Iguana_11.2_text.ps


During April 1938 the writer collected twelve chuckwallas in
order to make a study of the food habits of this species.

Specimens were collected in creosote bush and ocotillo associa-
tions at Borego Mountain, Tubbs Canyon, and Palm Canyon in
San Diego County, California.

Stomachs of the Borego Mountain specimens contained
stems and leaves of Phacelia sp. [the Phacelias, which include the
Desert Primrose, the Wild Heliotropes, and the Desert Bells];
leaves, stems and blossoms of Franseria dumosa [= Ambrosia
dumosa, the Burro Bush, Burro Weed, or White Bursage]; leaves
of Encelia farinosa [Brittlebush]; leaves and a seedling of
Eriogonum sp. [Buckwheat]; leaves of Ditaxis lanceolata
[Narrowleaf Silverbush]; blossoms and leaves of Larrea divaricata
[a Creosote Bush]; and the blossoms of Fouquieria splendens
[Engelmann Ocotillo] which the lizards had picked up around
the bases of these plants. Sand was also found in the stomachs
which contained the Fouquieria blossoms. Specimens from
Borego Mountain seemed to prefer the leaves and stems of
Franseria dumosa as their stomachs were filled largely with the
leaves and stems of this plant.

The stomachs of the 8 specimens from Tubbs Canyon con-

tained leaves of Encelia farinosa; leaves, seed-pods and stems of
Lotus sp. [the Trefoils]; leaves of Phacelia sp., seedling of Festuca
sp. [a Fescue]; blossoms, leaves and stems of Cryptantha sp. [the
Cryptanthas or White Forget-me-nots]; and the blossoms, leaves
and stems of Lotus strigosus [Strigose Bird’s-foot Trefoil]. These
specimens showed equal taste for F. dumosa and E. farinosa.

The single specimen collected at Palm Canyon contained
several large blossoms, about 10 x 15 mm. when pressed, of
Chænactis sp. [the Pincushions]; one blossom of Cryptantha sp.;
and the blossoms of Tropidocarpum gracile [Slender
Tropidocarpum, a Mustard].

No animal remains were found in any of the stomachs.
I am grateful to Mr. Frank F. Gander of the San Diego

Natural History Museum for assistance in the identification of
the plant material.

124 IGUANA  •  VOLUME 11, NUMBER 2  •  JUNE 2004 SHAW

H I S T O R I C A L  P E R S P E C T I V E S

An adult Sauromalus ater from the foothills of the Sierra de Las Asemblea, northern Baja California. Encelia farinosa (Brittlebush) and Franseria
dumosa (White Bursage) are visible in the background; both are eaten by Chuckwallas. Photograph by L. Lee Grismer.

Food Habits of the Chuckwalla, 
Sauromalus obesus1

Charles E. Shaw

San Diego Reptile Club, San Diego, California

1 Originally published in Herpetologica 1:153 (1939). Reprinted with
permission. Common names in brackets were not included in the
original publication. Also note that the species is now known as S. ater
(see article on p. 78).