January-february Tropospheric Climate for the Northern Hemisphere and the 11-year Solar Cycle, the QBO and the Southern Oscillation

Examined here is a recently discovered association between the 11-year solar cycle and the atmosphere that is most easily detectable when the two phases of the Quasi-biennial Oscillation (QBO) are considered individually rather than pooled. The influence of the Southern Oscillation (SO) for either of the two QBO phases is then combined with that of the solar cycle in the form of two-predictor multiple regression. The strong and well-defined relationship between the 11-year 10.7 cm solar flux cycle and the lower troposphere Northern Hemisphere January-February climate for QBO phase-stratified samples (van Loon and Labitzke 1988, Barnston and Livezey 1989) failed for the west QBO phase in 1989. Here, the opposing 1989 event is explained, at least in part, on the basis of the phase of the SO (the cold tropical Pacific SST event of 1988 to 1989). It is demonstrated that both the SO and the solar flux have moderate and quasi-independent correlations with the climate over certain regions, and where there is strong overlap they can work either in harmony or in opposition. In 1989 in North America the influences of the SO and the flux conflicted to an unprecedented extent, and the SO was the controlling influence in most regions of the continent (western Canada being one exception). The 1989 event draws attention to the smallness of the QBO phase-stratified samples and the still more serious holes in the two-dimensional sample space of flux and SO when both factors are viewed as predictors within one QBO phase

Functional Morphometric Analysis of the Furcula in Mesozoic Birds

The furcula displays enormous morphological and structural diversity. Acting as an important origin for flight muscles involved in the downstroke, the form of this element has been shown to vary with flight mode. This study seeks to clarify the strength of this form-function relationship through the use of eigenshape morphometric analysis coupled with recently developed phylogenetic comparative methods (PCMs), including phylogenetic Flexible Discriminant Analysis (pFDA). Additionally, the morphospace derived from the furculae of extant birds is used to shed light on possible flight adaptations of Mesozoic fossil taxa. While broad conclusions of earlier work are supported (U-shaped furculae are associated with soaring, strong anteroposterior curvature with wing-propelled diving), correlations between form and function do not appear to be so clear-cut, likely due to the significantly larger dataset and wider spectrum of flight modes sampled here. Interclavicular angle is an even more powerful discriminator of flight mode than curvature, and is positively correlated with body size. With the exception of the close relatives of modern birds, the ornithuromorphs, Mesozoic taxa tend to occupy unique regions of morphospace, and thus may have either evolved unfamiliar flight styles or have arrived at similar styles through divergent musculoskeletal configurations

Phylogenetic Analysis of Pelecaniformes (Aves) Based on Osteological Data: Implications for Waterbird Phylogeny and Fossil Calibration Studies

) were also assessed. The antiquity of these taxa and their purported status as stem members of extant families makes them valuable for studies of higher-level avian diversification. (sister taxon to Phalacrocoracidae). These relationships are invariant when ‘backbone’ constraints based on recent avian phylogenies are imposed.Relationships of extant pelecaniforms inferred from morphology are more congruent with molecular phylogenies than previously assumed, though notable conflicts remain. The phylogenetic position of the Plotopteridae implies that wing-propelled diving evolved independently in plotopterids and penguins, representing a remarkable case of convergent evolution. Despite robust support for the placement of fossil taxa representing key calibration points, the successive outgroup relationships of several “stem fossil + crown family” clades are variable and poorly supported across recent studies of avian phylogeny. Thus, the impact these fossils have on inferred patterns of temporal diversification depends heavily on the resolution of deep nodes in avian phylogeny

The Body Size-Dependent Diet Composition of North American Sea Ducks in Winter

Daily food requirements scale with body mass and activity in animals. While small species of birds have higher mass-specific field metabolic rates than larger species, larger species have higher absolute energy costs. Under energy balance, we thus expect the small species to have a higher energy value diet. Also the weight and time constraints for flighted and diurnal foragers should set a maximum to the amount of prey items taken in one meal and to the daily number of meals, respectively. Further, avoidance of competition causes the species to reduce the amount of shared prey in their diet. Some diet segregation is therefore to be expected between species. We tested these hypotheses and investigated the role of body mass in the diet composition of 12 sea duck species (Somateria mollissima, Somateria spectabilis, Somateria fischeri, Polysticta stelleri, Bucephala clangula, Bucephala islandica, Bucephala albeola, Melanitta nigra, Melanitta perspicillata, Melanitta deglandi, Histrionicus histrionicus and Clangula hyemalis) wintering in North America. This study was based on a literature survey with special emphasis given to the diet data from the former US Bureau of Biological Survey. The data supported our hypothesis that the energy value of winter diet of sea ducks scales negatively with body mass. Diet diversity also scaled negatively with body mass. Our results suggest the existence of a minimum for the energy value of avian diets