Since Baird (1855:332) described S. v. couchii and mentioned a specimen from Ciudad Victoria that was obtained by Berlandier, no other record from Tamaulipas has come to light. Probably the species obtained by Berlandier was introduced at Ciudad Victoria by man.
Sciurus aureogaster aureogaster Cuvier
Red-bellied Squirrel
1829. [Sciurus] aureogaster Cuvier, in Geoffroy St.-Hilaire, and F. Cuvier, Hist. Nat. Mamm., 6, livr. 59 pl. with text, September (binomen published only at end of work, table générale et méthodique, 7:4, 1842), type locality "California"; restricted to Altamira, Tamaulipas, by Nelson (Proc. Washington Acad. Sci., 1:38, May 9, 1899).
Distribution in Tamaulipas.—Tropical forest of southern part; north at least to Rancho Santa Rosa.
According to one collector (Schaldach), natives referred to Sciurus aureogaster as "ardilla pinta" or "ardilla colorada." He recorded in his field notes that S. aureogaster was most active between 7:00 and 9:00 a. m. and again from 3:00 to 5:00 p. m., that the nest was constructed of green oak leaves, and that the nest resembles somewhat in size and form that of S. carolinensis.
Of 53 specimens examined, 17 are black and one from 70 kilometers south of Ciudad Victoria is clearly more whitish than the others. Specimens from the northeastern part of the range of the species (= southeastern Tamaulipas) average darker than those from the south and west. In individuals that are not black, the ventral reddish color covers the shoulders and in some it extends between the shoulders to the median dorsal area.
Among females collected from December through May, only one, taken 43 kilometers south of Ciudad Victoria on March 17, was pregnant (one embryo).
The weight of seven adult males from Soto la Marina and the Sierra de Tamaulipas averaged 492.5 (400-575) grams.
Specimens herein reported from San Fernando provide the northernmost record of the species.
Records of occurrence.—Specimens examined, 53: San Fernando, 180 ft., 5; 9-1/2 mi. SW Padilla, 800 ft., 3; Rancho Santa Rosa, 25 km. N, 13 km. W Cd. Victoria, 260 m., 8; 3 mi. NE Guemes, 5; Soto la Marina (3 mi. N), 500 ft., 6; Sierra de Tamaulipas, 10 mi. W, 8 mi. S Piedra, 1200 ft., 6; 43 km. S Cd. Victoria, 1; Ejido Santa Isabel, 2 km. W Pan-American Highway, 2000 ft., 5; 70 km. (by highway) S Cd. Victoria, 6 mi. W of Pan-American Highway, 3; 2 mi. W El Carrizo, 7; Rancho Pano Ayuctle, 6 mi. N Gómez Farías, 300 ft., 2; Rancho Pano Ayuctle, 25 mi. N, 3 km. W El Mante, 300 ft., 1; 8 km. W, 10 km. N El Encino, 400 ft., 1.