But, from these three colors, you can mix all colors found in the spectrum. Selecting Three Primaries. Probably the best way to choose primary colors is to browse through various art instruction books until you find an artist that sees, and interprets, color in the same way as you do. Deciding on which three primary watercolors to begin with can seem quite daunting, especially if you are new to watercolor.
144 Field Manual of Wildlife Diseases: Birds Figure 16.4 During the 1973 outbreakof duck plague at Lake Andes NationalWildlife Refuge in South Dakota, morethan 40,000 mallards died. Photo by Milton Friend from adjacent Flanders Bay, apparently as a result of diseasetransmission from white Pekin ducks.ittle is known about the response of wild water-fowl to strain differences.Duck plague outbreaks are thought to be caused whenbirds that carry the virus shed it through fecal or oral dis-charge, thus releasing the virus into food and water withwhich susceptible birds may have contact.
There are many diseases that can affect waterfowl species. The infectious diseases described here are the most common viral diseases seen in domestic waterfowl species. It seems likely that viral diseases will assume greater future importance as causes of disease in waterfowl.Greater attention needs to be given to the study of this source of disease.uck Virus Hepatitis. Duck hepatitis (DH) is a highly fatal, contagious and rapidly spreading disease of young ducklings from one to 28 days of age. So far, three different viruses, duck hepatitis virus (DHV) type 1, 2 and 3, have been associated with these disease conditions.