Mick Marquiss

Microsatellite and mitochondrial DNA homogeneity among phenotypically diverse crossbill taxa in the UK.

Genetic differentiation within and between the three morphologically divergent crossbill species extant in the UK was assessed by comparison of allele frequencies at five unlinked microsatellite loci and DNA sequence variation across the mitochondrial control region. No significant differences in microsatellite allele frequency were found either between different populations of the same species or between the crossbill species themselves. A similar lack of genetic divergence was apparent from the mitochondrial sequence data. We resolved 33 different haplotypes, separated by low levels of sequence divergence (0–0.15%). Levels of divergence within and between species were not significantly different. Haplotypes formed a polyphyletic phylogeny, indicating that the crossbill species do not form genetically separate clades. Discordance between neutral DNA polymorphisms and adaptive morphological variation is discussed in relation to defining the systematic relationship between crossbill forms. If adaptive differences have arisen without a concomitant divergence in neutral DNA then attempting to define crossbill types from microsatellite and mitochondrial DNA without recourse to ecology and behaviour may be misleading.

Seasonal pattern in hawk predation on Common Bullfinches Pyrrhula pyrrhula: evidence of an interaction with habitat affecting food availability

Capsule Where predators occur, Bullfinch populations are probably limited as much by landscape structure as by the abundance of key food species. Aims To explore the interaction between food, cover and predation by comparing the seasonal patterns of the foraging behaviour of Common Bullfinches, with their frequency in the diet of Eurasian Sparrowhawks Accipiter nisus. Methods Foraging Bullfinches were observed in northeast Scotland from 1997 to 2004, documenting seasonal patterns in foods, proximity to cover, and relative abundance in three habitats. Seasonal changes in predation were assessed from the plucked remains of passerines killed by Sparrowhawks. Results The seasonal sequence and diversity of foods used by Bullfinches are described. Only rarely did they forage far from cover, mainly in December to February. Their relative abundance in three habitats suggested that they concentrated increasingly in uplands during winter, where they fed on heather seed at gradually higher elevations through to February. Within samples of plucked passerines, full-grown Bullfinches occurred predominantly in winter, newly fledged juveniles only in late summer and autumn. Bullfinches aggregated during autumn and winter, in particularly large groups when foraging on heather far from tree cover. Conclusions Seasonal patterns of predation and foraging behaviour fit the idea that Bullfinches are vulnerable to predation when a limited choice of food obliges them to forage far from cover. In the presence of Sparrowhawks, the food supply of Bullfinches is determined not by food abundance alone, but by its abundance in close proximity to cover. Key foods are those used when seed availability is at a seasonal low, prior to the switch to buds. Bullfinch population size is probably determined by food supply within habitat configurations at two spatial scales.

Breeding season diets of sympatric White-tailed Eagles and Golden Eagles in Scotland: no evidence for competitive effects

Capsule The breeding season diets of White-tailed Eagles and Golden Eagles in western Scotland were different, and there was no evidence of competition between the two species. Aim To test the hypothesis that the reintroduced White-tailed Eagles will have an adverse effect on Golden Eagles through competition for food. Methods Collections of prey remains at nests and regurgitated pellets during the breeding season were analysed. Temporal change in Golden Eagle territory occupancy and breeding productivity where the influence of White-tailed Eagles should be most evident was also examined. Results Diet breadth was similar between species but diet composition was significantly different, with White-tailed Eagles taking more sheep and aquatic or coastal food items, whereas Golden Eagles took more gamebirds (Galliformes), lagomorphs and other terrestrial prey. Diet overlap comparisons, between species-pairs that nested close together or far apart, rejected a hypothesis that there was competition for food, but partially supported an alternative hypothesis that diet overlap indicated abundant shared food. There was no indication that White-tailed Eagles have had any long-term effect on the breeding productivity or abundance of territorial Golden Eagles. Conclusions There is no evidence that reintroduced White-tailed Eagles are having an adverse effect on Golden Eagles through competition.

The first UK survey and population estimate of breeding Snow Bunting Plectrophenax nivalis

ABSTRACT Capsule: The first national survey for Snow Bunting Plectrophenax nivalis in the UK was carried out in 2011 and estimated the breeding population at 60 territories (95% confidence intervals = 48–83). Aims: To estimate breeding population size for Snow Buntings in the UK by surveying all sites with a history of breeding season occupation. Methods: Surveys were carried out in June 2011 to detect males on territory at sites where Snow Bunting had been recorded during the breeding season since 1970. Each site was visited at least once during the survey period; suitable habitat was searched and vantage point watches were conducted in order to detect singing males. Repeated visits to a sample of sites allowed a correction factor to be calculated in order to account for birds undetected during surveys. Results: In 2011, the number of Snow Bunting breeding in the UK (including adjusting for imperfect detection) is a minimum of 60 territories (95% CI = 48–83) using confirmed and probable breeding records of males. A less conservative estimate of 99 territories (95% CI = 88–114) results from including all records of males in suitable habitat. The vast majority of the population was found in the Cairngorm region, with isolated records in the north and west Highlands. Conclusion: The results of the 2011 survey are consistent with well-informed estimates of the Snow Bunting population made previously. This work provides a baseline and repeatable fieldwork and analytical methods enabling future change in the population to be quantified more rigorously.