Activity patterns of Capercaillie, Tetrao urogallus, during winter

Winter activity patterns of 16 radio-marked capercaillie, Tetrao urogallus , were studied during 1981–83 at Varaldskogen, SE Norway. Activity was confined to the light hours of the day, closely following the photoperiod. Diel distribution showed a major peak near sunset during every month. A second peak was found in the morning. This peak was comparable to the evening peak in early and late winter, but nearly disappeared in midwinter. Ambient temperature rather than photoperiod seemed to be the important proximate factor responsible for the changes in morning activity. By postponing activity to the afternoon, capercaillie avoids energy expenditure during the coldest morning hours.
Total daily activity (TDA) during the period November-April averaged about 3 h for both sexes. TDA of cocks was U-shaped with the lowest values (2.0 h) in December-January, whereas TDA of hens was fairly stable during November-March with mean value of 2.7 h, increasing abruptly to 4 h in April. TDA during December-January is believed to express the time used for feeding in pine trees. The significantly higher TDA of hens (26%) compared with cocks during this period may be explained by a higher relative heat loss of hens (body weights: hens 2.0 kg, cocks 4.3 kg). The increased level of activity during early and late winter among cocks was probably due to display and related territorial behaviour, whereas increased activity of hens during April probably was caused by a shift from feeding in pines to more time-consuming, selective feeding on the ground     

Habitat characteristics of Capercaillie Tetrao urogallus display grounds in southeastern Norway

Habitat composition of 39 capercaillie Tetrao urogallus display grounds was compared with available and unused habitats in two coniferous forest areas in southeastern Norway. Macro-habitat was described with respect to forest successional stage and topography. Micro-habitat was described with respect to microtopography, plant association, and forest stand structure. Totally, 28 variables were measured. A pronounced macro-habitat preference was found for elevated areas with forests older than 60-70 years. Micro–habitat composition varied considerably. However, a slight but significant preference was found for heterogeneous, open-spaced understory, and for visibility of more than 30 m. Suitable micro-habitats were abundant, and distribution of display grounds were mainly limited by macro-habitat characteristics, i.e. elevated, old forest areas.     

Capercaillie Tetrao urogallus in Scotland - demography of a declining population

Capercaillie Tetrao urogallus numbers declined in Scottish forests between 1992 and 1997, although the rate (mean 16% per year, 95% CL 1–30%) differed among forests. Hens declined more quickly than cocks despite the sex ratio in chicks favouring females. A probable explanation is that adult cocks lived longer. Juvenile survival was less than adult survival, largely because juveniles were more likely to die from hitting fences. Although poor reproduction was probably the main cause of the decline, this might not have occurred had fence strikes been substantially fewer.     

Rain, breeding success and distribution of Capercaillie Tetrao urogallus and Black Grouse Tetrao tetrix in Scotland

The number of chicks reared by Capercaillie was inversely related to the number of days with rain during and just after their hatching. However, rain had no detectable effect on the breeding success of Black Grouse on the same study area. The breeding distribution of Capercaillie in Scotland is more limited than that of Black Grouse, which extends into rainier areas. It is speculated that sexual selection for large size in Capercaillie has indirectly caused their chicks to be more vulnerable to rain and, consequently, has limited their distribution to less rainy areas.     

Nesting habitat,clutch size and nest failure of Capercaillie Tetrao urogallus in Scotland

CapsuleThe mean clutch size was 7.3, and habitat and year did not significantly affect nest failure rate.     

Release Factors of Breeding Activities in Capercaillie (Tetrao urogallus) Hens

The present 7-year study was conducted on a capercaillie (Tetrao urogallus) lek. The study included four years of continuous monitoring of reproductive behaviour of capercaillie in spring and a 3-year study of hen-cock relationships. We used a factorial Correspondence Analysis (CA) to assess the relationship between variables such as weather, release activity and cock display behaviour, as well as the presence and activity of hens. The statistical correlations between these factors were also summarized, showing that: there is no direct relationship between daily activity of hens on the lek and photoperiod; the behavioural interactions between cocks, their spatial and territorial organization, on the one hand, and hen activity and receptivity on the other, are reinforced by reciprocal interactions between the sexes.     

Habitat selection and diet of the Capercaillie Tetrao urogallus in Abernethy Forest,Strathspey, Scotland

Capsule Woodland characteristics are important for fully grown birds and for broods.

Aims To describe habitat selection and diet of the Capercaillie in ancient native pinewoods and Scots Pine Pinus sylvestris plantations, in order to provide a guide for forest management.

Methods Tree selection was studied in winter by locating droppings under trees along transects, and comparing those trees used by Capercaillie with those not used. Habitat selection by broods was studied by following radiotagged chicks or females with broods. Diet was described from the analysis of droppings.

Results In winter, Capercaillie preferred Scots Pines with wide crowns and large branches, and little surrounding Heather Calluna vulgaris, but avoided forest tracks. Female Capercaillie occurred in stands with a higher density of pines compared to males. The diet of fully grown birds comprised primarily Scots Pine needles between October and April. Scots Pine pollen cones were eaten during May, June and July. Bilberry Vaccinium myrtillus leaves and fruit were eaten in summer and autumn. Habitats used by broods had a higher percentage of Vaccinium sp. and smaller Scots Pines compared with random sites. Chicks hatch at the beginning of June, and in their first two weeks, their diet comprised Formicidae, Lepidoptera larvae and Coleoptera. In July and August, Lepidoptera larvae were rarely eaten but a higher percentage of chicks took vegetable material (particularly Bilberry fruit). In June, smaller numbers of invertebrates were generally trapped in mires of wooded bogs compared with areas of Heather and Vaccinium sp. in old woodland. Areas of Vaccinium sp. had the highest numbers of Formicidae, Coleoptera and Diptera, and especially Lepidoptera larvae. Numbers of Lepidoptera larvae declined during June and July as larvae pupated, explaining the reduction of Lepidoptera larvae in the diet of older chicks.

Conclusions Habitat management for Capercaillie should aim to provide old Scots Pine forest with a Vaccinium-rich field layer. Within Scotland, this may entail increasing the tree density in ancient native pinewoods but decreasing it in pine plantations. The removal or closure of tracks might increase the amount of woodland available to Capercaillie, by reducing human disturbance.     

Ranging behaviour of male capercaillie Tetrao urogallus outside the lekking ground in spring

During the breeding season, adult male capercaillies Tetrao urogallus display on leks in the early morning. During the day, they occupy more or less exclusive home ranges within 1 km of the lekking ground, but little is known about their movements and range use patterns during this period. In three spring seasons we monitored the daily movement of 15 radio-tagged adult males, associated with six different leks, in a coniferous forest of southeast Norway. The objective was to relate dynamics of male movement and spatial distribution to changes in food resource availability and mating-related activities. In late winter, males exhibited a pattern of short daily relocations (distance between bird locations in successive days) within small ranges. Relocation distances and home ranges then increased markedly during two weeks preceeding the main mating period. During the mating and post-mating periods, movements again decreased, followed by another short peak at the time when females with depredated nests return to the lek for remating. These temporal changes in range use were not related to changes in food resources and probably not to shifts in anti-predator behaviour, and they differed between age groups: The increase in relocation distance during the pre-mating period was most pronounced among young resident males (3 and 4 year-olds), and range area of older males were smaller and did not increase as much during this period. The observed age-related changes in space use may reflect an alternative mating strategy by young and subdominant males; they seek out females outside the lekking ground where competition from more dominant males is less intense.     

Simple and Effective Methods of Freezing Capercaillie (Tetrao urogallus L.) Semen

A continuous decline in the number and range of capercaillie (Tetrao urogallus L.) in many European countries can be observed, mostly due to habitat destruction by human activity, unecological forestry management, and increased density of natural predators. Ex situ in vitro gene banks provide a unique opportunity to preserve the genetic material for future generations. Simple and effective cryopreservation methods for capercaillie semen are discussed. Semen was collected from seven males kept in the Capercaillie Breeding Centre at Forestry Wisła in Poland. Within five minutes after collection, ejaculates were diluted with EK diluent, then divided into two parts, and subjected to two freezing procedures: in pellets and in straws. In fresh semen, ejaculate clearness, viscosity, color and volume, as well as sperm concentration, motility and morphology, were evaluated, while in frozen-thawed semen only motility and morphology of sperm were determined. Fertilizing ability of thawed semen was examined for samples frozen in straws. Significant (P<0.05) differences between individual males were found in relation to the majority of fresh semen traits: ejaculate volume averaged 102.1 µL (varying from 49.0 to 205.0); average sperm concentration was 632.5 x10⁶ mL^-1 (178.8–1257.1); percentage of live normal cells varied from 39.2 to 70.3% (58.7% on an average); percentage of motile cells ranged from 76.0 to 85.7%) and motility parameters were male dependent, as well. Both cryopreservation methods had a negative effect on morphology and motility of frozen-thawed semen; however, the straw method yielded 60.7% and the pellet method 42.5% of live cells in total in thawed semen (P<0.05), while the number of live normal (intact) cells was similar (22.4 and 22.2%, respectively). Egg fertility varied between 77.8 and 91.7% (average 84.4%). Both freezing procedures seem to be effective in obtaining acceptable viability and high fertilizing potency of thawed sperm and can be used to create a gene bank of capercaillie semen.     

Timing of breeding in Black Grouse Tetrao tetrix and Capercaillie Tetrao urogallus and distribution of insect food for the chicks

In Perthshire (Scotland), Black Grouse Tetrao tetrix broods less than 3 weeks old preferred herb-rich grassy flushes with Bog Myrtle Myrica gale , whereas in the northern Pennines (England), all broods were found on grass-dominated moorland or enclosed rough grazing habitats chiefly of grass and rushes. In both areas, broods used habitats with taller vegetation that had more invertebrates, particularly moth caterpillars and sawfly larvae (Sym-phyta, Hymenoptera). Within preferred habitats, broods were found in vegetation containing more flies (Diptera), plant bugs (Hemiptera) and ichneumon flies (Hymenoptera) than at randomly chosen sites. The main hatch of Black Grouse chicks in Perthshire coincided with the peak availability of moth caterpillars preferred by chicks. Broods in the Pennines hatched 1 week later than those in Scotland, and this later breeding in the south may be an adaptation to utilize the later peak biomass of sawfly larvae, the chief insect prey there. Data collected for Capercaillie Tetrao urogallus suggest a similar degree of synchronization between their peak hatch and the availability of moth caterpillars on Bilberry Vaccinium myrtillus.     

Habitat selection and diet of Western Capercaillie Tetrao urogallus in an atypical biogeographical region

Ecological features and conservation requirements of populations at the latitudinal limits of a species’ geographical range frequently differ from those in other parts of the range. Identifying such differences is key to implementing effective conservation strategies for threatened range‐edge populations especially, in the context of rapid global warming, at the lower‐latitude range edge. We studied habitat selection and diet of the endangered Cantabrian Capercaillie Tetrao urogallus cantabricus in a recently discovered population at the southernmost edge of the sub‐species’ range. This is the only Western Capercaillie population in the Mediterranean biogeographical region. We combined non‐systematic surveys based on questionnaires, reports and field sampling with data from radiotracking to assess habitat selection. Diet was surveyed by micro‐histological methods from droppings collected in the new population, which inhabits Pyrenean Oak Quercus pyrenaica forests and Scots Pine Pinus sylvestris plantations, and in two Cantabrian populations inhabiting Eurosiberian forests. Capercaillie preferred large (> 500 ha) and medium‐sized (100–500 ha) Pyrenean Oak forest fragments and large Scots Pine plantations. Forest fragments smaller than 100 ha and non‐forested habitats were always avoided. Diet differed markedly between Mediterranean and Eurosiberian populations. Bilberry Vaccinium myrtillus is common in the diet of most Capercaillie populations but was scarce in the study area and so was rare in the diet of the new population. Instead, Rockrose Halimium lasianthum was described for the first time as a major food resource for the Capercaillie and was consumed in autumn and winter. Pine needles were also heavily consumed in winter. We document for the first time the strong preference of Capercaillie for Pyrenean Oak forests and a moderately high consumption of the leaves, buds and acorns of this tree species throughout the year. Habitat selection and diet of this Mediterranean population differ from those of the core Cantabrian and other populations. Our results suggest a wider environmental tolerance (phenotypic plasticity) in the species than previously recognized. We advocate specific protection for this unique range‐edge Capercaillie population and its Pyrenean Oak forest habitat.     

No genetic evidence of sex-biased dispersal in a lekking bird, the capercaillie (Tetrao urogallus)

Sex-biased dispersal is often connected to the mating behaviour of the species. Even if patterns of natal dispersal are reasonably well documented for monogamous birds, only a few data are available for polygynous and especially lekking species. We investigated the dispersal of the capercaillie (Tetrao urogallus) by examining sex-specific gene flow among the leks. Genetic information was extracted using nuclear and mitochondrial molecular markers for sexed faecal samples and analysed by novel Bayesian statistical methods. Contrary to the traditional view that the males are highly philopatric and female is the dispersing sex, we found roughly equivalent gross and effective dispersal of the sexes. The level of polygamy has a strong influence on the effective population size and on the effective dispersal. The results do not support the theories that dispersal evolves solely as a result of resource competition or other advantages to males obtained through kin selection in lekking species.     

Viability and Management of an Endangered Capercaillie (Tetrao urogallus) Metapopulation in the Jura Mountains, Western Switzerland

The populations of Capercaillie (Tetrao urogallus), the largest European grouse, have seriously declined during the last century over most of their distribution in western and central Europe. In the Jura mountains, the relict population is now isolated and critically endangered (about 500 breeding adults). We developed a simulation software (TetrasPool) that accounts for age and spatial structure as well as stochastic processes, to perform a viability analysis and explore management scenarios for this population, capitalizing on a 24 years-long series of field data. Simulations predict a marked decline and a significant extinction risk over the next century, largely due to environmental and demographic stochasticity (average values of life-history parameters would otherwise allow stability). Variances among scenarios mainly stem from uncertainties about the shape and intensity of density dependence. Uncertainty analyses suggest to focus conservation efforts on enhancing, not only adult survival (as often advocated for long-lived species), but also recruitment. The juvenile stage matters when local populations undergo extinctions, because it ensures connectivity and recolonization. Besides limiting human perturbations, a silvicultural strategy aimed at opening forest structure should improve the quality and surface of available patches, independent of their size and localization. Such measures are to be taken urgently, if the population is to be saved.     

The bacterial microbiota in the ceca of Capercaillie (Tetrao urogallus) differs between wild and captive birds

The diet of wild capercaillie differs strongly between seasons. Particularly during winter, when energy demands are high and the birds forage solely on coniferous needles, microbial fermentations in the ceca are considered to contribute significantly to the energy requirement and to the detoxification of the resinous diet. Here, we present the first cultivation-independent analysis of the bacterial community in the cecum of capercaillie, using the 16S rRNA gene as a molecular marker. Cloning and fingerprinting analyses of cecum feces show distinct differences between wild and captive birds. While certain lineages of Clostridiales, Synergistetes, and Actinobacteria are most prevalent in wild birds, they are strongly reduced in individuals raised in captivity. Most striking is the complete absence of Megasphaera and Synergistes species in captive capercaillie, which are characterized by a large abundance of Gammaproteobacteria closely related to members of the genus Anaerobiospirillum, bacteria that are commonly connected with intestinal dysfunction. The community profiles of cecum content from wild birds differed between summer and winter season, and the cecum wall may be an important site for bacterial colonization. Our results corroborate the hypothesis that the bacterial community in the ceca of tetraonid birds changes in response to their highly specialized seasonal diets. Moreover, we propose that the observed differences in community profiles between wild and captive capercaillie reflects a disturbance in the bacterial microbiota that compromises the performance of the cecum and may be responsible for the high mortality of captive birds released into nature.     

Comparative Examination of Capercaillie (Tetrao urogallus L.) Behaviour Responses and Semen Quality to Two Methods of Semen Collection

Artificial insemination (AI) is very helpful in solving the reproductive and biodiversity problems observed in small, closed avian populations. The successful production of fertilized eggs using AI is dependent on the collection of good quality semen. Two methods of male sexual stimulation and semen collection from captive kept capercaillie (Tetrao urogallus L.), one of the most seriously endangered grouse species in Europe, are compared in this study. Ejaculates were obtained either with the use of a dummy female or by the dorso-abdominal massage method. Differences in the individual responses of the males to the two methods of semen collection as well as in their semen quality were noted. Only sperm concentration (432.4 x 10⁶ mL^-1 with dummy female and 614.5 x 10⁶ mL^-1 for massage method) was significantly affected by capercaillie stimulation method. Sperm motility and morphology were not affected (P≥0.05). Thus, for semen collection from captive kept capercaillie both methods can be used successfully. The dummy female can be an alternative to dorso-abdominal massage method, commonly used for semen collection from domesticated bird species.     

Estimating Population Size for Capercaillie (Tetrao urogallus L.) with Spatial Capture-Recapture Models Based on Genotypes from One Field Sample

We conducted a survey of an endangered and cryptic forest grouse, the capercaillie Tetrao urogallus, based on droppings collected on two sampling occasions in eight forest fragments in central Switzerland in early spring 2009. We used genetic analyses to sex and individually identify birds. We estimated sex-dependent detection probabilities and population size using a modern spatial capture-recapture (SCR) model for the data from pooled surveys. A total of 127 capercaillie genotypes were identified (77 males, 46 females, and 4 of unknown sex). The SCR model yielded atotal population size estimate (posterior mean) of 137.3 capercaillies (posterior sd 4.2, 95% CRI 130–147). The observed sex ratio was skewed towards males (0.63). The posterior mean of the sex ratio under the SCR model was 0.58 (posterior sd 0.02, 95% CRI 0.54–0.61), suggesting a male-biased sex ratio in our study area. A subsampling simulation study indicated that a reduced sampling effort representing 75% of the actual detections would still yield practically acceptable estimates of total size and sex ratio in our population. Hence, field work and financial effort could be reduced without compromising accuracy when the SCR model is used to estimate key population parameters of cryptic species.     

Comparing methods for estimating the abundance of Western Capercaillie Tetrao urogallus males in Pyrenean leks: singing counts versus genetic analysis of non-invasive samples

ABSTRACT

Population estimates of male Western Capercaillies Tetrao urogallus were carried out during the mating season using two methods: counts of singing males and non-invasive genetic analysis. Estimates of male numbers were 50% lower using the singing counts compared to the estimates obtained through genetic analysis, and underestimates were greatest when the number of Capercaillies was lowest.     

Modelling habitat use of Tetrao urogallus L. in Austria for conservation issues

Loss and deterioration of habitats are major threats for Tetrao urogallus in central Europe, where forests are highly fragmented and forest practices have distinctly changed during the last decades. Habitat models are important tools for conservation planning, often relying on presence–absence data. We mapped indirect signs of Tetrao urogallus presence as well as habitat variables over a series of seven study areas in the Austrian Alps, situated on limestone and on silicate rock. We modelled habitat use of Tetrao urogallus with one parametric approach (binary logistic regression) and two machine learning classification algorithms (classification trees and random forests) for both geological substrata separately. All three modelling approaches performed equally well in terms of accuracy or predictive power, but differed in model calibration. Three variables significantly contributed to all three habitat models on limestone and on silicate substrate, respectively, i.e. the cover of field-layer, the cover of dwarf shrubs and the proportion of deciduous trees in forest stands on limestone and the cover of field-layer, the canopy cover and the occurrence of Abies alba and/or Pinus sylvestris in forest stands on silicate rock. Some variables like the cover of Rubus sp. appeared in several models, which are not frequently mentioned in other studies. There have been some explanatory variables, which would have been missed, when applying just one single modelling approach, for example the occurrence of forest edges, the availability of canopy gaps and the supply of ant hills. Our results suggest differing habitat management strategies on limestone and on silicate rock. Considering the large spatial requirements of Tetrao urogallus the necessity of active habitat management for Tetrao urogallus becomes obvious.     

Description of population cycles of wood grouse (Tetrao urogallus L., 1758) through long-term monitoring

The paper discusses he dynamics of the cycles of long-monitored (1971–2012) wood grouse population inhabiting the experimental unit of the All-Russia Research Institute of Game Management and Fur Farming, as well as the dynamics of the cycles of 12 other populations in the Novosibirsk region that were subject to monitoring from 2000 to 2012. The population sizes were estimated using annual walk-through surveys conducted according to uniform methods. The chronograms were tested for latent harmonic components. The districts involved in the walk-through survey were attributed the spectra of population dynamics and evaluated in terms of periods and the power of the harmonic components of each spectrum. It was identified that the spectrum of the population dynamics was comprised of eight pronounced harmonic components differing in amplitude and power; the most powerful components referred to periods of 4.5 and 14.9 years. The relationship between the rate and the power of the dynamics of the wood grouse population cycles differs depending on the district of the Novosibirsk region. Moreover, there is a trend of increasing durations of low-frequency cycles in the northern direction. The sites inhabited by wood grouses feature natural environmental rhythms that can influence (prolong) the population cycles of this species.     

Increased DNA typing success for feces and feathers of capercaillie (Tetrao urogallus) and black grouse (Tetrao tetrix)

Noninvasive sampling, for example, of droppings or feathers, is a promising approach for molecular genetic studies on endangered and elusive animal species. Yet, such specimens are known for containing only minute amounts of DNA, resulting in lower typing success rates relative to analyses on fresh tissues such as muscle or blood. Furthermore, artefactual signals as well as contamination are more likely to occur when DNA is limited. To increase the reliability of DNA typing from noninvasive samples, optimized DNA extraction and polymerase chain reaction protocols were developed, taking advantage of developments in the forensic field aiming at successful molecular genetic analysis of DNA templates being low in quality and quantity. In the framework of an extensive monitoring project on population dynamics of capercaillie and black grouse in the Tyrolean Alps, feces samples and molted feathers from both species were collected. On a subset comprising about 200 specimens of either species, eight polymorphic short tandem repeat (STR) markers were analyzed to test these improved protocols. Besides optimizing DNA yields, both lowered sample consumption and reduced hands‐on time were achieved, and the rates of informative profiles amounted to 90.7% for capercaillie and 92.4% for black grouse. Similarly, high success rates had not been achieved in earlier studies and demonstrate the benefit of the improved methodology, which should be easily adaptable for use on animal species other than those studied here. The STR genotypes were not only powerful enough to discriminate among unrelated birds but also appeared fit for telling apart closely related animals, as indicated by Pi and Pi_sib values. The software package allelematch aided analysis of genotypes featuring possible dropout and drop‐in effects. Finally, a comparison between molecular genetic and morphology‐based species‐of‐origin determination revealed a high degree of concordance.