Hermit Thrush (Catharus guttatus)

Dellinger, Rachel; Wood, Petra Bohall; Jones, Peter W.; Donovan, Therese M.

doi:10.2173/bna.261

Cited by 32 publications

(8 citation statements)

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“…The life histories and ecology of these 4 species overlap extensively, but their spatial distributions correlate roughly with the elevational gradient of interest in the present study . Veery ( Catharus fuscescens ) occurs exclusively below 500 m and reaches its highest densities at 200 m to 400 m [41]; Bicknell's thrush ( Catharus bicknelli ) occurs exclusively above 1100 m and is an obligate high‐elevation specialist [42]; Swainson's thrush ( Catharus ustulatus ) occurs predominantly above 1100 m elevation and was captured only in this zone during the present study [43]; and the hermit thrush ( Catharus guttatus ) occurs primarily in dry uplands at 300 m to 800 m but is also the lone species of this complex that spans the entire elevational gradient of the present study, with low densities at both approximately 200 m and approximately 1100 m . No other species or closely related group of insectivorous birds is distributed across the entire elevational gradient of the study.…”

Section: Methodsmentioning

confidence: 91%

Avian, salamander, and forest floor mercury concentrations increase with elevation in a terrestrial ecosystem

Townsend

Driscoll²,

Rimmer³

et al. 2013

Enviro Toxic and Chemistry

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High-elevation ecosystems of the northeastern United States are vulnerable to deposition and environmental accumulation of atmospheric pollutants, yet little work has been done to assess mercury (Hg) concentrations in organisms occupying montane ecosystems. The authors present data on Hg concentrations in ground-foraging insectivorous songbirds, a terrestrial salamander, and forest floor horizons sampled along a forested elevational gradient from 185 m to 1273 m in the Catskill Mountains, New York, USA. Mean Hg concentrations in Catharus thrushes and the salamander Plethodon cinereus increased with elevation, as did Hg concentrations in all forest floor horizons. Mean Hg concentrations in organic soils at approximately 1200 m elevation (503.5 ± 17.7 ng/g, dry wt) were 4.4-fold greater than those at approximately 200 m. Montane ecosystems of the northeastern United States, and probably elsewhere, are exposed to higher levels of atmospheric Hg deposition as reflected in accumulation patterns in the forest floor and associated high-elevation fauna. This information can be used to parameterize and test Hg transport and bioaccumulation models of landscape-specific patterns and may serve as a monitoring tool for decision makers considering future controls on Hg emissions. Further investigation is needed into the potential effects of increased Hg concentrations on high-elevation fauna.

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Section: Methodsmentioning

confidence: 91%

Avian, salamander, and forest floor mercury concentrations increase with elevation in a terrestrial ecosystem

Townsend

Driscoll²,

Rimmer³

et al. 2013

Enviro Toxic and Chemistry

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“…The dataset covers n = 4937 locations surveyed between 2004 and 2009. The Hermit Thrush is a forest songbird associated primarily with mixed and coniferous forests at higher elevations (Jones and Donovan, 1996). We fit the following centered autologistic model to the data: where c i denotes the percentage of the i th areal unit having conifer or mixed cover and e i denotes the average elevation of the i th unit.…”

Section: Application To the Hermit Thrush Datamentioning

confidence: 99%

Autologistic models for binary data on a lattice

2011

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The autologistic model is a Markov random field model for spatial binary data. Because it can account for both statistical dependence among the data and for the effects of potential covariates, the autologistic model is particularly suitable for problems in many fields, including ecology, where binary responses, indicating the presence or absence of a certain plant or animal species, are observed over a two-dimensional lattice. We consider inference and computation for two models: the original autologistic model due to Besag, and the centered autologistic model proposed recently by Caragea and Kaiser. Parameter estimation and inference for these models is a notoriously difficult problem due to the complex form of the likelihood function. We study pseudolikelihood (PL), maximum likelihood (ML), and Bayesian approaches to inference and describe ways to optimize the efficiency of these algorithms and the perfect sampling algorithms upon which they depend, taking advantage of parallel computing when possible. We conduct a simulation study to investigate the effects of spatial dependence and lattice size on parameter inference, and find that inference for regression parameters in the centered model is reliable only for reasonably large lattices (n > 900) and no more than moderate spatial dependence. When the lattice is large enough, and the dependence small enough, to permit reliable inference, the three approaches perform comparably, and so we recommend the PL approach for its easier implementation and much faster execution.

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“…It is the only species of Catharus that winters north of Mexico. It switches from a diet primarily of arthropods in the breeding season to one heavily supplemented with fruit in the nonbreeding season (Jones and Donovan 1996). Wintering Hermit Thrushes maintain territories of less than 1 ha and show fidelity to these sites throughout the season ( Brown et al 2000).…”

Section: Study Speciesmentioning

confidence: 99%

“…Using methods modified from Strong and Sherry (2000), we plaeed a frame eovering 0.5 m^ near the center ofthe sampling area on top ofthe leaf litter. Observers spent 5 min searehing within the frame by seanning and flipping leaves individually to mimie a foraging Hermit Thrush (Jones and Donovan 1996). We eounted arthropods and reeorded their lengths (mm, head to abdomen tip) to create an index (average of sample sum of arthropod lengths) of arthropod biomass.…”

Section: Measures Of Food Availabilitymentioning

confidence: 99%

Resource Limitation Drives Patterns of Habitat Occupancy during The Nonbreeding Season for an Omnivorous Songbird

2011

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The role of food in limiting migratory birds during the nonbreeding period is poorly understood, in part because of the complexities of quantifying food availability and diet. We tracked overwinter changes in the availability of arthropods and fruits, the primary winter foods of the Hermit Thrush {Catharus guttatus), a short-distance migrant. Fruit availability declined over the winter, and arthropod availability fiuctuated with changing temperature. Concurrently, using fecal samples and stable isotopes, we tracked relative food consumption. In fecal samples fruit declined from early to mid season and ô"C and ô'^N i.sotope signatures in blood became more enriched, consistent with a decline in fruit consumption and an increase in arthropod consumption. Larger-bodied birds, predominantly males, maintained territories in which the abundance of arthropods was higher, had a greater proportion of arthropods in their diet and less variation in ô"C (indicator of a stable diet) and fat loads over the winter. In contrast, smaller-bodied birds, primarily females, gained fat midwinter in response to unpredictable and lower-quality resources. These results are consistent with both a size-mediated form of dominance and sexual habitat segregation, such that smaller bodied birds, mainly females, may be behaviorally excluded from optimal territories. Future research should focus on the long-term consequences of food limitation in the nonbreeding season and size and sex-mediated dominance behavior on both the condition of birds within a season and on subsequent breeding success and survival.Resumen. El rol que tiene el alimento para limitar a las aves migratorias durante el periodo no reproductivo es poco conocido, en parte por las complejidades que significa cuantificar la disponibilidad de alimento y la dieta. Seguimos los cambios a lo largo del invierno de la disponibilidad de artrópodos y frutos, la principal fuente de alimentos de Catharus guttatus, un migrante de corta distancia. La disponibilidad de frutos disminuyó a lo largo del invierno y la disponibilidad de artrópodos fluctuó con los cambios en la temperatura. Paralelamente, usando muestras fecales e isótopos estables, seguimos el consumo relativo de alimentos. En las muestras fecales, los frutos disminuyeron desde inicios hacia mediados de la estación y las firmas de los isótopos ô"C y ô'^N en sangre aparecieron enriquecidas, lo que fue consistente con una disminución en el consumo de frutos y un aumento en el consumo de artrópodos. Las aves con cuerpo más grande, predominantemente los machos, mantuvieron territorios en los cuales la abundancia de artrópodos fue mayor, tuvieron una mayor proporción de artrópodos en sus dietas y presentaron una menor variación en ô"C (indicador de una dieta estable) y en las cargas de grasa a lo largo del invierno. En contraste, las aves con cuerpos más pequeños, principalmente las hembras, adquirieron grasa a mediados del invierno en respuesta a recursos impredecibles y de menor calidad. Estos resultados son consistentes con una forma...

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Hermit Thrush (Catharus guttatus)

Cited by 32 publications

References 0 publications

Avian, salamander, and forest floor mercury concentrations increase with elevation in a terrestrial ecosystem

Avian, salamander, and forest floor mercury concentrations increase with elevation in a terrestrial ecosystem

Autologistic models for binary data on a lattice

Resource Limitation Drives Patterns of Habitat Occupancy during The Nonbreeding Season for an Omnivorous Songbird

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