Sökresultat

Brood size in the Great Tit (Parus major) was manipulated (increased, decreased, or unchanged) when nestlings were 5 days old. Both the frequency of second clutches and the interbrood interval were affected. The number of nestlings and hatching date, but not nestling and female mass, differed between first broods followed and not followed by second clutches. Hatching date and the number of nestlin

(1) We studied the effect of sex, size, age and prior occupancy on social dominance winter flock establishment in a population of marsh tits Parus palustris L. (2) When sex was accounted for, time of establishment in the winter flock-prior occupancy, was critical for the outcome of later aggressive interactions juveniles within flocks. Residents won all interactions with intruders irrespective con

Male marsh tits, Parus palustris, regularly feed their mates from the beginning of nest building until hatching. Over three periods (the 15 days preceding egg formation, egg formation/laying and incubation) the number of food passes by the male to the female increased significantly. There was a significant negative relationship between the frequency with which the male fed the female in the nest d

We studied the relative contribution of each sex and total effort expended in feeding nestlings in the great tit Parus major in relation to artificially altered brood size. A recent model suggests that feeding frequency should reflect the optimal trade-off between parental and fledgling survival, the former being negatively, the latter positively, influenced by high feeding frequencies. In both se

Employing a large number of antennas at the base station, massive MIMO significantly improves spectral efficiency and transmit power efficiency. On the other hand, massive MIMO also introduces unprecedented implementation challenges, especially in terms of processing and storage of large-size channel state information (CSI) matrices. Since on-chip memory is generally very expensive and has limited

(1) Trade-offs between brood size and offspring growth and survival were manipulating the size of 221 great tit Parus major L. broods between 1983 (2) Nestling mass, wing length and tarsus length were inversely related to Hatching date also affected nestling growth, but its effect differed between Intrabrood variability in nestling size increased with brood size. (3) Nestling survival was inversel

We studied the effects of manipulation of the size of first broods in the Great Tit Parus major on the size and breeding success of second clutches and its relation to the degree of clutch overlap. The rearing of first brood fledglings always overlapped with the laying of the second clutch and in most cases also with the incubation period of the latter. The degree of clutch overlap depended on the

This study reports an aviary experiment aimed at determining what affects social dominance in the great tit (Parus major), especially why older birds (adults) in nature normally dominate younger ones (juveniles). When birds were matched with respect to age, prior residency determined dominance. Without a difference in prior residency older birds dominated younger ones. However, when juvenile birds

In this study conducted in southeastern Ontario, Canada, we manipulated the length of outer tail feathers (streamers) of male barn swallows (Hirundo rustica) shortly after they returned to four small breeding colonies in the spring. Both streamers on most males in these colonies were experimentally either lengthened or shortened by 20 mm and as a result 10 randomly chosen males of each category ha

In an experimental study in Denmark, it was previously found that male barn swallows (Hirundo rustica) with elongated tail streamers obtained an apparent fitness advantage through earlier pairing, an increased frequency of second clutches, and higher total reproductive success per season. In a parallel study of five barn swallow colonies in Ontario, Canada, we also found that elongated males paire

The evolution of intense begging by dependent nestling birds has recently been the subject of several theoretical papers. The interesting problem here is that nestlings should be able to communicate their nutritional status to parents in ways that are less costly energetically and less likely to attract predators. Thus, conspicuous begging behaviour is thought to have evolved as a result of either

Male Barn Swallows (Hirundo rustica) help their mates to incubate in North America but not in Europe. In this study, conducted at four colonies in southeastern Canada, males contributed an average of 9% of the total amount of incubation during daylight hours. The total percent of time that eggs were incubated (nest attentiveness) by both sexes declined through the day, largely due to a response to

In the Marsh Tit Parus palustris, breeding performance improved with the age of both the male and the female parent-older birds produced larger clutches earlier in the season. The effect of male age, however, was mainly due to a positive association with the age of the female. When the effect of laying date was accounted for, there was no additional effect of female age on clutch-size. However, pa

Starlings show considerable variation in egg mass among clutches. Mean clutch egg mass was highly repeatable for females, but few characteristics of females were found to relate to egg mass. Egg mass related weakly to female age, but female age only explained a small part of the variation. Hatchling mass was strongly correlated with egg mass, but body mass at 14 d of age was unrelated to egg mass.

A cross-fostering experiment demonstrated that tarsus length of European starlings (Sturnus vulgaris) was heritable. The tarsus length of the foster-parent had no effect. A full-sib resemblance analysis showed that sibs were much more similar in tarsus length than explained by heritability alone. This was partly due to an effect of female mating status on offspring tarsus length. When nestling gro

Thermal performance of five bicycle helmets was evaluated with a thermal manikin head with six zones. Evaluation was made with physical and virtual experimental methods. Ambient temperature maintained at 24 °C and surface temperature of the thermal manikin head was set to 34 °C. Experiments were performed for air velocities of 1.6 m/s and 6 m/s. Heat transfer (W) of four thermal zones was recorded

Recent advances in high-intensity laser-produced plasmas have demonstrated their potential as compact charge particle accelerators. Unlike conventional accelerators, transient quasi-static charge separation acceleration fields in laser produced plasmas are highly localized and orders of magnitude larger. Manipulating these ion accelerators, to convert the fast ions to neutral atoms with little cha

The need for sustainable agricultural systems, which for example enhance soil organic carbon (SOC) content, has increased the interest for management with reduced tillage. In this study we used a Swedish long-term (20 yrs.) systems experiment, including reduced tillage (harrowing 10 cm) and plowing (moldboard plow 0–20 cm) combined with three levels of nitrogen (N) fertilization. With this setup w