Cassidix mexicanus prosopidicola Lowery: Great-tailed Grackle.—Small, postbreeding flocks composed of both adult and juvenal birds were seen moving along the edge of the laguna at Camp 1. In the morning the flocks flew south, and in the afternoon groups of similar size flew north, presumably to a roost at an undetermined distance north of our camp. Occasionally, a few birds stopped to rest or to forage on the dunes or in stands of mesquite. At Camp 2 on July 9, a postbreeding adult female and a well-grown, presumably independent juvenile were taken as they perched in a clump of mesquite in which we found three old nests of Cassidix; two of the nests were about four feet apart in one tree, and the third was in another tree 100 feet from the first.
Specimens (4): ♂ adult, 38988, testis 6 mm., no fat, 209 gm., 6 P old, Camp 1, July 7. Female, 38989, ova to 3 mm., fat, 115 gm., old brood patch, Camp 1, July 8. Female, 38990, ova to 1 mm., moderate fat, 107 gm., 7 P old, brood patch refeathering; ♂ juv., 38991, testis 3 × 1 mm., not fat, 172 gm., 6 P old; Camp 2, July 9.
Table 4.—Measurements in Millimeters of Adult Males of Cassidix Mexicanus
| Locality | No. | Wing | Tail | Tarsus | Weight in grams |
|---|---|---|---|---|---|
| Austin, Texas | 17-137[1] | 184.3 (173-200) | 203.8 (178-232) | 46.38 (41.8-50.0) | 225.6 June (204-253) 202.2 July (195-207) |
| San Patricio Co., Texas[2] | 5 | 185.2 (182-188) | 204.2 (190-219) | 46.74 (45.1-50.2) | 237.6 (228-245) |
| Barrier Is., Tamps. | 1 | 178 | 185 | 47.1 | 209 |
| Victoria, Tamps.[3] | 4 | 192.2 (186-200) | 224.2 (215-232) | 47.77 (46.0-49.1) | 254.3 (239-276) |
| Tampico, Tamps.[4] | 1 | 197 | 214 | 48.3 | 260 |
| Catemaco, Veracruz[5] | 1 | 193 | 216 | 48.2 | 257 |
[1] Data from Selander (1958: 370, 373). Sample sizes, as follows: wing, 137; tail, 119; bill length, 20 (June and July); tarsus, 133; weight, 17 for June, 3 for July.
[2] June 13, 1961; breeding condition.
[3] May 6, 1961; breeding condition.
[4] May 7, 1961; breeding condition.
[5] November 28, 1959.