Response of Bicknell’s Thrush (Catharus bicknelli) to boreal silviculture and forest stand edges: a radio-tracking study

Abstract

Society and regulatory regimes require that biodiversity conservation, and especially the protection of threatened species, be integrated into land-use planning and management. Bicknell's Thrush (Catharus bicknelli (Ridgway, 1882)) is an at-risk species breeding in montane balsam fir (Abies balsamea (L.) P. Mill.) dominated areas of northeastern North America. We monitored 34 individual Bicknell's Thrushes by radio telemetry in southern Quebec to examine the size, location, and habitat composition of their home ranges in areas where clear-cutting and precommercial thinning occurred. Home ranges of Bicknell's Thrush comprised more dense balsam fir stands and fewer thinned stands than available. Within home ranges, thrushes were found more frequently in unthinned balsam fir stands than in thinned stands, and they did not avoid edges. In fact, they were found disproportionately near edges of recently thinned stands. We conclude that Bicknell's Thrushes may coexist with forest management practices that maintain a landscape mosaic dominated by dense balsam fir patches interspersed with thinned stands.Résumé : Les objectifs sociétaux et la loi exigent que la conservation de la biodiversité, particulièrement la protection des espèces menacées, soit intégrée dans la planification et la gestion du territoire. La grive de Bicknell (Catharus bicknelli (Ridgway, 1882)) est une espèce menacée nichant dans les forêts montagnardes dominées par le sapin baumier (Abies balsamea (L.) P. Mill.) du nord-est de l'Amérique du Nord. Nous avons suivi 34 grives de Bicknell munies de radio-émetteurs dans le sud du Québec, dans le but d'examiner la taille, l'emplacement et la composition en habitat des domaines vitaux dans des secteurs ayant subi différents traitements sylvicoles. Les domaines vitaux des grives de Bicknell contenaient une proportion significativement plus importante de forêts denses que de secteurs soumis à des éclaircies précommerciales. À l'intérieur de leurs domaines vitaux, les grives se retrouvaient aussi davantage dans les peuplements denses que dans les peuplements éclaircis, et n'évitaient pas les lisières de peuplements. En fait, elles se retrouvaient de manière disproportionnée en bordure des peuplements récemment éclaircis. Nous concluons que la grive de Bicknell peut coexister avec des pratiques sylvicoles suivant lesquelles une mosaïque de paysages est dominée par des peuplements denses de sapins baumiers entremêlés de peuplements éclaircis.

Division within the North American boreal forest: Ecological niche divergence between the Bicknell's Thrush (Catharus bicknelli) and Gray‐cheeked Thrush (C. minimus)

“…For Bicknell's Thrush sources (Aubry, Desrochers, & Seutin, 2011;Connolly, Seutin, Savard, & Rompré, 2002;McKinnon, Askanas, & Diamond, 2014;Morse, 1979;Nixon, Holmes, & Diamond, 2001), I determined the relative abundance of each tree species at Bicknell's Thrush presence sites and averaged the abundance across studies.…”

Bicknell’s Thrush (Catharus bicknelli) habitat occupancy in Québec’s Laurentian Highlands

“…Most of Bicknell's Thrush breeding habitat in Canada occurs in southern Québec in the Appalachian Range and on the Laurentian Highlands north of the St. Lawrence River (COSEWIC 2009). In the latter region, breeding habitat occurs primarily at high elevation in dense balsam fir dominated stands within industrial forestland where clear-cuts and forest management practices aimed at reducing stem density (hereafter called precommercial thinning) may affect habitat quality (Higdon et al 2006, Chisholm and Leonard 2008, COSEWIC 2009, Aubry et al 2011. Habitat loss and impairment on breeding grounds have been suggested as the major threats to the species (COSEWIC 2009, Lloyd and.…”

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

“…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.…”

“…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. So far, there have been very few radio-tracking studies on the species on breeding grounds (Goetz et al 2003;Aubry et al 2011), which could be related to these difficulties.…”