The Turtles of Mexico: Land and Freshwater Forms by John M. Legler & Richard C. Vogt

Author:John M. Legler & Richard C. Vogt
Language: eng
Format: epub
ISBN: 9780520268609
Publisher: University of California Press

CONSERVATION AND CURRENT STATUS

Nearly all anthropogenic activities are deleterious to G. berlandieri. In the lower Rio Grande Valley of Texas (from Laredo downstream) land has been modified for agriculture or grazing since about 1900. In worst-case scenarios (e.g., “chaining” followed by plowing) virtually all the cover and food plants of the tortoises were destroyed. Introduced buffel grass (Cenchurus ciliaris) is taller than native buffalo grass and impedes the movements and vision of tortoises. These changes have reduced and fragmented the range and decreased the abundance of tortoises. The initial clearing devastates a tortoise population, but in resulting areas of managed pasturage overgrazing actually improves tortoise habitat by favoring more nearly open short grass–cactus associations (Auffenberg and Weaver, 1969; Judd and Rose, 2000).

About half of the range is in Mexico where virtually nothing is known about the species, but where the same kinds of habitat damage are occurring. In Tamaulipas 243,800 ha were modified for agriculture in 1953 versus an astounding 1,310,000 ha by 1988 (Judd and Rose, 2000).

Vehicles kill a significant number of tortoises on public and private roads throughout the range. The predilection of tortoises for roads is partly to blame for this.

Collecting for the pet trade has probably reduced some populations. Many specimens are said to reach California from northeastern Mexico via New Mexico in order to avoid Texas laws. Shipments of 4,000–8,000 specimens have been mentioned in the literature, and estimates of annual totals have been as high as 40,000. Judd and Rose (2000) concede that the practice exists but think its magnitude may be exaggerated.

In Mexico tortoises are killed, dried, and varnished for sale to tourists in border cities (from Cd. Acuñya to Matamoros). Of 346 mummified specimens reported by Judd and Rose (2000), 39 were Gopherus berlandieri (most were Kinosternon sp.).

The species is legally protected and considered threatened by agencies in Texas, but there is no state conservation plan. The species is not federally protected, and there is no federal recovery plan. The Convention on International Trade in Endangered Species (CITES), endorsed by the United States in 1973, endorses the requirement of export permits from the country of origin and places all Gopherus in Appendix II of the List of Endangered Species. Collecting of native fauna in Mexico requires a permit.

It is enforcement rather than the law that flags. Enforcement requires the ability to identify animals and a knowledge of the rules. Even if an illegal tortoise is confiscated, a law officer may not have the facilities to dispose of it properly. Tortoises confiscated by U.S. Customs at the United States-Mexican border are said to be released on the U.S. side of the border (Judd and Rose, 2000).

Thus far there seem to be no management plans or specific reserves for the species. Gopherus berlandieri may have suffered the least of all the Gopherus; much of its range occurs on blocks of private ranch land that are off limits to the public.

Populations studied by Auffenberg and Weaver (1969) are not protected on most of the lomas, some of which have been disturbed by military maneuvers, hunting, and residential development.

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