The importance of mature conifers to red crossbills in southeast Alaska

Holimon, William C.; Willson, Mary F.

doi:10.1016/s0378-1127(97)00157-6

Cited by 18 publications

(18 citation statements)

References 16 publications

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“…It may also be helpful to conservation of the beleaguered Eurasian red squirrel (Sciurus vulgaris L.), which, because of competition with the introduced American gray squirrel (Sciurus carolinensis L.), now exists primarily in non-mature conifer forests in the United King-dom (Lurz et al 1995) and potentially in Europe as well. Benkman (1993) and Holimon et al (1998) have made similar predictions for conifer seed dependent crossbills (Loxia spp. ).…”

Section: Introductionmentioning

confidence: 71%

“…For example, in the Pacific Northwest (PNW) of North America, only 14% of the original old-growth forest in Washington and Oregon, U.S.A., remains (Strittholt et al 2006). Unmanaged second-growth forests tend to have rotation ages of less than 100 years and may not necessarily develop attributes of mature conifer forests such as regular production of cone crops (Burns and Honkala 1990;Benkman 1993;Holimon et al 1998). Consequently, wildlife species that are apparently dependent on mature and old-growth coniferous forests such as tree squirrels in the genera Tamiasciurus and Glaucomys may decline on both local and global scales.…”

Section: Introductionmentioning

confidence: 99%

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Tree squirrel abundance and demography in managed coniferous forests of British Columbia are within the range of natural fluctuations of old-growth stands

Sullivan

Ransome²,

Sullivan³

et al. 2017

Can. J. For. Res.

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Abstract:The American red squirrel (Tamiasciurus hudsonicus Exrleben) and northern flying squirrel (Glaucomys sabrinus Shaw) are important mammal species in coniferous forests that are widely distributed across temperate and boreal ecological zones. Although T. hudsonicus and G. sabrinus apparently prefer late-successional forests, their population dynamics show no clear pattern in young second-growth and old-growth conifer forests. We used a compilation of study results that had standardized methodology and sampling effort to compare tree squirrel responses across a range of forest conditions. We tested the hypotheses (H) that abundance, reproduction, recruitment, and survival would be higher in (H 1 ) old-growth than second-growth stands, (H 2 ) unthinned than thinned second-growth stands, and (H 3 ) lightly than heavily thinned stands. Tree squirrel populations in old-growth stands were considered the "standard" treatment to which other treatments in second-growth stands (unthinned and variously thinned) were compared. Thinned stands were grouped into low, medium, and high densities of trees. Datasets from seven published studies included 2804 Tamiasciurus and 837 G. sabrinus individuals, 25 study years, and 158 trapping periods. Mean abundance of Tamiasciurus was similar among treatment stands, ranging from 0.62 to 1.29·ha −1 . Mean numbers of G. sabrinus were highest in old-growth stands at 0.65·ha −1 , followed by the low-and medium-density stands at 0.50·ha −1 , the high-density stands at 0.25·ha −1 , and finally the unthinned second-growth stands at a low of 0.12·ha −1 . In terms of effect size, mean proportional change in abundance, relative to that within old-growth stands, of both squirrel species in the three thinned stands were within the range of natural fluctuations in old-growth stands. Populations of Tamiasciurus in the unthinned stands were not within the range of fluctuations in the old-growth stands. Mean number of successful pregnancies and total recruits were similar among stands for Tamiasciurus, with variability in female breeding and winter survival. Mean number of recruits of G. sabrinus was highest in old-growth stands with no other differences in demographic attributes among stands. The biological significance of these differences in demographic variables was small in terms of effect sizes. Tamiasciurus and G. sabrinus seem to persist in a relatively broad range of young managed forest habitats, as well as in old-growth stands.Key words: coniferous forests, Glaucomys sabrinus, managed stands, old-growth forest, population dynamics, Tamiasciurus.Résumé : L'écureuil roux américain (Tamiasciurus hudsonicus Exrleben) et le grand polatouche (Glaucomys sabrinus Shaw) sont deux espèces de mammifères d'importance dans les forêts de conifères qui couvrent une grande partie des biomes tempérés et boréaux. Mis à part le fait que T. hudsonicus et G. sabrinus semblent préférer les forêts de fin de succession, leur dynamique des populations ne montre pas de tendances nettes dans les jeunes forêts d...

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Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Tree squirrel abundance and demography in managed coniferous forests of British Columbia are within the range of natural fluctuations of old-growth stands

Sullivan

Ransome²,

Sullivan³

et al. 2017

Can. J. For. Res.

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“…Mature conifer stands ensure a stable resource for seed‐eating birds, as recognized by Benkman () and Holimon et al . (). In winter, Nuthatches forage almost exclusively on pine seeds, caching them in the fissures of trunks.…”

Section: Discussionmentioning

confidence: 97%

Selection of mature and old stands byCorsicanNuthatchSitta whiteheadiin harvested forests

Villard

Besnard

Thibault

et al. 2013

Ibis

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In harvested forests, the bird community is largely determined by stand structure, which itself is determined by forestry practices. This study aimed to identify habitat variables determining the presence of Corsican Nuthatch Sitta whiteheadi – a threatened island endemic – in harvested Corsican Pine Pinus nigra laricio woods, with the aim of mitigating the impact of timber harvest on the bird. Comparison of occupied and unoccupied plots showed that this bird is found mostly in pure Corsican Pine stands, and is absent when more than 50% of trees are not this species. Nests were built in decaying pine snags between 20 and 100 cm diameter at breast height (dbh), but birds avoided stands with live pines < 70 cm dbh, and selected stands with pines > 80 cm dbh. Conservation of Corsican Nuthatch therefore depends on maintaining harvest rotations of more than 200 years, reducing the size of felling coupes in clear‐cutting systems or, preferably, practising selective cutting, maintaining a sufficient density of old trees and snags, and checking the encroachment of other tree species into Corsican Pine stands.

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“…Nest trees with larger crowns also may provide more routes to escape from predators (Ramos-Lara and Cervantes 2007) and more access to food sources. Larger trees with larger crowns produce more cones than do younger conifers (Holimon et al 1998). Although nest trees with larger crowns may be selected initially by primary cavity-nesters such as northern flickers, which tend to excavate their cavities in sites surrounded by denser forest (Arsenault 2004), Mearns's squirrels also may benefit from nesting in these trees.…”

Section: Discussionmentioning

confidence: 99%

“…Nonetheless, nests sites of male and female Mearns's squirrels only differed in nest tree condition, suggesting that both sexes may have similar nesting requirements. Using more live trees for nesting may provide female Mearns's squirrels with more protection against predators (Wiebe et al 2006) and easier access to cavities and food sources (Holimon et al 1998), especially during the breeding season. In other species, such as eastern fox squirrels (Sciurus niger), use of dreys and cavities by males and females is proportional within seasons, whereas in eastern gray squirrels (S. carolinensis) it differs between sexes (Edwards and Guynn 1995).…”

Section: Discussionmentioning

confidence: 99%

Nest-site characteristics of the montane endemic Mearns's squirrel (Tamiasciurus mearnsi): an obligate cavity-nester?

Ramos-Lara

Koprowski

Swann³

2013

Journal of Mammalogy

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The importance of mature conifers to red crossbills in southeast Alaska

Cited by 18 publications

References 16 publications

Tree squirrel abundance and demography in managed coniferous forests of British Columbia are within the range of natural fluctuations of old-growth stands

Tree squirrel abundance and demography in managed coniferous forests of British Columbia are within the range of natural fluctuations of old-growth stands

Selection of mature and old stands byCorsicanNuthatchSitta whiteheadiin harvested forests

Nest-site characteristics of the montane endemic Mearns's squirrel (Tamiasciurus mearnsi): an obligate cavity-nester?

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