In Finland, Capercaillie (Tetrao urogallus) populations have a history of serious decrease starting from the mid-20th century. The decline is temporally in line with the expansion of modern forestry practices that created major changes in the landscape. We used tetraonid route-censuses from 18 forestry board districts and Finnish forest inventories (data on forest stand structure) to analyze the decline in 1965-1988. We used information theoretical model selection to evaluate a set of log-linear second order autoregressive models, allowing for spatially correlated process errors. The average trend throughout the country corresponded to an annual decline of 4.01% (mean of local trends) ± 0.24% (SEM), parallel to a half-life of 17 years. The decline was surprisingly uniform throughout the country (SD = 1.01%) and most parsimoniously explained by a geographically constant log-linear trend. At the large scale of observation applied here, population trends could not be explained by the proportional increase of younger forest age classes (<40 years old and <80 years old, respectively). Our analysis does not support the hypothesis that the decline in Capercaillie numbers is due to changes in the forest age structure, but we cannot exclude the possibility that other factors behind the decline may have interacted with forestry in general. From a conservation point of view, we caution against overemphasizing the role of forest age especially at large spatial scales, but leaning also on other research, we recommend that more management efforts would go into the preservation of the overall forest cover and the original physiognomy in single forest patches.

SummaryAnimals' avoidance of humans or human activities can have several adverse effects on their distribution and abundance, and a frequent tool used by conservation managers to avoid such effects is to designate 'buffer zones' (or set-back distances or protection zones) around centres of animals' distribution within which human activity is restricted.A common method used to prescribe buffer zones involves one or two measures of disturbance distance: 'alert distance' (AD), the distance between the disturbance source and the animal at the point where the animal changes its behaviour in response to the approaching disturbance source, and 'flight initiation distance' (FID), the point at which the animal flushes or otherwise moves away from the approaching disturbance source.Recommendations on 'safe-working distances' (essentially, buffer zones around breeding sites) have been made for a number of UK breeding bird species, but without any objective justification. With recent changes in Scottish legislation on human access to the countryside and protection of some breeding birds' nest sites there was therefore a need to review available information on disturbance distances for 26 'priority' bird species which breed in Scotland.Preliminary assessment revealed few previous studies quantifying disturbance distances for the study species, and so an expert opinion survey was conducted in which opinion was solicited on 'static' and 'active' disturbance distances (i.e. AD and FID, respectively) when birds were approached by a single pedestrian when incubating eggs and when with chicks. The survey resulted in 89 respondents providing 1083 opinions on disturbance distances.It was difficult to validate independently the results of the survey, because relatively few empirical studies had been conducted on disturbance distances for the study species. Subjectively, however, the survey appeared to give similar 4 results to those of research based on quantified field observations, although distance estimates in the expert survey may have been slightly high in some species.A number of descriptive statistics for AD and FID are presented for each of the species from the expert opinion survey, including upper distances which incorporated 90 % of opinions on AD (although it is highlighted that AD is probably impossible to measure in practice for many species when breeding).Species accounts, describing the results of a literature review for each study species (and related species) on disturbance distances, are also presented and include published information on AD and FID, responses to a number of disturbance sources, previously prescribed buffer zones and forestry practices, when relevant.Expert opinion is typically used as a stopgap in research as a bridge between empirical evidence and policy (although our review suggested that it is probably frequently misused in this field by not being a temporary measure and with insufficient validation) and, given the shortage of empirical field studies, it is recommended that the expert survey r...

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