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Kathy Martin - One of the best experts on this subject based on the ideXlab platform.
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woodpeckers and other excavators maintain the diversity of cavity nesting vertebrates
Journal of Animal Ecology, 2021Co-Authors: Kurtis M Trzcinski, Kristina L Cockle, Andrea R. Norris, Max Edworthy, Karen L Wiebe, Kathy MartinAbstract:Woodpeckers and other excavators create most of the holes used by secondary Tree-cavity nesting vertebrates (SCNs) in North American temperate mixedwood forests, but the degree to which excavators release SCNs from nest-site limitation is debated. Our goal was to quantify how excavators maintain the diversity and abundance of secondary cavity nesters in a temperate forest through the creation of Tree Cavities. We examined the short- and long-term (legacy) effects of excavators (principally woodpeckers, but also red-breasted nuthatches and black-capped chickadees) on forest biodiversity using longitudinal monitoring data (1732 nest Cavities, 25 sites, 16 years) in British Columbia, Canada. Sites with higher densities of excavator nests had more Cavities available, higher species richness of SCNs, and higher nest density of SCNs, indicating the importance of a standing stock of Cavities. Years with higher nesting densities of excavators were followed by years with higher SCN diversity, indicating that the creation of nesting opportunities through fresh excavation releases SCNs from community-wide nest-site limitation. We also show that excavators leave a "legacy" of biodiversity (species richness and abundance) at a site by accumulating Cavities at rates faster than they become unusable by decay or destruction. By quantifying site-level effects of cavity excavation on the SCN community, our study highlights the key role of excavators as ecosystem engineers that maintain forest wildlife biodiversity.
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Rainfall and nest site competition delay Mountain Bluebird and Tree Swallow breeding but do not impact productivity
The Auk, 2020Co-Authors: Anna Drake, Kathy MartinAbstract:Optimizing breeding phenology, an important aspect of fitness, is complex for migratory species as they must make key timing decisions early, and remotely, from breeding sites. We examined the role of weather (locally and cross-seasonally), cavity availability, and competitive exclusion in determining among-year variation in breeding phenology over 17 yr for 2 migratory, cavity-nesting birds: Mountain Bluebirds (Sialia currucoides; n = 462 nests) and Tree Swallows (Tachycineta bicolor; n = 572) using natural Tree Cavities in British Columbia, Canada. We assessed weather effects within the winter and migratory range and at our study sites. We quantified competition as the proportion of Cavities occupied by European Starlings (Sturnus vulgaris) (for both species) and Mountain Bluebirds (for Tree Swallow only) in each year. For 229 bluebird and 177 swallow nests with known fates, we tested whether late years resulted in reduced productivity. Although the effects were small, heavy rainfall and strong diurnal westerly winds during migration were associated with breeding delays for Mountain Bluebirds. However, cavity availability (earlier breeding with increases) had a 5–8 × greater effect on timing than migratory conditions. There was no evidence that starling competition delayed bluebirds. In Tree Swallows, greater local daily rainfall was associated with delayed breeding, as was starling abundance (the effect of starlings was 1.4 × smaller than that of rainfall). Neither bluebird abundance nor cavity availability changed swallow phenology. Neither species showed reduced productivity in late breeding years. In both species, individuals that bred late relative to conspecifics within-year had smaller clutches and greater probability of nest failure. We conclude that breeding ground conditions, particularly cavity limitation and local rainfall (for swallows), are important drivers of breeding phenology for our focal species, but that the productivity cost of late years, at least for Tree Swallows, is minimal.
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Reproductive output for Tree Swallows nesting in Tree Cavities and nest boxes, in interior British Columbia, Canada.
2018Co-Authors: Andrea R. Norris, Kathy Martin, Kathryn E. H. Aitken, Stanley PokornyAbstract:(a) Mean number of eggs laid (clutch size) (b) mean number of chicks hatched, (c) mean hatch day (Julian hatch day), and (d) percent of nests to fledge ≥ 1 young. Sample size indicated at the base of each column. Error bars indicate standard errors of the mean.
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the diversity distribution and conservation status of the Tree cavity nesting birds of the world
Diversity and Distributions, 2017Co-Authors: Yntze Van Der Hoek, Gabriel Gaona, Kathy MartinAbstract:Aim Globally, many bird species nest in Tree Cavities that are either excavated or formed through decay or damage processes. We assembled an overview of all Tree-cavity nesters (excavators and non-excavators) in the world, analysed their geographic distribution and listed the conservation status of all species. Location This is a global analysis of species from every continent except for Antarctica where the lack of Trees precludes the occurrence of this group. Methods We reviewed the online version of the Handbook of the Birds of the World Alive, http://www.hbw.com/, and primary literature for species known to nest in Tree Cavities, with Tree Cavities defined as holes that a bird can enter such that it is not visible from the outside. We classified species by nester type (excavator or non-excavator, and obligate or facultative where possible), conservation threat status and zoogeographic region, and tested for statistical differences in species distributions across realms using chi-square tests. Results At least 1878 species (18.1% of all bird species in the world) nest in Tree Cavities, of which we considered 355 to be primary excavators, 126 facultative excavators and 1357 non-excavators (we were unable to classify nesting type for 40 species). At least 338 species use Cavities created by woodpeckers (Picidae), excluding reuse by woodpeckers themselves. About 13% (249 species) of Tree-cavity nesters experience major threats (i.e., status of vulnerable, endangered or critically endangered). The highest richness of Tree-cavity nesters is found in the Neotropical (678 species) and Oriental (453) regions, and the highest proportion of threatened species in Australasia (17%). Main conclusion Maintenance of a continual supply of Cavities, a process in which woodpeckers and the processes of decay play critical roles, is a global conservation priority as Tree Cavities provide important nesting sites for many bird species.
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Maintaining ecosystem resilience: functional responses of Tree cavity nesters to logging in temperate forests of the Americas
Scientific Reports, 2017Co-Authors: José Tomás Ibarra, Kristina L Cockle, Michaela Martin, Kathy MartinAbstract:Logging often reduces taxonomic diversity in forest communities, but little is known about how this biodiversity loss affects the resilience of ecosystem functions. We examined how partial logging and clearcutting of temperate forests influenced functional diversity of birds that nest in Tree Cavities. We used point-counts in a before-after-control-impact design to examine the effects of logging on the value, range, and density of functional traits in bird communities in Canada (21 species) and Chile (16 species). Clearcutting, but not partial logging, reduced diversity in both systems. The effect was much more pronounced in Chile, where logging operations removed critical nesting resources (large decaying Trees), than in Canada, where decaying aspen Populus tremuloides were retained on site. In Chile, logging was accompanied by declines in species richness, functional richness (amount of functional niche occupied by species), community-weighted body mass (average mass, weighted by species densities), and functional divergence (degree of maximization of divergence in occupied functional niche). In Canada, clearcutting did not affect species richness but nevertheless reduced functional richness and community-weighted body mass. Although some cavity-nesting birds can persist under intensive logging operations, their ecosystem functions may be severely compromised unless future nest Trees can be retained on logged sites.
Griffith, Simon C - One of the best experts on this subject based on the ideXlab platform.
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Interspecific aggression for nest sites: Model experiments with long-tailed finches (Poephila acuticauda) and endangered gouldian finches (Erythrura gouldiae)
American Ornithologists Union, 2016Co-Authors: Pearce Dhanya, Pryke Sarah, Griffith, Simon CAbstract:For cavity-nesting birds, Tree Cavities often represent a critical, defendable, and limiting resource that is frequently under intense interspecific competition. However, the dynamics of interspecific conflict resolution, especially between species of similar size, are often unclear. We experimentally tested aggression and nest-defense behaviors in Gouldian Finches (Erythrura gouldiae) and Longtailed Finches (Poephila acuticauda), two sympatric, cavity-nesting estrildid finches that are very similar in size, ecology, and nest-site requirements. Mounted taxidermic models of conspecific and heterospecific nest-site competitors (black and red Gouldian Finch morph and Long-tailed Finch models), as well as a control noncompetitor (Black-chinned Honeyeater [Melithreptus gularis]), were presented to Gouldian and Long-tailed finches. These two competing species differed in their overall responses to simulated intruders and in their relative aggression toward conspecific and heterospecific intruders. Long-tailed Finches reacted more quickly to models, approached closer, and were more likely to attack models (i.e., make physical contact) than Gouldian Finches, which suggests that Long-tailed Finches are intrinsically more aggressive. In addition, Long-tailed Finches were more aggressive toward Gouldian Finches than toward conspecific models. By contrast, Gouldian Finches were more aggressive to conspecific models and avoided approaching Long-tailed Finch models. Male Gouldian Finches were particularly aggressive toward conspecifics, and red head-color morphs were more aggressive than black morphs. These results suggest that the outcomes of competitive asymmetries within and between these species are driven by differences in aggression. Together with the substantial overlap in nest-site use, the Long-tailed Finch's aggressive domination of limited nest sites may lead to competitive exclusion of the endangered Gouldian Finch
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Interspecific aggression for nest sites : model experiments with long-tailed finches (Poephila acuticauda) and endangered gouldian finches (Erythrura gouldiae)
'University of California Press', 2011Co-Authors: Pearce Dhanya, Pryke, Sarah R, Griffith, Simon CAbstract:For cavity-nesting birds, Tree Cavities often represent a critical, defendable, and limiting resource that is frequently under intense interspecific competition. However, the dynamics of interspecific conflict resolution, especially between species of similar size, are often unclear. We experimentally tested aggression and nest-defense behaviors in Gouldian Finches (Erythrura gouldiae) and Longtailed Finches (Poephila acuticauda), two sympatric, cavity-nesting estrildid finches that are very similar in size, ecology, and nest-site requirements. Mounted taxidermic models of conspecific and heterospecific nest-site competitors (black and red Gouldian Finch morph and Long-tailed Finch models), as well as a control noncompetitor (Black-chinned Honeyeater [Melithreptus gularis]), were presented to Gouldian and Long-tailed finches. These two competing species differed in their overall responses to simulated intruders and in their relative aggression toward conspecific and heterospecific intruders. Long-tailed Finches reacted more quickly to models, approached closer, and were more likely to attack models (i.e., make physical contact) than Gouldian Finches, which suggests that Long-tailed Finches are intrinsically more aggressive. In addition, Long-tailed Finches were more aggressive toward Gouldian Finches than toward conspecific models. By contrast, Gouldian Finches were more aggressive to conspecific models and avoided approaching Long-tailed Finch models. Male Gouldian Finches were particularly aggressive toward conspecifics, and red head-color morphs were more aggressive than black morphs. These results suggest that the outcomes of competitive asymmetries within and between these species are driven by differences in aggression. Together with the substantial overlap in nest-site use, the Long-tailed Finch's aggressive domination of limited nest sites may lead to competitive exclusion of the endangered Gouldian Finch.9 page(s
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Nest-site utilisation and niche overlap in two sympatric, cavity-nesting finches
'CSIRO Publishing', 2010Co-Authors: Brazill-boast James, Pryke, Sarah R, Griffith, Simon CAbstract:Determining the relative access of a species to critical limiting resources requires knowledge of the spectrum of their resource utilisation (niche space) and that of potential competitors, and the frequency distribution of resources in the environment. We used this theoretical framework to assess the relative access to nesting sites and the potential for interspecific competition between two sympatric cavity-nesting finches. Gouldian (Erythrura gouldiae) and Long-tailed (Poephila acuticauda) Finches are both estrildid finches with similar ecological requirements, gross morphology and geographical ranges. By measuring the characteristics of all Tree-Cavities in an area of breeding habitat, and identifying those used by each of the two species, we were able to quantify the relationship between total available variation and variation in use by Gouldian and Long-tailed Finches. Using a likelihood-based method, we found that Longtailed Finches exhibited a broader niche than Gouldian Finches with respect to available variation, and that these niches overlapped. Using these data we estimated that the effective availability of suitable nesting sites for Long-tailed Finches was 38% greater than for Gouldian Finches. Their relatively specialised niche and overlap with a more generalist competitor has the potential to constrain reproduction for Gouldian Finches, and will have implications for the conservation of remaining populations of this endangered species.8 page(s
Kristina L Cockle - One of the best experts on this subject based on the ideXlab platform.
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woodpeckers and other excavators maintain the diversity of cavity nesting vertebrates
Journal of Animal Ecology, 2021Co-Authors: Kurtis M Trzcinski, Kristina L Cockle, Andrea R. Norris, Max Edworthy, Karen L Wiebe, Kathy MartinAbstract:Woodpeckers and other excavators create most of the holes used by secondary Tree-cavity nesting vertebrates (SCNs) in North American temperate mixedwood forests, but the degree to which excavators release SCNs from nest-site limitation is debated. Our goal was to quantify how excavators maintain the diversity and abundance of secondary cavity nesters in a temperate forest through the creation of Tree Cavities. We examined the short- and long-term (legacy) effects of excavators (principally woodpeckers, but also red-breasted nuthatches and black-capped chickadees) on forest biodiversity using longitudinal monitoring data (1732 nest Cavities, 25 sites, 16 years) in British Columbia, Canada. Sites with higher densities of excavator nests had more Cavities available, higher species richness of SCNs, and higher nest density of SCNs, indicating the importance of a standing stock of Cavities. Years with higher nesting densities of excavators were followed by years with higher SCN diversity, indicating that the creation of nesting opportunities through fresh excavation releases SCNs from community-wide nest-site limitation. We also show that excavators leave a "legacy" of biodiversity (species richness and abundance) at a site by accumulating Cavities at rates faster than they become unusable by decay or destruction. By quantifying site-level effects of cavity excavation on the SCN community, our study highlights the key role of excavators as ecosystem engineers that maintain forest wildlife biodiversity.
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Maintaining ecosystem resilience: functional responses of Tree cavity nesters to logging in temperate forests of the Americas
Scientific Reports, 2017Co-Authors: José Tomás Ibarra, Kristina L Cockle, Michaela Martin, Kathy MartinAbstract:Logging often reduces taxonomic diversity in forest communities, but little is known about how this biodiversity loss affects the resilience of ecosystem functions. We examined how partial logging and clearcutting of temperate forests influenced functional diversity of birds that nest in Tree Cavities. We used point-counts in a before-after-control-impact design to examine the effects of logging on the value, range, and density of functional traits in bird communities in Canada (21 species) and Chile (16 species). Clearcutting, but not partial logging, reduced diversity in both systems. The effect was much more pronounced in Chile, where logging operations removed critical nesting resources (large decaying Trees), than in Canada, where decaying aspen Populus tremuloides were retained on site. In Chile, logging was accompanied by declines in species richness, functional richness (amount of functional niche occupied by species), community-weighted body mass (average mass, weighted by species densities), and functional divergence (degree of maximization of divergence in occupied functional niche). In Canada, clearcutting did not affect species richness but nevertheless reduced functional richness and community-weighted body mass. Although some cavity-nesting birds can persist under intensive logging operations, their ecosystem functions may be severely compromised unless future nest Trees can be retained on logged sites.
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nest niche overlap among the endangered vinaceous breasted parrot amazona vinacea and sympatric cavity using birds mammals and social insects in the subtropical atlantic forest argentina
The Condor, 2017Co-Authors: Kristina L Cockle, Eugenia Bianca BonaparteAbstract:ABSTRACT Many forest bird species require Tree Cavities for nesting, and share this resource with a diverse community of animals. When Cavities are limited, niche overlap can result in interspecific competition, with negative consequences for threatened populations. Vinaceous-breasted Parrots (Amazona vinacea) are endangered cavity nesters endemic to the subtropical Atlantic Forest, where Cavities are scarce. We examined nest niche overlap among Vinaceous-breasted Parrots and 9 potential competitors (birds and mammals >140 g, and social insects) in Argentina, considering (1) timing of breeding, (2) characteristics of Cavities (depth, entrance diameter, height), Trees (diameter at breast height [DBH], species, condition), and habitat (surrounding land use, distance to edge), and (3) interspecific cavity reuse. During 10 breeding seasons we studied nests and roosts, measured their characteristics, and monitored Cavities to detect reuse. We used multinomial logistic regression to determine whether the 6 most...
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linking fungi Trees and hole using birds in a neotropical Tree cavity network pathways of cavity production and implications for conservation
Forest Ecology and Management, 2012Co-Authors: Kathy Martin, Kristina L Cockle, Gerardo RobledoAbstract:Abstract In tropical forests and savannahs worldwide, hundreds of species of cavity-nesting vertebrates depend, for nesting and roosting, on the limited resource of Tree Cavities. These Cavities are produced by avian excavators and decay processes in Trees infected with heart-rot fungi. Conservation of cavity-nesting communities requires a solid understanding of how Cavities are produced and used; however, no studies have examined the interactions among cavity producers and consumers in tropical forest. Moreover, the role of heart-rot fungi in producing Cavities for nesting vertebrates has not been studied at the community level anywhere in the world. We studied a “nest web”, or interspecific hierarchical network of cavity producers and users, in the Atlantic forest, a tropical biodiversity hotspot of high conservation concern, in South America. We searched for active nests in Tree Cavities from 2006 to 2010, and determined the species of Trees, heart-rot fungi, and avian excavators that produced the Cavities and the species of non-excavating birds (secondary cavity-nesters) that used them. We identified two main pathways that produced the Cavities used by non-excavators. Thirty-three percent of passerine nests and 9% of non-passerine nests were in Cavities produced by avian excavators; the majority of nests (83% overall) were in Cavities produced directly by decay processes including mechanical damage, invertebrate damage, and fungal decay (non-excavated Cavities). Trees bearing Cavities produced by excavators were 2/3 the diameter of those bearing non-excavated Cavities, had eight times the odds of being dead, and 37 times the odds of being colonized with heart-rot fungi in the family Polyporaceae s.l. (vs. Hymenochaetaceae that were dominant in Trees bearing non-excavated Cavities). In contrast to nest webs in North America, the Atlantic Forest nest web was characterized by high diversity and evenness of interactions, whereby non-excavating bird species did not depend on any one species of Tree, fungus or avian excavator for cavity production. The community should thus be relatively robust to extinctions of cavity producing species. However, on-going destruction of large living Trees with non-excavated Cavities is likely to disrupt the major pathway of cavity production, and may result in a shift toward greater dependence on excavated Cavities in smaller, dead Trees, infected with Polyporaceae and occupied primarily by passerine birds. To conserve cavity-using communities in tropical forests, governments and certification agencies should implement policies that result in the retention of several large living Trees per hectare.
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supply of Tree holes limits nest density of cavity nesting birds in primary and logged subtropical atlantic forest
Biological Conservation, 2010Co-Authors: Kristina L Cockle, Kathy Martin, Mark C DreverAbstract:Abstract Tree Cavities are proposed to limit populations and structure communities of cavity-nesting birds. Although the greatest diversity of cavity-nesting birds is found in tropical and subtropical moist forests, little is known about how tropical logging affects the abundance of Cavities or cavity-nesting birds. We compared the abundance of Cavities and cavity nests between primary and selectively-logged subtropical moist Atlantic forest in Argentina, and conducted the first before-after controlled nest-box addition experiment to determine whether nest sites limit the breeding density of cavity-nesting birds in tropical or subtropical moist forest. Visual inspection of 86 Cavities identified through ground-surveys revealed that only 19% were suitable for nesting birds, suggesting that cavity abundance may be overestimated in the literature on tropical forests. Suitable Cavities were found in fewer than 1% of 1156 Trees 100 cm dbh. Logged forest had half the basal area of primary forest, one third the density of large Trees, nine times fewer Cavities suitable for nesting birds, and 17 times fewer active nests. When we added nest boxes, nesting density increased on treatment plots but not on control plots in both logged and primary forest, suggesting that cavity supply can limit nest density even in relatively undisturbed forest. This is the first experiment to show how reduced cavity supply in logged tropical forest can limit breeding density of cavity-nesting birds. International initiatives such as forest certification should promote tropical timber management strategies that conserve large live cavity-bearing Trees.
Kouki Jari - One of the best experts on this subject based on the ideXlab platform.
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Nest Tree characteristics of Grey-headed Woodpeckers (Picus canus) in boreal forests
BirdLife Finland, 2020Co-Authors: Pakkala Timo, Tiainen Juha, Pakkala Heikki, Piha Markus, Kouki JariAbstract:Woodpeckers are important species in forest ecosystems because they make Tree Cavities that are microhabitats for several other taxa. However, even in boreal areas where most Tree Cavities are made by woodpeckers, the properties of woodpeckers’nest Trees and Cavities are poorly known. We studied nest Tree characteristics of the Grey-headed Woodpecker (Picus canus) in a 170-km2 forest-dominated area in southern Finland during 1987–2019. The data included 76 nest Trees with 80 nest Cavities in five different Tree species. During the study period, 44% of all nesting attempts were in old Cavities.Nestswere found in four forest types, but the proportions of nest Tree species differed between them. In all, aspen (Populus tremula) with 70% of nest Trees, and with 71% of nest Cavities was the dominant cavity Tree species. Most nest Trees (85%) were dead or decaying, and most Cavities (70%) were excavated at visible trunk injury spots. The mean diameter of a nest Tree at breast height (DBH) was 37.2 cm and the mean height of a cavity hole was 7.8 m; these were significantly positively correlated. The results highlight the importance of large aspens as nest cavity sites for the species. Conservation and retention of groups of large aspens in main habitats, including clear-cuts, are important for continuous availability of nest Trees. This applies particularly to managed boreal forest landscapes where scarcity of suitable Trees may be a limiting factor for the species.202
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Nest Tree characteristics of Grey-headed Woodpeckers (Picus canus) in boreal forests
2020Co-Authors: Pakkala Timo, Tiainen Juha, Pakkala Heikki, Piha Markus, Kouki JariAbstract:Woodpeckers are important species in forest ecosystems because they make Tree Cavities that are microhabitats for several other taxa. However, even in boreal areas where most Tree Cavities are made by wood-peckers, the properties of woodpeckers' nest Trees and Cavities are poorly known. We studied nest Tree characteristics of the Grey-headed Woodpecker (Picus cams) in a 170-km(2) forest-dominated area in southern Finland during 1987-2019. The data included 76 nest Trees with 80 nest Cavities in five different Tree species. During the study period, 44% of all nesting attempts were in old Cavities. Nests were found in four forest types, but the proportions of nest Tree species differed between them. In all, aspen (Populus tremula) with 70% of nest Trees, and with 71% of nest Cavities was the dominant cavity Tree species. Most nest Trees (85%) were dead or decaying, and most Cavities (70%) were excavated at visible trunk injury spots. The mean diameter of a nest Tree at breast height (DBH) was 37.2 cm and the mean height of a cavity hole was 7.8 m; these were significantly positively correlated. The results highlight the importance of large aspens as nest cavity sites for the species. Conservation and retention of groups of large aspens in main habitats, including clear-cuts, are important for continuous availability of nest Trees. This applies particularly to managed boreal forest landscapes where scarcity of suitable Trees may be a limiting factor for the species.Peer reviewe
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Nest Tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in boreal forest landscapes
BirdLife Suomi, 2019Co-Authors: Pakkala Timo, Tiainen Juha, Pakkala Heikki, Piha Markus, Kouki JariAbstract:Tree Cavities, and especially Cavities made by woodpeckers, are important microhabitats in forest ecosystems. However, the properties of woodpecker nest Trees and Cavities are poorly known even in boreal areas where most Tree Cavities are made by woodpeckers. We studied the nest Tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in a 170-km2 forest-dominated area in southern Finland during 1987–2018. The data included 97 nest Trees with 106 nest Cavities in five deciduous Tree species. During the study period, more than one nest cavity (2–3) was excavated in 7% of all cavity Trees. Nests were found in three forest types, but the proportions of nest Tree species differed between them. Birch (Betula spp.) was the most common nest Tree species with 40% of nests. Nest Trees were either dead (79%) or decaying (21%), and the majority (69%) had a broken top. The mean diameter at breast height (DBH) of a nest Tree was 24.7 cm and the mean height of a cavity hole was 3.3 m; size and height were significantly positively correlated. The mean ratio of cavity height in relation to the respective nest Tree height was 0.49, and did not depend on the nest Tree condition. The results highlight the importance of dead and decaying deciduous Trees as nest cavity sites for this small woodpecker species. Provision of suitable cavity Trees during forest management is important to maintain breeding and cavity building opportunities for the Lesser Spotted Woodpecker in managed forests.201
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Nest Tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in boreal forest landscapes
2019Co-Authors: Pakkala Timo, Tiainen Juha, Pakkala Heikki, Piha Markus, Kouki JariAbstract:Tree Cavities, and especially Cavities made by woodpeckers, are important microhabitats in forest ecosystems. However, the properties of woodpecker nest Trees and Cavities are poorly known even in boreal areas where most Tree Cavities are made by woodpeckers. We studied the nest Tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in a 170-km(2) forest-dominated area in southern Finland during 1987-2018. The data included 97 nest Trees with 106 nest Cavities in five deciduous Tree species. During the study period, more than one nest cavity (2-3) was excavated in 7% of all cavity Trees. Nests were found in three forest types, but the proportions of nest Tree species differed between them. Birch (Betula spp.) was the most common nest Tree species with 40% of nests. Nest Trees were either dead (79%) or decaying (21%), and the majority (69%) had a broken top. The mean diameter at breast height (DBH) of a nest Tree was 24.7 cm and the mean height of a cavity hole was 3.3 m; size and height were significantly positively correlated. The mean ratio of cavity height in relation to the respective nest Tree height was 0.49, and did not depend on the nest Tree condition. The results highlight the importance of dead and decaying deciduous Trees as nest cavity sites for this small woodpecker species. Provision of suitable cavity Trees during forest management is important to maintain breeding and cavity building opportunities for the Lesser Spotted Woodpecker in managed forests.Peer reviewe
James D Gilardi - One of the best experts on this subject based on the ideXlab platform.
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reproductive parameters in the critically endangered blue throated macaw limits to the recovery of a parrot under intensive management
PLOS ONE, 2014Co-Authors: Igor Berkunsky, Gonzalo Daniele, Federico Pablo Kacoliris, Jose A Diazluque, Carmen Silva P Frias, Rosana Mariel Aramburu, James D GilardiAbstract:Rediscovered in the wild twenty years ago, the breeding biology of wild Blue-throated Macaws remains largely unexplored, yet is essential to its effective conservation and recovery. Here, we analyse reproductive parameters in an intensively managed wild population of Blue-throated Macaws, providing the first data on the breeding biology of this critically endangered species. During the six-year study period, 2007–2012, the number of active breeding pairs either remained constant or decreased, depending on the site, and no new breeding pairs were discovered despite extensive searching. We documented nesting attempts in natural Cavities in dead palms or live hardwoods, and artificial nest boxes. Egg-laying was concentrated during the end of dry season and the beginning of the wet season, August through December. Hatching failure was the greatest cause of egg losses. Half of the breeding attempts of Blue-throated Macaws produced at least one fledging, on average two, after a 85 days nestling period. An average of 4.3 nestlings per year fledged from all known wild nests combined. Each pair lost roughly 65% of its initial reproductive investment at each nesting attempt. In most successful nesting attempts of individualized pairs, a new nesting attempt was not detected the following year. All monitored breeding pairs showed high nest site fidelity, reusing hardwood-Tree Cavities and nest boxes. Our findings will aid conservation efforts by refining current actions and prompting new approaches towards the conservation and recovery of the Blue-throated Macaw.
