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Our study reveals for the first time in a quantitative manner the differences in eggshell thickness and elemental composition between pigment spots and adjacent plain eggshell regions in bird species from three developmental modes, i.e. altricial (Great Reed Warbler Acrocephalus arundinaceus), semi-precocial (Black-headed Gull Chroicocephalus ridibundus, Mediterranean Gull Ichthyaetus melanocephalus, Sandwich Tern Thalasseus sandvicensis and Black Tern Chlidonias niger) and precocial species (Western Capercaillie Tetrao urogallus and Black Grouse Lyrurus tetrix). From a broader biological/biogeochemical perspective, our data broaden the knowledge in the heterogeneity of elemental composition between adjacent spotted-plain regions of eggshells, previously demonstrated in galliform birds, which differ in colour for many chemical elements. These differences, however, were distinctive of individual species and varied between chemical elements. There emerged a clear and consistent trend of higher elemental concentrations within pigment spots compared to plain eggshell regions, particularly in the case of five elements: C, Pb, Cu, Cr and Al. The most important and novel finding of our study is that even though the eggshells of gulls and terns (semi-precocial species) and of the passerine (altricial species) were thinner in the spotted regions (there was thus less shell material) compared with those of precocials (the eggshells being thicker eggshells at the spots), the spotted regions of all these eggs contained disproportionally higher concentrations of most major and minor chemical elements. Hence, this appears to be a general rule across all birds, regardless of the eggshell thickness in the spotted or plain regions and/or their developmental mode. In other words, this finding confirms that the thickness of the eggshell itself does not affect the concentrations of elements, and that the key issue related to this is the presence of one or more protoporphyrin layers along with the accompanying pool of chemical elements within the spotted eggshell region. [ABSTRACT FROM AUTHOR] more...

The Northern German Black Grouse metapopulation has been affected since decades by a sharply decline that has ultimately led to a reduced genetic variability. Gastrointestinal parasitoses are common among Black Grouse, but it is not clear if they have a further negative impact on the development of this already threatened metapopulation. Therefore, between 2011 and 2014, the occurrence and seasonal variation of gastrointestinal parasites were assessed by coproscopical investigations of Black Grouse feces collected in the nature conservation area of the "Lüneburg Heath". Feces were obtained also from individuals during capture and re-capture activities. In total, 1,187 fecal samples were analyzed, of which 365 were caecal and 822 were rectal feces samples. 86% of the caecal and 95% of the rectal feces samples were parasite negative. Of the positive samples, oocysts of Coccidia spp. showed the highest prevalences of 12.1% in caecal and 1.1% in rectal samples, respectively. Helminths of the species/genera Trichostrongylus tenuis, Ascaridia spp., Heterakis spp., Capillaria spp., and Syngamus trachea were also observed, but at remarkably lower prevalences. High and moderate excretion intensities were observed only for coccidian oocysts. Coccidian infections revealed a seasonal pattern, occurring mostly during autumn and winter. Nematode eggs occurred more frequently in spring and summer. Four of the seven Black Grouse that were caught and equipped with GPS transmitters, presented high excretion intensities of coccidian oocysts. Despite high/moderate oocyst excretion, no negative health impact was observed, suggesting low pathogenicity of the infecting coccidia species or subsided infections. In contrast to previous studies, this Black Grouse population showed low prevalences of a rather narrow spectrum of parasites. We did not observe any negative impact of parasite infections on this population, which could be responsible for its decline. Thus, causes of decline are to be ascribed to other proximate and ultimate factors. [ABSTRACT FROM AUTHOR] more...

Studies on the foraging ecology of wildlife species are of fundamental importance, as foraging decisions are closely linked to ecological key issues such as resource partitioning or population dynamics. Using Black grouse as a model system, we applied Fourier-transform infrared spectroscopy (FTIRS) to address some key questions in foraging ecology: (1) does FTIRS allow for determining plant taxa and plant parts? Can FTIRS suggest variation in digestibility of food and physiological mechanisms of consumers? (2) Can FTIRS be used to track changes in diets among populations? (3) Can FTIRS capture plants' phenology and shifts in diet? To answer these questions, we analyzed crop and gizzard contents of Black grouse via FTIRS looking for specific spectra and bands of plant taxa and plant parts. We compared spectral signals of undigested plant material and intestinal droppings, gained from wild-living birds and from aviaries. Our analyses yielded characteristic spectral fingerprints for several food plants and plant parts. Spectral fingerprints could differentiate between needles of J. communis and P. mugo and between fruits of J. communis, Sorbus sp., and Vaccinium sp. Spectral signals differed more between undigested material and crop samples than between crop and gizzard samples. Differences were more pronounced for berries than for needles. Apart from these differences, some fingerprints persisted for certain food items. The diverse foraging regime of wild-living individuals compared to captive Black grouse was reflected by spectral signals. Thus, FTIRS is a promising approach to explore variation in food choice of grouse species by means of non-invasively gained fecal samples. [ABSTRACT FROM AUTHOR] more...

There is widespread interest in the relationship between individual genetic diversity and fitness-related traits (heterozygosity-fitness correlations; HFCs). Most studies have found weak continuous increases of fitness with increasing heterozygosity, while negative HFCs have rarely been reported. Negative HFCs are expected in cases of outbreeding depression, but outbreeding is rare in natural populations. Negative HFCs may also arise through viability selection acting on low heterozygosity individuals at an early stage producing a skew in the heterozygosity distribution. We tested this idea using survival and clutch parameters (egg mass, egg volume, chick mass, clutch size) in female Black Grouse Lyrurus tetrix and carried out simulations to determine how survival selection may impact the HFCs measured using clutch parameters. We show that survival is positively related to both individual heterozygosity and female body mass. There was a positive effect of body mass on all clutch parameters, but the selective mortality of females with both low heterozygosity and low body mass led to overrepresentation of high heterozygosity-low body mass females and hence a negative relationship between egg volume and heterozygosity. Using simulated data, we show that survival selection acting on both low body mass and low heterozygosity leads to a skew in the quality of breeding females, resulting in negative HFCs with egg volume. Our results indicate that survival selection can strongly influence the strength and direction of any HFCs that occur later in life and that only an integration of all aspects of individual reproductive investment and reproductive success can enable us to fully understand how heterozygosity can shape individual fitness. [ABSTRACT FROM AUTHOR] more...

Around the nests of many birds of prey the pressure of nest predators is decreased. This attracts other bird species to breed near nests of those birds of prey in order to benefit from protection conferred. This study examines the possible protective effect of the Northern Goshawk ( Accipiter gentilis) on two of its main prey species, the Black Grouse ( Tetrao tetrix) and the Capercaillie ( Tetrao urogallus). If the Goshawk reduces the number of corvids robbing grouse nests, there should be a larger proportion of grouse females with broods near Goshawk nests during late summer. We compared the proportion of grouse females with the broods observed in wildlife-triangle counts, which were performed along a 12-km-long equilateral triangle in relation to distance from a successful Goshawk nest. Where Goshawks had nested inside a triangle, the proportion of Black Grouse females with a brood was 20 % higher than in situations where a Goshawk had nested 2-3 km away from the center of the triangle. On the other hand, the number of adult Black Grouse rose as the distance from the Goshawk nest increased, but this pattern did not hold with chick abundance. No distance effect was found for Capercaillie. This study thus provided indirect evidence based on quantitative data that Goshawks may create a protective effect for one of its main prey. [ABSTRACT FROM AUTHOR] more...

In recent years, the Fourier transform infrared spectroscopy (FT-IR) was used to assess the diet, digestibility or nutritional values of food items of ruminants. However, it has never been used to analyse the diet of grouse species. Commonly used methods have so far been direct observations of birds and microscopical analyses of droppings. The sample preparation and comparison of microscopical analyses is a highly time-consuming procedure. The comparison is based on morphological structures of epidermal cells, like the shape of cells, stomata or trichomes. In contrast, the sample preparation for the FT-IR and the subsequent measuring is simple and quickly done. We investigated the diet of Black Grouse ( Tetrao tetrix L.) in two study areas with infrared spectroscopic methods comparing summer and winter droppings' content with plant reference material. The study areas are located in the provinces of Salzburg and Upper Austria, Austria. In our study, samples were measured in the mid- and near-infrared range. We tried to determine the dominating content of faecal samples at species, genera or family level or at least to assign samples to one of four main plants groups (i.e. woody plants, heathers, herbs and grasses). Our results showed a dominance of Larix decidua within the group of woody plants in both areas and, within the group of heathers, a dominance of Calluna vulgaris and Rhododendron hirsutum in one study area. Partially, our results are in marked contrast to other studies conducted in the Alps, as Vaccinium myrtillus was not detected in the samples. For further methodological studies, faecal sampling over larger areas, larger samples of plant reference material (including seeds and other parts of plants at different seasons), taking more samples per dropping and synchronous comparisons of microscopic analyses as well as FT-IR spectroscopy, are recommended. [ABSTRACT FROM AUTHOR] more...

In the Italian Alps the intensification of winter sports represents an increasing threat for Black Grouse ( Tetrao tetrix). During the winters 2010/2011 and 2011/2012, characterised by different amounts of snowfall, 58 droppings from as many snow burrows were collected in three areas with different human disturbance to evaluate its effects on Black Grouse stress responses. Subjects in highly disturbed area showed higher concentrations of corticosterone metabolites during the winter with high snow cover highlighting a relationship between animals' stress and regular winter sports. As human-induced stress may contribute to population decline, tourism management should be planned to support Grouse conservation. [ABSTRACT FROM AUTHOR] more...

The Black Grouse ( Tetrao tetrix L.), listed in Annex 1 of the European Bird Directive, inhabits the vulnerable alpine treeline ecotone. Reacting sensitively to modifications of the environment, it can be regarded as an indicator species. To assess summer habitat use, we measured habitat parameters and recorded faeces (intestinal droppings) of Black Grouse on a mountain chain of the Northern Limestone Alps at the northern fringe of its distribution. In the area, the existing hiking trails are frequently used by hikers in summer. We modelled summer habitat use and included effects of hiking trails testing three different buffer radii around hiking trails (i.e., 50, 100 and 150 m); the buffer radius of 50 m significantly contributed to the final model of habitat use. Altitude, cover of grasses/herbs, canopy cover of woody plants <5 m, canopy cover of woody plants ≥5 m, grazing intensity, and the interaction term cover of grasses/herbs × canopy cover of woody plants ≥5 m combined with presence-absence of hiking trails best predicted the occurrence of Black Grouse. Our calculations yielded lower probabilities of Black Grouse occurrence areas adjacent to hiking trails (odds of presence reduced by 93 %). Terrestrial mapping of indirect signs and the statistical model were appropriate to depict significant differences of probabilities of occurrence within and outside the buffer zone around hiking trails. Considering the habitat variables in the model, enhancing small-scale habitat heterogeneity seems to be a recommendable habitat management strategy; by creating a fine mosaic of higher woody plants, dwarf shrubs and open, grassy habitat patches, a rich supply of food and cover can be provided within short distances. [ABSTRACT FROM AUTHOR] more...

The factors influencing the selection of Black Grouse Tetrao tetrix winter roost sites and choice of roosting strategy (open-air roosts vs. snow burrows, or 'igloos') were assessed in the Alps, including the influence of winter diet, snow conditions and habitat at different scales. Of 337 roosts detected, 31 % were igloos and 69 % were open-air roosts. At the larger scale (30 × 30 m), ground curvature, altitude, slope, southerly aspect and mountain pine Pinus montana uncinata cover were positively correlated with roost presence. At the smaller scale (10 m radius), roost presence was positively correlated with a northerly aspect, cover of green alder Alnus viridis, and a low cover of vegetation downslope from the roost. Roosting strategy was related to temperature and snow conditions (with more igloos when snow depth was greater, but fewer igloos when a hard snow crust had formed). The winter diet of the Black Grouse mostly comprised mountain pine needles (84 % of droppings). The results suggest that a range of factors influence choice of roost site, including predator avoidance, food availability and topography. The latter showed contrasting effects at different scales, suggesting that Black Grouse select colder sites (with deeper snow) within warmer areas (energetically more favourable). Management to encourage the mountain pine, whilst maintaining scattered green alder in the understorey, is likely to improve Black Grouse winter habitat quality. Choice of roosting strategy is, however, dictated by weather conditions. If the reduction in precipitation and snow cover continues as forecast, open-air roosting might be more frequent in the future. However, open-air roosting might increase predation risk, which could be deleterious for the species' conservation. [ABSTRACT FROM AUTHOR] more...

The cold periods of the Pleistocene have had a striking impact on the diversification of most organisms in temperate regions. Phylogeographic patterns and postglacial expansion are poorly understood in the Black Grouse ( Tetrao tetrix). This species is widely distributed across Eurasia, and has been divided into a number of subspecies on the basis of morphological differences and geographic isolation. To investigate the evolutionary history of the species, 143 samples from different regions were examined for a mtDNA control region fragment. Overall, analyses of mtDNA gave support for the divergence between Tetrao tetrix tetrix, T. t. ussuriensis and T. t. mongolicus. The analyses reveal the effects of colonisation out of glacial refugia on the genetic diversity and genetic structure of Black Grouse. The phylogeographical results are consistent with a demographic population expansion following a bell-shaped mismatch distribution, a star-shaped phylogeny and low nucleotide diversity. Patterns of postglacial dispersal imply that Black Grouse from southern Europe have been restricted to this area, and did not contribute to the genetic diversity of northern Europe. Instead, Black Grouse spread out to northern Europe from a refugium in the east and a possible one in western Europe, following the retreat of glacial ice sheets, although both refugia remain unidentified. We suggest that T. t. britannicus and T. t. viridanus correspond to northern T. t. tetrix, and that this lineage has diverged from the other subspecies. This division is tentative due to limited sampling, but it will facilitate the management of different evolutionary significant units of the species. [ABSTRACT FROM AUTHOR] more...

The Black Grouse Tetrao tetrix is primarily a lekking species, although in some populations solitary display is also common. We analysed data from a 25-year-long survey of an increasing Black Grouse population in the western Italian Alps in order to test whether the numbers of males adopting different tactics conformed to patterns expected, based on the hypothesis that dominant birds occupy the leks and solitary displaying birds are subordinate, and that the tendency for birds to be excluded from leks increases with lek size. Four predictions were made to test this hypothesis: (1) the proportion of solitary males would increase as the overall population increases, (2) there would be a threshold at which there is little or no increase in the size of the lekking population, but continued increase in the population of solitary displaying birds, (3) available lek habitat would be occupied prior to an increase in solitary displaying males, and (4) there would be an increase in the use of less preferred habitat by solitary displaying males as the total population increases. Population trends varied according to display status, in that the lekking population reached an apparent threshold while the number of solitary males continued to increase, and there was an expansion of the range of solitary males into higher altitudes in years when the population was larger. However, there was no increase in the proportion of solitary males as the total population increased. Furthermore, there was no suggestion that suitable lek habitat was limiting, as the number of leks and the mean size of those leks continued to increase throughout the study period. Although two predictions were supported, the precise patterns of trends, and results of additional analyses, suggested that solitary display is more likely to be an alternative rather than a subordinate tactic. Several factors may promote this apparent dual display tactic in Black Grouse, but habitat structure in this and other Alpine populations is likely to be a key influence. [ABSTRACT FROM AUTHOR] more...

Sex-biased dispersal is a common phenomenon in most birds. In general, males breed at or near their site of birth while most of the females disperse. We investigated the dispersal patterns and genetic structure of lekking Black Grouse Tetrao tetrix based on ten microsatellite loci. Data for 469 individuals from 25 localities spaced from 45 to 558 km apart revealed low levels of genetic differentiation and high connectivity among studied sites due to female-biased dispersal. The spatial distribution of the genetic variation did not follow an isolation by distance pattern neither for females nor for males. STRUCTURE identified three clusters of male individuals but without any geographical pattern. Only one cluster was identified for females. Several tests of sex-biased dispersal were executed. Most of them showed no difference between sexes, but the mean assignment index and F showed a statistically significant female-biased dispersal. Therefore, we consider that the northern Swedish Black Grouse population is a panmictic population. The amount of gene flow throughout time has been consistent with dispersal and with no strong effect of forest fragmentation in the region. [ABSTRACT FROM AUTHOR] more...

Differences in the ability to sustain chronic stress can underlie the variation in individuals' fitness directly or indirectly by impairing the expression of condition-dependent signals used in female mate choice. Therefore, understanding the effect of the stress response on individuals' fitness is key to identifying the mechanism of sexual selection. We tested the hypothesis that an indicator of stress-the heterophil/lymphocyte ratio (H/L ratio)-is related to several major components of male fitness in the lekking Black Grouse ( Tetrao tetrix), a species with intense male-male competition. The H/L ratio accurately measured the stress response, as it increased within a few hours of trapping and during the months prior to the mating season. The H/L ratio was positively related to the expression of morphological traits, suggesting that males of higher 'quality' might be able to express elaborated ornaments and better cope with stressful conditions or with changes in health status. However, in Black Grouse, ornaments are (partly) independent of behavioural display and are under only weak selective pressure. Therefore, the H/L ratio was not significantly related to male mating success and survival to the following year. Under natural conditions, observed levels of the H/L ratio might not be associated with strongly deleterious effects because of behavioural adjustments. Mechanisms other than the stress response may mediate the observed variance in male mating success. [ABSTRACT FROM AUTHOR] more...

Deciphering the effects of climatic conditions on population dynamics is of major importance in understanding how organisms are likely to be affected by climate changes. Using data from broad-scale annual censuses between 1990 and 2007, we show that winter and summer North Atlantic Oscillations affect several breeding success indicators of the Black Grouse ( Tetrao tetrix) in the French Alps. We did not find any trend in hen counts or breeding indexes over the study period. Surprisingly for a bird specialised in cold climates, we show that Black Grouse optimise their reproductive output for positive values of the winter NAO corresponding to the average NAO index of the last 30 years. Extreme NAO values lead to lower breeding success, indicating that the grouse may be more able to track trends in climate than an increase in the frequency of extreme years. Our result show that, at least from a short-term perspective, Black Grouse productivity is not threatened by a trend towards warmer climatic conditions in the Alps, but may be affected by an increased frequency of extreme years. We advocate the use of the NAO as a climate proxy rather than using heavily noised and biased local climate descriptors in studies focusing on the global response to climate over a large spatial scale. [ABSTRACT FROM AUTHOR] more...

Here, we describe genetic diversity of lekking and non-lekking populations of Black Grouse Tetrao tetrix in the mountains bordering the Czech Republic. In total, 250 individuals from eight lekking and eight non-lekking study sites were genotyped at 11 microsatellite loci. Significant pair-wise F values between the different regions indicated low dispersal between localities, and birds could be assigned to three main mountain ranges (Šumava Mts, Krkonoše Mts and Krušné Mts). We found lower genetic diversity at study sites with solitary displaying males compared to sites where birds aggregate at leks. Additionally, genetic diversity was significantly more strongly associated with type of display than with spatial location of the sites. Given that lekking behaviour may be related to population density, we suggest that a shift from lekking to solitary displaying males is an alarming sign for conservationists indicating decreasing effective population sizes and declining populations. [ABSTRACT FROM AUTHOR] more...

A correction to the article "The dynamics of alternative male mating tactics in a population of Black Grouse Tetrao tetrix in the Italian Alps" that was published in the March 2013 issue is presented. more...