We implanted satellite transmitters into eight juvenile Common Mergansers to investigate post-fledging movements from their natal river in southcentral Alaska. Subsequently, they moved widely throughout portions of western and southcentral Alaska up to 750 km from their natal areas during fall and winter months. Transmitters of two birds (one male and one female) continued to send location data into their second year and allowed us to determine the location and timing of the flightless molt period for each bird. Overall, our data suggest that juvenile Common Mergansers range widely immediately after fledging, that second year males and females may differ in their movement patterns, and that these movements have implications for population genetic structure of this species.
-Within-clutch variability in shape of 1743 eggs from 301 nests of Emperor Geese (Chen canagicus) laid over a 5-yr period was measured. Individual females laid similar shaped eggs in successive years, and eggs among clutches within females could not be distinguished. Cluster analysis correctly identified 69.9% of 136 known conspecific parasitic eggs. Repeatability estimates of elongation (0.73), sphericity (0.72), maximum width (0.69) and radius of the point (0.68) were high and similar to repeatability estimates of egg mass and volume of other species. Although width, volume and area measurements varied inversely with spring population size, shape variables did not. The consistency in shape variables despite changes in egg size suggests that shape variables may be used to separate and identify individuals within and among years despite changes in the population that may result in changes in egg size. Differences in egg shape among eggs within a nest are viable criteria for identifying parasitic eggs, especially when used in conjunction with other methods. VARIACION INTRAESPECIFICA EN LA FORMA DE LOS HUEVOS DE CHEN CANAGICUS Sinopsis.-Por 5 afios se midieron 1743 huevos pertenecientes a 301 nidos de Ganzo Emperador (Chan canagicus) para tratar de determinar variaci6n en la forma de estos dentro de la camada. Hembras particulares pusieron huevos de similar tamaiio en afios sucesivos, y no se pudo distinguir entre huevos de las mismas hembras. Mediante anflisis de agrupacion, se pudo identificar correctamente el 69.9% de 136 puestos por hembras parasiticas. Estimados de repetici6n de elongaci6n (0.73), esferidad (0.72), ancho maiximo (0.69) y radio del punto (0.68) resultaron altos y similares a estimados de repetici6n de masa de huevos y volumen de otras especies. Aunque el ancho, volumen y medidas de area variaron inversamente con el tamanio de la poblaci6n primaveral, no se encontro lo mismo para variables de tamaiio. La consistencia en variables de tamanio (a pesar de los cambios en el tamanio de los huevos que puede haber) sugiere que las variables en tamanio pueden ser utilizadas para separar e identificar individuos, en un anio particular o a traves de los afios. Las diferencias en tamanio entre huevos de un mismo nido, puede ser utilizadas como un buen criterio para identificar huevos de hembras parasiticas, especialmente cuando se utilice este criterio en uni6n a otros metodos. Individuals of some species of wild birds lay eggs that vary in color, marking pattern, weight and shape (e.g., Boag and van Noordwijk 1987, Koskimies 1957, Lessells et al. 1989, Thomas et al. 1989). Repeatability of egg volume or mass among individuals is also high in some species (e.g., Leblanc 1989, Lessells et al. 1989, Ojanen et al. 1979, Prince et al. 1970, van Noordwijk et al. 1981, but see Duncan 1987). As a result of high variability and repeatability among females, it may be possible to identify eggs laid in nests by other females (intraspecific parasitic egg laying) (e.g., Freeman 1988, Thomas et al. 1989, Yom-Tov 1980). For
Since the late 18th century bird populations residing in the Aleutian Archipelago have been greatly reduced by introduced arctic foxes (Alopex lagopus). We analyzed data from microsatellite, nuclear intron, and mitochondrial (mtDNA) loci to examine the spatial genetic structure, demography, and gene flow among four Aleutian Island populations of the Common Eider (Somateria mollissima) much reduced by introduced foxes. In mtDNA, we found high levels of genetic structure within and between island groups (ΦST = 0.643), but we found no population subdivision in microsatellites or nuclear introns. Differences in genetic structure between the mitochondrial and nuclear genomes are consistent with the Common Eider's breeding and winter biology, as females are highly philopatric and males disperse. Nevertheless, significant differences between islands in the mtDNA of males and marginal significance (P = 0.07) in the Z-linked locus Smo 1 suggest that males may also have some level of fidelity to island groups. Severe reduction of populations by the fox, coupled with females' high philopatry, may have left the genetic signature of a bottleneck effect, resulting in the high levels of genetic differentiation observed in mtDNA (ΦST = 0.460–0.807) between islands only 440 km apart. Reestablishment of the Common Eider following the fox's eradication was likely through recruitment from within the islands and bolstered by dispersal from neighboring islands, as suggested by the lack of genetic structure and asymmetry in gene flow between Attu and the other Near Islands.
Some statistics in “Biochemical and clinical responses of Common Eiders to implanted satellite transmitters” were miscalculated due to missing data. We provide corrected values for the affected variables. Corrected data did not affect the conclusions of the paper.
Objectives: Ischemic mitral regurgitation (IMR) is secondary to myocardial ischemia or myocardial infarction. Little information exists if left ventricular (LV) remodeling and outcome of these patient groups differ after mitral valve plasty (MVP) and coronary artery bypass grafting (CABG).
