Bicknell's Thrush (Catharus bicknelli)

Townsend, Jason M.; McFarland, Kent P.; Rimmer, Christopher C.; Ellison, Walter G.; Goetz, James E.

doi:10.2173/bna.592

Cited by 23 publications

(27 citation statements)

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“…Although this concern may be reduced at present because of a downturn in the pulp and paper industry and because the province has put measures in place to safeguard old growth forests (Government of Newfoundland and Labrador 2014), there is a need to assess the importance of old growth forests to these thrushes. Also, the ecology of Gray-cheeked Thrushes shows many similarities to that of the closely related Bicknell's Thrush, which was considered to be a third subspecies of Graycheeked Thrush until 1995 (Rimmer et al 2015). Bicknell's Thrushes make extensive use of young fir stands that regenerate after clearcutting or natural forest succession, with abundance peaking 11-13 years postdisturbance (Nixon et al 2001, Rimmer et al 2015, Chisholm and Leonard 2008, Aubry et al 2011; however, the use of dense, regenerating clearcuts by Gray-cheeked Thrushes has not been studied.…”

Section: Introductionmentioning

confidence: 99%

“…Also, the ecology of Gray-cheeked Thrushes shows many similarities to that of the closely related Bicknell's Thrush, which was considered to be a third subspecies of Graycheeked Thrush until 1995 (Rimmer et al 2015). Bicknell's Thrushes make extensive use of young fir stands that regenerate after clearcutting or natural forest succession, with abundance peaking 11-13 years postdisturbance (Nixon et al 2001, Rimmer et al 2015, Chisholm and Leonard 2008, Aubry et al 2011; however, the use of dense, regenerating clearcuts by Gray-cheeked Thrushes has not been studied. Consequently, there is a need for locally relevant information on the habitat requirements of Graycheeked Thrushes in Newfoundland, in particular their response to forest management.…”

Section: Introductionmentioning

confidence: 99%

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Gray-cheeked Thrush (Catharus minimus minimus) distribution and habitat use in a montane forest landscape of western Newfoundland, Canada

Whitaker¹,

Taylor²,

Warkentin³

2015

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ABSTRACT. Once abundant, the Newfoundland Gray-cheeked Thrush (Catharus minimus minimus) has declined by as much as 95% since 1975. Underlying cause(s) of this population collapse are not known, although hypotheses include loss of winter habitat and the introduction of red squirrels (Tamiasciurus hudsonicus) to Newfoundland. Uncertainties regarding habitat needs are also extensive, and these knowledge gaps are an impediment to conservation. We investigated neighborhood (i.e., within 115 m [4.1 ha]) and landscape scale (i.e., within 1250 m [490.8 ha]) habitat associations of Gray-cheeked Thrush in a 200-km² study area in the Long Range Mountains of western Newfoundland, where elevations range from 300-600 m and landcover was a matrix of old growth fir forest, 6-to 8-yearold clearcuts, coniferous scrub, bogs, and barrens. Thrushes were restricted to elevations above ~375 m, and occurrence was strongly positively related to elevation. Occurrence was also positively related to cover of tall scrub forest at the neighborhood scale, and at the landscape scale showed curvilinear relations with the proportion of both tall scrub and old growth forest that peaked with intermediate amounts of cover. Occurrence of thrushes was also highest when clearcuts made up 60%-70% of neighborhood landcover, but was negatively related to cover of clearcuts in the broader landscape. Finally, occurrence was highest in areas having 50% cover of partially harvested forest (strip cuts or row cuts) at the neighborhood scale, but because this treatment was limited to one small portion of the study area, this finding may be spurious. Taken together, our results suggest selection for mixed habitats and sensitivity to both neighborhood and landscape-scale habitat. More research is needed on responses of thrushes to forestry, including use of older clearcuts, partially harvested stands, and precommercially thinned clearcuts. Finally, restriction of thrushes to higher elevations is consistent with the hypothesis that they have been impacted by squirrels, because squirrels were rare or absent at these elevations. Leur occurrence était aussi positivement associée aux peuplements de grands arbustes à l'échelle locale; à l'échelle du paysage, l'occurrence montrait des relations curvilignes avec la proportion de grands arbustes et de vieilles forêts et culminait en présence de valeurs intermédiaires de ces deux types forestiers. L'occurrence des grives était aussi maximale lorsque les coupes totales comptaient pour 60 à 70 % de la couverture terrestre locale, mais était négativement associée aux parterres de coupes totales à l'échelle du paysage. Enfin, l'occurrence était le plus élevée dans les endroits qui comportaient 50 % de couvert forestier partiellement récolté (coupes par bande ou par rangée) à l'échelle locale, mais étant donné que ce traitement était limité à une seule petite partie de l'aire d'étude, ce résultat pourrait se révéler faux. Pris dans leur ensemble, nos résultats semblent indiquer que les grives sélectionnent des milieux mixtes e...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gray-cheeked Thrush (Catharus minimus minimus) distribution and habitat use in a montane forest landscape of western Newfoundland, Canada

Whitaker¹,

Taylor²,

Warkentin³

2015

ACE

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“…Whereas the Northern subspecies favors dense, low stature coniferous and deciduous thickets across its range (Todd 1963, Godfrey 1986, Kessel 1998, Lowther et al 2001, Marshall 2001, Gray-cheeked Thrushes on Newfoundland appear to make more limited use of deciduous thickets, and instead are characteristically associated with windswept coastal conifer thickets, conifer scrub, regenerating clearcuts dominated by young balsam fir (Abies balsamea), and high elevation, oldgrowth balsam fir forests (Lamberton 1976, Vassallo and Rice 1981, Thompson et al 1999, Marshall 2001. These latter elements suggest habitat affinities similar to those of Bicknell's Thrushes (Rimmer et al 2001). The island of Newfoundland, which falls within the Boreal Softwood Shield Bird Conservation Region (BCR8; Bird Studies Canada and NABCI 2014), is also the only extensive portion of the Graycheeked Thrush breeding range typified by southern boreal vegetation types.…”

Section: Introductionmentioning

confidence: 92%

“…Marshall (2001) also noted the intermediate size and coloration of Gray-cheeked Thrushes breeding on Newfoundland and suggested that in the past they may have intergraded with Bicknell's Thrushes along the north shore of the Gulf of St. Lawrence. Following Ouellet (1993), Bicknell's Thrush was recognized as a separate species (Catharus bicknelli) based on morphology, vocalizations, and genetic differences (Monroe et al 1995, AOU 1998, Rimmer et al 2001, Dickinson and Christidis 2014. However, treatment of the Northern and Newfoundland Gray-cheeked Thrush groupings is not consistent, with some referring to them as distinct subspecies (e.g., Godfrey 1986, Ouellet 1996, Lowther et al 2001, Dickinson and Christidis 2014, and others interpreting the differences between these two groups as representing a cline within a single monotypic species (Wallace 1939, Marshall 2001.…”

Section: Introductionmentioning

confidence: 99%

Taxonomy and distribution of the imperilled Newfoundland Gray-cheeked Thrush, Catharus minimus minimus

FitzGerald¹,

Whitaker²,

Ralston³

et al. 2017

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ABSTRACT. Gray-cheeked Thrushes breeding on Newfoundland are purported to be a distinct subspecies (Catharus minimus minimus) and have declined precipitously since the 1980s. To assess the validity of Gray-cheeked Thrush subspecies we collected blood samples and morphological measurements from 51 individuals captured at 15 sites in Newfoundland and Labrador (2013-2015). Analysis of mitochondrial (ND2) and nuclear intron (ADAM-TS 6, FIB7) sequences from these and additional samples from Nova Scotia, Newfoundland, Labrador, Quebec, Alaska, and Siberia showed low genetic variation at both nuclear loci, and shallow mitochondrial divergence between subspecies; there were no shared haplotypes between thrushes from Newfoundland / Nova Scotia (n = 41) and those from western Labrador and further west (n = 24). Thrushes from Newfoundland also had shorter wing chords, tails, and culmens and less black in the mandible compared to those from western Labrador and Quebec. Samples from the southeast coast of Labrador (n = 13) included ND2 haplotypes both from Newfoundland and western Labrador plus one putative hybrid that was phenotypically a Gray-cheeked Thrush but that had a Bicknell's Thrush (C. bicknelli) ND2 haplotype and was heterozygous at a segregating site in FIB7. We detected thrushes during point counts at 7 of 24 sites on Newfoundland, but failed to detect them at 10 historically occupied sites on Newfoundland or in the reported distribution gap between subspecies in Labrador. Sites where thrushes have apparently disappeared had less shrub habitat within 1250 m and more large broadleaf trees within territory-scale areas compared to sites where they persist. Additionally, red squirrels (Tamiasciurus hudsonicus) are an introduced species on Newfoundland and thrush occurrence was > 3x higher at sites where red squirrels were not detected. Our results support previous designations of C. m. minimus from Newfoundland and southeastern Labrador as a subspecies distinct from C. m. aliciae found further west.

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“…Indeed, the species breeds in high-elevation on northeastern North America forest dominated by dense balsam fir (Abies balsamea) forest stands (Connolly et al 2002;Aubry et al 2011Aubry et al , 2016Townsend et al 2015), with generally ≥20 000 stems/ha. The combination of rough terrain and very high density of balsam fir stems adds to the aforementioned difficulties with the use of conventional, on-the-ground radio-tracking of Bicknell's Thrush.…”

Section: Introductionmentioning

confidence: 99%

A Low-Cost Technique for Radio-Tracking Wildlife Using a Small Standard Unmanned Aerial Vehicle

Tremblay

Desrochers

Aubry³

et al. 2017

J. Unmanned Veh. Sys.

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Recent advances in using unmanned aerial vehicles (UAVs) to study wildlife offer promise and may improve data collection efficiency, and small UAVs, such as multirotor platforms, are suitable for this task because they are easy to deploy, can fly over terrain that is difficult to access on foot, and can be programmed to follow specific trajectories. The objective of our study was to determine whether a small UAV could be outfitted with a radio receiver to pick up signals from radio-transmitters worn by small forest birds (Catharus bicknelli and C. ustulatus). We compared radio-monitoring using an UAV and a ground-based vehicle. The detection of over 50% of the tagged birds in the 50 m altitude flights is indicative of the real potential of the concept. This is supported by a signal strength significantly stronger and more constant than ground-based signals. The signal receptor experienced no significant interference from the UAV electronics, thus enabling a "clean" set of detections from the birds. Based on these preliminary results, we conclude that UAVs can yield useable data from animals wearing light-weight transmitters. Radio-tracking birds with UAVs presents strong potential for applications in all types of forest stands, or even in the radio-tracking of multiple species or taxa.Key words: radio-telemetry, Bicknell's thrush Catharus bicknelli, Swainson thrush Catharus ustulatus, unmanned aerial vehicle.Résumé : Les récents progrès de l'utilisation des véhicules aériens sans pilote (UAV) pour étudier de la faune sont prometteuses et peuvent améliorer l'efficacité de la collecte des données et de petits UAVs tels que les plates-formes multi-rotors sont intéressants car ils sont faciles à déployer, peuvent voler sur un terrain qui est difficile d'accès et peuvent être programmés pour suivre des trajectoires spécifiques. L'objectif de notre étude était de déterminer si un petit UAV pourrait être équipé d'un récepteur radio pour capter les signaux de radio-émetteurs portés par deux oiseaux forestiers (Catharus bicknelli et C. ustulatus). Nous avons comparé la radio-surveillance à l'aide d'un UAV et d'un véhicule au sol. La détection de plus de 50 % des oiseaux marqués dans les 50 m vols d'altitude est une indication du potentiel réel de cette application. De plus, nous avons observé une intensité de signal plus forte et plus constante avec les survols d'UAV que les signaux obtenues à partir du sol avec un véhicule terrestre. Aucune interférence significative de l'électronique d'UAV n'a été remarquée, offrant ainsi un ensemble « propre » de détections des signaux des oiseaux.

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Bicknell's Thrush (Catharus bicknelli)

Cited by 23 publications

References 0 publications

Gray-cheeked Thrush (Catharus minimus minimus) distribution and habitat use in a montane forest landscape of western Newfoundland, Canada

Gray-cheeked Thrush (Catharus minimus minimus) distribution and habitat use in a montane forest landscape of western Newfoundland, Canada

Taxonomy and distribution of the imperilled Newfoundland Gray-cheeked Thrush, Catharus minimus minimus

A Low-Cost Technique for Radio-Tracking Wildlife Using a Small Standard Unmanned Aerial Vehicle

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