Illinois 75-D Anas americana 166 Jan 5 Univ. Calif. Campus, Alameda Co., Calif. Oryzae group. Jan 10 same locality - the 34 costus brought in over the weekend, and tagged and banded yesterday, are all from Gray Lodge Refuge, Butte Co., Calif. In addition to those birds, B5 infected with a light dose of malaria, was also turned loose with the rest of the flock. In all, 39 birds are in the pen. Jan 11 same locality - V6 has set up territory & defense in the SE corner of the pen - chasing every bird except B5 out of the area, with some putting but with considerable vigor. Even when out of the territory area, other birds avoid this one, and it shows some aggressiveness even in the pool. It is also this bird that I have observed moving debris with its bill, searching for insects. The loose mallard in the pen doesn't seem to antagonize the defending bird as it spends most of it time in the territorial corner. Jan 13 same locality B5, tagged replaced with LB6 weighed 402 gmo, 28 mm bursa, sex probably F, flat shield of class I. /G/S - retagged P10, weight 443 grams, probably F by leg length, shield class I F, bursa 25 mm. No hole where last tag was lost, pin and all are gone. Both this and the preceding bird have