausible that these specimens represent stem lineage grebes. Although more material is needed to resolve the phylogenetic position of the Truckee grebes, our analysis offers insight into the tempo of grebe evolution by placing the Miocene taxon Thiornis sociata within the dabchick clade. Thiornis sociata provides a minimum age calibration of 8.7 Ma for the basal divergence among dabchicks. Based on the recovery of a nonmonophyletic Tachybaptus and placement of the Western Hemisphere ‘Tachybaptus’ dominicus as the basal member of the otherwise exclusively Eastern Hemisphere dabchick clade, we resurrect the genus Limnodytes for this extant species (Limnodytes dominicus). Our results also nest the large, long-necked Aechmophorus grebes within the genus Podiceps, as the sister taxon to Podiceps major.
Richard T. Kingsford - One of the best experts on this subject based on the ideXlab platform.
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Conservation of waterbirds in Australia
Pacific Conservation Biology, 2013Co-Authors: Richard T. KingsfordAbstract:There are 93 species of Australian waterbirds, predominantly dependent on freshwater, inland saline or estuarine ecosystems. They include diverse species predominantly from six major groups: grebes (Podicipediformes); ducks, geese and swans (Anseriformes); pelicans and cormorants (Pelecaniformes); egrets, ibises, spoonbills (Ciconniiformes); cranes, rails and crakes (Gruiiformes) and shorebirds (Charadriiformes). I analysed the content of 382 publications on Australian waterbirds in relation to life history and threats. There were 4.08 publications per species, with most publications biased towards the Anseriformes (6.95 publications per species). There were relatively few publications on Gruiformes (1.13 per species) or Podicipediformes (0.33 per species). There is reasonably good knowledge of distribution, abundance, diet and foraging and habitat use, but there were generally few examples of integration of these data into population modelling, a particularly useful tool for conservation of species. Significant gaps exist in the understanding of basic life history and movement patterns, critical for conservation; these are particularly accentuated for cryptic species. Opportunities exist to collection basic information, directed towards modelling population dynamics. As with most of the world’s organisms, habitat loss and degradation remain the major threat to waterbirds in Australia. The ongoing pressure on water resources and developments of estuaries continue to cause decline of waterbirds, exacerbated by secondary threats including climate change, disease, hunting, pollution and disturbance. Hunting continues to have an impact, but it is relatively poorly modelled, requiring more investment by governments charged with its management. Effective conservation of Australian waterbirds and their wetland habitats depends on mitigating habitat loss and degradation, primarily dependent on political will not knowledge.
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Australian waterbirds - products of the continent's ecology
Emu - Austral Ornithology, 2002Co-Authors: Richard T. Kingsford, F. I. NormanAbstract:Some aspects of the ecology of 93 waterbird species, found predominantly on freshwater ecosystems, are reviewed. These species, belonging to six major orders — Anseriformes (ducks, geese and Black Swan), Podicipediformes (grebes), Pelecaniformes (Australian Pelican and cormorants), Ciconiiformes (herons, ibis, spoonbills and bitterns), Gruiformes (cranes, rails, crakes and gallinules), and Charadriiformes (waders and terns) — use a wide range of habitats and about half occur throughout the continent. Knowledge of their ecology remains poor for many waterbirds, particularly cryptic and rare species, and is moderate to good for hunted species. Life histories of Australian waterbirds differ from their counterparts elsewhere. Australia’s highly variable climate and river-flooding patterns create wetland habitats, the spatial and temporal variability of which strongly influence the ecology of local waterbirds. Many waterbirds respond to newly generated habitats to feed and/or breed and then disperse or die as wetlands dry. Regular movements are not common in most Australian species although some, particularly waders, migrate between Northern Hemisphere breeding grounds and non-breeding habitat in Australia. Breeding of Australian waterbirds coincides with food abundance in the southern spring, the wet season in the tropics and following floods inland. Habitat loss through draining of wetlands, regulation of rivers, diversion of water for irrigation and floodplain development are currently the major threats to waterbirds. Other potentially threatening processes include exotic plants and animals, pollution, climate change and over-harvesting but evidence for the impact of these factors remains poor. Understanding of waterbird, particularly waterfowl, ecology has contributed significantly to the conservation management of wetlands in Australia. Research on single species, studies of movements using satellite technology, further investigation of the effects of hunting, long-term monitoring and large-scale analyses of the availability of wetland habitat should be future research priorities.
Daniel T. Ksepka - One of the best experts on this subject based on the ideXlab platform.
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Fossil grebes from the Truckee Formation (Miocene) of Nevada and a new phylogenetic analysis of Podicipediformes (Aves)
Palaeontology, 2013Co-Authors: Daniel T. Ksepka, Amy M. Balanoff, Michael A. Bell, Michel D. HousemanAbstract:Podicipediformes is a cosmopolitan clade of foot-propelled diving birds that, despite inhabiting marine and lacustrine environments, have a poor fossil record. In this contribution, we describe three new grebe fossils from the diatomite beds of the Late Miocene Truckee Formation (10.2 ± 0.2 Ma) of Nevada (USA). Two postcranial skeletons and an associated set of wing elements indicate that at least two distinct grebe species occupied the large, shallow Lake Truckee during the Miocene. Phylogenetic analysis of morphological data supports a basal divergence between a clade uniting the dabchicks (Tachybaptus, Limnodytes, Poliocephalus) and a clade uniting Podilymbus, Rollandia, Podiceps and Aechmophorus. Missing data, combined with a paucity of informative skeletal characters, make it difficult to place the Truckee grebes within either of these major clades. Given the weak projection of the cnemial crests compared with extant grebes, it also remains plausible that these specimens represent stem lineage grebes. Although more material is needed to resolve the phylogenetic position of the Truckee grebes, our analysis offers insight into the tempo of grebe evolution by placing the Miocene taxon Thiornis sociata within the dabchick clade. Thiornis sociata provides a minimum age calibration of 8.7 Ma for the basal divergence among dabchicks. Based on the recovery of a nonmonophyletic Tachybaptus and placement of the Western Hemisphere ‘Tachybaptus’ dominicus as the basal member of the otherwise exclusively Eastern Hemisphere dabchick clade, we resurrect the genus Limnodytes for this extant species (Limnodytes dominicus). Our results also nest the large, long-necked Aechmophorus grebes within the genus Podiceps, as the sister taxon to Podiceps major.
Luis G. González - One of the best experts on this subject based on the ideXlab platform.
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observaciones sobre la nidificacion del patico zambullidor tachybaptus dominicus Podicipediformes podicipedidae en la isla de margarita venezuela
SABER. Revista Multidisciplinaria del Consejo de Investigación de la Universidad de Oriente, 2015Co-Authors: Luis G. González, Gedio Marin EspinozaAbstract:Por primera vez se documenta fotograficamente al Patico Zambullidor ( Tachybaptus dominicus ) anidando en la Isla de Margarita, Venezuela. El seguimiento se comenzo el 25/03/2009. El nido flotante estaba mayoritariamente construido con material vegetal herbaceo. Los dos huevos, de color blanco, fueron puestos en dias sucesivos. Durante el dia, los huevos fueron cubiertos con briznas de vegetacion para protegerlos de la insolacion y/o camuflarlos. La incubacion se realizo en la noche. Los pichones eclosionaron a los 22 dias. Solo hasta que el segundo pichon se lanzo al agua, fueron a encontrarse con los padres, alejados a unos 20 m del nido. Uno de los padres desplego las alas y permitio a los pichones subirse a su dorso. P alabras clave : Eclosion, incubacion, nido, pichones, reproduccion. ABSTRACT We photographed to Least Grebe ( Tachybaptus dominicus ) nesting in Margarita Island Venezuela. The laying monitoring commenced on 25 March 2009. The floating nest was built with Tipha fibers; it contained two white eggs. During diurnal period, when the ambient temperature reaches its maximal, the parents covered the nest with wet vegetation debris presumably to prevent overheating of the eggs and/or to camouflage. The hatching carried out in the night. The chicks hatched on 22 days. During hatching the parents stayed to ~20 m distant. Only as soon as both chicks launched into the water, they swim toward its parents. One parent display his wings and the youngs climbed onto the back. K ey words : Chickbirth, hatching, nest, chicks, reproduction.
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OBSERVACIONES SOBRE LA NIDIFICACIÓN DEL PATICO ZAMBULLIDOR (Tachybaptus dominicus: Podicipediformes, PODICIPEDIDAE) EN LA ISLA DE MARGARITA, VENEZUELA NESTING OF LEAST GREBE (Tachybaptus dominicus: Podicipediformes, PODICIPEDIDAE) ON MARGARITA ISLAND
2015Co-Authors: Luis G. GonzálezAbstract:We photographed to Least Grebe (Tachybaptus dominicus) nesting in Margarita Island Venezuela. The laying monitoring commenced on 25 March 2009. The floating nest was built with Tipha fibers; it contained two white eggs. During diurnal period, when the ambient temperature reaches its maximal, the parents covered the nest with wet vegetation debris presumably to prevent overheating of the eggs and/or to camouflage. The hatching carried out in the night. The chicks hatched on 22 days. During hatching the parents stayed to ~20 m distant. Only as soon as both chicks launched into the water, they swim toward its parents. One parent display his wings and the youngs climbed onto the back.
Amy M. Balanoff - One of the best experts on this subject based on the ideXlab platform.
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Fossil grebes from the Truckee Formation (Miocene) of Nevada and a new phylogenetic analysis of Podicipediformes (Aves)
Palaeontology, 2013Co-Authors: Daniel T. Ksepka, Amy M. Balanoff, Michael A. Bell, Michel D. HousemanAbstract:Podicipediformes is a cosmopolitan clade of foot-propelled diving birds that, despite inhabiting marine and lacustrine environments, have a poor fossil record. In this contribution, we describe three new grebe fossils from the diatomite beds of the Late Miocene Truckee Formation (10.2 ± 0.2 Ma) of Nevada (USA). Two postcranial skeletons and an associated set of wing elements indicate that at least two distinct grebe species occupied the large, shallow Lake Truckee during the Miocene. Phylogenetic analysis of morphological data supports a basal divergence between a clade uniting the dabchicks (Tachybaptus, Limnodytes, Poliocephalus) and a clade uniting Podilymbus, Rollandia, Podiceps and Aechmophorus. Missing data, combined with a paucity of informative skeletal characters, make it difficult to place the Truckee grebes within either of these major clades. Given the weak projection of the cnemial crests compared with extant grebes, it also remains plausible that these specimens represent stem lineage grebes. Although more material is needed to resolve the phylogenetic position of the Truckee grebes, our analysis offers insight into the tempo of grebe evolution by placing the Miocene taxon Thiornis sociata within the dabchick clade. Thiornis sociata provides a minimum age calibration of 8.7 Ma for the basal divergence among dabchicks. Based on the recovery of a nonmonophyletic Tachybaptus and placement of the Western Hemisphere ‘Tachybaptus’ dominicus as the basal member of the otherwise exclusively Eastern Hemisphere dabchick clade, we resurrect the genus Limnodytes for this extant species (Limnodytes dominicus). Our results also nest the large, long-necked Aechmophorus grebes within the genus Podiceps, as the sister taxon to Podiceps major.