David Baines

The implications of grazing and predator management on the habitats and breeding success of black grouse Tetrao tetrix

1. Data on black grouse densities and breeding success were collected from five blocks of moorland, each consisting of four moors, between 1991 and 1993. Moors within a block differed in grazing intensity of either sheep or red deer and the presence of a gamekeeper. Results obtained were related to differences in grazing and predator management. 2. Moors with higher intensities of grazing had vegetation, on average, 32% shorter and had 36% less vertical vegetation cover. Grazing had no significant effect on species composition. 3. Heavily grazed moors supported 41% fewer invertebrates ; threefold fewer Lepidoptera larvae and half as many Araneae and Hemiptera. 4. Highest densities of male (2.1 km -2 ) and female black grouse (3.4 km -2 ) were found on lightly grazed moors. Density did not differ between keepered and unkeepered moors. 5. Black grouse breeding success not only differed between years and regions, but also between managements, being 37% lower on heavily grazed moors. The presence of a gamekeeper was not associated with higher breeding success. 6. The presence of a gamekeeper was associated with three times fewer carrion crows. 7. The results suggest that lower numbers of large herbivores allow the development of good ground cover with high numbers of preferred insects, which may permit black grouse to survive in situations where they would otherwise be severely reduced by predators.

Dispersal, survival and causes of mortality in black grouse Tetrao tetrix in northern England

Between autumn 1998 and spring 2000, 70 black grouse Tetrao tetrix (48 poults and 22 adults) were equipped with radio transmitters in the North Pennines, England. We recorded timing and distances of dispersal, survival rates and causes of death. First-year survival rates differed between years, but in each year were highest in late autumn prior to dispersal, when predation by stoats Mustela erminea and raptors accounted for three-quarters of deaths. First-year grouse survival was lower than that of adult birds owing to predation in the autumn and winter by raptors and stoats. The annual adult survival rate of 0.72 was higher than those found in most other European studies. By contrast, breeding success was low. Dispersal was confined to first-year hens, with distinct dispersal periods in late autumn (mean 10.3 km) and again in early spring (mean 5.8 km). Natal dispersal resulted in none of the first-year hens breeding within the study area. Adults of either sex and first-year cocks showed high site fidelity. This has practical repercussions when considering prescriptive management to aid species recovery and range expansion in relation to habitat fragmentation at both the local and regional levels.

Factors affecting unintentional harvesting selectivity in a monomorphic species

1. Changes in the abundance of populations have always perplexed ecologists but long-term studies are revealing new insights into population dynamic processes. Long-term data are often derived from harvest records although many wild populations face high harvesting pressures leading to overharvesting and extinction. Additionally, harvest records used to describe population processes such as fluctuations in abundance and reproductive success often assume a random off-take. 2. Selective harvesting based on phenotypic characteristics occurs in many species (e.g. trophy hunting, fisheries) and has important implications for population dynamics, conservation and management. 3. In species with no marked morphological differences between the age and sex classes, such as the red grouse Lagopus lagopus scoticus during the shooting season, hunters cannot consciously select for a specific sex or age class during the shooting process but harvest records could still give a biased reflection of the population structure because of differences in behaviour between age and sex classes. 4. This study compared age and sex ratios in the bag with those in the population before shooting for red grouse at different points in the shooting season and different densities, which has rarely been tested before. 5. More young than old grouse were shot at large bag sizes and vice versa for small bag sizes than would be expected from the population composition before shooting. The susceptibility of old males to shooting compared to females increased with bag size and was high at the first time the area was shot but decreased with the number of times an area was harvested. 6. These findings stress that the assumption made in many studies that harvest records reflect the age and sex ratio of the population and therefore reflect productivity can be misleading. 7. In this paper, as in the literature, it is also shown that number of grouse shot reflects grouse density and therefore that hunting selectivity might influence population dynamics in a cyclic species. 8. The study is not only relevant for red grouse but applies to systems showing interactions between selective harvesting and wider ecological processes, such as age- and sex-related parasitism and territoriality, which may drive population fluctuations.

Correlated Evolution and Dietary Change in Fossil Stickleback

The importance of trophic ecology in adaptation and evolution is well known, yet direct evidence that feeding controls microevolution over extended evolutionary time scales, available only from the fossil record, is conspicuously lacking. Through quantitative analysis of tooth microwear, we show that rapid evolutionary change in Miocene stickleback was associated with shifts in feeding, providing direct evidence from the fossil record for changes in trophic niche and resource exploitation driving directional, microevolutionary change over thousands of years. These results demonstrate the potential for tooth microwear analysis to provide powerful insights into trophic ecology during aquatic adaptive radiations.

Variations in the Vital Rates of Black Grouse Tetrao tetrix in the United Kingdom

Abstract In the United Kingdom, black grouse Tetrao tetrix are in severe decline with only 6,500 displaying males in 1995-1996 and a range retraction of 28% between 1972 and 1991. Recent declines have been greatest in central and southern Scotland and parts of Wales and contrast with relative stability in northern England. We compare the demography of black grouse in three regions: North Wales, northern England and the Scottish Highlands. Patterns in annual fecundity, measured as fledglings per breeding female, were correlated between regions, suggesting that annual weather patterns common across regions may be a key determinant of breeding success. Site related effects such as habitat quality or management were also significant in northern England and North Wales. Male population growth rates at leks were positively correlated with fecundity in the previous year. Fecundity was highest in North Wales and the Scottish Highlands at 1.7 chicks per female in August compared to 1.3 in northern England. Variations in the annual fecundity of radio-tagged females were linked to differences in brood survival rather than clutch survival, which did not differ among years. We found a non-significant trend for juvenile survival to be lower in North Wales (0.18) than in either northern England (0.65) or the Scottish Highlands (0.56). Similarly, annual adult survival also tended to be lower in North Wales (0.44) than in either northern England (0.70) or the Scottish Highlands (0.66). Predation was the main cause of death in all regions, with red fox Vulpes vulpes and raptors being the chief predators in North Wales and the Scottish Highlands and stoat Mustela erminea in northern England. The last 10 years have seen the implementation of a series of black grouse recovery projects in the UK. An understanding of the limiting demographic stage in each project area is critical before appropriate remedial management prescriptions can be implemented.

Seasonal and between-sex differences in the diet of Black Grouse Tetrao tetrix

Capsule Dietary differences between sexes and seasons reflected diversity in plant availability and habitat preferences. Aims To analyse Black Grouse diet through the identification of plant and invertebrate material found in the crop. Methods Crops were dissected and the content categorized into plant species and components (i.e. leaf, stem, flower, fruit and seed). Multivariate analysis was used to test for seasonal, sex- or location-related differences in the diet. Results Plant fragments accounted for 98% of the diet and included 53 plant species or taxa. Invertebrates made up the remaining 2%. Diet varied significantly between seasons and sexes. Both sexes ate more ericaceous shrubs in autumn and winter, with females eating more than males. The plant parts eaten varied seasonally. In summer, fruits, flowers and seeds were favoured over leaves, which dominated in winter. Conclusions With few trees, birds were reliant upon Heather in autumn and winter.

Current status and recent trends in numbers and distribution of Black Grouse Tetrao tetrix in northern England

Capsule Surveys of Black Grouse in northern England in 1998, 2002 and 2006 show population recovery in the form of increases in both numbers and range. Aims To quantify the population size and range of Black Grouse in northern England. Methods Male black grouse attending leks were surveyed in 1998, 2002 and 2006. These results were put in context with a longer-term trend in northern England, using annual counts from a non-random sample of leks in the North Pennines between 1989 and 2006. Results Numbers of males increased from 773 in 1998 to 1029 in 2006. Range increased from 74 occupied 5-km grid squares in 1998 to 93 in 2006. Conclusion The English Black Grouse population is increasing in both numbers and range, but has become fragmented into two subpopulations, one in North Northumberland, the other in the North Pennines.

Effects of weather and timing on counts of breeding Snipe Gallinago gallinago

Capsule Snipe numbers are assessed most accurately at dusk and at low wind speeds. Aims To identify factors affecting the variability and efficiency of breeding Snipe surveys and to assess the validity of current survey methods for estimating breeding densities or monitoring population change. Methods The effects of cloud cover, rain, wind, diurnal and seasonal timing on estimated densities of breeding Snipe were assessed using data from early morning and evening surveys on moorland during mid-April to early June. The effects of diurnal and seasonal timing of surveys were examined using data from counts of Snipe made at three-hour intervals throughout the day on four dates. Results Estimated total Snipe densities and densities of drumming Snipe declined as wind speed increased (25% and 39% lower, respectively, at force 2–3 on the Beaufort scale and 46% and 83% lower at force 4–5 compared to force 0–1). Drumming Snipe density estimates were 266% higher in light rain than dry conditions. Numbers of drumming Snipe were highest at dusk and low numbers of Snipe were encountered during the middle of the day. There was seasonal variation in drumming activity, with little drumming during late April and early May. Conclusions Surveys of breeding Snipe should not be undertaken when wind exceeds force 3 on the Beaufort scale (or 19 km/h). In situations where only small areas need to be surveyed but absolute numbers are desirable, point counts at dusk will be the most effective method.

Impact of nest visits by human observers on hatching success in Lapwings Vanellus vanellus: a field experiment

Capsule Increased nest visits during incubation did not reduce Lapwing clutch survival whereas nesting in pastures with high Black-headed Gull Larus ridibundus abundance did.

Impact of unintentional selective harvesting on the population dynamics of red grouse.

1. The effect of selective exploitation of certain age, stage or sex classes (e.g., trophy hunting) on population dynamics is relatively well studied in fisheries and sexually dimorphic mammals. 2. Harvesting of terrestrial species with no morphological differences visible between the different age and sex classes (monomorphic species) is usually assumed to be nonselective because monomorphicity makes intentionally selective harvesting pointless and impractical. But harvesting of the red grouse (Lagopus lagopus scoticus), a monomorphic species, was recently shown to be unintentionally selective. This study uses a sex- and age-specific model to explore the previously unresearched effects of unintentional harvesting selectivity. 3. We examine the effects of selectivity on red grouse dynamics by considering models with and without selectivity. Our models include territoriality and parasitism, two mechanisms known to be important for grouse dynamics. 4. We show that the unintentional selectivity of harvesting that occurs in red grouse decreases population yield compared with unselective harvesting at high harvest rates. Selectivity also dramatically increases extinction risk at high harvest rates. 5. Selective harvesting strengthens the 3- to 13-year red grouse population cycle, suggesting that the selectivity of harvesting is a previously unappreciated factor contributing to the cycle. 6. The additional extinction risk introduced by harvesting selectivity provides a quantitative justification for typically implemented 20-40% harvest rates, which are below the maximum sustainable yield that could be taken, given the observed population growth rates of red grouse. 7. This study shows the possible broad importance of investigating in future research whether unintentionally selective harvesting occurs on other species.