Population and ecological effects of variation and interaction of energetic parameters in birds with special reference to Great Tit Parus major and Pied Flycatcher Ficedula hypoleuca

Abstract

Gavrilov, V.M., Kerimov, A.B., Golubeva T.B., Ilyina, T.A. & E.V.Ivankina (1998): Population and ecological effects of variation and interaction of energetic parameters in birds with special reference to Great Tit Parus major and Pied Flycatcher Ficedula hypoleuca. Avian Ecology and Behaviour 1:87-101. The long-term change in population phenotypic and social structure and the effect of male plumage colour on its basal metabolic rate (BMR) were studied in the populations that occupy nest boxes in an optimal habitat near Zvenigorod, Moscow Region. Mean colour type of flycatcher males varied from 4.1 (n=84 in 1993) to 4.8 (n=68, in 1988), on average 4.4 (n=412 , n=8 years) in all years. The age of males varied from 1 to 5 years. There is a significant difference (p<0.05) between second-year and adult values of average body mass. Trends in changes of colour type during the lifetime of individual birds lead to a decrease in class 1 of Drost's 7-class scale. The plumage may become darker during the first three years, but after the 2nd year the plumage colour usually becomes stable. The correlations between BMR and plumage colour were measured in three age classes: second-year males (n=l year), old adult males of known age (2+n years, where n>=0), and adult males of unknown age. Darker males are characterized by higher level of BMR. Correlation between BMR and colour type (x-colour type ranging from 1 [the darkest], to 7 [the lightest]; the darkest type in the study population was 2) is: BMR(mlO 2 /bird*hour)=52.78-2.14*x, n=57, r=-0.429. To avoid the effect of age, the equations were represented for second-year males: BMR(mlO 2 /bird*hour)=50.67-1.96*x, n=25, F=6.10, r=-0.457, R 2 =20.97% adult males of known age (2+n years, where n≥0): BMR(mlO 2 /bird*hour)=60.76-4.40*x, n=17, F=3.44, r=-0.527, R 2 =27.72% In Great Tit P. major, social rank was scored according to a four point scale (1-the highest position). Rank estimation was based on the results of encounters and waiting order of males at feeding tables. The correlation between ventral stripe size and social rank (r =0.352, n=46, p<0.05 for the entire winter season from October to March) increased in the sedentary group outside the breeding season. Ventral stripe size as a main status-related feature tended to correlate with singing activity. BMR was found to have an indirect relation to status in subsequent breeding settlement: in spite of the small sample size, there was a tendency to strong correlation between BMR and location of breeding territory within previous flock area (r s =-0.749, n=7, p=0.07). Central sedentary males had high BMR, while peripheral sedentary males had low values of BMR. The surface of breeding territory correlated with the BMR level of male. Diversity in BMR values represents a basis for a population structure: males, which have high BMR level, occupy larger and better breeding territories; they use energy-consuming behavioural strategies (e.g. increase in singing activity and patrolling larger territory). Thus the territoriality is basic to the structure of populations. Larger and better territory-main stimulus in competitive interactions within populations.