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Reproductive skew occurs when a few individuals monopolize breeding output, which can act as a mechanism of natural selection. However, when population sizes become small, reproductive skew can depress effective population size and worsen inbreeding. Identifying the cause of reproductive skew is important for mitigating its effect on conservation of small populations. We hypothesized that superb parrots Polytelis swainsonii, which strongly select for the morphology of tree cavity nests, may be reproductively skewed toward pairs that monopolize access to nests. We use SNP genotyping to reconstruct a pedigree, estimate molecular relatedness and genetic diversity of wild superb parrot in the Australian Capital Territory. We successfully genotyped 181 nestlings (a census between 2015–2019) and showed they were the progeny of 34 monogamous breeding pairs. There was a strong reproductive skew – 21 pairs bred only once producing 40% of the nestlings, whereas 13 pairs bred two to four times, producing 60% of the total nestlings. Five of these repeat‐breeders produced 28% of all nestlings, which was nearly triple the productivity of one‐time breeders. Repeat breeders usually monopolized access to their nest cavities, but the few pairs that switched nests did not differ in fecundity from those that stayed. The cause of nest switching was unknown, but uninterrupted access to a suitable nest (not minor variations in morphology between nests) better predicted fitness of breeding superb parrots. Pedigrees offer powerful insights into demographic processes, and identifying reproductive skew early provides opportunities to proactively avoid irreversible loss of genetic diversity via conservation management. We identify new research questions based on our results to clarify the relationship between access to resources and breeding success. [ABSTRACT FROM AUTHOR]

Context. The iconic grass-trees (Xanthorrhoea semiplana) of Australia are used by many animal species, but their role as shelters against weather extremes is poorly known. The severe contribution ofthe fungal pathogen Phytophthora cinnamomi to grass-tree deaths and current burning practices could affect small animal conservation by exacerbating impacts of weather extremes. Aims. We examined the buffering role of X. semiplana canopies against extreme weather at four sites in the Mount Lofty Ranges, South Australia. Methods. We measured ambient temperature, temperatures under grasstree canopies, and 2 m away atrandom locationsin summer(>35°C) and in winter(<13°C) over 24-h periods at each study site. We scored soil dryness under the canopies during and after heavy rainfall. Key results. Temperatures under grass-tree canopies were more stable and with smallerrangesthan other temperatures, and showed dramatic differences in summer when conditions were up to 20°C cooler than ambient. Temperatures were higher under grass-trees at night in winter. The soil under the largest canopies was completely dry during and after heavy rainfall. Conclusions. Xanthorrhoea semiplana buffers ground-dwelling animals against temperature extremes and rain so that the animals maintain their thermal resistance. Animals may choose foraging times based on grass-tree availability. The largest grass-trees provide the bestshelter. Implications.Considerable grass-tree deathsfrom P. cinnamomi infestation, together with removal or burning, can have dramatic detrimental consequences for their habitat value and the survival of wildlife using them as shelter. [ABSTRACT FROM AUTHOR]

Fire is an important agent of tree cavity creation and loss in some forest ecosystems. Even though cavity‐bearing trees may be replaced over decades post fire, cavity‐nesting animals depend on uninterrupted access to suitable nesting sites. Balancing the impacts of fire on the availability and recruitment of suitable tree cavities for wildlife is important. We studied fire effects on trees with suitable nests for Critically Endangered Orange‐bellied Parrots Neophema chrysogaster to evaluate how to optimize suitable cavity availability both now and into the future. We used field surveys to quantify the age‐class distribution of trees across the species' historical range, and climbed them to reveal that only 16% of Smithton peppermints Eucalyptus nitida supported a potentially suitable nest cavity. We incorporated this information into a simulation that explored the impacts of fire on the occurrence of nest trees over a century under different fire regimes. We predicted that more frequent and severe fires resulted in lower probabilities of persistence of nesting sites for Orange‐bellied Parrots. Management of the foraging habitat of Orange‐bellied Parrots requires regular burning of moorlands adjacent to the forests where they nest. Our simulations show that preventing regular burning of these forests is important to maximize the probability of persistence of nesting habitat for Orange‐bellied Parrots. We show that by incorporating field data on the true availability of habitat, it is possible to simulate the uncertain impacts of fire on future perpetuation of suitable nesting cavities for wildlife. [ABSTRACT FROM AUTHOR]

Populus euphratica Oliv., an indicator species for eco-environmental change in arid areas, plays a key role in maintaining the stability of fragile oasis–desert ecosystems. Owing to human interference as well as to the harshness of the natural environment, P. euphratica forests have suffered severe damage and degradation, with trunk cavities (i.e., hollows) becoming increasingly pronounced, and thus posing a great threat to the growth, health, and survival of the species. Currently, there is a gap in our understanding of cavity formation and its distribution in P. euphratica. Here, cavities in the trunks and branches of a P. euphratica in a typical transect (Arghan) along the lower Tarim River were studied based on field positioning observations combined with laboratory analysis. The results revealed a large number of hollow-bearing P. euphratica stands in the study area; indeed, trees with hollows accounted for 56% of the sampled trees, with approximately 159 trees/ha. Sixty-six percent of hollow trees exhibited large (15 cm ≤ cavity width (CW) < 30 cm) or very large (CW > 30 cm) hollows. The main types of cavities in the trees were trunk main (31.3%), trunk top (20.7%), branch end (19.5%), and branch middle (19.5%). Tree parameters, such as diameter at breast height (DBH), tree height (TH), east–west crown width (EWCW), height under branches (UBH), and crown loss (CL) were significantly different between hollow and non-hollow trees. Both cavity height and width were significantly and positively correlated with DBH and CL, as well as with average crown width (ACW) (p < 0.001) and the distance from the tree to the river. The proportion of P. euphratica trees with cavities showed an overall increasing trend with increasing groundwater depth. Our findings show that cavities in P. euphratica varied with different tree architectural characteristics. Water availability is a major environmental factor influencing the occurrence of hollowing in desert riparian forests. The results provide scientific support for the conservation and sustainable management of existing desert riparian forest ecosystems.

Tree hollows are an important landscape resource used by fauna for shelter, nesting, and predator avoidance. In fire-prone landscapes, wildfire and climate may impact hollow dynamics; however, assessments of their concurrent impacts are rare. We conducted a field survey at 80 sites in the Sydney Basin bioregion (Australia) to understand how fire frequency, fire severity, mean annual temperature, and mean annual precipitation concurrently impacted the site-density of small- (<5 cm entry width), medium- (5–10 cm entry width) and large-size (>10 cm entry width) tree hollows and tree basal scars (which mediate hollow formation via invertebrate access to heartwood), when tree-size and dead/live status were considered. A unimodal relationship occurred between medium- and large-sized hollow densities and fire frequency and severity, respectively, with hollow densities greatest at intermediate frequencies/severities. Increases of 1.82, 1.43, and 1.17 hollows per site were observed between the 1 (reference) and 2, 2 and 3, and 3 and >3 fire frequency categories. Increases of 1.26, 1.75 and 0.75 hollows per site were observed between the low (reference) and moderate, moderate and high, and high and very high fire severity categories. Fire severity was also positively associated with basal scar density, with increases of 2.52, 8.15, and 8.47 trees per site between the low (reference) and moderate, moderate and high, and high and very high categories. A weak positive and stronger negative association was observed between mean annual temperature and small-sized hollow and basal scar density, respectively. Dead and medium-sized tree density was positively associated with medium-sized hollow and basal scar tree density, respectively. Collectively, our results suggest that wildfires, and in some cases climate, have diverse and size-specific impacts on tree hollow and basal scar density. Our results imply that fire regimes that allow for moderately severe wildfire will promote larger-sized tree hollows, which are a limiting resource for many fauna species. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Veteran trees are keystone structures and play vital roles in ecosystems. Tree hollows, which are filled with a mix of leaves and wood that is transformed by the biotic community into wood mould, represent an important microhabitat. Tree hollow communities consist of three major groups of organisms: microbes, mesofauna (nematodes, mites and springtails) and macrofauna (beetles, millipedes and other insects). Little is known about the interplay between associated biota and their importance for decomposition and wood mould production. The aim of this study was to test how initial food web complexity in artificial tree hollows influences community structure, decomposition, and wood mould production. We used large wooden boxes to imitate natural hollows, and mounted them on 20 veteran oaks in Southern Norway. The food webs were manipulated into three levels: (i) a complex community with macrofauna and mesofauna, (ii) a simple community without macrofauna, and (iii) only the defaunated material. Three boxes (one of each treatment, N = 60 boxes) were mounted on each oak and left in the field from May 2017 to October 2019 (28 months). After the field experiment, macrofauna and mesofauna were collected and identified, mass loss in the boxes was determined, and nitrogen and phosphorus concentrations in the wood mould were measured. We found that the complex community treatment had the greatest diversity of beetles and the highest number of predatory macrofauna. The nematodes within the complex community treatment had greater trophic structuring with K‐selected species associated with stable conditions. The nematodes communities also indicated that the complex community had a balanced decomposition pathway, while the simple community was dominated by fungi and the defaunated community by bacteria. Lastly, we found that the boxes with the complex community treatment had the highest overall rate of mass loss, and greater amounts of wood mould with higher concentrations of nitrogen and phosphorus. Our results indicate that macrofauna in artificial hollows increase trophic structuring, enhance decomposition rates and wood mould production, and mediate the decomposition pathway. These findings highlight the importance of food web complexity for promoting biodiversity and ecosystem functioning in veteran tree hollows. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Tree hollows are an important landscape resource used by fauna for shelter, nesting, and predator avoidance. In fire-prone landscapes, wildfire and climate may impact hollow dynamics; however, assessments of their concurrent impacts are rare. We conducted a field survey at 80 sites in the Sydney Basin bioregion (Australia) to understand how fire frequency, fire severity, mean annual temperature, and mean annual precipitation concurrently impacted the site-density of small- (10 cm entry width) tree hollows and tree basal scars (which mediate hollow formation via invertebrate access to heartwood), when tree-size and dead/live status were considered. A unimodal relationship occurred between medium- and large-sized hollow densities and fire frequency and severity, respectively, with hollow densities greatest at intermediate frequencies/severities. Increases of 1.82, 1.43, and 1.17 hollows per site were observed between the 1 (reference) and 2, 2 and 3, and 3 and >3 fire frequency categories. Increases of 1.26, 1.75 and 0.75 hollows per site were observed between the low (reference) and moderate, moderate and high, and high and very high fire severity categories. Fire severity was also positively associated with basal scar density, with increases of 2.52, 8.15, and 8.47 trees per site between the low (reference) and moderate, moderate and high, and high and very high categories. A weak positive and stronger negative association was observed between mean annual temperature and small-sized hollow and basal scar density, respectively. Dead and medium-sized tree density was positively associated with medium-sized hollow and basal scar tree density, respectively. Collectively, our results suggest that wildfires, and in some cases climate, have diverse and size-specific impacts on tree hollow and basal scar density. Our results imply that fire regimes that allow for moderately severe wildfire will promote larger-sized tree hollows, which are a limiting resource for many fauna species.

The decline of critical habitat structures, such as large old trees, is a global environmental challenge. The cavities that occur in these trees provide shelter and nesting sites for many species but can take centuries to develop. Artificial cavities, including nest boxes and carved logs, offer an increasingly important conservation response. However, current methods of designing, manufacturing and deploying such habitats have constraints that limit innovation, feasibility and effectiveness. In response, this article aims to provide new and broadly useable methods that can improve the design of habitat structures for cavity‐dependent animals.To address the shortcomings of existing methods, we develop an approach that uses computer‐aided design techniques of generative and parametric modelling to produce structures that satisfy stakeholder needs, computer‐aided manufacturing techniques of 3D printing and augmented‐reality assembly to build functional prototypes, and computer‐assisted techniques of laser scanning and data‐driven design to support installation, monitoring and iterative improvement of designs. We demonstrate this approach through a case‐study project that designs and instals habitat structures for the powerful owl Ninox strenua, a cavity‐dependent and threatened bird.Through a comparison with existing methods, our pilot study shows that computer‐aided design and manufacturing can provide novel and useful approaches to develop artificial habitat‐structures. Computer‐aided design finds geometries that approximate the complex characteristics of natural tree cavities and automatically produces new versions to suit diverse sites or species. Computer‐aided manufacturing integrates materials that match the performance of naturally occurring habitat structures and facilitates the assembly of complex geometries by non‐experts. Computer‐assisted techniques produce precisely fitting and easy‐to‐instal designs, which support gradual improvement through ongoing prototyping and evaluation.These capabilities highlight how advanced design techniques can improve aspects of artificial habitat‐structures through geometric innovation, novel construction techniques and iterative exploration. Significantly, computational approaches can result in designs that can perform well, are easy to construct and instal and are applicable in many situations. Our reusable workflow can aid in the tasks of practical conservation and support ecological research by effectively negotiating the needs of both humans and target species. [ABSTRACT FROM AUTHOR]

Artificial tree hollows (e.g., nest‐boxes) are commonly deployed to mitigate the loss of mature trees within human‐disturbed landscapes. Their effectiveness as a habitat resource, and thus conservation management tool, is strongly influenced by the suitability of internal microclimate conditions. In south‐eastern Australia, spout hollows are a nesting resource used by a diverse community of vertebrate species. We tested the suitability of a novel nest box design (spout boxes) that mimicked the physical characteristics of spout hollows. We monitored the occupancy (n = 193) and internal microclimate (n = 131) of natural hollows and spout boxes within a woodland where natural tree hollows were once abundant. Both natural hollows and spout boxes were occupied and used for breeding by birds and mammals. Natural hollows had consistently higher humidity, and thermal maxima and minima were buffered, when compared with spout boxes. These differences were largely explained by wall thickness. Spout boxes displayed even more extreme temperature variation and lower humidity when not shaded. While more extreme microclimate conditions did not prevent usage, tolerable thresholds for hollow‐dependent species may soon be exceeded under current climate change projections. Managers need to carefully consider nest box design and positioning to ensure the suitability of these supplementary resources for conservation purposes. [ABSTRACT FROM AUTHOR]

Abstract Cryptococcosis is a fungal infection caused by members of the Cryptococcus gattii and C. neoformans species complexes. The C. gattii species complex has a strong environmental association with eucalypt hollows (particularly Eucalyptus camaldulensis), which may present a source of infection. It remains unclear whether a specific mycobiome is required to support its environmental survival and growth. Conventional detection of environmental Cryptococcus spp. involves culture on differential media, such as Guizotia abyssinica seed agar. Next‐generation sequencing (NGS)‐based culture‐independent identification aids in contextualising these species in the environmental mycobiome. Samples from 23 Australian tree hollows were subjected to both culture‐ and amplicon‐based metagenomic analysis to characterize the mycobiome and assess relationships between Cryptococcus spp. and other fungal taxa. The most abundant genera detected were Coniochaeta, Aspergillus, and Penicillium, all being commonly isolated from decaying wood. There was no correlation between the presence of Cryptococcus spp. in a tree hollow and the presence of any other fungal genus. Some differences in the abundance of numerous taxa were noted in a differential heat tree comparing samples with or without Cryptococcus‐NGS reads. The study expanded the known environmental niche of the C. gattii and C. neoformans species complexes in Australia with detections from a further five tree species. Discrepancies between the detection of Cryptococcus spp. using culture or NGS suggest that neither is superior per se and that, rather, these methodologies are complementary. The inherent biases of amplicon‐based metagenomics require cautious interpretation of data through consideration of its biological relevance.

Cryptococcosis is a fungal infection caused by members of the Cryptococcus gattii and C. neoformans species complexes. The C. gattii species complex has a strong environmental association with eucalypt hollows (particularly Eucalyptus camaldulensis), which may present a source of infection. It remains unclear whether a specific mycobiome is required to support its environmental survival and growth. Conventional detection of environmental Cryptococcus spp. involves culture on differential media, such as Guizotia abyssinica seed agar. Next‐generation sequencing (NGS)‐based culture‐independent identification aids in contextualising these species in the environmental mycobiome. Samples from 23 Australian tree hollows were subjected to both culture‐ and amplicon‐based metagenomic analysis to characterize the mycobiome and assess relationships between Cryptococcus spp. and other fungal taxa. The most abundant genera detected were Coniochaeta, Aspergillus, and Penicillium, all being commonly isolated from decaying wood. There was no correlation between the presence of Cryptococcus spp. in a tree hollow and the presence of any other fungal genus. Some differences in the abundance of numerous taxa were noted in a differential heat tree comparing samples with or without Cryptococcus‐NGS reads. The study expanded the known environmental niche of the C. gattii and C. neoformans species complexes in Australia with detections from a further five tree species. Discrepancies between the detection of Cryptococcus spp. using culture or NGS suggest that neither is superior per se and that, rather, these methodologies are complementary. The inherent biases of amplicon‐based metagenomics require cautious interpretation of data through consideration of its biological relevance. [ABSTRACT FROM AUTHOR]

Nomadic species are globally threatened by anthropogenic habitat change, but management options to address their decline are limited. Their unpredictable settlement patterns pose major challenges for conservation because identifying where to implement action is difficult. We address this challenge by pre‐empting settlement patterns in a nomadic species using data from a long‐term study of the critically endangered, cavity‐nesting swift parrot (Lathamus discolor) and by taking action at the sites identified. We detected flower bud growth (the primary settlement cue) and deployed artificial nests at 3 predicted breeding sites before the birds arrived. At the broad breeding‐range scale, swift parrots settled wherever bud abundance was highest, including the study area. Within the study area, artificial nest occupancy was greatest at the site with abundant historical natural nesting sites. At the local scale, we found significant effects of study site and distance to forest edges on nest box occupancy by swift parrots. Despite significant differences in thermal properties between artificial and natural nests, we found no differences in clutch size, brood size, or body condition of swift parrots in each. Monitoring settlement patterns and future food availability of nomadic wildlife can empower conservation managers to make predictions about breeding and target ecologically relevant times and locations when deploying conservation resources. Our study is an example of how conservation challenges posed by nomadic species can be overcome, and demonstrates that with effective monitoring, practical action can be targeted to address acute conservation needs and augment habitat availability. © 2018 The Wildlife Society. By monitoring food availability and nest site use of nomadic animals at broad scales, we show it is possible to predict where to deploy conservation resources. We deployed nest boxes to increase the availability of habitat based on predicted settlement, which provided additional habitat of comparable quality to natural nesting sites for a critically endangered nomadic bird. [ABSTRACT FROM AUTHOR]

Highlights • Individuals of the small marsupial, Antechinus flavipes, use multiple den sites. • Habitat structures used most frequently for dens (large trees, logs) are rare. • A single prescribed burn of low coverage (40–50%) removed 31% of known dens. • The loss of hollows in trees and logs may also affect other hollow-using species. • We recommend retaining patches of long-unburned forest to ensure suitable habitat. Abstract Prescribed burning is used in fire-prone environments worldwide to reduce fuel loads and the severity and spread of future wildfires. Forest habitat structures, such as large trees, dead trees and logs are highly flammable, yet also are essential for animal species that require hollows (cavities) as den sites for shelter and reproduction. We examined the effects of experimental prescribed burns on the use of den sites by a small marsupial, the yellow-footed antechinus Antechinus flavipes , in south-eastern Australia. Specifically, we radio-tracked individual A. flavipes to identify forest habitat structures preferred as den sites and recorded the fate of known den sites following patchy prescribed burns. We found that large living trees and dead trees were used as den sites disproportionately to their relative abundance in the forest. While all marked individuals of A. flavipes survived the immediate impacts of patchy prescribed burns, almost a third (16/52) of den sites identified before burning were lost, including 17% of trees (4/23) and 48% of logs (10/21). The vulnerability of den sites to prescribed burns can be attributed to the decay-dependent effect of fire on both trees and logs, whereby, the amount of damage from fire is related to the structure’s pre-fire condition (i.e. whether dead or alive, amount of decay). Large trees and large logs are scarce in this dry forest ecosystem and their replacement is likely to take a century or more due to the slow growth rates of trees. The ecological impacts of prescribed burning on habitat structures used by A. flavipes and other hollow-using species can be moderated by: (1) carrying out patchy, rather than complete burns; (2) ensuring the inter-fire interval is sufficient to allow time for replenishment of resources; and (3) planning at a regional scale to maintain an appropriate spatial pattern of post-fire age-classes, including areas retained as long-unburned (e.g. >50 years) in which resources such as deep litter, large logs and dead trees can accumulate. [ABSTRACT FROM AUTHOR]

Abstract Dispersal is a key trait of species enabling gene flow among populations. For species persistence dispersal may therefore be crucial especially in a patchy or changing environment. Tree hollows are a patchy habitat as their number is locally limited and in addition to that, habitat quality of tree hollows differs. Both factors are important for colonization by saproxylic insects as species may be specialized on a particular age or quality of a tree hollow and may be dispersal-limited. Intensive forest management may further decrease the number of tree hollows and increase distances between them, if trees with hollows are removed. However, not much is known about the dispersal abilities of most saproxylic species, even though such knowledge could improve conservation efforts. To investigate the genetic population structure of saproxylic species, we collected saproxylic organisms with emergence traps from 40 hollows in beech trees in a managed forest in Germany (approximately 14 × 14 km). We focused on three threatened species, one coleopteran and two dipteran (Anaspis ruficollis , Scraptiidae; Criorhina floccosa , Syrphidae; Xylomya maculata , Xylomyidae) emerging from our tree hollows. Microsatellite analysis was used to assess gene flow among tree hollows and population genetic structure. In contrast to other studies reporting limited dispersal in saproxylic insects, we found no indication for restricted gene flow in all three species investigated. However, we studied relatively abundant species and our study site may not have been large enough to detect genetic substructure. This study indicates that the amount and quality of a suitable habitat may at least in some cases be more limiting than the physical ability to disperse. [ABSTRACT FROM AUTHOR]

ABSTRACT: Cavity‐nesting birds and mammals exhibit species‐specific nest‐site selection for tree characteristics and cavity dimensions. Although trees and their cavities change as they age, with trees becoming softer and cavities becoming larger, it is not known how their value as nesting resources varies with age. In the context of wildlife and forest management, we investigated the relative value of generating a supply of fresh cavities, which are thought to be of high quality, versus protecting cavities as they age and expand in interior volume. For 21 years (1995–2016), we monitored the formation and occupancy of tree cavities used by >30 species of birds and mammals in interior British Columbia, Canada. Cavity occupancy by secondary users was highest 1 year post‐excavation (53%), then declined to 40% after 2 years, remained at 33 ± 7% (SD) between 3 and 16 years of age, and increased to 50% use from 17–20 years post‐excavation. Excavators that reused cavities (woodpeckers [Picidae], nuthatches [Sitta spp.]) strongly selected 1‐ and 2‐year‐old cavities, large‐bodied non‐excavators (ducks, raptors, squirrels) selected mid‐aged cavities, and mountain bluebirds (Sialia currucoides) and tree swallows (Tachycineta bicolor) selected most strongly for the oldest cavities. Cavities created in living aspen trees (Populus spp.), especially those excavated by northern flickers (Colaptes auratus), maintained high occupancy by secondary users across cavity age, and provided the bulk of cavities used in this system. Altogether, these results show that a diverse excavator community is needed to generate a supply of fresh cavities in the ecosystem, and retention of the mid‐aged and older cavities will help support larger species. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Context: Tree-related microhabitats (TreMs), such as trunk cavities, peeled bark, cracks or sporophores of lignicolous fungi, are essential to support forest biodiversity because they are used as substrate, foraging, roosting or breeding places by bryophytes, fungi, invertebrates and vertebrates. Biodiversity conservation requires the continuous presence of TreMs in a forest. However, little is known about their dynamics. Moreover, we usually have only cross-sectional TreM data (observations of many trees at a single time), making it difficult to estimate TreM formation rates., Method: This study adapted the methods of survival and reliability analysis to model the rate of TreM formation per unit of diameter increment as a function of tree diameter at breast height ( DBH). We tested three variants of this model: the TreM formation rate independent of, proportional to or increasing nonlinearly with DBH. We calculated the likelihood of the models, considering cross-sectional observations either of TreM presence/absence or TreM number on trees of different sizes. We calibrated the models in six subnatural montane forests dominated by European beech ( Fagus sylvatica) and silver fir ( Abies alba) - in the French Pyrenees. Assuming an annual DBH increment value, the annual formation rate of TreMs was predicted both at the level of the tree and at the level of the forest stand., Results: This method provides a coherent framework to model the probability that a TreM forms on a tree during a unit growth step and produces realistic predictions of TreM accumulation on trees. TreM formation accelerated as trees grew for A. alba but not for F. sylvatica. The TreM formation rate was twice as fast on F. sylvatica as on A. alba. We estimated a formation of 0·82-1·28 TreMs/ha per year and 0·5-0·9 TreM-bearing trees/ha per year in the subnatural forests studied., Synthesis and applications: This method makes rigorous modelling of the formation of TreMs possible during the growth of trees and forest stands. The quantitative evaluation of TreM fluxes will help to design forest biodiversity conservation strategies favouring the development and temporal continuity of TreMs. [ABSTRACT FROM AUTHOR]

Population limitation is the outcome of cumulative and synergistic processes that act on species over multiple spatial scales. Tree cavity dependent animals are good case studies for exploring processes that potentially limit populations across multiple scales. Fine-scale cavity characteristics have important consequences for predator exclusion and fecundity, while broad-scale processes (food or habitat availability) can determine population viability. We considered the relative importance of cavity morphology in limiting the breeding success of a critically endangered secondary cavity nesting bird that is severely affected at broad scales by nest predation. Swift Parrots (Lathamus discolor) select nest cavities where the minimum entrance diameter is positively associated with cavity depth, floor diameter and maximum entrance diameter. These cavity characteristics are adaptive because they exclude native predators by physically preventing access to the nest chamber; only one introduced nest predator is able to overcome this passive nest defence. Introduced Sugar Gliders (Petaurus breviceps) could prey on Swift Parrot nests irrespective of nest cavity morphology. We found no effect of cavity morphology on the number of eggs laid or fledglings reared by Swift Parrots. This suggests that fine-scale nest cavity characteristics do not influence the nest success of Swift Parrots beyond their effectiveness in excluding native Tasmanian predators. [ABSTRACT FROM AUTHOR]

Nest boxes are frequently used in conservation programs for tree-cavity dependent wildlife. There is growing concern that the poor insulation properties of nest boxes may produce an ecological trap, because species may require microclimates less extreme or less variable than those experienced inside nest boxes. I investigated the fitness consequences of nest box use in a non-flying mammal. Fifty-two of 104 squirrel gliders ( Petaurus norfolcensis) trapped over a 3-year period used nest boxes. Population modelling of the capture data revealed that the probability of apparent survival increased with increasing nest box use. There was no difference in breeding frequency between females that used or did not use nest boxes. There was no evidence that offspring development was hindered within nest boxes. These findings may arise because: (1) gliders could access tree hollows during extreme temperatures, (2) ambient temperatures were mild during the study, (3) gliders construct leaf nests which insulate against low temperatures in winter, and (4) gliders breed between autumn and spring when temperatures are relatively benign. The estimate of annual survival of animals using nest boxes (0.60), was equivalent to estimates at locations where squirrel gliders were either reliant on nest boxes (0.54) or on tree cavities (0.55) for shelter. Studies such as this need to be conducted on a range of species across a range of locations to better understand the influence of nest box use on non-flying mammals. [ABSTRACT FROM AUTHOR]

Beierochelifer peloponnesiacus peloponnesiacus (Beier, 1929) is recorded for the first time from Slovakia. These records are based on two males found in tree microhabitats at two localities, both with forest-steppe character with xerothermic vegetation. A full description of the specimens of this rare subspecies is provided and the main diagnostic characters are discussed. [ABSTRACT FROM AUTHOR]

An important goal for the conservation of tropical forest biodiversity is to maintain adequate supplies of tree cavities to support diverse communities of cavity-nesting and roosting vertebrates over the long term, especially in human-modified landscapes. The conservation and replacement of nesting cavities depend critically on cavity persistence, which is predicted to decline with increasing anthropogenic impact to the habitat, and to vary according to characteristics of trees and excavators. We used Cox proportional-hazards models to study the factors influencing persistence of 277 cavities used by 43 species of nesting birds in 38 species of trees, across a gradient of human impact in the subtropical Atlantic Forest of Argentina, 2004–2016. Median cavity persistence was 6 years, with 79% of cavity losses caused by the collapse of either the whole tree or the section of the tree holding the cavity. Contrary to predictions, cavity persistence did not vary across habitats (primary forest, degraded forest, farm) or excavator types (true woodpecker vs. weak excavator). Persistence was highest (median > 10 years) for non-excavated cavities in live trunks of healthy trees, and increased with tree size and species-specific wood density. Thus, although logging and conversion to farmland remove most cavities, the cavities that remain in these human-modified habitats provide high quality, multi-annual nest sites for forest birds. Preserving and restoring these cavities should be a priority for conservation of forest vertebrates. The positive effect of species-specific wood density on cavity persistence suggests a trade-off in rates of cavity turnover, whereby cavities are produced early but lost quickly in fast-growing (low wood density) pioneer tree species, and produced late but persist much longer in slow-growing (high wood density) climax species. [ABSTRACT FROM AUTHOR]

Woodland and forest degradation, driven predominately by agricultural and pastoral production, is a crisis facing many species globally, in particular hollow-dependent fauna. Large predatory species play important roles in both ecosystems and conservation strategies, but few studies have examined habitat selection of such species in intensively human-modified landscapes. We quantified habitat selection and resource use by a large, top-order and threatened snake (carpet python, M orelia spilota), between adjacent areas of high and low anthropogenic modification in inland Australia, a region that has undergone considerable alteration since European settlement. At the low-impact site, snakes preferred tree hollows and a structurally complex understorey, whereas at the high-impact site, snakes preferred homestead attics. Based on the decline of the species in this region, however, high-impact landscapes may only support snakes when they are adjacent to low-impact habitats. Invasive species comprised a large part of snake diets in both landscape types. Carpet pythons, with large home ranges and habitat requirements that overlap with many smaller threatened mammalian and avian fauna, are generally well liked and easily identifiable by rural landholders. Accordingly, they may play a key role in conservation strategies aimed at the protection of woodland and hollow-dependent fauna in heavily modified landscapes of Australia's inland regions. However, invasive species, which tend to contribute to declines in native species inhabiting arid and semi-arid Australia, are beneficial and important to pythons. Our study therefore highlights the diversity of effects that two major threats to biodiversity - habitat loss and invasive species - can have on different species within the same ecosystem. [ABSTRACT FROM AUTHOR]

Tree cavity dependent animals are sensitive to changes in cavity availability in forests. Fire is important in the long-term dynamics of cavity creation and loss, but there are few data on how fire impacts nesting resource availability for animals. We assessed the survival of 189 trees and 191 cavities used for nesting by an endangered secondary cavity nesting bird, the swift parrot Lathamus discolor , over a decade. A subset of monitored trees were burned in an uncontrolled fire. At the site of that fire, we compared swift parrot habitat quality before and after burning. We also evaluated the risk of total tree collapse due to stem destabilisation from basal scarring by calculating the critical failure stress for all monitored trees. Modelled persistence of unburned swift parrot nest cavities was more than twice that of scorched cavities over ten years. Likewise, unburned nest trees were more likely to still be standing at the end of the ten years than scorched trees. Fire caused an acute local increase in cavity and tree collapse. At the site of the fire, 62.8% of scorched nest cavities were destroyed compared to only 9.1% over the unburned remainder of the study area. Likewise, 48.6% of scorched nest trees collapsed at the fire affected site, compared to only 3.8% of unburned trees elsewhere. Burning associated tree collapse led to a significant decrease in tree diameter at breast height and number of potential cavities at monitored plots. This destroyed most of the existing nest cavity resource for swift parrots at the local scale and cavity abundance is unlikely to be replenished quickly. Loss of nesting resources may outweigh longer-term benefits of fire as an agent of cavity creation if animals miss opportunities for reproduction in locations where habitat is diminished by cumulative stochastic events and anthropogenic changes. [ABSTRACT FROM AUTHOR]

Surrogates are commonly used for monitoring biodiversity under a wide range of scenarios. However, surrogates are not often evaluated under diverse ecological conditions, and this hinders the identification of spatial and temporal boundaries of a surrogate’s relationship with its biodiversity metric, including whether a surrogate can predict biodiversity responses to environmental change. We adapted a causal framework from the medical literature and applied this framework to investigate the consistency of a well-established habitat surrogate of arboreal marsupials: hollow-bearing trees. We tested the consistency of the relationship between hollow-bearing trees and arboreal marsupials across four long-term studies (>10 years) covering different habitat types and environmental disturbance. We also tested the ability of the change in hollow-bearing trees over time to predict the change in arboreal marsupials over time. We found a somewhat consistent relationship between hollow-bearing trees and relative abundance of arboreal marsupials, but the mechanistic details of this relationship varied both by location and by species of arboreal marsupial. Similarly, the surrogate approach was not able to predict trends over time, a result likely due to differences in natural temporal variation between the surrogate and target species of interest. Our investigation demonstrates that habitat surrogates can be very useful for certain aspects of monitoring programs, but that serious limitations prevail when trying to monitor changes over time, or if information on species-specific responses is required. Our new framework can be readily applied to any biodiversity surrogate with an established mechanistic link between the surrogate and biodiversity metric of interest. [ABSTRACT FROM AUTHOR]