نتایج جستجو برای: anas platyrhynchos
تعداد نتایج: 1372 فیلتر نتایج به سال:
Data are often collected from wild animals that have been marked at unknown age. As a result, standard probability models, fitted by maximum likelihood, cannot incorporate agedependence in probabilities of annual survival. We propose and fit new mixture models to ring-recovery data on birds ringed of unknown age, in which it is possible to incorporate age dependence in survival. It is shown tha...
We determined the effects of a commonly used mosquito (Culicidae) larvicide (Califor nia Golden Bear Oil�, also GB-1111) on body mass and survival of mallard (Anas platyrhynchos) ducklings and on target and nontarget invertebrates. Field studies con ducted on natural ponds located in salt marshes in south San Francisco Bay indicated that GB-1111 had an initial impact on potential invertebrate...
Reconstructing species trees by incorporating information from many independent gene trees reduces the confounding influence of stochastic lineage sorting. Such analyses are particularly important for taxa that share polymorphisms due to incomplete lineage sorting or introgressive hybridization. We investigated phylogenetic relationships among 14 closely related taxa from the mallard (Anas spp....
In 1967, the first confirmed diagnosis of duck plague (DP) in the USA was made from pekin ducks (Anas platyrhynchos domesticus) on commercial duck farms on Long Island, New York. Within 10 mo, DP was confirmed as the cause of death in migratory waterfowl on a Long Island bay. This paper reviews 120 DP epizootics reported from 1967 to 1995 that involved waterfowl species native to North America ...
The blue colours of the speculum of the mallard (Anas platyrhynchos), both male and female, and the green head feathers of the male arise from light interacting with stacks of melanosomes residing in the feather barbules. Here, we show that the iridescent colours can be quantitatively explained with an optical multilayer model by using a position-dependent effective refractive index, which resu...
We conducted large-scale, systematic sampling of influenza type A virus in migratory waterfowl (mostly mallards [Anas platyrhynchos]) at Ottenby Bird Observatory, southeast Sweden. As with previous studies, we found a higher prevalence in fall than spring, and among juveniles compared with adults. However, in contrast to other studies, we found that prevalence in spring was sometimes high (mean...
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