Occupancy of chainsaw-carved hollows by an Australian arboreal mammal is influenced by cavity attributes and surrounding habitat

Best, Katherine A.; Haslem, Angie; Maisey, Alex C.; Semmens, Kristin; Griffiths, Stephen R.

doi:10.1016/j.foreco.2021.119747

Cited by 10 publications

(16 citation statements)

References 75 publications

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“…Recent studies trialling the use of cavities carved directly into trees have reported promising results, with a range of native hollow-dependent birds and mammals visiting and using these novel supplementary shelters (Hurley and Harris 2014;Bengtsson and Wheater 2021;Terry et al 2021;Best et al 2022). However, little is known about microclimate conditions inside mechanically carved hollows (Griffiths et al 2018;McComb et al 2021), particularly during weather extremes.…”

Section: Discussionmentioning

confidence: 99%

“…Less is known about ongoing maintenance requirements and longevity of CHs and LHs. The artificial hollows we monitored are part of a larger, ongoing study, which has shown that ~12% of CHs (using the same design as in this study) require a small amount of maintenance 5 years after installation to cut back wound wood that begins to occlude entrance holes (Best et al 2022). Carving CHs into dead trees would eliminate the problem of wound wood growth closing over entrances Harris 2014, 2015), but introduces other uncertainties about longevity (i.e.…”

Section: Management Implicationsmentioning

confidence: 98%

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Chainsaw hollows carved into live trees provide well insulated supplementary shelters for wildlife during extreme heat

2022

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Context. Supplementary shelters for hollow-dependent fauna, such as timber or plywood nest boxes, have much drier and less thermally insulated cavity microclimates than do natural tree hollows. Hollow-dependent endotherms can experience hyperthermia and dehydration when occupying poorly insulated nest boxes during extreme heat. Aims. We investigated the effectiveness of three different types of artificial hollows in buffering hollow-dependent birds and mammals against hyperthermia and dehydration during extremely hot summer weather (ambient air temperatures >40°C). Methods. We recorded microclimate (temperature and relative humidity) data inside (1) chainsaw hollows carved into live trees, (2) log hollows, and (3) plywood nest boxes, during extremely hot weather events in Australia in December 2019-January 2020 (austral summer). We quantified temporal variation in microclimates inside the different supplementary shelters relative to ambient conditions and used statistical models to evaluate the effects of different factors (wall thickness and solar exposure) on internal microclimates. Key results. Microclimates inside chainsaw hollows were significantly different from those in log hollows and nest boxes, remaining >16°C cooler and 50 percentage points more humid than ambient conditions when daytime air temperatures reached 45°C. In comparison, nest boxes closely tracked ambient conditions throughout the day. Log hollows had an intermediate microclimate profile, getting warmer and drier than chainsaw hollows during the day, but remaining cooler and more humid than nest boxes. Conclusions. Our results showed that artificial hollows more effectively mimic the stable microclimates inside naturally occurring hollows if placed inside the tree (e.g. carved into the tree trunk of live trees), rather than attached to the outside. Implications. The chainsaw hollow design we tested could provide microclimate refugia that reduce the risks of hollow-dependent wildlife experiencing either hyperthermia in regions with hot summer climates, or hypothermia in areas with cold winters. We encourage managers to consider incorporating chainsaw hollows into existing nest box programs to provide fauna with well insulated microclimate refugia.

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Section: Discussionmentioning

confidence: 99%

Section: Management Implicationsmentioning

confidence: 98%

Chainsaw hollows carved into live trees provide well insulated supplementary shelters for wildlife during extreme heat

2022

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“…This indicates a need for periodic removal of woundwood from around the entrance to slow growth sufficiently to keep it open (which we are now trialing). This is also an issue with carved hollows (Best et al 2022).…”

Section: Discussionmentioning

confidence: 99%

Creating entrances to tree cavities attracts hollow‐dependent fauna: proof of concept

Ellis

Taylor

Rhind

2022

Restoration Ecology

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Redressing the paucity of tree hollows is essential for conservation of hollow‐dependent fauna in many landscapes around the world. We describe a method of accelerating availability of natural hollows in regenerating landscapes by mechanically creating entrances in tree stems that have existing voids or internal decay but have not yet developed entrances. We trialed this method in woodland and forest of south‐eastern Australia in 39 stems in the closely related tree genera Eucalyptus and Angophora. Exploratory drilling of 10‐mm diameter holes was used to detect the presence of internal decay or voids. We then drilled 40‐, 65‐, or 90‐mm diameter entrance holes, depending on the size of the potential cavity, 2.4–4.8 m above ground level. Camera traps showed that drilled entrances were investigated or used within hours of creation. A diverse suite of invertebrates, reptiles, mammals, and birds were recorded entering or leaving entrances, including threatened species. All 39 holes were used by animals with up to six vertebrate taxa using some entrances. Two bird species excavated material from within cavities, and three species of marsupial were recorded taking nesting material into the cavities. This trial provides evidence that adding entrances to currently inaccessible internal cavities in trees has potential to accelerate development of habitat for hollow‐dependent fauna, particularly in regenerating vegetation.

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“…Studies in southern Australia have shown that bats can take several years to find and start using newly installed bat boxes (Irvine & Bender 1995; Bender 2011), so it is possible that with adequate time, had they remained open, the carved fissures may have become occupied. Two more recent Australian studies have documented bats visiting and inspecting larger‐volume box‐type hollows carved into the trunks of Eucalyptus trees using motion‐ and heat‐activated camera traps, though this was during the night, and neither recorded direct or indirect evidence of bats roosting inside them during either the night or day (Rueegger 2017; Best et al 2022). In the Northern Hemisphere, Soprano pipistrelles ( Pipistrellus pygmaeus ) have been recorded day‐roosting inside hollows carved into live common oak ( Quercus robur ) trees (Bengtsson & Wheater 2021).…”

Section: Discussionmentioning

confidence: 99%

“…In the Northern Hemisphere, Soprano pipistrelles ( Pipistrellus pygmaeus ) have been recorded day‐roosting inside hollows carved into live common oak ( Quercus robur ) trees (Bengtsson & Wheater 2021). Mechanically carved cavities designed to replicate other types of tree hollows have also been recorded being used by various other hollow‐dependent birds and mammals (Bengtsson & Wheater 2021; McComb et al 2021; Best et al 2022). Therefore, we are hopeful that, with the maintenance we conducted in 2021 to re‐open entrances to the carved fissures, they will eventually become occupied, and we are continuing to monitor them for signs of use by bats, growth of wound wood, and production of kino.…”

Section: Discussionmentioning

confidence: 99%

“Set and forget” does not work when it comes to fissure roosts carved into live trees for bats

Griffiths

Lentini

Semmens

et al. 2022

Restoration Ecology

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Interest in carving cavities directly into trees to provide habitat for hollow-dependent wildlife is rapidly growing among researchers, conservation practitioners, community groups, and land managers. Monitoring programs have shown that some of the designs and approaches used to create these structures encourage uptake by fauna. However, evidence for occupancy of "bat specific" fissure cavities is lacking even though they are already being enthusiastically installed and advocated for by the arboriculture industry. To address this, we conducted a field trial to test the efficacy of carved bat fissure cavities (carved fissures), which had entrances designed to replicate the types of natural cracks and crevices that develop in live tree stems which are commonly used by bats. We found that the entrances to all 174 of the carved fissures we installed across 83 live trees were closed by wound wood growth within 6 years of installation, while some were closed by kino (sap produced by Eucalypteae spp.) flow within as little as 3 months. During surveys conducted while entrances to the carved fissures were still open, we did not record any direct or indirect evidence of bats (or any other vertebrates) using them as roosts. These results highlight the urgent need for systematic research, encompassing a broader range of carved designs, tree species, and environmental contexts to assess whether these types of fissure cavities that are carved into live trees can actually provide habitat for bats in the medium-to long-term.

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Occupancy of chainsaw-carved hollows by an Australian arboreal mammal is influenced by cavity attributes and surrounding habitat

Cited by 10 publications

References 75 publications

Chainsaw hollows carved into live trees provide well insulated supplementary shelters for wildlife during extreme heat

Chainsaw hollows carved into live trees provide well insulated supplementary shelters for wildlife during extreme heat

Creating entrances to tree cavities attracts hollow‐dependent fauna: proof of concept

“Set and forget” does not work when it comes to fissure roosts carved into live trees for bats

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