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

Ramos-Lara, Nicolás; Koprowski, John L.; Swann, Don E.

doi:10.1644/12-mamm-a-113.1

Cited by 7 publications

(5 citation statements)

References 33 publications

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“…Mearns's squirrels also rely on tree cavities for nesting (Ramos‐Lara et al. ), and both sexes were observed frequently inspecting tree cavities which also may have contributed to increased overlap with other conspecifics, particularly breeding females (Peterson & Gauthier ; Hanski et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, the fact that individuals nest communally during summer and that ≥2 squirrels nest in different cavities of the same tree (Ramos‐Lara & Koprowski ; Ramos‐Lara et al. ), which is rare in congeners (Munroe et al. ), suggests that this species is non‐territorial.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, in xeric coniferous forests of Baja California, Mexico, Mearns's squirrels (Tamiasciurus mearnsi) do not store cones in middens (Lindsay 1981;Koprowski et al 2006), and only one adult male was observed once in 2 yr of radiotelemetry monitoring feeding on a small cache of 20-30 lodgepole pine cones (Ramos-Lara 2012); however, individuals occasionally scatter hoard single food items in branches of trees (Ramos-Lara 2012). Furthermore, the fact that individuals nest communally during summer and that ≥2 squirrels nest in different cavities of the same tree (Ramos-Lara & Koprowski 2012;Ramos-Lara et al 2013), which is rare in congeners (Munroe et al 2009), suggests that this species is non-territorial. Thus, the species provides an excellent opportunity to test the hypotheses on the spacing behavior of Tamiasciurus occurring in coniferous forests but without the constraints of defending larder hoards or small caches of cones.…”

Section: Introductionmentioning

confidence: 99%

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Spacing Behavior of a Non‐Larder‐Hoarding Tamiasciurus: A Study of Mearns's Squirrels in Xeric Coniferous Forests

Ramos-Lara

Koprowski

2014

Ethology

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In ecosystems with seasonal fluctuations in food supply many species use two strategies to store food: larder hoarding and scatter hoarding. However, because species at different geographic locations may experience distinct environmental conditions, differences in hoarding behavior may occur. Tree squirrels in the genus Tamiasciurus display variation in hoarding behavior. Whereas red (Tamiasciurus hudsonicus) and Douglas's (Tamiasciurus douglasii) squirrels in mesic coniferous forests defend territories centered around larder hoards maintaining non‐overlapping home ranges, red squirrels in deciduous forests defend small scatter‐hoarded caches of cones maintaining overlapping home ranges. As in other rodent species, variation in hoarding behavior appears to influence the spacing behavior of red and Douglas's squirrels. In contrast, Mearns's squirrels (Tamiasciurus mearnsi) in xeric coniferous forests neither rely on larder hoards nor appear to display territorial behavior. Unfortunately, little is known about the ecology of this southernmost Tamiasciurus. Using radiotelemetry, we estimated home‐range size, overlap, and maximum distance traveled from nest to examine the spacing behavior of Mearns's squirrels. Similar to scatter‐hoarding rodents, maximum distance traveled from nest was greater for males during mating season, whereas those of females were similar year round. Although no seasonal differences were detected, male home ranges were three times larger during mating season, whereas those of females were smaller and displayed a minor variation between seasons. Home ranges were overlapped year round but contrary to our expectations, overlap was greater during mating season for both sexes, with no detectable relationship between male home‐range size and the number of females overlapped during mating season. Overall, the results appear to support our hypothesis that in the absence of larder hoards, the spacing behavior of Mearns's squirrels should be different from larder‐hoarding congeners and more similar to scatter‐hoarding rodents.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spacing Behavior of a Non‐Larder‐Hoarding Tamiasciurus: A Study of Mearns's Squirrels in Xeric Coniferous Forests

Ramos-Lara

Koprowski

2014

Ethology

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“…Building potential niche models based on these climate variables is not recommended for areas of high heterogeneity where weather stations are few and sparsely distributed, which is the case in the SMO (Cayuela et al 2009; Di Febbraro et al 2013; Bucklin et al 2015; Sandoval et al 2020). Instead, our set of topographic variables describe attributes of the terrain related to the physical conditions of the microhabitats of the species (Jianzhang et al 2006; Ramos-Lara et al 2013; Badgley et al 2017; Sandoval et al 2020; Wu et al 2023). Because of the extreme ruggedness of the SMO, slope, aspect, and HLI are strongly linked to the amount of solar radiation intercepted by the terrain, which in turn determines local microclimates and hence the local composition of flora and fauna (Bennie et al 2008).…”

Section: Methodsmentioning

confidence: 99%

An ecoregionalization of the Sierra Madre Occidental, México, based on non-volant, small mammal distributions

2023

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The Sierra Madre Occidental (SMO) is the largest mountain range in Mexico, spanning nearly 1,400 km from northwest to southeast. It is a region of high ecological complexity, yet, few attempts at ecoregionalization are available. Using Maxent and five high-resolution (30 m) physiographic layers, we generated niche models for 33 species of small, non-flying mammals. We generated a proposal of regions based on the proportion of overlap of all possible pairs of species niches (ordinated using PCoA) and environmental data. We compared the resulting ecoregionalization with the most detailed regionalizations of the SMO available, based on floristic, vegetational, and bird distribution data. PCoA revealed two major axes of variation related to elevation and humidity, and therefore to vegetational composition. Our regionalization is consistent with previous regionalizations in recognizing a tropical and a xerophilous region, but not a transitional Madrean Tropical. We identified the highlands as a north-south continuum, and a transitional region was identified between the xerophilous and highland areas. Differences in ecoregional patterns in taxa as different as mammals and plants, are evidence that the SMO's complexity goes beyond the more traditional Nearctic-Neotropical subdivision.

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“…Tree hollows, or tree cavities, are important structural habitat features in forest and woodland ecosystems. Globally, almost one in five bird species nest in tree hollows, and they are also critical habitat for many species of mammals and invertebrates (Ramos‐Lara et al., 2013; Landvik et al., 2016; Van der Hoek et al., 2017). In the Australasia region, more than 300 avian species nest in tree hollows, the majority of which are secondary cavity‐nesters, meaning they cannot create their own tree hollows and rely on hollows created by other processes (Van der Hoek et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

The impact of a mega‐fire on tree hollow loss and nest box occupancy by secondary cavity‐nesting cockatoos

Berris,

Barth,

Welz

2024

Austral Ecology

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Tree hollows are important structural habitat features for secondary cavity‐nesting birds, however, there has been limited research on how fire severity and frequency affect hollow abundance. Following a mega‐fire on Kangaroo Island during the 2019–2020 Australian bushfire season, we conducted an opportunistic post‐fire assessment of the fate of 144 monitored hollows in Eucalyptus cladocalyx and Eucalyptus leucoxylon trees used by endangered glossy black‐cockatoos (Calyptorhynchus lathami halmaturinus) and yellow‐tailed black‐cockatoos (Zanda funerea). We investigated the relationship between burn severity, inter‐fire interval, tree species and landscape position on the likelihood of tree hollow loss. We also compared the occupancy of nest boxes by both cockatoo species in fire‐affected catchments pre‐fire (2015–2017; 59 nest boxes) and post‐fire (2020–2022; 52 nest boxes). Surveys revealed that 64.4% of monitored tree hollows within the burnt area were destroyed, as were the trees that contained them. Most monitored tree hollows (76.9%) were in areas that had not experienced fire in >50 years prior to the 2019–2020 fires. Tree hollow loss in 2020 was 29 times greater than the mean annual loss of 1.6% recorded in the 22 years prior. Burn severity, inter‐fire interval, landscape matrix and tree species were poor predictors of hollow loss. However, increasing distance from forest edge slightly increased the probability of hollow loss. Post‐fire, the proportion of nest boxes used for nesting by glossy black‐cockatoos per annum increased to 0.70 ± 0.09, compared to 0.50 ± 0.03 pre‐fire. However, the proportion of nest boxes used for nesting by yellow‐tailed black‐cockatoos per annum remained similar (post‐fire 0.32 ± 0.12; pre‐fire 0.28 ± 0.05). The mega‐fires on Kangaroo Island in 2019–2020 resulted in tree hollow loss on a much larger scale than recorded in the 22 years prior, and subsequently, nest boxes have become an important resource for the endangered glossy black‐cockatoo.

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

Cited by 7 publications

References 33 publications

Spacing Behavior of a Non‐Larder‐Hoarding Tamiasciurus: A Study of Mearns's Squirrels in Xeric Coniferous Forests

Spacing Behavior of a Non‐Larder‐Hoarding Tamiasciurus: A Study of Mearns's Squirrels in Xeric Coniferous Forests

An ecoregionalization of the Sierra Madre Occidental, México, based on non-volant, small mammal distributions

The impact of a mega‐fire on tree hollow loss and nest box occupancy by secondary cavity‐nesting cockatoos

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