Capercaillie Research Articles

Population dynamics of an endangered forest bird using mark–recapture models based on DNA-tagging

Populations of vertebrates are built of individuals of different sex, age class or stage, which often affect distinctly the population dynamics. Such intrapopulation partitioning of vital rates needs to be identified to develop efficient conservation actions. Using DNA extracted from feces and feathers we combined DNA-tagging and mark–recapture analyses to evaluate sex-specific population dynamics of an endangered population of capercaillie (Tetrao urogallus; Phasianidae). We built encounter histories for 120 individuals in the mating seasons of 2009–2011, in a study area of about 424 km2. Minimum number of individuals per mating season and estimates of population size ranged 56–67 and 76–115, respectively. Estimates of population size were consistently lower in multiple-season, open-population models than in single-season closed-population models. The super-population in the study area was 149 individuals for the whole study period. Sex-ratio was notably male-biased. Probability of recapture p ranged 0.62–0.70, and was similar for males and females. Female apparent survival φ was lower than expected, and much lower than male apparent survival. It includes however movements in and out of the sampled population, thus comparison with previously reported values based on conventional tagging should be cautious. Females showed higher turnover, indicated by higher probability β of entering the sampled population, and higher number of entries from the super-population, Bgross. Realized population growth rate ʎ was > 1 for both females and males. The combination of non-intrusive DNA-tagging and the analytical framework of mark–recapture models provided inferences on population dynamics that would have been hardly feasible with conventional methods. Male-biased sex ratios, higher female turnover and seemingly low female apparent survival were our key findings. While the whole population needs continuous monitoring, we believe that adult females deserve priority attention in evaluation and design of conservation actions.

Structural complexity in managed and strictly protected mountain forests: Effects on the habitat suitability for indicator bird species

Increasing the proportion of unmanaged forests in multi-functional forest landscapes is a primary goal of international and national conservation strategies aiming at restoring natural properties in structurally simplified forests. However, the development of structural features and associated habitat suitability for forest species is largely unknown and even controversially discussed, as the development of newly established reserves is unidirectional and passes through dense maturation stages. This may negatively affect open forest species in the first phase after reserve designation. We evaluated the effects of management cessation on key habitat characteristics of four mountain forest bird species indicative of different structural components: Capercaillie (Tetrao urogallus), Hazel grouse (Bonasa bonasia), Three-toed woodpecker (Picoides tridactylus) and Pygmy owl (Glaucidium passerinum) across four mountain regions in Central Europe. Habitat suitability was modelled based on 300 forest sites selected independently of their management status, and predicted to an independent dataset of 42 strictly protected forest reserves in the same regions. We then compared forest reserves to managed forests with species presence or absence with regard to habitat suitability and key habitat structures and related both to the time since reserve designation. For all model species, except Pygmy owl, habitat suitability in forest reserves was significantly higher than in managed forests with species’ absence, but not different from managed forests with species presence. For the species associated with open forest structures (Capercaillie, Hazel grouse, Pygmy owl) habitat suitability was significantly related to the “reserve age”: reserves in the first three decades after management cessation showed a significant decrease in suitability, which increased afterwards up to the maximally recorded time of 100 years. No such correlation was found for the Three-toed woodpecker associated with deadwood and barkbeetle infestations following temporally unpredictable disturbance events. Structural characteristics varied greatly in abundance and distribution, with open structures being related to the time since reserve designation. We therefore recommend focusing on mature, near-natural and structurally diverse forests when designating new strict forest reserves.

Assessing the performance of object‐oriented LiDARpredictors for forest bird habitat suitability modeling

AbstractHabitat suitability models (HSMs) are widely used to plan actions for species of conservation interest. Models that will be turned into conservation actions need predictors that are both ecologically pertinent and fit managers’ conceptual view of ecosystems. Remote sensing technologies such as light detection and ranging (LiDAR) can describe landscapes at high resolution over large spatial areas and have already given promising results for modeling forest species distributions. The point‐cloud (PC) area‐based LiDARvariables are often used as environmental variables inHSMs and have more recently been complemented by object‐oriented (OO) metrics. However, the efficiency of each type of variable to capture structural information on forest bird habitat has not yet been compared. We tested two hypotheses: (1) the use ofOOvariables inHSMs will give similar performance asPCarea‐based models; and (2)OOvariables will improve model robustness to LiDARdatasets acquired at different times for the same area. Using the case of a locally endangered forest bird, the capercaillie (Tetrao urogallus), model performance and predictions were compared between the two variable types. Models usingOOvariables showed slightly lower discriminatory performance thanPCarea‐based models (average ΔAUC = −0.032 and −0.01 for females and males, respectively).OO‐based models were as robust (absolute difference in Spearman rank correlation of predictions ≤ 0.21) or more robust thanPCarea‐based models. In sum, LiDAR‐derivedPCarea‐based metrics andOOmetrics showed similar performance for modeling the distribution of the capercaillie. We encourage the further exploration ofOOmetrics for creating reliableHSMs, and in particular testing whether they might help improve the scientist–stakeholder interface through better interpretability.

Comparison between lek counts and bioacoustic recording for monitoring Western Capercaillie (Tetrao urogallus L.)

Bioacoustics is the study of animal sounds. The importance of bioacoustics for biological research and the survey and monitoring of bird populations is becoming increasingly recognized. This is particularly the case for the capture of long-term data on rare species that are prone to disturbance or are otherwise difficult to survey. The global population of the Western Capercaillie (Tetrao urogallus L.; hereafter ‘Capercaillie’) is declining, and its status in the UK is highly precarious. Current methods for monitoring this species are subject to a number of constraints that affect the quality of collected data. Bioacoustics could provide a useful complement to these existing methods, in particular for the assessment of activity at leks. This study used acoustic recorders to survey Capercaillie vocal activity for a month at ten lek sites, and quantified the numbers of calls produced. Traditional lek count surveys were undertaken at all sites during this time. The recorded vocal activity data (1) correlated with the number of birds recorded by human surveyors, (2) indicated that traditional surveys may be causing some disturbance at the lek sites, and (3) showed that call numbers are related to temporal and environmental variables. The bioacoustic approach can provide high-quality, long-term data, that can be effectively combined with the traditional lek survey technique. It should be utilized more frequently as a survey and monitoring tool to provide structured, coherent results that can be used to aid conservation efforts.

Altitudinal Shift of Tetrao urogallus in an Alpine Natura 2000 Site: Implications for Habitat Restoration

Capercaillie (Tetrao urogallus L.), a territorial galliform species, is known to prefer mature conifer stands with canopy gaps and a vigorous understory of ericaceous species. Capercaillie is a useful umbrella species that has recently shown declining population trends and distribution changes in its southern geographic range. We aim to identify and assess the possible changes in summer capercaillie habitat selection between 2001 and 2011 in the Scanuppia Natura 2000 site (south-eastern Alps). The area is dominated by spruce (Picea abies (L.) Karsten) forests, followed by mixed forests, scrub, and open habitats. In both years, summer presence–absence of capercaillie was verified through the detection of droppings over 10 m radius circular plots located along contour lines (1500–1800 m). A set of environmental and habitat features was also surveyed. While overall population numbers remain unchanged over the surveyed period, results have shown an altitudinal shift in capercaillie distribution. Habitat variables had a stronger effect on the presence of capercaillie in 2001 than in 2011. Land cover and climate change are likely among the drivers of the shift in altitudinal distribution. This confirms the relevance of habitat restoration actions and to monitor changes in factors explaining capercaillie habitat selection.

Eggshell resorption, and embryonic mobilization and accumulation of calcium and metals in eggs of wild and captive Capercaillies Tetrao urogallus

Although it is fairly well known that eggshells are the major source of Ca and other micronutrients for developing avian embryos, potential anatomical and/or ecological correlates explaining the variation in embryo-induced depletion of micronutrients from eggshells remain to be addressed. Using unhatched eggs at various developmental stages and post-hatched eggshells of wild and captive-bred birds of a large precocial species, the Capercaillie Tetrao urogallus, we explored two major questions. (i) Do egg size, regional eggshell thickness as well as levels of two major micronutrients (Ca and Mg) and eight trace elements (Cr, Cu, Mn, Fe, Co, Cd, Pb and Zn) measured in egg shells and contents vary with embryonic age within and between wild and captive-bred bird eggs? (ii) How the proportions of eggshell elements become depleted during the entire process of embryogenesis? The eggshells of wild Capercaillies were thinner at the equator and the sharp pole, and contained more Mg and Ca, while in their contents there was more Cu, Cd and Pb compared with captive birds. All ten metal concentrations measured in the egg contents increased (from 15% to 285% more) with the age of embryos. The concentrations of six elements measured in eggshells (Cu, Mn, Fe, Co, Cd and Zn) decreased consistently (from 15 to 70% less) during embryogenesis. This suggests the presence of these elements in the innermost decalcified shell layer and their further mobilization into the embryos/egg contents. Our results strongly imply that most trace elements present in the egg contents/developing embryos are mobilized from the eggshells. We highlight the fact that knowledge of the magnitude of embryogenesis-related functional changes in the physical (such as shell thickness) and chemical traits of the eggs and eggshells of oviparous vertebrates is fundamental for drawing correct inferences regarding the response of an individual to variable environmental conditions.

Considering landscape connectivity and gene flow in the Anthropocene using complementary landscape genetics and habitat modelling approaches

A comprehensive understanding of how rapidly changing environments affect species gene flow is critical for mitigating future biodiversity losses. While recent methodological developments in landscape ecology and genetics have greatly advanced our understanding of biodiversity conservation, they are rarely combined and applied in studies. We merged multifaceted landscape habitat modelling with genetics to detect and design biological corridors, and we evaluated the importance of habitat patches to test corridor efficacy for gene flow in a fragmented landscape. We examined an isolated population of an endangered umbrella species, the capercaillie (Tetrao urogallus), in the Western Carpathians; they have experienced habitat deterioration and accompanying population declines in recent decades. To detect spatial patterns of genetic distances, we combined and optimized resistance surfaces using species distribution modelling, structural and functional connectivity analyses, multivariate regression approaches, and Moran’s eigenvector maps at hierarchical scales. Larger habitat patches had better gene flow among them, and we confirmed a broken metapopulation network characterised by a pattern of isolation by the environment. Distance to human settlements explained landscape genetic patterns better than other environmental and landscape features, MaxEnt resistance, Conefor resistance surfaces, and the pairwise Euclidean distances among individuals. The closer individuals were to settlements, the more pronounced were the effects of logging and other negative factors on their connectivity. Merging multifaceted landscape habitat modelling with genetics can effectively test corridor efficacy for gene flow, and it represents a powerful tool for conservation of endangered species.

Complete mitochondrial genome of the Western Capercaillie Tetrao urogallus (Phasianidae, Tetraoninae).

The Western Capercaillie (Tetrao urogallus) is a galliform bird of boreal climax forests from Scandinavia to eastern Siberia, with a fragmented population in southwestern Europe. We extracted the DNA of T. urogallus aquitanicus and obtained the complete mitochondrial genome (mitogenome) sequence by combining Illumina and Sanger sequencing sequence data. The mitochondrial genome of T. urogallus is 16,683 bp long and is very similar to that of Lyrurus tetrix (16,677 bp). The T. urogallus mitogenome contains the normal 13 protein-coding genes (PCGs), 22 transfer RNAs, 2 ribosomal RNAs, and the control region. The number, order, and orientation of the mitochondrial genes are the same as in L. tetrix and in other species of the same and other bird families. The three domains of the control region contained conserved sequences (ETAS; CSBs), boxes (F, E, D, C, B, BS box), the putative origin of replication of the H-strand (OH) and bidirectional promoters of translation (LSP/HSP).

How many of them? Genetic diversity, survival and effective population size of the capercaillie population from the Gorce Mountains

Population size and effective population size are important factors affecting probability of extinction of small, isolated population. Hence, from conservation perspective, it is recommended to monitor changes in population size of endangered species. Genetic methods, based on genetic profiling of non-invasive samples of biological material, despite some limitations, were proved to be efficient method in tracking individuals in the field and estimate populations' parameters. We used this strategy to investigate isolated population of the capercaillie (Tetrao urogallus) in the Gorce Mountains. In two study periods (2012–2013 and 2017–2018) almost 400 faeces and feathers were collected. Microsatellite genotyping was performed to identify individuals and estimate genetic diversity. We found that population is stable in terms of size and genetic indices, although allelic richness has significantly increased between 2012–2013 and 2017–2018. In the overall study period (2012–2018) there were 52 individuals identified. However, only 10 birds were found in both study periods. This suggests low survival in the population. Moreover, genetic data indicated low effective population size of the capercaillie in the Gorce Mts. Thus, we suggest that monitoring, either genetic and based on field-surveys, should be implemented in the management and protection of this population.

Bioclimatic and environmental suitability models for capercaillie (Tetrao urogallus) conservation: Identification of optimal and marginal areas in Rodopi Mountain-Range National Park (Northern Greece)

Capercaillie is a species of particular conservation importance for Europe due to the observed population decline in various parts of its distribution. In the current study, the environmental and habitat requirements of the species are investigated at the southernmost range of its European distribution (Rodopi Mountain-Range National Park, northern Greece) using a set of 95 observations of species presence and a maximum-entropy (MaxEnt) modeling approach. A bioclimatic dataset derived from the Bioclim open source database and a set of environmental variables, mainly forest land-cover types and topographical variables, were employed to explain the current distribution of the species and to delineate potentially suitable areas for its distribution. The best scale per environmental variable was chosen among three different spatial scales (10 ha, 100 ha and 500 ha), in order to build a multiscale environmental model. According to our results, the species demonstrated a very narrow niche which is determined primarily by bioclimatic factors while a number of habitat requirements within a strict bioclimatic zone where also identified. It requires wet areas with mean summer temperature not exceeding 10 °C, which are only found at the higher altitudes of the National Park. Α strong tendency was also found for capercaillies to inhabit forest stands of norway spruce (Picea abies) with a minimum cover of 10% at an intermediate scale of 100 ha, followed at a larger scale i.e. 500 ha by pure beech (Fagus spp.) forests or mixed with pines (Pinus spp.), where optimum tree density ranges from 50% to 80%. Bioclimatic and environmental presence-prediction maps were reclassified in four suitability classes (unsuitable, marginal, sub-optimal, optimal), based on three Maxent thresholds (Minimum Training Presence, Fixed Cumulative Value 5 and Value 10). Monitoring the marginal climatic zone for the species and ensuring suitable habitats within it is the key for the species conservation in its southernmost part of its distribution.

Analysis of microstructure and difference of 6 species of remiges in Galliformes

To study the microstructure and difference of remiges in galliformes, the Silver Pheasant (Lophura nycthemera), golden pheasant (Chrysolophus pictus), Blue Eared Pheasant (Crossptilon auritum), Koklass Pheasant (Pucrasia macrolopha), Himalayan Snowcock (Tetraogallus himalayensis) and Thunderbird (Tetrao urogallus) were selected as the representative of six species of endangered birds. The scanning electron microscopy (SEM) was adopted to photograph and count the hooked barbule, cilia and ventral tooth, meanwhile, the single factor analysis of variance of different remiges was carried out by Spss 11.5 software. The results show that remiges are mainly composed of hook feathers and proximal barbule, and there are hook feathers on the side of a small hook, but also with cilia. Proximal barbule is mainly composed of ventral tooth, whose number and shape are the main features. The number of hooked barbule, cilia and ventral tooth of proximal barbule of the remiges of the different birds were significantly different or significant differences among the two species, which could provide the basis for identification.

Capercaillie (Tetrao urogallus) eggshell pigmentation, maculation and thickness

Eggshells properties (mainly thickness, pigmentation and shape) vary within avian taxa across species, and intraspecifically with age, environmental conditions or individual features of the animals. The properties and appearance of eggshells are important for successful breeding both for birds kept in captivity and in breeding centres and those living in their natural environment. The presented study focuses on the association between the pigmentation, maculation and eggshell thickness of Western Capercaillie (Tetrao urogallus) kept in captivity. The eggs were collected during the entire egg-laying season in order to determine the factors which influence eggshell pigmentation and thickness across the laying period. We found that at the equator surface the lightest eggs had a tendency to be thinner than the darkest ones. In addition, eggshells with a smooth pattern were thinner at the equator, especially when compared to the mottled ones. There was no statistically significant association between the eggshell overall lightness (eggshell pigmentation except the concentrated pigment spots), maculation and eggshell thickness at the blunt and sharp ends of the eggshell. Eggshells were on average 5.5% thicker at spots than in other areas. The obtained results suggest that the spot pigment forms an additional layer on the Capercaillie eggshell and does not compensate for the loss of thickness, as observed in some bird species (Passeriformes, Falconiformes).

THE CAPERCAILLIE (TETRAO UROGALLUS) BODY WEIGHT: SPATIAL VARIABILITY IN THE WEST OF THE RANGE

We studied spatial variation of the body weight in adult capercaillie (Tetrao urogallus) using materials compilated from the literature, mostly for Western Europe. The data on > 4,300 males and > 1,000 females were grouped, respectively, into 45 and 29 mean population estimates; the principles of rejection, correction and grouping of initial data are presented. High values of male weight (≥ 4.2 kg) were located within the strip of land running from eastern France to western Belarus and northern Ukraine, which covered the range of T. u. major. To the north and south of this strip, their weight showed a clinal decrease with minimal values in the north (Swedish and Finnish Lapland: 3.7-3.8 kg) and southwest (Cantabria, Pyrenees: 3.3-3.4 kg). Such a disposition supports the opinion about a discrepancy between prediction by Bergman' rule and observed variation in the weight of West European capercaillie. However, weight in southern populations (Cantabria, Pyrenees, Eastern and Southern Carpathians, Rhodopes) increases from west to east in accordance with this rule, confirming the opinion on its correctness for monophyletic taxa. In general, the weight of females follows the variation pattern of males, although the reliability of estimates for females is substantially lower, mainly due to smaller samples. For the entire region on average, the weight of females reaches ~ 47.5 % of the weight of males, which is consistent with previously reported estimates. Possible causes for distortions of mean population weight values are discussed.

Molecular analysis of cox-1 and 18S rRNA gene fragments of Eimeria species isolated from endangered grouse: capercaillie (Tetrao urogallus) and black grouse (Tetrao tetrix)

This paper is the first record describing the molecular analysis of Eimeria species occurring in capercaillie (Tetrao urogallus) and black grouse (Tetrao tetrix) which inhabit northern Eurasia and are species critically endangered of extinction. Actions undertaken to protect endangered species, such as breeding individuals in closed aviaries, could allow saving those birds, but they also pose risk of accidental healing of invasive diseases, like coccidiosis. Therefore, an investigation was conducted on fecal samples collected from the capercaillies and black grouse originating from the Kirov region (Russia) and breeding centers located in Poland. Results indicate that the average prevalence of Eimeria revealed 72% (average OPG = 3548) and 80% (average OPG = 5220) in capercaillies and black grouse respectively. Most of the Eimeria spp. oocysts were non-sporulated; however, two different morphological types were observed. The phylogenetic analysis of cox-1 and 18S rRNA genes revealed the analyzed Eimeria sequences to belong to two species. In addition, it showed some similarities between both analyzed genes. Most of the sequences obtained from both grouse species coccidia belonged to one species partially homologous to the Eimeria spp. isolated from ring-necked pheasant (approx. 94 and 96% for cox-1 and 18S rRNA genes, respectively). Two strains isolated from capercaillies imported from Russia were related to turkey coccidia: E. innocua and E. dispersa (97–99% homology) in the cox-1 gene analysis and only one of them was related to those Eimeria species in the 18S rRNA gene analysis (98–99% homology).

Additive positive effects of canopy openness on European bilberry (Vaccinium myrtillus) fruit quantity and quality

The European bilberry, Vaccinium myrtillus L. (Ericaceae), is an important food resource for many mammals, insects and birds in forests, including the threatened capercaillie (Tetrao urogallus). For capercaillie, a sufficient amount of bilberry fruits is crucial to store enough body fat for the winter period. Studies have shown that V. myrtillus reproduction is influenced by canopy openness, but specific effects of flower availability, light conditions and pollinators on fruit production remain unclear. We therefore assessed bud, flower and fruit abundance as well as quality traits for V. myrtillus fruits under shade, semi-shade and sun conditions in 12 50 × 50 m plots in the Black Forest National Park, Germany from April to July 2017. We further observed and identified flower-visiting insects and calculated the seed set for fruits.With greater canopy openness, flower buds and fruit abundance increased. The few fruits that developed in the shade had fewer ovules compared to fruits growing under higher light availability. In the sun, seed set was highest, suggesting higher pollinator activity on these microsites. We identified five flower-visiting insect species of the genera Andrena, Bombus and Lasioglossum. The results show that canopy openness can trigger a number of additive positive effects on the number of flowers and hence potential fruits but also their quality due to an enhanced pollinator activity. Active canopy opening could therefore be used to increase bilberry availability for capercaillie. Management plans to support capercaillie populations however, should also consider the time lag between active canopy opening and flowering response in V. myrtillus.

Modelling Capercaillie (Tetrao urogallus) lek sites distribution and their limiting factors in a central Norwegian managed forest landscape

Forest management has substantially altered Fennoscandian forests through clear-cutting practices started during the 1950s. Impacts on the natural biodiversity in mature boreal forest have been inevitable. The Capercaillie (Tetrao urogallus) is often regarded as an indicator species for natural old growth forest, displaying on traditional lek sites during spring. In a heterogeneous forest landscape of two adjoining municipalities in central Norway we studied whether forest management or other environmental factors can have influenced the lek distribution. We identified 15 active leks and 12 recently abandoned leks. The maximum entropy distribution modelling (MaxEnt) was used to investigate factors associated with lek distribution at two different scales, where the scale reflecting the lek site areas gave the most adequate result. Active leks were predominantly associated with mature stands of forest. In 65% of the study area the habitat suitability for lekking was most influenced by forest management. Furthermore, the recently abandoned leks were found less frequently in low productive and mature forests than the still active ones, implying that previous leks in productive forest stands may have been lost through logging. Based on our data we have developed models for the predicted distribution and the current limiting factors, showing that altered forest management could improve lek site suitability in large parts of this boreal forest.

Habitat suitability modulates the response of wildlife to human recreation

Outdoor recreation activities are growing in popularity, causing increasing pressure on wildlife. There are various ways in which wildlife reacts to recreation activities, ranging from behavioural to physiological responses, with regional variation in response-intensity within the same species. We tested whether the effects of human recreation are modulated by overall structural habitat suitability, using a model that included vegetation and topography, at both the regional and local habitat use scale. By undertaking a systematic, plot-based survey over 13 years in 13 study regions across central Europe, we studied how recreation infrastructure and habitat suitability interact and affect the variation in regional densities and local habitat use of an endangered model species: the western capercaillie (Tetrao urogallus). Both regional densities and local habitat use varied greatly between study years and regions. Capercaillie densities were positively correlated with average habitat suitability, but significantly reduced when over 50% of the area was influenced by recreation activities. Habitat suitability was the main predictor determining local habitat use. Recreation infrastructures were avoided: the effect being stronger in poor habitat conditions, while slightly mediated by high habitat suitability. Our results indicate that effects of recreation activities might be mitigated by improving habitat suitability; however this has limits because it only affects local scale habitat use but not regional densities. We stress the importance of recreation-free areas which must cover extensive (i.e. >50%) parts of the species range.

Forest structure following natural disturbances and early succession provides habitat for two avian flagship species, capercaillie (Tetrao urogallus) and hazel grouse (Tetrastes bonasia)

Boreal and mountainous forests are a primary focus of conservation efforts and are naturally prone to large-scale disturbances, such as outbreaks of bark beetles. Affected stands are characterised by biological legacies which persist through the disturbance and subsequent succession. The lack of long-term monitoring data on post-disturbance forest structure precludes understanding of the complex pathways by which natural disturbances affect forest structure and subsequently species presence. We analysed the response of capercaillie (Tetrao urogallus) and hazel grouse (Tetrastes bonasia) to bark beetle infestations. We combined high-resolution airborne light detection and ranging (LiDAR) with a 23-year time series of aerial photography to quantify present-day forest structure and stand disturbance history. Species presence was assessed by collecting droppings of hazel grouse and capercaillie in a citizen science project. Structural equation models showed that the probability of hazel grouse presence increased with increasing disturbance, and the probability of both hazel grouse and capercaillie presence increased with succession. Indirect effects of bark beetle infestations, such as a reduced abundance of deciduous trees and an enhanced herb layer cover, were positively associated with capercaillie presence. Decreasing canopy cover increased the probability of hazel grouse presence. The high temporal and spatial heterogeneity of bark beetle infestations created forest structures that meet the contrasting habitat requirements of both, capercaillie and hazel grouse. This heterogeneity resulted from biological legacies such as decomposing snags, and the simultaneous regrowth of natural regeneration. A benign-neglect strategy towards bark beetle infestations could hence foster capercaillie and hazel grouse in mountainous forests.

Shit happens \u2026 and persists: decay dynamics of capercaillie (Tetrao urogallus L.) droppings under natural and artificial conditions

Feces of wildlife species are commonly used indicators for species’ presence or relative abundance. These might however be biased due to inconspicuousness, due to rapid decay and disappearance, or due to high site-dependent variance in decay dynamics. Mapping of indirect signs is a frequently applied approach to study habitat use or distribution of grouse species. However, only a few studies addressed avian dropping decay up to now, and no study focused on dropping decay of European grouse species. Consequently, we conducted field surveys and greenhouse trials, studying time spans over which capercaillie (Tetrao urogallus) droppings persist and factors influencing the decay rates (i.e., habitat type, small mammal access, and precipitation regime). In the field survey, after an exposure of 98 days, only 6% of droppings (n = 156) decayed completely and most droppings remained nearly unchanged. The decay rate was influenced by microsite conditions (i.e., vegetation and location), with lowest decay rates in areas with little ground vegetation or on tree stubs. Destruents were not found to play a major role in affecting decay rate. The greenhouse trial revealed the impact of precipitation on the decay rate of droppings (n = 400): under high-amount and high-intensity precipitation regime droppings decayed faster compared to low-amount and low-intensity precipitation. The slow decay rate, and resulting long time period that they can be detected, therefore means that capercaillie droppings are a valid proxy for species’ occurrence.

A first test of unattended, acoustic recorders for monitoring Capercaillie Tetrao urogallus lekking activity

ABSTRACTCapsule: Automated acoustic recording can be used as a valuable survey technique for Capercaillie Tetrao urogallus leks, improving the quality and quantity of field data for this endangered bird species. However, more development work and testing against traditional methods are needed to establish optimal working practices.Aims: This study aims to determine whether Capercaillie vocalizations can be recognized in lek recordings, whether this can be automated using readily available software, and whether the number of calls resulting varies with location, weather conditions, date and time of day.Methods: Unattended recording devices and semi-automated call classification software were used to record and analyse the display calls of Capercaillie at three known lek sites in Scotland over a two-week period.Results: Capercaillie calls were successfully and rapidly identified within a data set that included the vocalizations of other bird species and environmental noise. Calls could be readily recognized to species level using a combination of unsupervised software and manual analysis. The number of calls varied by time and date, by recorder/microphone location at the lek site, and with weather conditions. This information can be used to better target future acoustic monitoring and improve the quality of existing traditional lek surveys.Conclusion: Bioacoustic methods provide a practical and cost-effective way to determine habitat occupancy and activity levels by a vocally distinctive bird species. Following further testing alongside traditional counting methods, it could offer a significant new approach towards more effective monitoring of local population levels for Capercaillie and other species of conservation concern.