Vertebrates from the Barrier Island
of Tamaulipas, México

BY

ROBERT K. SELANDER, RICHARD F. JOHNSTON,
B. J. WILKS, AND GERALD G. RAUN

University of Kansas
Lawrence
1962

University of Kansas Publications
Museum of Natural History

Volume 12, No. 7, pp. 309-345, pls. 5-8.

June 18, 1962

Vertebrates from the Barrier Island
of Tamaulipas, México

BY

ROBERT K. SELANDER, RICHARD F. JOHNSTON,
B. J. WILKS, AND GERALD G. RAUN

University of Kansas
Lawrence
1962

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Theodore H. Eaton, Jr.

Volume 12, No. 7, pp. 309-345
Published June 18, 1962

University of Kansas
Lawrence, Kansas

PRINTED BY
JEAN M. NEIBARGER, STATE PRINTER
TOPEKA, KANSAS
1962

29-3002

Vertebrates from the Barrier Island
of Tamaulipas, México

BY

ROBERT K. SELANDER, RICHARD F. JOHNSTON, B. J. WILKS, and GERALD G. RAUN

Lying between the Gulf of Mexico and the Laguna Madre de Tamaulipas is a narrow barrier island extending from the delta of the Rio Grande south for 140 miles to within 185 miles of Tampico, Tamaulipas (Plate 5). This island, like most of coastal Tamaulipas, has been all but neglected by zoological collectors. Consequently, little is known of the kinds, distribution, and seasonal status of the vertebrates occurring there. The present paper is a report on land vertebrates collected and observed on the northern part of the barrier island of Tamaulipas from July 6 to 10, 1961. Our collection, which has been deposited in the Museum of Natural History, The University of Kansas, consists of 63 reptiles, 33 mammals, and 97 birds (58 skins, 19 skeletons, and 20 alcoholics).

Acknowledgments

We are especially indebted to Dr. Charles H. Simpson of Sinton, Texas, who generously placed at our disposal his truck, a four-wheel drive "Land Rover," without which travel on the island would have been difficult. We also acknowledge a loan of field equipment provided by Dr. Clarence Cottam, Director of the Welder Wildlife Research Foundation, Sinton, Texas.

Financial support for the present research was provided by grants from the National Science Foundation to The University of Texas (G 15882) and to The University of Kansas (G 10043).

Permits to collect vertebrates in México were supplied by Ing. Luis Macias Arellano, El Director General, Departamento de Conservación de la Fauna Silves, México, D. F.

We are indebted to Dr. Richard H. Manville for arranging a loan of specimens of Geomys personatus tropicalis in the United States National Museum. Dr. Marshall Johnston kindly identified specimens of plants from the barrier island. Several bones of birds and mammals were identified by Dr. Pierce Brodkorb and Dr. E. L. Lundelius. Mr. J. Knox Jones identified some of the mammalian material, and Dr. W. E. Duellman verified the identifications of the lizards; we thank all of these men for their willing assistance.

The Ecological Setting

The barrier island of Tamaulipas geologically and ecologically resembles Padre Island, of the Gulf coast of lower Texas, north of the mouth and delta of the Rio Grande. South of the delta, the island in Tamaulipas is a narrow strip of sand less than a mile in average width and is broken by a series of narrow inlets or "passes" through which water from the Gulf of Mexico mingles with that of the Laguna Madre de Tamaulipas. The passes are subject to recurrent opening and closing. North of the mouth of the Río Soto la Marina, eight passes are designated by local fishermen, but only three, the Third, Fourth, and Fifth, were open at the time of our visit.

The Laguna Madre de Tamaulipas is described by Hildebrand (1958) in connection with a preliminary study of the fishes and invertebrates there. The average depth is probably less than 70 cm. and the waters are hypersaline. In the time of the recent drought in Texas and northeastern México, salinity varied from 108 to 117 parts per thousand in the northern part of the laguna near Arroyo del Tigre (measurements taken in March, 1955) to from 39 to 48 parts per thousand in the southern part near Punta Piedras (measurements taken in October and November, 1953, and in March, 1954). Discussions of the geologic history, ecology, and zoogeography of the lagoons of the Gulf coast of the United States are given by Hedgpeth (1947; 1953).

Localities in coastal Tamaulipas mentioned in the text of this paper are shown on Plate 5.

The principal animal habitats are found in three vegetational associations (plates 6 and 7). On flats and low dunes lying between, and partly sheltered by, larger active dunes, small clumps of Croton punctatus and a sedge (Fimbristylis castanea) are the only conspicuous plants. Near the western edge of the dunes, Ipomoea pescaprae var. emarginata is mixed with Croton, and there are scattered clumps of shrubby wolf-berry (Lycium carolinianum var. quadrifidum), and mesquite (Prosopis juliflora).

The dunes are relatively stabilized on the western side of the island, and there we found moderately dense stands of mesquite trees reaching heights of from eight to 10 feet. Prickly-pear cactus (Opuntia lindheimeri) was common in those stands of mesquite, and we saw an occasional yucca tree. A fairly dense ground cover was formed by blanket-flower (Gaillardia pulchella), marsh-elder (Iva sp.), Flaveria oppositifolia, Enstoma exaltatum, and Croton capitatus var. albinoides.

A more open, xeric expression of the mesquite-cactus vegetation occurs on exposed, low clay dunes (see description by Price, 1933) located on alkaline flats bordering the laguna. At the time of our visit, most of the mesquites in these stands were dead or dying, the cactus was abundant, and the ground cover, which was sparse, included drop-seed (Sporobolus virginicus), ragweed (Ambrosia psilostachya), and Commicarpus scandens.

On alkaline flats flooded by hypersaline waters of the laguna following heavy rains, Batis maritima is found in the lower areas, but on the slightly elevated areas there is low and almost continuous cover of Monanthochloë littoralis, in which can be found Batis, Borrichia fructescens, Salicornia sp., Iva sp., and sea-lavender