Declining reproductive output in capercaillie and black grouse – 16 countries and 80 years

ABSTRACTCapsule: Black Grouse population increases were greatest where new native woodland (NNW) within 1500 m of leks comprised approximately 30% of land area and averaged 5 years old.Aims: To examine whether change in a population of Black Grouse Lyrurus tetrix in Scotland was associated with the creation of native woodland.Methods: We examined whether lek location, size and change in size were associated with habitat and topography surrounding leks. We also examined vegetation differences in NNW and adjacent unplanted moorland.Results: From 2002 to 2012 the number of lekking male Black Grouse increased by 90%. Lek occurrence was positively associated with the amount of NNW edge habitat. Leks were larger where there was more adjacent NNW. Lek increases were greatest where NNW plots comprised approximately 30% land area, and were 5 years old, within a 1500 m radius. Plots aged more than approximately 20 years old were associated with Black Grouse population declines. NNW supported taller and denser important field-layer vegetation than adjacent moorland, likely due to grazing exclusion.Conclusions: Subject to longer-term management commitments to stimulate continued regrowth of the important field layer and maintain benefits for Black Grouse, expansion of native woodland could contribute to landscape-scale recovery of Black Grouse after decades of decline.

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.

Since 2017, a reinforcement programme was developed to save the last, endangered, Belgian population of black grouse (Lyrurus tetrix), in the High Fens Natural Park. To improve the success of this programme, an analysis of past data of this population was undertaken to understand the causes of its past decline. A time series analysis was applied, using annual spring male census data recorded between 1967 and 2016. In the period 1967–1993, there was a fluctuation around an equilibrium of a population of ca. 40–45 males. The peak of 85 males observed in 1971 was probably due to a succession of several favourable years in terms of environmental conditions, albeit without an exceptional annual growth rate. It seems that fox density, by using the occurrence of rabies as a proxy, has an impact on the black grouse population. After 1993, the population dynamic changed drastically, decreasing continuously until finally reaching quasi-extinction. On average, the population lost 15.4% of its size each year. Climate models, applied in previous studies to explain these population trends in the High Fens, failed to describe this major modification in this population’s dynamic and its recent decline. We suggest that this negative effect was mainly induced by a significant increase in predation by red fox (Vulpes vulpes), whose abundance has increased considerably since the 1990s, in particular, as a consequence of the eradication of fox rabies. We also discuss alternative hypotheses, such as the impact of other predator species, modification of the natural environment and climatic modifications.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10344-023-01642-w.

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.

The processes of kin selection and competition may occur simultaneously if limited individual dispersal, i.e. population viscosity, is the only cause of the interactions between kin. Therefore, the net indirect benefits of a specific behaviour may largely depend on the existence of mechanisms dampening the fitness costs of competing with kin. Because of female preference for large aggregations, males in lekking species may gain indirect fitness benefits by displaying with close relatives. At the same time, kin selection may also lead to the evolution of mechanisms that dampen the costs of kin competition. As this mechanism has largely been ignored to date, we used detailed behavioural and genetic data collected in the black grouse Lyrurus tetrix to test whether males mitigate the costs of kin competition through the modulation of their fighting behaviours according to kinship and the avoidance of close relatives when establishing a lek territory. We found that neighbouring males’ fighting behaviour was unrelated to kinship and males did not avoid settling with close relatives on leks. As males’ current and future mating success are strongly related to their behaviour on the lek (including fighting behaviour and territory position), the costs of kin competition may be negligible relative to the direct benefits of successful male-male contests. As we previously showed that the indirect fitness benefits of group membership were very limited in this black grouse population, these behavioural data support the idea that direct fitness benefits gained by successful male-male encounters likely outbalance any indirect fitness benefits. Kin selection might be involved in the formation of groups because the fitness benefits of increasing group size can be accrued when groups hold close relatives. However, the fitness costs of competing with kin could counter-balance these indirect fitness benefits unless mechanisms enabling individuals to limit kin competition. Here we show in a lekking species that males do not modulate their fight frequency and intensity according to their kinship and do not avoid establishing territories with closely related neighbours. As the indirect fitness benefits of group display were very small in this system and as this study shows that males do not show any sign of kin competition avoidance, the indirect effects associated with male group display are likely to be very small.

Mechanisms of drought-induced population decline in an endangered wallaby

Fatty acid composition of depot fats in some game birds (Tetraonidae)

We studied 1964-1983 population dynamics of three species of tetraonids, capercaillie (Tetrao urogallus), black grouse (Tetrao tetrix) and hazel grouse (Bonasa bonasia) in Finland. The data comprise species-specific quantitative estimates of bird numbers in 11 provinces during the 20-yr period. Autocorrelation functions calculated from the trend-corrected data suggest that the population fluctuations are cyclic in all three species, cycles most frequently displaying six-yr periodicity. A model acknowledging long-term trend and incorporating linear combination of sine and cosine transforms of time mimics the fluctuations reasonably well. The coefficients of determination ranged from 25% to 88% depending on species and province. Fitting the same model to 1897-1930 hunting statistics of black grouse from south-western Finland indicates that such a clockwork-like dynamics has been ticking at least from the beginning of this century. An analysis of variance of the lengths of increase and decrease phases of the population cycles further confirm the symmetric regularity of the tetraonid dynamics. No differences were found among species or provinces. A theoretical analysis, based on projection matrix techniques, shows that it is unlikely that such a regular cyclicity could be driven solely by intrinsic components of the population structure. The domain of other possible factors responsible for the clockwork-like dynamics is explored.

The Black Grouse was considered „main game” in the game species of historical Hungary, but Hungarian hunters never had a way to hunt it widely, so no real hunting cult could develop in Hungary. Already in 1872, under Law VI of 1872, the hunting season was limited to the spring displaying (March, later April-May), and the chicks had to be spared all year round. Restrictions were introduced for the first time in Hungary to protect the Wood Grouse and the Black Grouse, which can be considered the first step in bird protection in Hungary. Hunting was typically a well-known individual hunting method, hunting from a hide, which was made more effective by calling. Cocks were lured partly by imitating the calls of younger competitors and partly by imitating the calls of hens. There are also references in the literature to the use of decoy birds, or „artificial cocks”. Hunting with dogs, drive hunts and bush hunts are also mentioned in domestic descriptions of Black Grouse hunting, but their importance is not significant, and trapping, which was already part of poaching in the second half of the 19th century, was not as important as for the Hazel Grouse. Although its meat was described as tasty and it was traded, it was not a significant economic factor compared to commercial game meat but was consumed for its curiosity. In the period 1884-1909, the main area of known Black Grouse hunting bags (n = 2 723 specimens) in historical Hungary was the North, East and South Carpathian regions. The most stable populations at the turn of the 19th and 20th centuries were found in the highland regions (counties of Árva, Gömör-Kishont, Liptó, Szepes, 28.3% in total). The Transylvanian areas showed an earlier decline of the species than the Felvidék. In the present territory of Hungary, the last occurrences of the species in the lowlands were in the late 19th century, while only occasional occurrences are known from the first half of the 20th century in Northern Hungary. Its decline is certainly not due to overexploitation, and this is supported by the hunting bag data from the manors. With the suboptimal habitats, the species had almost completely disappeared from the territory of former historic Hungary by the 20th century. Within our current borders between 1883 and 2010, several attempts at introduction, initially for hunting and later for conservation purposes, were made, but all failed due to the lack of suitable habitat for the Black Grouse.

During 1980-84 I studied the fates of 821 artificial nests, 96 naturally occurring capercaillie (Tetrao urogallus) nests, and 12 black grouse (T. tetrix) nests at Varaldskogen, Norway. In 4 of the 5 years artificial nests with poor cover had higher loss rates than natural capercaillie nests. In 1981 natural capercaillie nests had a higher loss rate than artificial nests with poor cover. In 1981 the loss rate of natural capercaillie and black grouse nests increased as the season progressed, while the loss rate of artificial nests was constantly low. Capercaillie nests were probably detected by scent by predators most years, while predators oriented mainly by sight probably robbed most artificial nests. Loss of artificial nests was not an index to the loss of capercaillie nests. In artificial nests the losses depended on nest cover; however, natural capercaillie nests in poor cover had higher losses than nests in good cover only during 1 year. J. WILDL. MANAGE. 52(1):123-126 Many bird species suffer high nest losses. Because artificial nests are easy to make they have been used to study the causes of nest losses and predator hunting strategies (Goransson et al. 1975, Boag et al. 1984, Angelstam 1986). In some studies (Henry 1969, Dzieciolowski and Matuszewski 1982, Miiller 1985) results from experiments with artificial nests have been extrapolated to natural nests. This has been done even though the relation between losses in natural versus artificial nests has not been properly evaluated. I compared nest losses of artificial nests with losses of naturally occurring capercaillie and black grouse nests (unprepared depressions in the ground) to determine if predation on artificial nests could be used as an index to predation on natural nests. The experiment was designed to separate predators that used scent from those that mainly relied on sight to locate the prey. This study was financed by the Norwegian Directorate of Nature Conservation and T. Gotaas Fund. The study was conducted in close collaboration with P. Wegge. His help and advice were essential. B. B. Larsen, L. Kastdalen and the rest of the staff at Varaldskogen Field Station assisted in the field. K. E. Erikstad, N. C. Stenseth and P. Angelstam gave valuable comments about the manuscript. S. BondrupNielsen and R. W. Dimmick have kindly improved the language. STUDY AREA This study was conducted at Varaldskogen (60010'N, 12030'E) in Hedmark County, Norway, situated in the Middle Boreal Zone (Abrahamsen et al. 1977). Norway spruce (Picea abies) and Scots pine (Pinus silvestris) were the dominating tree species, and blueberry (Vaccinium spp.) and heather (Calluna vulgaris) dominated the ground layer. Potential egg-predators were red fox (Vulpes vulpes), pine marten (Martes martes), badger (Meles meles), stoat (Mustela erminea), weasel (Mustela nivalis), hooded crow (Corvus corone cornix), common raven (C. corax), and jay (Garrulus glandarius).

The composition of the summer-autumn diet of the Black grouse (Lyrurus tetrix) in the south of the forest zone ranging from Poland to the Urals has been thoroughly studied, but questions about the actual ratios of food consumed remain open. The feeding strategy of the birds in late summer and early autumn is also unknown. To partially fill in these gaps, we analyzed the craw contents of the birds hunted in the southern taiga (n = 22) and in coniferous-broadleaf forests (n = 24) in July–October 1987–2023. The plant genera Trifolium, Hieracium, Rumex, Sonchus and other herbs growing in a grassland or at forest edges formed the main part of the diet (% wet weight) in both black grouse populations studied. The basis of animal food was also represented by insects of open landscapes: grasshoppers (Acrididae) and leaf beetles (Chrysomelidae). The main diet components (75–76% wet weight) constituted only ~20% of the total food lists, indicating something close to oligophagy: long food lists with only a few food items being important and most food species found to be consumed in very small quantities. The relations between the estimates of wet weight (%) and the occurrence of food were expectedly weak, but large weights could correspond to either low or high occurrence estimates; this situation should make comparisons across literary sources difficult. The total absence of any fragments of heather shrubs (Ericaceae) in the diet of both populations along with the absence of any berries in the nutrition of the southern taiga individuals were unexpected. In contrast to other L. tetrix populations from the southern forests of the Russian Plain, the attention the study birds paid to food objects proved to be dispersed across many food species, possibly owing to the long time span of our datasets. Nevertheless, the most probable reason for all habits of the Black grouse noted seems to lie in a decreased human agricultural activity (grain growing and haymaking) and ousting the birds from forest-meadow edges by people (via recreation and gathering berries and mushrooms) deep inside grassland habitats, where the forage base for black grouses has apparently been much more variable and less predictable than under the discontinuous forest canopy more familiar to the birds.

AimMountains host complex ecosystems whose wide range of ecological conditions over small geographical distances makes them biodiversity hotspots. To ensure their long‐term conservation, a better understanding of the interaction between climate change and modifications in land use is necessary. Most studies have focused on only one of these factors at a time, leading to incomplete predictions. In this study, we explored the relative contribution of both recreative activities and climate change on the population dynamics of the black grouse (Tetraotetrix), an emblematic cold‐adapted species of the Alps.MethodsWe used data from a network of 47 monitoring sites dispersed around the French Alps and surveyed since the 1980s or 1990s. We estimated black grouse population growth rates using state‐space models and tested for effects of biotic and abiotic pressures on both long‐term trends and inter‐annual variations in these rates.ResultsPopulation trajectories were strongly heterogeneous in space; nevertheless, a general decline at the edge of the black grouse distribution area was revealed in the southern pre‐Alps. We found very little influence of hunting and new ski lift cables installation on inter‐annual variability in population growth rate. In contrast, our results suggest strong impact of climatic conditions and phenology. While temperature positively influenced growth rate, precipitation had a negative effect. Early snowmelt and vegetation season were correlated with high positive values of annual population growth rates.Main conclusionsBirds in mountain habitats may be drastically affected by ongoing climate change, perhaps to a greater extent than by an increase in recreational activities. However, other human activities in the mountains (such as animal grazing or forest exploitation) that were not taken into consideration in this study might also have a strong impact on habitat structure and indirectly affect populations’ growth.

На основе оригинальных данных, полученных в 2017–2022 гг. на территории двух ООПТ регионального значения, а также литературных источников и сведений респондентов со- ставлены фаунистические списки птиц, выявлены доминанты и субдоминанты. В Челябинском (городском) бору с прилегающими территориями с 1987 по 2022 гг. зарегистрирован 151 вид, из них достоверно и предположительно гнездящихся – 74. В 2017–2022 гг. доминантами в гнездо- вой период были зяблик и пеночка-теньковка, группу субдоминантов составили большая синица, пухляк и мухоловка-пеструшка. Трансформация экосистемы бора за период с 1980-х по 2010-е гг. привела к исчезновению тетерева, обыкновенного козодоя, беркута, кобчика, а на сопредельных территориях – камышницы, кулика-сороки, серой куропатки, перепела, болотной совы. Под дей- ствием рекреации произошло сокращение числа и обилия наземно-гнездящихся видов: исчезла обыкновенная овсянка, лесной конек стал немногочислен и составляет всего 2% от населения птиц. У ряда гнездящихся видов (тетеревятник, длиннохвостая неясыть, обыкновенный снегирь, зяблик) отмечены этологические адаптации, свидетельствующие о синурбизации. В менее антро- погенно нарушенном Каштакском бору за период 2018–2022 гг. обнаружено больше гнездящихся и предположительно гнездящихся видов (81), в число которых вошли урбофобные (канюк, тете- рев, глухарь), общий список птиц составил 101 вид. В гнездовое время доминировали зяблик, пеночка-теньковка и лесной конек, в группу субдоминантов входили большая синица, мухолов- ка-пеструшка и обыкновенная горихвостка. Based on original data obtained in 2017–2022 on the territory of two specially protected natural areas of regional significance, as well as literary sources and information from respondents, faunistic lists of birds were compiled, dominants and subdominants were identified. In the Chelyabinsk (City) Forest with adjacent territories 151 species were recorded from 1987 to 2022, of which 74 are reliably assumed to be nesting. In 2017–2022 the dominants in the nesting period were Chaffinch and the Wood Warbler, the group of subdominants was made up of the Great Tit, the Willow Tit and the European Pied Flycatcher. Transformation of the ecosystem of the Chelyabinsk forest from the 1980s to the 2010s led to the disappearance of Black Grouse, Eurasian Nightjar, Golden Eagle, Redfooted Falcon, and in adjacent territories – Common Moorhen, Eurasian Oystercatcher, Grey Partridge, Common Quail, Short-eared Owl. Under the influence of recreational activities, there was a reduction in the number and abundance of ground-nesting species: the Yellowhammer has disappeared; the Tree Pipit is not numerous and comprises up only 2% of the total bird population. A number of nesting species (Northern Goshawk, Ural Owl, Eurasian Bullfinch, Chaffinch) showed ethological adaptations indicating synurbization. In the less anthropogenically disturbed Kashtak Forest for the period 2018–2022 more breeding and presumably nesting species were found (81), including urbophobic species (Common Buzzard, Black Grouse, Western Capercaillie); the total list of birds was 101 species. During the nesting period, the Chaffinch, the Wood Warbler and the Tree Pipit dominated, the group of subdominants included the Great Tit, the European Pied Flycatcher and the Common Redstart.

An epizootic of sarcoptic mange among red foxes Vulpes vulpes reached central Norway in 1976, and by 1986 it had spread to the whole country, resulting in a severe decline in the red fox population. We analyse the change in the hunting bags of the predator species red fox and pine marten Martes martes , and the prey species capercaillie Tetrao urogallus , black grouse Tetrao tetrix , mountain hare Lepus timidus and willow grouse Lagopus I. lagopus from the period prior to and during the mange epizootic. The data are gathered from publications by Statistics Norway and are based on answers from more than 5,000 hunters yearly. On the national level, the hunting bags of capercaillie, black grouse, mountain hare and pine marten were significantly negatively correlated with that of the red fox. When the time series at the national level were detrended, there were positive correlations between the hunting bags of all species without time lag, except that of pine marten, which lagged one year behind the other species. At the local level there were negative correlations between the hunting bag of red fox and those of the small game species except for willow grouse. The study confirms that the red fox is a keystone predator in Scandinavia.

Biodiversity loss was a central argument for redefining sustainable forest management in the 1990s, but threatened species remain poorly addressed in forestry governance. Management history of the Capercaillie (Tetrao urogallus) population in the Baltic States reveals a high potential of socially valued threatened species for developing the missing forestry–conservation interfaces. We review the history of the Baltic Capercaillie population since the 19th century, showing how its status transformed, both ecologically and socially, from a famous hunting target to the most widely protected forest species in the region. Compilation of recent national survey data confirms that at least 3450 lekking males currently survive in 961 leks; they are distributed between six large and about twenty small populations. During the 20th century, lek sizes decreased and local extirpations spread from South-Baltic mosaic lands to northern forests. As a social response, innovative management initiatives have repeatedly enabled periods of population stability and local recoveries. The most recent developments in Capercaillie conservation combine elements from the historically separated nature conservation, forestry and game-management approaches. The consistency of such social responses despite political upheavals suggests that iconic species can culturally stabilize long-term sustainable development.