YANKEE DESERTERS- The blue birds are flocking in from Grant's wide spread wings, and are daily reaching Richmond by scores in advance of the "Great digger." Among the arrivals on Saturday was about a full company of the Fifth New Hampshire regiment, recently on guard duty at Point Lookout. They state that a regiment of negroes took their places there, and they were hurried to Grant to help fill up the gaps made in Grant's ranks by Lee's artillery. One solitary, red bird, or zoo-zoo, came in and reported himself as the last of the New York Duryea(sic) Zouaves left out of one hundred, who went into the battles below with Grant. He was disconsolate looking enough, but bore himself as became the "last of the Mohicans."
-Daily Richmond Examiner, June 6, 1864
I assume the "Zoo-zoo" was a member of the 5th New York who had transferred into the 146th New York after the original regiment mustered out. The records show that regiment losing some 46 enlisted men missing during the first few weeks of June, 1864
And of course it is "Zou Zou."