Red Squirrel Nests in Witches' Brooms in Douglas-Fir Trees

Tinnin, Robert O.; Forbes, Richard B.

doi:10.2307/3536629

Cited by 11 publications

(14 citation statements)

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“…Red squirrel use of broom type and location was consistent with Vahle (1978) and Parks et al (1999). Red squirrel nests in our study occurred more frequently in Type II and III than in Type I brooms, also reported by Parks et al (1999) and Tinnin and Forbes (1999). Vahle (1978) reported that red squirrel nests were ,3 m from the bole of the tree, similar to our findings.…”

Section: Discussionsupporting

confidence: 91%

“…Resource managers need information on wildlife use of brooms in Douglas-fir trees to help them develop management prescriptions for retention or removal of infected trees. Descriptions of characteristics of brooms used by wildlife are rare (but see Parks et al 1999, Tinnin and Forbes 1999, Marshall et al 2000, Garnett et al 2006. We therefore chose to investigate wildlife use of brooms and to focus our study on use of brooms by red squirrels.…”

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confidence: 99%

“…Vahle (1978) hypothesized that the increased foliage cover provided by brooms provided substantial nest protection. We used this hypothesis, research by Parks et al (1999), and Tinnin and Forbes (1999) to develop hypotheses about nest and foraging or caching use of brooms in Douglas-fir by red squirrels in Arizona and New Mexico. We hypothesized that broom type, size (as measured by platform size and volume), and location (distance of broom from the bole) would affect broom use by red squirrels.…”

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confidence: 99%

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Red Squirrel Use of Dwarf Mistletoe-Induced Witches' Brooms in Douglas-Fir

Hedwall

Chambers

Rosenstock

2006

Journal of Wildlife Management

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Douglas‐fir dwarf mistletoe (Arceuthobium douglasii) is a prevalent species in southwestern mixed‐conifer forests, affecting host trees by reducing growth and seed production and increasing mortality. Dwarf mistletoe infections can also form witches' brooms, which are profusely branched, dense masses of distorted host branches in the crowns of infected trees. Despite their impact on trees, brooms provide nesting, roosting, and foraging habitat for many wildlife species. To determine whether red squirrels (Tamiasciurus hudsonicus) selected brooms for nesting, foraging, or caching sites, we compared use of brooms in Douglas‐fir (Pseudotsuga menziesii) in mixed‐conifer forests in northern Arizona and New Mexico, USA, in 1998 and 1999. Douglas‐fir brooms are classified into 3 distinct forms based on structure and point of origin on the tree. Type I brooms form from an infection near the terminal end of a branch. Type II brooms form from an infection ≤1 m from the tree trunk (bole); the supporting branch usually grows vertically from the point of infection, parallel to the bole. Type III brooms result from an infection on the bole, creating a dense profusion of branches and often forming a platform. We selected trees of 3 size classes (10–25‐, 26–40‐, >40‐cm dbh) from stands and examined them for signs of red squirrel use (e.g., nesting, food storage). Red squirrels selected Type II and III brooms located closer to the bole and with larger platform size for nesting. They selected Type II and III over Type I brooms for caching and foraging use. Retaining Type II and III brooms that have platforms >700 cm2, volumes >15 m2, and are located 4.5–10 m above ground will retain this habitat element for red squirrels.

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Section: Discussionsupporting

confidence: 91%

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confidence: 99%

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Red Squirrel Use of Dwarf Mistletoe-Induced Witches' Brooms in Douglas-Fir

Hedwall

Chambers

Rosenstock

2006

Journal of Wildlife Management

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“…Dwarf mistletoes are studied a lot, particularly from the perspective of forest disease impacts on timber production and pest management. Recently, however, research has demonstrated positive effects of dwarf mistletoes on stand-level biodiversity and wildlife habitat (Bennetts et al 1996;Tinnin and Forbes 1999;Watson 2001), which has pointed to the need for a better understanding of dwarf mistletoes in the context of ecosystem and community ecology.…”

Section: Introductionmentioning

confidence: 99%

Spatial and population characteristics of dwarf mistletoe infected trees in an old-growth Douglas-fir western hemlock forest

Shaw¹,

Chen²,

Freeman³

et al. 2005

Can. J. For. Res.

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We investigated the distribution and severity of trees infected with western hemlock dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones subsp. tsugense) in an old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) -western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest. With the use of Hawksworth six-class dwarf mistletoe rating system, infection status was assessed for 3516 hemlock and true firs ≥5 cm diameter on a 12-ha stem-mapped plot located in the Cascade Mountains of southwest Washington State. Within the plot, 33% of the area had some level of infection and 25% (719) of western hemlocks, 2.2% (12) of Pacific silver fir (Abies amabilis (Dougl.) Forbes), and 29% (2) of noble fir (Abies procera Rehd.) trees were infected. Infected trees are larger than uninfected trees, on average, and within the infected tree population, the severely infected trees averaged larger than lightly infected trees. Abundant dwarf mistletoe in larger trees definitely positions the dwarf mistletoe population for future spread. Ripley's K analysis indicates a negative association between infected and uninfected hemlock trees, confirming that the infected trees form distinct dwarf mistletoe infection centers. The infection centers are actively spreading at their margins, which was confirmed by nearest neighbor analysis. Heavily infected trees had a negative association with uninfected trees, while lightly infected trees had a positive association with uninfected trees.Résumé : Les auteurs ont étudié la distribution des arbres infectés par le faux-gui de la pruche (Arceuthobium tsugense (Rosendahl) G.N. Jones subsp. tsugense) et la sévérité de la maladie dans une forêt ancienne de Douglas (Pseudotsuga menziesii (Mirb.) Franco) et de pruche de l'Ouest (Tsuga heterophylla (Raf.) Sarg.). Le degré d'infection, basé sur le système d'évaluation à six classes de Hawksworth, a été évalué pour 3516 pruches et espèces du genre Abies ≥5 cm de diamètre dans une placette cartographiée de 12 ha située dans la chaîne des Cascades, au sud-ouest de l'État de Washington. À l'intérieur de la parcelle, 33 % de la superficie était infectée et 25 % (719) des pruches de l'Ouest, 2,2 % (12) des sapins gracieux (Abies amabilis (Dougl.) Forbes) et 29 % (2) des sapins nobles (Abies procera Rehd.) étaient infectés. Les arbres infectés étaient en moyenne plus gros que les arbres non infectés et parmi les arbres infectés, les arbres sévèrement infectés étaient plus gros que les arbres légèrement infectés. L'abondance de faux-gui dans les plus gros arbres favorisera la dispersion future de la population de faux-gui. L'analyse du K de Ripley indique qu'il y a une relation négative entre les pruches infectées et non infectées confirmant que les arbres infectés constituent des centres d'infection distincts du faux-gui. Les centres d'infection s'étendent activement à la marge tel que confirmé par l'analyse du plus proche voisin. Les arbres sévèrement infectés avaient une relation négative avec les arbres non infectés alors que les arbres légèrement ...

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“…Red squirrels (Tamiasciurus hudsonicus) frequently use witches' brooms induced by Douglas-fir dwarf mistletoe for nesting sites in northern Arizona and they use these brooms for caching food as well (Patton and Vahle 1986;Hedwall 2000). Red squirrels have also been reported nesting in witches' brooms in Colorado (Hatt 1943), Washington (Tinnin and Forbes 1999) and Oregon (Lemons 1978). Abert squirrels (Sciurus aberti) have commonly been reported to use dwarf mistletoe-induced witches' brooms in ponderosa pine for nesting sites in northern Arizona (Garnett 2001).…”

Section: Research On Dwarf Mistletoes and Wildlife Interactionsmentioning

confidence: 99%

Comparison of dwarf mistletoes (Arceuthobium spp., Viscaceae) in the western United States with mistletoes (Amyema spp., Loranthaceae) in Australia—ecological analogs and reciprocal models for ecosystem management

Shaw

Watson²,

Mathiasen³

2004

Aust. J. Bot.

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Whereas the biology, physiology and systematics of mistletoes have been explored in considerable detail, their ecology has received less attention and our understanding is highly fragmentary. A conspicuous exception is the dwarf mistletoes (Arceuthobium spp.)—a genus that exclusively parasitises coniferous trees, including many commercially valuable species in the forests of the western United States. Accordingly, these plants have been the subjects of intensive cross-disciplinary research for the past five decades, initially from a control and management perspective but extending into most aspects of their ecology and life history. This review summarises our understanding of dwarf mistletoes, focusing on recent developments in the areas of mistletoe–wildlife interactions, fire, ecosystem ecology and conservation biology. We also compare dwarf mistletoes with Australian mistletoes in the genus Amyema, a diverse suite of species found throughout the continent. Despite fundamental differences in their evolutionary origin and most aspects of their autecology and life history, the genera exhibit many similarities in terms of their ecological role in forests and woodlands, and their influence on stand- and forest-scale dynamics. In particular, both groups provide nesting resources for a range of birds and mammals, and nutritional resources for a diverse assemblage of species. Both also interact with fire, potentially leading to changes in successional dynamics at the stand scale. At an applied level, both groups are widely considered as pests but, as our understanding of these keystone species improves, they have the potential to serve as sensitive ecological indicators for their respective ecosystems. Key research priorities are identified for further research on both groups of mistletoes and more explicit comparative research, with Arceuthobium serving as a valuable template for future work on Amyema and Australian mistletoes in general.

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Red Squirrel Nests in Witches' Brooms in Douglas-Fir Trees

Cited by 11 publications

References 7 publications

Red Squirrel Use of Dwarf Mistletoe-Induced Witches' Brooms in Douglas-Fir

Red Squirrel Use of Dwarf Mistletoe-Induced Witches' Brooms in Douglas-Fir

Spatial and population characteristics of dwarf mistletoe infected trees in an old-growth Douglas-fir western hemlock forest

Comparison of dwarf mistletoes (Arceuthobium spp., Viscaceae) in the western United States with mistletoes (Amyema spp., Loranthaceae) in Australia—ecological analogs and reciprocal models for ecosystem management

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Red Squirrel Nests in Witches' Brooms in Douglas-Fir Trees

Cited by 11 publications

References 7 publications

Red Squirrel Use of Dwarf Mistletoe-Induced Witches' Brooms in Douglas-Fir

Red Squirrel Use of Dwarf Mistletoe-Induced Witches' Brooms in Douglas-Fir

Spatial and population characteristics of dwarf mistletoe infected trees in an old-growth Douglas-fir  western hemlock forest

Comparison of dwarf mistletoes (Arceuthobium spp., Viscaceae) in the western United States with mistletoes (Amyema spp., Loranthaceae) in Australia—ecological analogs and reciprocal models for ecosystem management

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Spatial and population characteristics of dwarf mistletoe infected trees in an old-growth Douglas-fir western hemlock forest