House Martins Delichon Urbica Research Articles

Geographical Trends in Breeding Parameters of Swallows Hirundo rustica and House Martins Delichon urbica

Geographical trends in demographic traits were studied in Swallow Hirundo rustica and House Martin Delichon urbica from populations in the western Palaearctic. Clutch size increased with latitude in Swallow second clutches and with longitude in House Martin second clutches. The number of broods per season decreased latitudinally and for the House Martin longitudinally as well. The number of eggs per pair per breeding season thus decreased with latitude in both species and with longitude in the House Martin. It is suggested that the difference in the longitudinal response between the two species is due to the higher and thus more weatherinfluenced foraging niche of the House Martin. Hatchability of House Martin eggs increased with latitude. Between year population size variations increased with latitude in the Swallow. Ashmole's (1961) hypothesis did not account for geographical trends in clutch size. Geographical variation in nest predation could not explain variance in clutch size. Royama's (1969) model on clutch size trends taking food availability, time available for feeding and the temperature-dependent energy requirements of young into consideration explained a large fraction of the variance in clutch size among both species. The absolute metabolic level of the nestlings decreased from north to south.

Short-Term Variability in Energy Turnover by Breeding House Martins Delichon urbica: A Study Using Doubly-Labelled Water (D218O)

(1) Energy expenditure by free-living house martins Delichon urbica L. was measured using the doubly-labelled water (D2180) technique. All birds were rearing young of the same age at the time of our measurements. We made simultaneous observations of the attributes of individual birds, their activity and their environment, to allow daily variation in energy turnover to be understood. (2) Thirteen factors, out of thirty-nine examined, showed a significant correlation with ADMR (average daily metabolic rate, cm3 CO2 g-1 h-l). Of these, four were significant in an analysis by stepwise multiple regression: ranked in order of importance they were, food abundance (positive), keel length (negative), feeding activity (positive) and foraging distance (negative). Exclusion of the third ranked variable, allowed inclusion of a fifth, A body mass of adults. (3) There was no evidence for a direct effect of the physical environment on ADMR: significant correlations for ambient temperature and windspeed probably indicated effects which acted via the food supply, with corresponding changes in the foraging activity of martins. (4) Two tests demonstrated that the regression models yielded valid predictions, incidentally substantiating their value as interpretive as well as predictive models. (5) In conclusion we divided the effects on daily energy turnover by house martins into two main categories; it was affected by what the bird did (time-activity budgets) and what the bird was (body-size). Changes in resource levels and associated variations in foraging patterns, together with the effect of intrinsic individual differences, explained 53% of variation in ADMR.

Structure in avian growth patterns: a multivariate study of passerine development

A series of four principal component analyses was applied to data on the nestling development of three passerines, the Blue tit Parus caeruleus, House martin Delichon urbica and House sparrow Passer domesticus. The pattern of weight development in the tit and sparrow was largely controlled by selection for growth rate and for final size but in the martin final size was due to the prevailing levels of nestling food. Development in all three species was primarily through size increase in all growth measures but the differential development of individual organs or body constituents nevertheless accounted for 15% or more of the variance in developmental pattern. Blue tit young in broods of above average size sacrificed differential development to maintain size increase. Species specific differences in the integration of weight and plumage development and their sensitivity to hatching weight and hatching order were explicable as adaptive modifications of developmental pattern to the nature of each species' food supply. The value of such individual measures of development as weight and feather growth is assessed in the light of multivariate analysis of arrays of such variables.