21. CONSERVATION IMPLICATIONS OF EXOTIC …. CONSERVATION IMPLICATIONS OF EXOTIC GAME RANCHING IN THE TEXAS HILL COUNTRY EDMUNDO HUERTA-PATRICIO1, KARYN. D. CAMERON2†, GUY N. CAMERON2,

Abstract

We analyzed the importance of exotic game ranching forthe conservation of native plants and animals in the TexasHill Country. We focused on non-native herbivorous ar-tiodactyls that have become an integral component of theTexas Hill Country ecosystem. We examined informa-tion about habitat, reproduction, and diet of these spe-cies, and the possible competition that may occur betweenexotic and native species in the Texas Hill Country, likewhite-tailed deer. We also analyze the socio-economicfactors that motivate the expansion of exotic game ranch-ing. We found that the Edwards Plateau is the natural re-gion in Texas with the highest density of exotic gamespecies. Moreover, the Axis deer is the exotic species thathas had the highest population levels over the last severalyears. Biological information about feeding behavior re-vealed that white-tailed deer are an inferior competitorto exotic species and that this native species is the firstspecies to suffer under intense competition. Exotic gamespecies replace white-tailed deer on poor quality or over-grazed range. We suggest that expansion of exotic gameranching in the Texas Hill Country can serve as a toolfor conservation of the Edwards Plateau. On the onehand, game ranching can diversify the economy ofranchers by providing venison for market, agriculturaltax exemptions, and trophy hunting, and, on the otherhand, by controlling free-ranging exotic species thatcompete with white-tailed deer and other native ungu-late species.

Resumen

Se analizó la importancia del manejo de artiodáctilos exó-ticos para la conservación de la flora y fauna nativas de laregión de Texas Hill Country también llamada meseta deEdwards. Los artiodactilos exóticos se han convertido enun componente integral del ecosistema en Texas HillCountry. Estudiamos la información existente acerca delhábitat, reproducción y dieta de estas especies así comola posible competencia con las especies nativas de TexasHill Country, como el venado cola blanca. Se analizaronlos factores socio-económicos que han sido motor parala expansión del manejo de exóticos en esta región deTexas. Encontramos que la meseta de Edwars es la regiónde Texas con una mayor densidad de artiodactilos exóti-cos, siendo el venado Axis la especie con los niveles másaltos en la población a través de varios años. La informa-ción biológica recabada sobre la conducta alimenticia re-vela que el venado cola blanca es un competidor inferiora las especies exóticas siendo la primer especie nativa ensufrir daños bajo una competencia intensa. Las especiesexóticas remplazan al venado cola blanca en tierras sobrepastoreadas o de baja calidad. En el presente estudio su-gerimos que el manejo adecuado de especies exóticas deartiodactilos puede contribuir y tener un papel clave en laconservación de Edwars Plateau. Por un lado, el manejode exóticos puede diversificar la economía de los ranche-ros proporcionándoles un mercado de carne, abstenersedel pago de impuestos agrícolas e ingresos por caza ma-yor, y por otro lado, controlando el libre pastoreo de las

HUERTA-PATRICIO EDMUNDO, CAMERON KARYN D., CAMERON

GUY N., AND MEDELLÍN RODRIGO A. CONSERVATION IMPLICA-TIONS OF EXOTIC GAME RANCHING IN THE TEXAS HILL COUNTRY,CAP. 21: 237-252. En: SÁNCHEZ-CORDERO V. y MEDELLÍN R.A.(Eds.) CONTRIBUCIONES MASTOZOOLÓGICAS EN HOMENAJE A

BERNARDO VILLA, 706 p. Instituto de Biología, UNAM; Institutode Ecología, UNAM; CONABIO. México, 2005. ISBN 970-32-2603-5.

21. CONSERVATION IMPLICATIONS OF EXOTIC GAMERANCHING IN THE TEXAS HILL COUNTRY

EDMUNDO HUERTA-PATRICIO1, KARYN. D. CAMERON2†, GUY N. CAMERON2, RODRIGO A. MEDELLÍN1

1Instituto de Ecología, UNAM2Department of Biological Sciences, University of Cincinnati

2†Deceased

CONTRIBUCIONES MASTOZOOLÓGICAS EN HOMENAJE A BERNARDO VILLA238

Exotic species have increased in abundance in manynatural ecosystems and their impact on native spe-cies is of critical concern for conservation biologists(Luken 2000; Mack et al. 2000; Pimentel et al. 2000).Since both exotic plants and animals alter commu-nity structure and function and can reduce abun-dance or increase extinction of native species(Beckett et al. 1998; Bruce et al. 1995; Gordon 1998;Mauchamp 1997; Suarez and Case 2002), they mustbe considered in the overall processes of conserva-tion planning and ecosystem management. Creationof preserves and restoration of habitats must con-sider or plan for potential invasion and consequentimpact by exotic species. In addition, and of poten-tially more importance to conservation biologists,is that numerous anthropogenic activities may ac-celerate the rate of invasion by exotic species, e.g.,climate change, habitat fragmentation, urban sprawl(Donovan et al. 1997; Brawn and Robinson 1996).

Exotic game species in the Texas Hill Countrypresent numerous issues with regard to conserva-tion of native plants and animals of this area. Wefocus primarily on non-native herbivorous artiodac-tyls that were introduced for game ranching and havebecome an integral component of the Texas HillCountry ecosystem. We examine habitat, reproduc-tion, and feeding behavior of these exotic species,outline circumstances under which competition mayoccur between exotic and native species, and con-sider economic and sociological motivating forcesbehind growth of the industry of exotic game ranch-ing. Finally, we discuss directions in which conser-vation efforts may proceed given existing knowledgeconcerning exotic game ranching in this region.

Legal Restrictions and HistoricalBackground of Exotic Game Species

Federal controls on exotic game animals limit theirintroduction into the United States. The Lacey Actof 1900 was the first law that regulated introduc-

tions. It stated that “... it shall be unlawful for anyperson or persons to import into the United Statesany foreign wild animal or bird except under specialpermit from the United States Department of Agri-culture” (Ramsey 1969).

The state of Texas has few laws that regulatemanagement or harvesting of exotic game animals.Article 978 of the Texas Penal Code of 1925 grantsthe Texas Parks and Wildlife Commission “ ... theauthority, power, and duty to provide by proclama-tion, rule or regulations, periods of time when it shallbe lawful to take a portion of the wildlife resourceof said counties….” (Ramsey 1969). Section 15 ofthis Article defines the wildlife resources to be gameanimals and game birds. This law grants power tothe state to regulate hunting of these game species.

Article 892, which defines animals considered tobe game animals, was revised in 1965 to exclude ex-otic game from the legal definition of game species.It states “wild deer, wild elk, wild antelope, wilddesert bighorn sheep, wild black bear, wild gray orcat squirrels, wild fox squirrels or red squirrels, col-lared peccary or javelina, and the American bison orbuffalo are hereby declared to be game animalswithin the meaning of this Act” (Ramsey 1969).Because they are not game animals, exotic game spe-cies are exempt from all state laws regulating hunt-ing and management policies promulgated by theTexas Parks and Wildlife Department (TPWD). Assuch, they are in the same legal category of privateproperty as domestic livestock. Domestic livestockalso are considered private property and all manage-ment decisions such as stocking rate, method ofgrazing, and period of harvest are determined byindividual landowners. This legal status of exoticspecies, particularly when they are not contained inthe manner of traditional domestic livestock, cre-ates ambiguities in terms of broad-scale managementgoals.

History. The first introduction of exotic deer(axis, sika, barashinga, and sambar) and blackbuck

Key words: Competition, conservation, domestic ungu-lates, Edwards Plateau, exotic species, feeding preferenc-es, foraging behavior, game ranching, Texas Hill Country,White-tailed deer.

especies exóticas que compiten con el venado cola blancay otras especies de ungulados.

Palabras clave: Competencia, conservación, unguladosdomésticos, Planicie Edwards, especies exóticas, prefe-rencias alimentarias, comportamiento alimentario, faunacinegética, condado de Texas Hill, venado cola blanca.

CONSERVATION IMPLICATIONS OF EXOTIC GAME RANCHING IN THE TEXAS HILL COUNTRY 239

antelope to Texas is thought to have been in early1940’s (Winckler 1985). Currently, six species com-promise 77% of total confined exotic animals and99% of free-ranging exotic game animals in the state:the axis deer (Axis axis), fallow deer (Dama dama),sika deer (Cervus nippon), blackbuck antelope(Antilope cervicarpa), nilgai antelope (Boselaphustragocamelus), and aoudad sheep (Ammotraguslervia). Nilgai antelope represent 49% of total free-ranging exotic animals in Texas, but are found pre-dominately in south Texas.

Study Site. Gould (1969) defined 10 natural re-gions of Texas based upon an environmental analy-sis that included examination of ecological factorssuch as climate, soil, topography, and biota. Rela-tive to other natural regions of Texas, the EdwardsPlateau has the highest concentration of exotic gameranches and contains 68% of the total number ofconfined exotics within the state (Texas Parks andWildlife 1989). The magnitude of growth in exoticgame ranching with respect to six major exotic spe-cies is illustrated by analyzing the number of exot-ics between 1966 and 1988 (Texas Parks and Wildlife1989).

The Edwards Plateau contains approximately 9.6million ha of rolling hills and spring-fed streams thatcut across limestone-underline soils, forming can-yons and steep hillsides; this is the so-called HillCountry of Texas. The Edwards Plateau extendsfrom Brewster and Pecos counties in the west toLlano, Blanco, and Hays counties in the east, andfrom Nolan and Taylor counties in the north toUvalde County in the south. This area forms an ec-otone between the Mixed Mesophytic Forest of theeastern USA, the Madrean Evergreen Woodland ofMexico, and the Great Plains grasslands of the cen-tral USA (Amos and Gehlbach 1988). Each of theseecosystems is represented within the Edwards Pla-teau to varying degrees and in characteristic combi-nations. Rainfall on the western edge is <38 cm/year and on the eastern edge is >84 cm/year (Gould1969). There are 271 days/year without precipita-tion and the most rainfall is during May, June, andSeptember. Subfreezing winters and hot summerswith occasional short droughts characterize the cli-mate.

Limestone soils support woodlands dominatedby oaks and juniper (especially live oak, Quercusvirginiana, and Ashe juniper, Juniperus ashei). Gran-ite soils contain oaks almost exclusively. Upland soils

are dark, calcareous clays and clay loams that arelargely stony and gravelly. Bottomland soils includeminor areas of dark, calcareous clayey alluvial soils.Flatter areas with deeper soils are characterized byshortgrasses (common curly mesquite, Hilaria be-langeri; Texas grama, Bouteloua rigidiseta; buffalograss, Buchloe dactyloides; and Texas winter-grass,Stipa leucotricha). Steeper areas with shallower soilscontain midgrasses (little bluestem, Schizarchyriumscoparium and side-oats grama, Bouteloua curtipen-dula; Amos and Gehlbach 1988).

The Edwards Plateau is rangeland predominately,with agriculture confined to deeper soils and val-leys. The excellent mixture of forage plants in thisarea supports cattle, sheep, and goat ranches.

Competition Between Exotic, Native, andDomestic Ungulates

The Edwards Plateau is a center of Texas ranchingand livestock operations. This area also containshabitat for >3.5 million native white-tailed deer(Texas Parks and Wildlife 1990). One of the mostpressing issues is to understand the impact that ex-otic species may have upon native species present inthe Texas Hill Country and to learn whether pres-ence of exotic game species affects potential com-petition between native and domestic herbivores.Such evaluations are key to establishing managementpolicies for exotic game species in the Texas HillCountry. To formulate conservation goals and tojudge the desirability of exotic game ranching, it isimportant to understand the ecology of exotic, na-tive, and domestic herbivores as well as the nativevegetation of the area. Biological characteristics ofexotic game species and their interactions with thehabitat on the Edwards Plateau form a knowledgebase with which interactions among different her-bivores, wild and exotic, may be evaluated (Annex1, 2).

Exotic game species, native species, and domes-tic ungulates are all integral elements of the TexasHill Country ecosystem. Interactions among theseherbivores influence their population levels and af-fect distribution and abundance of vegetation. Physi-ological requirements of white-tailed deer limit itsfood consumption to plants low in fiber that areeasily digestible. As such, diet of white-tailed deeris limited to two forage classes, forbs and browse.Because of this narrow diet, white-tailed deer are an


inherently inferior competitor, and will be the firstspecies to suffer under intensive competition withexotic ungulates. Livestock and exotics are muchmore flexible in their diets and are able to alternatebetween all three forage classes on both herb-domi-nated and browse-dominated ranges (Figs. 1 and 2;Stuth and Sheffield 1981).

In addition, domestic ungulates also are moreflexible in their diet than native ungulates (Figs. 1and 2). Dietary patterns are exacerbated by environ-mental conditions, such as temperature and rainfall

that also influence amount and quality of vegetationavailable to these herbivores and may indirectly af-fect intensity of competition (e.g., seasonal patterns;Fig. 3 and 4; McMahan 1964).

Under competition, white-tailed deer show themost obvious signs of malnutrition. In addition, ef-fects of competition on white-tailed deer will bemore severe during seasons, particularly summer, inwhich forage conditions are less than optimal be-cause vegetative growth is limited by environmen-tal factors such as high temperature, low rainfall, and

Fig. 1. Feeding habits (estimated relative percentage of forage classes consumed) for exotic game species, domesticspecies, and white tailed deer on an herb-dominated range of Edwards Plateau (data from Stuth and Sheffield 1981).

Fig. 2. Feeding habits (estimated relative percentage of forage classes consumed) for exotic game species, domesticspecies, and white tailed deer a browse-dominated range of Edwards Plateau (data from Stuth and Sheffield 1981).


occasional drought. If the range has already beendepleted by livestock and exotic ungulates, white-tailed deer can suffer extensive nutritional damageduring stressful seasons. Additional nutritional re-quirements of bearing and nursing fawns and grow-ing antlers make these environmental conditionseven more difficult for white-tailed deer (McMah-an 1964). Exotic species may be classed together withlivestock animals as generalist feeders. When theirpreferred forage is unavailable they readily switch

to whatever class of forage is available. Such flexi-bility in diet gives exotics an advantage over white-tailed deer and, thereby, increases susceptibility ofdeer to competition and poor range conditions.Such stresses are not felt to the same degree bylivestock or exotic species because they are able toswitch to forage that is most available, that ade-quately meets their nutritional needs, and that al-lows them to fulfill normal physiological anddevelopmental processes.

Fig. 3. Comparison of feeding preferences (percentage of each forage class consumed; g = grass, f = forb, b: browse)between white tailed deer and domestic herbivores in diferent seasons of the year on an ungrazed pasture (data fromMcMahan, 1964).

Fig. 4. Comparison of feeding preferences (percentage of each forage class consumed; g = grass, f = forb, b: browse)between white tailed deer and domestic herbivores in different seasons of the year on a heavilygrazed pasture (datafrom McMahan, 1964).


Only a few studies have examined directly effectsof competition between white-tailed deer and exot-ic ungulates. One study described by Armstrong(1981) was conducted at the Kerr Wildlife Manage-ment Area, near Hunt, Texas. This study focusedon the interaction between sika deer and white taileddeer on an enclosed 39 ha pasture with no huntingor predation. Before competition for food becamesevere, sitka deer increased from 6 to 27 individualsand white-tailed deer increased from 6 to 18 indi-viduals. When availability of forbs and browse de-clined, intense competition reduced white-taileddeer population to 6 individuals, but sitka deer con-tinued to expand to 32 individuals because theyswitched to remaining types of vegetation. After 9years there were 59 sitka deer and no white-taileddeer in the pasture. In a parallel study with axis deerand white-tailed deer, similar results were obtained.These studies indicated that exotic game species weresuperior competitors to white-tailed deer and willdisplace them on overgrazed ranges.

In terms of conservation, it is necessary to ques-tion the desirability of displacement of native spe-cies by exotic species. With the goal of preservingthe Texas Hill Country ecosystem, including itsnative plants and animals, it becomes a matter ofpriorities when determining an appropriate man-agement plan for exotic species. There is not onlythe issue of displacement of native white tailed-deer by exotic game animals, but also the relatedissue of preserving endemic plant or animal spe-cies which may be deleteriously affected by pres-ence or uncontrolled growth of exotic species. Thepaucity of knowledge about possible impact of ex-otic animals on native flora and fauna leaves thefuture of the Texas Hill Country ecosystem un-predictable.

Predation of exotic, nativeand domestic ungulates

Exotics could be exposed to the same predators asnative or domestic ungulates such as lynx, foxes,coyotes, mountain lions, bears, eagles or even do-mestic dogs. For example, in Texas ranching areasAxis deer will be hunted by coyotes and bobcats,but axis deer have a good alarm system. They barkand stamp their feet if a coyote is sighted. This is

the same defense strategy that is used in India whenaxis deer sight a tiger, giving a higher pitched barkrather than the usual alarm call (Mungall andSheffield 1994).

Leopards and wolves are chief predators of na-tive ibex. In Texas ibex females and kids are killedby coyotes lynx and wolverine. Bears, foxes andprobably jackals add Ibex to their diets (Mungall andSheffield 1994).

In Texas, ranches report that domestic dogssometimes kill aoudad sheep. In unsettled parts ofCalifornia, mountain lions kill grown aoudad sheep(Mungall and Sheffield 1994).

Parasites and Diseases

Exotics in the Texas Hill Country have been freeof diseases and parasites and they do not play amajor role in spread of pathogenic organisms inwildlife or livestock. The most serious parasites anddiseases isolated include catarrhal fever in axis deer,the nematode Elaeophora schneideri in aoudad sheep,stomach worms in ranch aoudad sheep, and coccidi-osis in blackbuck antelope. Animals actually devel-oping these symptoms are likely to die.

Internal parasites like flukes (trematodes), flat-worms (cestodes), and roundworms (nematodes)have been found in several species of Texas exotics.The same parasite can affect different hosts in dif-ferent ways. For example, Elaeophora scheideri thathas devastated aoudad sheep produces no apparenteffect in white-tailed deer or in its definitive host,the mule deer. Elk in Colorado, Arizona, and NewMexico lose up to half their calves to this parasite inbad years in addition to suffering blindness, gangreneand antler deformities among older individuals.

In general Texas exotics have a low incidence ofdisease and usually a light parasite burden. UnitedStates quarantine laws require that animals import-ed from foreign countries are confined for observa-tion before they are released. If is it clear that thepotential of infections of diseases and parasites ex-ist, today’s regulations have greatly reduced the risk,but they cannot be eliminated (Mungall and Shef-field 1994). A very important factor is that diseaseand parasite outbreaks are more apt to occur whereanimal densities are high and are spread where ani-mal become free-ranging.


Hypotheses for the Expansion of GameRanching in Texas

Economic Motivations. Gray and Fowler (1981) pro-vide an outlook on the future of ranching in Texas.They explain that costs and fees will increase andranchers on private lands will find that game ranch-ing exceeds the profitability of range livestock op-erations, particularly after 1985. Exotic gameranching provides a means of diversification of theirranch economy and thus allows them greater op-portunity to achieve a profit.

Many authors have discussed economic benefitsof exotic game ranching (Matzke 1983; Mellink1991; Parkes et al. 1996; Van deer Waal and Dekker2000). Many works suggest that game ranching is agood alternative for conservation of natural areasand it involves human communities around thoseareas or natural parks. A lot of these studies havebeen conducted in Africa but, many of these prin-ciples could be applied to areas like the Texas Hillcountry, New Mexico or the North of Mexico.

In other countries it has been proved that gameranching will produce a great socio-economic im-pact. For example, in the northern province of SouthAfrica game ranching contributes significantly to theeconomy especially through hunting and live gametrade. Hunting makes the largest contribution toannual turnover of the game-ranching industry fol-lowed by live game trade and ecotourism (Van derWaal and Dekker 2000).

In other cases commercial exploitation as a pestcontrol mechanism has been an option. In NewZealand commercial harvesting of red deer for gamemeat and by-products has culled over 2 million deersince 1960 and reduced the national populationfrom over 1 million to a current population size ofca 250 000 deer, a 75 % reduction overall (Parkes etal. 1996).

Venison Sales. In many countries in Africa meatsales from game ranching have been successful forthose communities involved (McRae 1998; Prins etal. 2000). For example in Nigeria over 90% of bothurban and rural Nigerians accept bush meat as foodand game ranching is justified because of rapid re-production, biological efficiency, and adaptation toharsh environments (Akosim et al. 1999).

Prospect for a strong venison market in the nearfuture provides an incentive for many ranchers toenter into exotic game ranching. The marketing

strategy for exotic game venison is aimed at the in-creasing health-consciousness of the general publicand its desire for a low-fat, low-cholesterol alterna-tive to beef (Texas Department of Agriculture 1989).In addition, the currently existing demand for veni-son is being met by venison imported primarily fromNew Zealand. The opportunity for ranchers in Texasto fulfill this current and likely expanding demandis tremendous. Advantages of exotic game venisonover sheep and cattle ranching include: (1) exoticsconvert forage to meat more efficiently; (2) deermature earlier and continue reproducing longer, (3)venison yields a higher proportion of meat/animal;(4) demand currently exceeds world supply; and, (5)deer produce better quality and quantity of meat onland that is less productive for other types of agri-cultural production (Texas Department of Agricul-ture 1989).

Agricultural Tax Exemptions. An advantage toharvesting exotic game animals for venison as op-posed to other economic activities associated withexotic game ranching is qualification for agriculturaltax exemptions. Ranchers who demonstrate thatprimary use of their land is raising exotic animalsfor harvest and commercial sale have their land ap-praised on the basis of its productivity value ratherthan its market value, thereby significantly lower-ing their taxes (State Property Tax Board 1990). Thegoal of tax exemption is to encourage ranchers toraise exotic game for venison and to facilitate thisaspect of the exotic game industry. Thus, ranchersraising exotics for the primary purpose of trophyhunting or the sale of broodstock do not qualify forthis tax exemption.

Trophy Hunting. Many ranchers have built theentire income for their ranch around the practice ofhunting exotic game animals as trophies. Such ranch-ers may not only provide exotic animals to be huntedbut may also provide guides, housing, accommoda-tions, and many other amenities to entice huntersto their property. However, trophy hunting onlyharvests males and leaves the possibility of over-population by remaining females. Highest prices arepaid for largest males with greatest antler spread andmost beautiful coat color. Consequently, ranchersmust bear the financial burden of supporting ani-mals until they reach this age that depends on theirhealth and the health of the rangeland. There is lesslikelihood that the market for trophy hunting ofexotic game animals will approach the market po-


tential of harvesting meat for venison because oflimitation of interested hunters who can afford sucha hunt.

Sale of Broodstock. The market for exotic gamebroodstock is limited in the sense that exotic gameranching in Texas has certain definite boundaries.There are a limited number of areas in the state whereexotic game will survive and reproduce successfully.Many ranchers without their own populations of ex-otic species may turn increasingly toward businessesthat provide broodstock. Finally, there may be anincrease in regulation of sale and transport of exot-ics among ranchers as exotic game becomes moreviable in the economy of Texas that could limit fi-nancial advantages of providing broodstock.

Non-Economic Motivations. Exotic game ranch-ing requires a substantial initial investment of capi-tal by landowners to purchase exotic animals andprepare their property to contain them by installinghigh, deer-proof fences. Landowners would notmake such an investment if it were not going to ben-efit them economically in the long term. Non-eco-nomic motivations, such as aesthetic value andconservation efforts may outweigh other consider-ation for some landowners. A significant propor-tion of ranchers feel that their ranches serve thepurpose, although not necessarily exclusively, ofproviding protection for exotic game threatened intheir native habitat (Texas Parks and Wildlife 1989;Fig. 5). While primary motivating factors for exotic

game ranching may be economic, it is clear that thereare also non-economic motivating factors

Exotic Game Ranching: Pros and Cons

Specific goals of organizations like The Nature Con-servancy with respect to the Texas Hill Country areto: (1) protect and preserve all of the ecosystem’skey elements and functions, (2) recognize and in-corporate the diverse needs of the central Texaspeople, and (3) coordinate the work of numerousgroups and individuals. These goals may be under-stood in a broader context as aims of any conserva-tion organization committed to preservingbiodiversity. The accomplishment of these goals of-ten is viewed as diametrically opposed to manage-ment of natural resources for economic gain.However, this view ignores the fact that theeconomy and ecology of a region may be inextrica-bly linked. The short-term perspective of economicgrowth and the long-term perspective of ecologicalconservation must be merged into an alternative andmore encompassing vision of natural resource man-agement and protection.

There is strong opposition to the introduction ofexotic artiodactyls (Courtnay 1978; Morrison 1988;Dietrich 1989) and a debate as to how to maintainecosystem integrity with the introduction of exotics,Some authors report serious alterations in the habi-tat after the introduction of exotics (Ebenhard 1988),

Fig. 5. Percentage of ranches that participate in different types of ranching activities involving exotic game species inthe Texas Hill Country (source: TPWD, 1989).


but this damage had been observed only in islands orin large continental masses like Australia or NewZealand where plants and animals have been isolatedfor many years and they have not developed defensesagainst large herbivores.

Some authors defend the introduction of exot-ics by using an argument concerning the paleoeco-logical history of prairie ecosystems of NorthAmerica (Mellink 1991). Paleocological historyshows that humans colonized the American conti-nent in the late Pleistocene (11 000 years ago). It isbelieved that as a consequence 70% of the megaher-bivores went extinct (Martin and Klein 1984). Manyecological niches remained empty in American prai-ries, and plant and animal dispersal was modifiedwithout the presence of megaherbivores. The bestexample is mesquite which has no native herbivoreswho consume it. In the last 2000 years these plantsdeveloped a defense against herbivory (Janzen andMartyn 1982). Planned introduction of exotics mayhelp to restore megaherbivores richness and someof the ecological process lost in the Pleistocene(Mellink 1991).

Intensive, hands-on management of ranches mustbe attained for exotic game ranching to be compat-ible with goals of preserving ecological integrity and

encouraging economic growth of the Texas HillCountry ecosystem. Game ranching may be compat-ible with these goals of conservation when (1) ranchescontain poor quality or overgrazed rangeland, (2)economic diversification provides income to ranch-ers, and (3) marketable venison is produced by har-vesting exotic game (sale of broodstock and trophyhunting are less economically viable; see flow-diagrambelow). Such intensive management and formulationof a land-use plan would support conservation goalsbut would require landowners to improve their prop-erty and manage herds of exotic animals. Under theseconditions, exotic game ranching would allow con-servation strategies to be implemented and also wouldencourage an ecologically sensitive, sustainable formof economic growth and development.

In assessing undesirable conditions of exoticgame ranching, it is necessary to perform a conser-vation cost-benefit analysis and to weigh effects ofa particular course of action on both ecology andeconomy of the Texas Hill Country (see flow-chartbelow). The most significant factor that contributesto conditions of exotic game ranching not beingcompatible with conservation goals is a lack of man-agement. Poor or indifferent management produc-es effects that interfere with efforts to preserve

Conditions when exotic game ranching is compatible with conservation goals

Census populations periodically during theyear. Monitor the range quality in terms ofavailability of plant species relative to the di-etary needs. Good knowledge of the dietarypreferences of all herbivores. This monitor-ing would detect signs of competition

Conditions under which exotic gameranching may be compatible with the

goals of conservation

Ability of exotic game animals to utilize lowquality, but generally abundant forage makesthem desirable grazing animals in poor-qual-ity or overgrazed rangeland

Exotic game species provideeconomic diversification. Ex-otic game may be harvested forvenison

Exotic game ranching based on intensive man-agement and the formulation of a specific land-use plan would support the goals ofconservation groups

Domestication of exotic game pro-vides benefits to ranchers and con-servation interests, as well as to theaverage meat consumer. In termsof environmental impact, exoticgame pose a milder threat thancattle

Landowner activities


Conditions when exotic game ranching is not compatible with conservation goals

Conditions under which exotic gameranching may not be compatible withthe goals of conservation

Displacement of native species

Aesthetics; individuals and orga-nizations whose goal is to main-tain the unique ecology of thisregion oppose exotic species

Propose establishing a bioreservein the Texas Hill Country with thepremise that this region hosts aunique native ecology

Possibility to displace native spe-cies, such as native white-taileddeer in Texas Hill Country, that areeither inferior competitors or lowin abundance

Exotics may influence vegetationpatterns of the Texas Hill Coun-try decreasing availability of pre-ferred forage of white-tailed deer(Huston 1981)

Palatable species will be replacedby unpalatable species and the rateof vegetative productivity will de-cline (Pieper 1981)

Introduction of exotic gameanimals poses several poten-tial problems

The establishment of free-ranging populations of ex-otic game animals is a directresult of improper manage-ment

ecological integrity of the region and attempts tocomply with needs of the people will be ineffective.One such effect of poor management is the estab-lishment of free-ranging populations of exotic gameanimals that pose problems associated with over-grazing, deterioration of rangeland, competition,and possible displacement of native species. Con-trol or elimination of free-ranging populations pro-motes conditions of exotic game ranching consistentwith the goals of conservation.

Actions conservation organizations mayemploy

Information Database:

• Establishment of a single source of informationon exotic game ranching is crucial to preserva-tion of the Texas Hill Country ecosystem. Infor-mation would be provided on biology of particularexotic species, ecological conditions to which they

are best adapted, effects of competition and di-etary overlap between exotics, white-tailed deer,and domestic livestock, economic aspects of gameranching, census data on exotics, and long-termconservation-based management techniques.

• An Information Center would provide ranchersinterested in exotic game with the opportunityto educate themselves about different facets ofexotic game ranching before making the neces-sary initial capital investment.

• Contributions from ecologists, range managers,agriculture economists, ranchers, conservationorganization, state agencies, and private citizenswould be crucial.

Consulting Services

• Conservation organizations could provide a con-sulting service for ranchers interested in exoticgame that would assist landowners with specificproblems. This service would work in conjunc-


tion with the Information Database to ensure thatlandowners were aware of different options thatexotic game provide as well as consequences ofexotic game ranching with respect to other ranch-ing activities.

• A comprehensive consulting service would pro-vide landowners with the opportunity to estab-lish specific goals for land use with the assistanceof a diversity of valuable resources.

Promotion of Venison Industry

• To encourage intensive management of exoticanimals, it may be desirable for conservation or-ganizations to form partnerships with key indi-viduals or groups who may be influential inestablishment of the venison industry. Conser-vation groups could form partnerships with pri-vate companies to encourage harvesting practicesbased on sustainable use of land.

• Conservation groups may be a liaison betweenbusinesses and landowners to promote system-atic harvesting of exotic animals for venison andto encourage creation of additional harvesting com-panies as supply of harvestable exotic game grows.

• Conservation groups could work cooperativelywith government agencies to promote consump-tion of venison from exotic game and could play animportant role in marketing of this venison.

Scientific Research

• Lack of scientific knowledge concerning exoticgame species and the effects that their presencemay have on the Texas Hill Country restricts ef-forts to establish widespread protection of thearea to a superficial level. Conservation groupscould initiate further scientific research as well ascollaborate with universities and governmentagencies to establish firm empirical bases uponwhich management decisions may be made.

• Additional data are needed on impact of compe-tition between native and exotic ungulates, im-pact of ungulates upon quality of rangeland andother plants and animals, and direction that veg-etation of the region is developing.

• Models should be constructed to forecast theecological future of the Texas Hill Country basedon current and future patterns of use by land-owners.

Censusing

• Censuses of exotic game populations have beeninadequate to provide comprehensive knowledgeof the number of exotics ungulates in Texas.

• TPWD has conducted some censuses with volun-tary surveys that are sent only to ranches that areknown to have populations of exotic game. Thismethod only detects growth of know exotic gameherds and does not take into account the spreadof free-ranging exotics into new areas.

• Conservation agencies could improve these cen-suses and extend them to lands inadequately cov-ered.

• Reliable population censuses of free-ranging ani-mals are vital to conservation plans because theyare not subject to any form of management orpopulation control.

Economic Models

• Conservation groups could assist in analysis ofeconomics of exotic game ranching through for-mation of economic models based on principlesof ecologically sustainable growth and develop-ment. Will short-term economic benefits of ex-otic game ranching be sustainable?

• Economic analyses would incorporate findingsfrom scientific research and results from currentexotic game ranching ventures. In-depth analy-ses of, for example the venison industry, wouldfacilitate formation of comprehensive, long-termmanagement plans

Education

• Educating and establishing lines of communica-tion between different people involved in exoticgame ranching and in conservation organizationswill be significant. This is, arguably, the most im-portant strategy that agencies may use to achievethe dual goals of preserving the unique ecologyof the Texas Hill Country and supporting eco-nomic growth and development in the area. In-cluding all constituencies in a frequent and opendialogue is critical to achieve conservation goals.

• Such an educational process will be reciprocal andwill provide both conservation groups and ranch-ers with a more thorough understanding of eachother’s goals and rationale.


Parasite control

• Avoid keeping high densities to ensure adequatenutrition.

• Review life cycles of parasites to identify the vul-nerable stage and establish the best treatment.

• Isolate new arrivals in settling pastures before re-lease into the range.

• Check animals frequently to aid early detectionof abnormalities.

• Treatment for internal parasites by providing feedmixed with a vermicide has its best applicationfor animals routinely fed commercial ration andkeep in enclosures separately by species.

• Controlled burning can destroy ticks and reducetheir cover.

Conclusions

• Exotic game ranching provides conservation or-ganizations with the opportunity to demonstratethe ability of conservation principles to meetneeds of both the biological and human compo-nents of an ecosystem.

• Identification of conditions under which exoticgame ranching may or may not be compatible withconservation goals will help concentrate efforts onproviding support for the more positive aspects ofexotic game ranching in the Texas Hill Country.

• Establishment of a positive relationship betweenexotic game ranchers in the area and increaseddialogue between conservation groups and land-owners will facilitate cooperation between con-servation and economic interests.

• A well planed management of exotics could con-tribute to reestablishing the richness of megaher-bivores and ecological process of the Pleistocenebefore human colonization of the American con-tinent.

Acknowledgments

We thank L. Carver and N. Farmer for guidance ofKDC in the Humanities Honors Program, Univer-sity of Texas, and C. Pease, University of Texas, andT. Cook, The Nature Conservancy, for advise onKDC’s Senior Honors Thesis. We also thank review-ers for suggestions to improve this manuscript. KDCwas supported by a University of Texas PresidentialScholarship.

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Ann

ex 1

. Bio

logi

cal c

hara

cter

isti

cs o

f exo

tic

ungu

late

s in

Tex

as (

Ran

sey

1969

; But

ts e

t al.

1982

).

Phys

ical

Bri

ght

redd

ish-

tan

coat

wit

hw

hite

spot

s in

roug

hly

long

itu-

dina

l row

s, a

dark

dor

sal s

trip

e,un

derp

arts

, in

nerl

egs

and

unde

rtai

l ar

e w

hite

. The

ave

r-ag

e w

eigh

t fo

r a

mal

e 17

5po

unds

, fo

r a

fem

ale

120

poun

ds.

Man

y co

lor

vari

atio

ns,

the

mos

t co

mm

on c

oat

colo

rs a

rebl

ack,

whi

te a

lbin

o, a

nd t

hety

pica

l fal

low

with

spot

s in

the

sum

mer

and

a u

nifo

rm g

reyi

shbr

own.

Wei

ght:

150

pou

nds

mal

e an

d 10

0 po

unds

fem

ale.

The

re ar

e se

vera

l rac

es in

Tex

as.

Japa

nese

sik

a th

e m

ost

com

-m

on, h

as a

brow

nish

-oliv

e w

in-

ter f

ur. T

he ru

mp

patc

h is

whi

tesh

arpl

y bo

rder

ed b

y bl

ack.

Fe-

mal

e ar

e us

ually

ligh

ter c

olor

edth

an th

e m

ales

.

Hab

itat

Ope

n co

untr

y at

low

ele

va-

tion

s in

fore

sted

reg

ion.

Of-

ten

asso

ciat

ed w

ith

mix

edde

cidu

ous

fore

st. T

he n

ativ

eha

bita

t in

Ind

ia i

s an

ope

nde

cidu

ous

fore

st w

ith g

rade

sin

to

thor

n sc

rub.

T

heir

mov

emen

ts ar

e in

fluen

ced

byte

mpe

ratu

re, f

ood

and

wat

erav

aila

blity

Pla

ins,

non

-mou

ntai

ns o

rhi

lly co

untr

y w

ith d

ense

gra

ssco

ves,

spar

se w

oods

or b

ushy

area

s. In

Tex

as th

ey ar

e fo

und

in w

oodl

ands

, sc

rubl

ands

,an

d sa

vann

a ha

bita

ts.

Bel

t of

bro

ad-l

eafe

d an

dm

ixed

for

est

wit

h m

oder

ate

win

ters

sou

th o

f the

trop

ical

zone

, ex

clud

ing

the

coni

fe-

rous

for

est

of t

he n

orth

ern

type

with

dee

p sn

ow c

over

.

Soci

al

Mat

riar

chal

fa

mil

ygr

oup

Gre

gari

ous.

Sm

all h

erds

fem

ales

w

ith

thei

ryo

ung.

Mal

es s

epar

ate

grou

ps.

Join

wit

h fe

mal

es i

nm

atin

g se

ason

.

Gre

gari

ous

and

herd

sco

nsis

t of d

ozen

s of a

ni-

mal

s at

cer

tain

per

iods

.In

win

ter

they

dis

pers

eth

roug

hout

the

fore

st in

smal

l fam

ily g

roup

s an

din

spri

ng th

ey m

ove

into

the

gras

s op

en a

rea.

Soci

al

Rep

rodu

ctio

n

1 fa

wn

per b

reed

ing

atte

mpt

.B

reed

ing

seas

on M

ay to

Au-

gust

.G

esta

tion

: 7.5

mon

ths

Mon

oest

rous

, mat

ing

seas

onO

ctob

er-N

ovem

ber,

faw

ning

seas

on Ju

ne-J

uly.

Ges

tati

on,

230

days

.

Poly

estr

ous

fem

ale,

a s

ingl

efa

wn.

Bre

edin

g pe

riod

: Sep

tem

ber-

Nov

embe

r, f

awin

g pe

riod

May

-Jun

e. G

esta

tion

: 22

0da

ys

Die

t

Bro

wse

r.In

a p

astu

re w

itho

ut g

razi

ngpr

essu

re:

gras

s, f

orbs

and

brow

se in

equ

al a

mou

nts.

Hea

vily

gra

zed

past

ure:

larg

eam

ount

s of

gra

ss.

42%

bro

wse

, 28

% f

orbs

and

29 %

gra

ss (K

err W

ild. M

anag

.A

rea

1982

)

Bro

wse

rs,

they

eat

gra

ss i

nsu

mm

er, c

hest

nuts

in th

e fa

ll,yo

ung

shoo

ts,

drie

d le

aves

,m

osse

s and

lich

ens i

n th

e w

in-

ter.

53%

bro

wse

, 39%

gra

ss, 5

%fo

rbs

and

3 %

oth

ers

(Ker

rW

ild. M

anag

198

2)

Bro

wse

rs,

in s

umm

er t

hey

pref

er g

rass

-lik

e pl

ants

as w

ell

as le

aves

and

sm

all s

hoot

s of

tree

s and

bus

hes.

52%

bro

wse

,37

% g

rass

es 1

2 %

forb

s (K

err

Wild

. Man

ag 1

982)

Axi

s de

er

Fallo

w d

eer

Sika

dee

r

Ori

gin

Indi

a

Med

iter

rane

an,

Sout

hern

Eur

ope

and

Asi

a M

inor

Sout

hern

hal

f of

east

ern

Asi

a


Ann

ex 1

. Bio

logi

cal c

hara

cter

isti

cs o

f exo

tic

ungu

late

s in

Tex

as (

Ran

sey

1969

; But

ts e

t al.

1982

) (C

onti

nue)

Bla

ckbu

ckan

telo

pe

Aou

dad

shee

p

Ori

gin

Indi

a

Nor

ther

n A

fric

afr

om th

e A

tlant

icco

ast o

f the

Red

Sea

and

sout

h to

the

Suda

n an

d th

eno

rth

bend

of t

heN

iger

Riv

er.

Phys

ical

Wei

ght:

mal

e, 8

0-90

pou

nds

and

fem

ales

70-

80 p

ound

s.M

atur

e m

ales

hav

e a

blac

k co

atco

lor,

fem

ales

and

youn

g m

ales

have

a o

rang

e ta

n co

lor

, A

llha

ve a

sha

rply

def

ined

whi

tepa

tch

arou

nd e

ach

eye.

Aou

dad

shee

p ar

e taw

ny b

row

nw

ith

dark

bro

wn

area

s ar

ound

the

head

and

for

equa

rter

s.M

ales

and

fem

ales

ret

ain

the

sam

e co

at c

olor

atio

n ye

arar

ound

.W

eigh

t: m

ales

300

pou

nds

and

fem

ale

150

poun

ds.

In I

ndia

the

y en

com

pass

esth

e no

rthe

rn,

cent

ral,

and

sout

hern

pla

ins

and

open

woo

dlan

ds.

Wel

l ad

apte

d to

plai

ns a

reas

, m

ay a

lso

befo

und

in a

reas

tha

t ar

e re

la-

tive

ly d

ry,

flat

, an

d ha

ve a

nop

en c

anop

y. I

n Te

xas,

the

maj

ority

of t

he b

lack

buck

an-

telo

pe i

nhab

it t

he E

dwar

dsPl

atea

u re

gion

.

It is

foun

d in

des

ert a

nd se

mi-

dese

rt r

egio

ns,

pref

erri

ngro

ugh

and

rock

y te

rrai

n.

Hab

itat

Soci

al

Gre

gari

ous,

Mal

es a

ndFe

mal

es m

ay b

e tog

ethe

rin

mix

ed g

roup

s, p

seud

oha

rem

s or

in

sepa

rate

sing

le-s

ex g

roup

s or

som

e m

ay b

e so

litar

y.

Gre

gari

ous,

usu

ally

liv

ein

sm

all

fam

ily g

roup

sco

nsis

ting

of

an a

dult

mal

e an

d fe

mal

e w

ith

thei

r of

fspr

ing.

Rep

rodu

ctio

n

Giv

e bi

rth

to a

sin

gle

faw

naf

ter

a ge

stat

ion

of

5m

onth

s, an

d th

e in

terv

al b

e-tw

een

faw

ns i

s ge

nera

lly 6

mon

ths.

Fem

ales

giv

e bir

th to

a si

ngle

lam

b. T

he g

esta

tion

per

iod

is a

bout

154

-161

day

s.

Die

t

Gra

zers

, m

ore

succ

ulen

tgr

owth

and

shor

t-m

id g

rass

esas

wel

l as

mor

e xe

roph

ytic

brow

se p

lant

s, s

uch

as A

caci

asp

. In

Texa

s th

ey a

re g

raze

rsan

d on

ly i

n su

mm

er d

oes

brow

se c

onsu

mpt

ion

equa

l or

surp

ass

that

of g

rass

.

Gra

zers

, gra

ss m

ade

up a

sub-

stan

tial

por

tion

of t

he a

ouda

dsh

eep

diet

thr

ough

out

the

year

. Con

sum

ptio

n of

bro

wse

spec

ies

was

inv

erse

ly r

elat

edto

the

ava

ilabi

lity

of h

erba

-ce

ous f

orag

e an

d se

emed

to b

ea

lees

pre

ferr

ed f

orag

e cl

ass

(Ker

r W

ild. M

anag

198

2).


Ann

ex 2

. Bio

logy

of W

hite

-Tai

led

Dee

r an

d di

et o

f dom

esti

c liv

esto

ck

Whi

te-t

aile

dde

er

Cat

tle

Shee

p

Goa

ts

Ori

gin

Nat

ive

toA

mer

ica

Phys

ical

The

sum

mer

coa

t is

a r

eddi

shbr

own

wit

h a

whi

te p

atch

on

the t

hroa

t, in

side

the e

ar, o

n th

est

omac

h, in

side

thig

hs, a

nd o

nth

e un

ders

ide

of t

he t

ail.

Inw

inte

r the

coa

t is g

ray

or g

ray-

ish

brow

n.

Hab

itat

Are

a re

lati

vely

ope

n. I

n pa

r-tic

ular

“ed

ges’

’ whe

re th

ere

isan

abu

ndan

ce o

f ne

w p

lant

grow

th. O

n th

e E

dwar

ds P

la-

teau

it

is i

n re

lati

vely

ope

n,w

oodl

and-

sava

nna v

eget

atio

nw

here

bro

wse

spe

cies

are

com

mon

.

Soci

al

Gre

gari

ous

and

from

mat

riar

chal

fa

mil

ygr

oups

. Dur

ing

faw

ning

the

adul

t sep

arat

e th

em-

selv

es f

rom

the

gro

upan

d m

ove

alon

e to

giv

ebi

rth.

A

dult

m

ales

grou

ps o

f 2-

4 in

divi

du-

als

from

Feb

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Documents

21. CONSERVATION IMPLICATIONS OF EXOTIC …. CONSERVATION IMPLICATIONS OF EXOTIC GAME RANCHING IN THE TEXAS HILL COUNTRY EDMUNDO HUERTA-PATRICIO1, KARYN. D. CAMERON2†, GUY N. CAMERON2,