Ecology and energetics of breeding Puffins (Fractercula artica) : variations in individual reproductive effort and success

This study investigated reproductive effort and success of individual Atlantic Puffins (Fratercula arctica) on the Isle of May, Firth of Forth, Scotland. It placed particular emphasis on the role of body condition in breeding. An energetics approach was taken, where individual ’quality’ was considered in terms of foraging efficiency. The study also investigated whether breeding entailed costs for Puffins, in terms of individual survival and future reproductive potential, and whether such costs were mediated through body condition. Colour-ringed pairs of Puffins were followed through 3 successive breeding seasons and their reproductive performance and condition were monitored. Energy reserves carried by individuals (body condition indices) were estimated from live mass and body dimensions, using a carcass-derived equation to predict lean wet mass. Attempts were made at increasing the effort of rearing young, by playing chick begging calls and exchanging chicks between burrows, and decreasing effort, by supplementary feeding of young. Field energy expenditures were measured for a sample of parents during chick rearing using the doubly-labelled water technique, and these were compared with other potential measures of reproductive effort. The breeding success of individual parents was not related to body condition when a correlative approach was taken. Field metabolic rates (FMR’s) of 9 adults rearing young averaged 3.67 +/- 0.65 s.d cm' CO2 g'd ' or 874 +/- 151 kJd ' (c.3.5 times basal metabolic rate). Individual FMR’s were not related to other measures of reproductive effort used in the study. The above results were evaluated using graphical models, to demonstrate mechanisms by which the confounding effects of inter-individual differences in foraging efficiency on body condition could mask relationships between body condition, FMR and reproductive performance. The body condition of parents which experienced a decrea.se in rearing effort or an increase in effort did not differ significantly from that of controls at the end of the rearing period. This occurred even though parents whose young were fed substantially decreased the number of feeds they delivered to their young. Despite the apparent lack of an effect of the feeding treatment on condition, control pairs showed a lower return rate to the colony, lower breeding success, and produced young in ’poorer’ condition at peak mass than experimental parents whose young were fed for them in the previous year. The higher reproductive success of the experimental group suggested that Puffins on the Isle of May (control group) incurred inter-year reproductive costs when rearing young under natural conditions. These results were obtained in years when breeding conditions appeared to be relatively unfavourable for Puffins on the Isle of May, consistent with the view that reproductive costs may only be detectable in ’bad’ years. Mediation of such costs through body condition was not demonstrated, perhaps because the measure of condition used was unsuitable for Puffins; potential energy depots were discussed in relation to the life style of Puffins compared to other seabirds. Quantifying disturbance was not an original aim of the study but during fieldwork it became apparent that Puffins were sensitive to handling. The effects that handling and general disturbance had on the results of the .study were addressed but were unlikely to have influenced any of the conclusions presented

Survival rates of rehabilitated guillemots

SIGLEAvailable from British Library Document Supply Centre-DSC:2354.730(186) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Factors influencing the survival of Puffins Fratercula arctica at a North Sea colony over a 20-year period

A long-term colour-ringing and resighting programme on the Isle of May, Scotland which involved 734 adult Puffins Fratercula arctica was used to estimate annual survival rates over the period 1973-94 and to investigate some of the factors which influenced survival. Except in 1990 when survival was extremely low, estimated annual survival always exceeded 0.89. There was, however, evidence of a temporal change with survival rates being consistently lower during the second half of the study. This pattern was best described by a stepped model with survival rates of 0.975 (SE 0.004) between 1973 and 1980, 0.924 (0.006) between 1981 and 1994 and a separate value of 0.806 (0.026) for 1990. The decline in survival after 1980 was apparent in all age classes and could not be attributed to a slight change in the study area covered shortly afterwards. There was no evidence that survival rates differed between the sexes but we did find a significant age effect with birds estimated to be 20-25 or more years old either surviving or reproducing much less well than younger individuals

Population, distribution, movements and survival of fish-eating birds in Great Britain

Part of a co-ordinated research programme with the MAFF, the Environment Agency and the National Assembly for Wales.Available from British Library Document Supply Centre-DSC:99/39596 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Survival of Afro‐Palaearctic passerine migrants in western Europe and the impacts of seasonal weather variables

Populations of migratory songbirds in western Europe show considerable variation in population trends between species and regions. The demographic and environmental causes of these large-scale patterns are poorly understood. Using data from Constant Effort mist-netting studies, we investigated relationships between changes in abundance, adult survival and seasonal weather conditions among 35 western European populations of eight species of migratory warblers (Sylviidae). We used cross-species and within-species comparisons to assess whether annual variation in survival was correlated with weather conditions during passage or winter. We estimated survival using CJS mark-recapture models accounting for variation in the proportion of transient individuals and recapture rates. Species wintering in the humid bioclimatic zone of western Africa had significantly higher annual survival probabilities than species wintering in the arid bioclimatic zone of Africa (the Sahel). Rainfall in the Sahel was positively correlated with survival in at least some populations of five species. We found substantially fewer significant relationships with indices of weather during the autumn and spring passage periods, which may be due to the use of broad-scale indices. Annual population changes were correlated with adult survival in all of our study species, although species undergoing widespread declines showed the weakest relationships