SOUTH TEXAS WILDLIFE

J. R. THOMASSON A publication of the Caesar Kleberg Wildlife Research Institute Fall 2006 at Texas A&M University-Kingsville Volume 10, No. 3

reduced search and handling times for the bobcat. The former Director of the CKWRI, Dr. Sam Beasom, headed research in the early 1970s that stud- ied bobcat diets in southern Texas. He examined 51 bobcat stomachs during a dry year (1971), and com- pared the findings to 74 stomachs from a wet year (1972). During the dry year, bobcats consumed 21 prey species. Although cotton rats and rabbits were not commonly observed in the wild in 1971, they still were the dominant prey accounting for 38% and 18% by volume in bobcat stomachs, respectively. In 1972, fol- lowing rainfall that enhanced habitat conditions, over 100 cotton rats per mile were observed several times. Because of the abundance of cotton © Tom Urban rats and rabbits following rainfall, bobcat diet contained these 2 species Bobcats and Drought enough, then cascading effects almost exclusively. This was appar- eventually impact bobcats through ent when comparisons by percent by Michael Tewes and reduction of their prey base as fewer occurrence in the bobcat diet were Lon Grassman, Jr. rodents and rabbits occur. In Texas, the hispid cotton rat This Issue Drought conditions can have and eastern cottontail are important severe consequences on wildlife in bobcat diets. They are large-size South Texas Bobcats page 1 in Texas. We often hear of dismal prey, relative to the other potential By The Numbers page 2 harvest predictions for deer and prey, with rabbits weighing 2–4 quail following extended dry peri- lbs and cotton rats about 9 oz. In CKWRI News page 2 ods. Many other wildlife can be addition, both prey can irrupt with Did You Know? page 3 severely affected by drought condi- high densities during normal or wet tions as well. If the drought is severe periods. Attributes of large prey Landscape Management page 3 Editor’s Note: Dr. Tewes is a research scientist at size and periodic high abundance What Do They Eat? page 4 CKWRI, directing the Feline Research Program, and make these food items a profitable professor at Texas A&M University-Kingsville. Dr. Advisory Board page 4 Grassman, Jr. is a research scientist at CKWRI. prey with high energy content and  made long extraterritorial forays, Lost and Found presumably in search of prey. This pattern also was observed in south- We are looking for past students ern Texas, as bobcats demonstrated and faculty of CKWRI. If you know where a past CKWRI family member increased dispersal during periods of can be located, please forward their low prey abundance. information to Lori Alvarez at 361- Bobcat pregnancy rates and litter 593-4025 or e-mail us at CKWRI@ sizes seem to be affected by low prey tamuk.edu. density. Drought-induced declines in and a decrease in survival. Most of prey availability reduced pregnancy these effects are related to reduced rates of bobcats in Oklahoma. In prey and quality of habitat used by southern Texas, Blankenship found bobcats. Although the bobcat is that the number of litters and kittens adaptable, the scourge of drought decreased as prey declined, and no can still affect this wild cat. ~ female bobcats were observed rais- © Tom Urban ing kittens on the study site during 3 made which indicated that these years of low prey abundance. CKWRI NEWS 2 prey species solely comprised Prey abundance strongly 93% of the bobcat stomachs during affects survival of bobcat kittens. New Book to be Published the wet year, but only 33% during During periods of scarce prey, adult the dry year. Bobcats apparently females are believed to feed them- Dr. Lenny Brennan, Endowed responded to a change in prey avail- selves before feeding their kittens. Chair of the Richard M. Kleberg, ability by concentrating their hunting ­Blankenship found a 94% survival Jr. Center for Quail Research at efforts on cotton rats and rabbits rate of bobcats during high prey CKWRI, has put the finishing when these prey were abundant abundance and 44% during low prey touches on the soon to be released during the wet year. This informa- abundance. Lower bobcat survival book Texas Quails: Ecology and tion suggests that when cotton rats may vary with social class, with Management. Lenny served as and rabbits are scarce, bobcats shift transient bobcats experiencing lower editor and chapter contributor of to other food resources. survival than resident bobcats. this seminal work. The book is We have found that drought can Three tagged adult bobcats in divided into 3 sections: Ecology and reduce prey abundance, which in turn Idaho that starved to death during a Life History of Texas Quails; Quail can affect bobcat diet, home range period of low prey had body weights Populations in the Ecoregions of and habitat use, health, reproduction, 64–69% lower than their previous Texas–Management Opportunities and survival. At the Rob and Bessie capture weights. In Texas, Blanken- and Research Challenges; and Cul- Welder Wildlife Refuge in southern ship observed 2 bobcats that starved ture, Heritage and Future of Texas Texas, Dr. Terry Blankenship found during periods of low prey and found Quails. In the forward, Katharine bobcats increased their home range a bobcat in poor condition that was Armstrong, former Chair of Texas size about 100% during low prey probably killed by coyotes. Parks and Wildlife Commission, abundance. Also, bobcats increased In summary, bobcats are affected wrote that “Anyone with an interest their use of grasslands and water by drought in various ways, includ- in Texas quails—hunter, landowner, sources because alternate prey spe- ing a switch in diet to less preferable manager, researcher, or biologist— cies (e.g., wading birds, waterfowl) prey, expansion of their territories, should have a copy of this book.” occurred in these areas. a reduction in reproduction effort, The book, published by Texas A&M Following a prey decline in Press, will be available in February Idaho, researchers found some bob- Consider giving a tax-deductible 2007 from them or commercial out- donation to CKWRI cats expanded their home range and lets. Preprint orders can be made at www.tamu.edu/upress. By The Numbers

32 number of species of bats found in Texas South Texas Natives Receives New Tractor 5 height in feet of the whooping crane (Grus americana) It has been said that “diamonds 125,000 estimated number of hatchlings of Kemps’ Ridley sea turtle are a girl’s best friend,” but earlier produced in North America (TPWD fact sheet) this fall a shiny new orange tractor  Did You Know? Predators of the roseate spoonbill are primarily coyotes and raccoons, which feast on the eggs and young birds unable to fly. The last gray wolves reported in Texas were in 1970 from Brewster County. (The Mammals of Texas, Davis and Schmidly)

migratory bird species. Additionally, uses during the 1970s. However, it provides habitat for about one-half researchers at CKWRI have devel- of all butterfly species found in the oped brush management plans for United States. A diverse rodent com- white-tailed deer in southern Texas The new South Texas Natives tractor being used to harvest sideoats grama. munity also occurs in the thornshrub, emphasizing the importance of thus providing prey resources for maintaining dense thornshrub cover. numerous predators. Furthermore, These brush management plans was Paula Maywald’s diamond. state and federally-listed threatened delineate a landscape consisting of Paula, who is the director of South and endangered wildlife species a habitat mosaic of interconnected Texas Natives, was happy to see reside within the thornshrub habitat brush habitat blocks interspersed the new tractor gifted to South of southern Texas. For example, with small clearings, which improve Texas Natives by the Stone Brothers researchers at CKWRI have found white-tailed deer habitat. This type (Stormy & Reagan Stone). It is a the ferruginous pygmy-owl in areas of landscape brush management 70-hp Kubota tractor with a front- of mesquite-thicket thornshrub habi- plan would also benefit numerous end loader attachment for mounting tat with large-diameter trees. wildlife species by providing a het- an 8-ft. flail-vac for harvesting seed. Southern Texas is also renowned erogeneous landscape incorporating South Texas Natives would have for trophy white-tailed deer and bob- thornshrub cover. Openings in the been unable to harvest seed from white quail. Large tracts of habitat habitat provide feeding areas for production fields without this trac- are retained by private landowners bobwhites and white-tailed deer. tor, thereby delaying the release of for the management of these game Openings also provide nesting sites several species of grasses for com- species. Dense thornshrub cover for the numerous ground-nesting mercial production. ~ provides white-tailed deer, bob- birds that occur in the region. whites, Rio Grande wild turkeys, and Substantial areas of dense mature other game species shade during the thornshrub left undisturbed will pro- hot summer and insulation from heat vide habitat for ocelots, ferruginous Landscape Management for loss during winter. South Texas Wildlife The dense thorn- shrub also pro- by Aaron M. Haines, vides protection Aaron D. Tjelmeland, and from predators. Timothy E. Fulbright Unfortunately, the Tamaulipan The South Texas region is home thornshrub in to a unique ecosystem known as the southern Texas Tamaulipan thornshrub. This eco- (especially along system contributes to a unique vari- the Rio Grande ety of habitats that support a wide River) is consid- diversity of animal life. It is used ered an endan- by nearly 400 types of breeding or gered ecosystem. This is in large part Editor’s Note: Dr. Haines is a former student at due to over 90% CKWRI and is currently a postdoctoral research scientist at the Center for Research on Invasive of thornshrub hab- Species and Small Populations at the University itat within south- © Timothy Fulbright of Idaho. Mr. Tjelmeland is a graduate student at CKWRI and Texas A&M University-Kingsville ern Texas being studying under the direction of Dr. Fulbright. Dr. cleared for urban Creating a mosaic of interconnected brush habitat blocks Fulbright is a research scientist at CKWRI and interspersed with open clearings is necessary for a successful professor at Texas A&M University-Kingsville. and agricultural landscape brush management strategy in southern Texas.  Advisory Board The Advisory Board of the Caesar Kleberg Wildlife Research Institute provides leadership in all aspects of our work. We are indebted to them for their com- mitment to CKWRI and its mission. T. Dan Friedkin A. C. Jones, IV Diane Scovell David Garza Lagüera David Winfield Killam Stuart W. Stedman Henry R. Hamman Stephen J. “Tio” Kleberg Arthur “Buddy” Temple, III George C. “Tim” Hixon Kenneth E. Leonard (Chairman) Karen Hunke James A. McAllen Ben F. Vaughan, III Barry Coates Roberts

between tracts of thornshrub will an increase in wildlife aesthetics allow the interchange of individu- and wildlife values (i.e., hunting, als among populations, which may nature photography, and ecotour- facilitate genetic diversity. ism opportunities) to the landowner. The protection and restoration In addition, government incentive of dense thornshrub habitat with a agreements provided by the Farm landscape brush management plan Bill, conservation easements, and An aerial view showing a landscape brush management system (Los Ebanos requires participation from local pri- safe harbor agreements may offer Biological Research Station and private vate landowners, because important further benefits that encourage land- cattle ranch). tracts of potential and existing dense owners to preserve, maintain, and thornshrub cover are privately owned expand thornshrub habitat. pygmy-owls, migratory and breeding within southern Texas. Thus, the University researchers and fed- birds, butterflies, and rodents, while benefits of establishing a landscape eral and state biologists and wildlife simultaneously providing escape and brush management plan should be managers can work with private thermal cover for game species. In promoted to private landowners. landowners to develop landscape addition, brush-dominated corridors Ultimately, the benefits will include brush management plans for the benefit of wildlife. This can be done What Do They Eat? effectively if landowners are aware The swift (kit) fox eats a wide range of prey including small of the benefits of thornshrub cover mammals, birds, reptiles, amphibians, and insects, and will also to the unique and diverse wildlife consume seeds and other vegetative material. found in the Tamaulipan thornshrub ­ecosystem. ~ The northern harrier eats a wide range of prey items, including small Visit our web page at rodents and mammals, birds, amphibians, and reptiles. http://www.ckwri.tamuk.edu

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Editor: Alan Fedynich, Ph.D.

SOUTH TEXAS WILDLIFE is printed on recycled paper