Page:Condor15(6).djvu/34

 222 THE CONDOR V.XV rest. Here they would remain in one spot, often stuck in the mud, until death oc- cured. A later symptom of the disease was the development of a whitish-green or yellowish diarrhoea. During the later stages of the disease the sick birds were often found barely holding the head up or with the neck and head extended out upon the ground as if dead. While in this languid state, and under conditions of great heat and dry- ness, the eyes often became closed due to the formation and drying of matter in them, the birds being unable to clean themselves. At times flesh flies deposited their eggs or larvae in the corners of the eyes, and this doubtless gave rise to the opinion on the part of some people that the birds were dying from "worms in the eyes". The mouths and throats of the sick birds were often dry and parched, due to cessation of drinking and feeding. When a large flock of ducks on a levee was approached, most of the birds would fly off while the invaders were still several hundred yards or a quarter of a mile away. But in these flocks it was nearly always to be noted that some of the birds would lose distance and lag behind in the flight, and often times Fig. 73. MAIN CAtP (A) FROt WHICH EXPERItENrAL WORK WAS CARRIED ON; NOTE KAFFIR CORN FIELD IN BACKGROUND would alight after a short journey, apparently weak or disinclined to follow.- Other birds would make no attempt to go when the main flock arose. On closer approach, these individuals, if on the water, would swim off with fair rapidity; if on land, those able to travel would make an effort to get into the water and swim off. Many would attempt to fly and, after half swimming and half flying for a distance, would gain wing and fly perhaps a quarter of a mile, but more likely only a short distance, when they would slow down quickly and flutter onto the water. Others would not clear the water at all, but simply race along the top of the lake creating a big commotion, splashing the water violently, often quacking loudly as they made every possible effort of head, wings and legs to get out of the way. If the enemy got too close, many would try to dive. Sometimes they would remain down in the water several seconds, even twenty or thirty seconds, and then come up in another place several yards away. But the more seriously stricken birds would not be able to get much more than the head out of sight. Sick birds out upon the lake could nearly always be recognized even at a consid- erable distance because they sat lower in the water, being water-logged, and not