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The Mexican free-tailed bat (Tadarida brasiliensis) is one of the most widely distributed bat species in the Western Hemisphere. Despite their prevalence in urban environments, limited research has been conducted to determine the features of buildings or of the surroundings that might affect the likelihood of a building being selected by Mexican free-tailed bats as a roost. Our study objectives were to improve the current understanding of Mexican free-tailed bat's urban roosting preferences with regard to both microhabitat and macrohabitat. Between August 2010 and August 2012, we conducted acoustic surveys and emergence observations and examined 218 buildings in Waco, TX, USA. A total of 54 day-roosts for Mexican free-tailed bats was identified. At the microhabitat scale, modeling of building characteristics and opening characteristics showed that bats preferred to roost in tall and abandoned buildings. Roost exits were more likely the results of structural damage to buildings and less likely to have vege...

We measured habitat associations in the rodent fauna at the Lyndon B. Johnson National Grassland in north-central Texas from May to August 2011. We recorded five species: hispid cotton rat (Sigmodon hispidus) was most abundant, followed by deer mouse (Peromyscus maniculatus), hispid pocket mouse (Chaetodipus hispidus), fulvous harvest mouse (Reithrodontomys fulvescens), and white-footed mouse (P. leucopus). Cotton rat density increased with grass cover; this effect was stronger for lower and middle quantiles of the abundance distribution. We found weak habitat correlates for P. maniculatus and R. fulvescens. This report is one of few describing the mammalian fauna of the vanishing Grand Prairie ecoregion.

Forests of eastern Texas represent the westernmost extent of the southern pine forests and part of the pine belt of the forested Gulf coastal plain. Bat community assemblages in similar forests throughout southeastern United States have been documented in various studies, but only scant data are available for Texas. The purpose of this study was to characterize the assemblage and investigate reproductive patterns of the summer bat community in the austroriparian forest of eastern Texas. Using mist nets, we captured bats during summers 2009–2011 and recorded species, gender, age and reproductive condition. We captured 382 bats of eight species: Seminole Lasiurus seminolus (n = 163), evening Nycticeius humeralis (n = 86), big brown Eptesicus fuscus (n = 57), eastern red Lasiurus borealis (n = 31), southeastern myotis Myotis austroriparius (n = 21), tri-colored Perimyotis subflavus (n = 19), Mexican free-tailed Tadarida brasiliensis (n = 4), and hoary Lasiurus cinereus (n = 1) bats. Analysis of reproductive data suggests that three of these species (big brown, evening, and Seminole bats) may be following a reproductive strategy—extended seasonal monoestry (births of single litters spanning a particular season)—different than their previously reported pattern of synchronous monoestry.

Characteristics of edges affect the behavior of species that are active in and near edges. Forest canopies may provide edge-like habitat for bats, though bat response to edge orientation has not been well examined. We sampled bat activity in quaking aspen ( Populus tremuloides Michx.) forest canopies and edges in Heber Valley, Utah, during summer 2009 using Anabat detectors. Categorization and regression tree (CART) analysis of echolocation characteristics (e.g., frequency, duration) identified two guilds based on characteristic frequency (i.e., high- and low-frequency guilds). We used linear regression to compare characteristics of canopy and edge vegetation (e.g., tree height, diameter at breast height) to bat activity levels. Activity levels of high-frequency bats did not respond differentially to edge vegetation; low-frequency bat activity seemed to respond to canopy height. Activity levels of high-frequency bats were significantly greater than low-frequency bats in both edges and canopies. We detected significantly more bat activity in forest edges than in forest canopies, indicating the importance of edges to bats in forests.

Les captures multiples de petits mammiferes (de >1 animal dans un meme piege) amenent souvent a conclure a une activite de formation de couple chez les rongeurs arvicolines et cricetines. Nous analysons les donnees d'une etude de piegeage de 2 ans afin de determiner si les especes, les souris des moissons fauves (Reithrodontomys fulvescens J.A. Allen, 1894) et(ou) les souris pygmees du Nord (Baiomys taylori (Thomas, 1887)), se deplacent en paires accouplees des deux sexes. Une majorite significative des evenements de captures multiples (MCE) chez R. fulvescens comprenait les deux sexes, alors que la composition des sexes des paires chez B. taylori ne differait pas d'une composition aleatoire. La probabilite des captures multiples est en relation positive significative avec l'abondance, mais non avec le rapport des sexes chez les deux especes. Les captures multiples de B. taylori sont plus nombreuses en hiver, ce qui peut indiquer que les animaux peuvent s'associer afin de se blottir l'un contre l'autre pour se rechauffer. Les masses des individus captures seuls et en groupe ne different pas significativement chez les deux especes, ce qui indique l'absence de biais dans les pieges. Une seule paire de sexes differents prise en couple (R. fulvescens) a ete capturee de nouveau en couple et plusieurs animaux des deux sexes et des deux especes ont ete captures en compagnie de plusieurs autres individus. Nous concluons que les R. fulvescens se deplacent en compagnie de partenaires pour des periodes variables; en revanche, nous ne trouvons aucune indication que les captures multiples de B. taylori soient reliees au comportement reproducteur.

This study investigated effects of a prescribed burn on the small mammal community and vegetative cover in a tallgrass prairie remnant in east central Texas. Small mammals were live-trapped 8 mo before and 8 mo after a prescribed burn. Vegetation sampling confirmed drastic reduction of cover after fire in the grassland sections of the prairie. Relative abundances (captures/100 trapnights) of pygmy mice (Baiomys taylori) and cotton rats (Sigmodon hispidus) significantly decreased after the fire, whereas deer mice (Peromyscus maniculatus) significantly increased following fire. Cotton rat and pygmy mouse abundances were positively correlated with grassy litter and negatively correlated with bare ground, whereas deer mouse abundance was positively correlated with bare ground. Relative abundances of B. taylori, S. hispidus and P. maniculatus in burned sections returned to preburn levels in 8 mo. Hispid pocket mice (Chaetodipus hispidus) were not captured until after the prescribed burn. This is the f...

The range of the northern pygmy mouse (Baiomys taylori) continues to expand through Texas and into adjacent states. We report a new record for B. taylori in Hunt County, near its poorly understood northeastern limit in Texas. This record, together with results from other recent surveys, suggests that the northern pygmy mouse might only now be realizing the extent of range projected in the literature >25 years ago.

We studied 7 urban roosts occupied by Mexican free-tailed bats (Tadarida brasiliensis) in downtown Waco, Texas, from August 2001 to September 2002. We examined frequency of roost use, colony sizes, and roost fidelity in relation to gender. Use of roosts and colony sizes were highest in the fall and lowest in the winter, but fluctuated widely during the study. These roosts were not used by maternity colonies, and patterns of occupancy suggested that they served as stopover sites during migratory seasons. Individual bats exhibited high fidelity to discrete roosts included in the study. However, the bats commonly left the study area, suggesting that populations are defined at greater spatial scales than we included in this study. Male bats were recaptured more often and spent more days in the study area than female bats, suggesting a sexual difference in roosting behavior.

Burrow systems of 43 individuals representing 7 species of pocket gophers (Geomyidae) in Texas (Geomys breviceps, G. bursarius, G. personatus, G. texensis, Thomomys bottae) and Jalisco, Mexico (Cratogeomys fumosus, Pappogeomys bulleri) were excavated, measured, described, and compared. All burrow systems consisted of a main tunnel with several to many side branches. Burrow systems of most species included chambers serving as nest sites, food caches, and latrines. Vertically oriented spiral tunnels are reported for the first time for G. breviceps, G. texensis, and C. fumosus. Regression analyses revealed that mean tunnel depths and diameters varied significantly by species in direct relation to body size. Mean length of tunnel systems varied significantly by species (longest in G. breviceps and shortest in T. bottae), but variation was not correlated with body size.

The 11 species of pocket gophers (Geomys bursarius, G. personatus, G. pine tis G. texensis, Thomomys bottae, T. bulbivorus, T. talpoides, Pappogeomys bulleri, P. castanops, Crato­ geomys tylorhinus, Orthogeomys heterodus) that we examined exhibit a distinctive suite of auditory characters: otic capsule of thick trabecular bone, a bone-encased stapedial artery having a very narrow lumen (except in P. bulleri), absence of the stapedius muscle, and most notably a stapes with a highly convex hollow footplate that protrudes into the vestibule of the inner ear. Qualitatively, all species of pocket gophers that we examined were similar. Quantitatively, there was little intraspecific variation in meristic features with regard to sex, but ontogenetic variation was significant with most features increasing in size with increas­ ing skull dimensions. Interspecifically, measured auditory features scaled positively with condylobasal length. For most functional auditory features (e.g., areal ratios, lever-arm ratios), intraspecific (sex or age) and interspecific variations were insignificant. The peculiar morphology of geomyid ears might serve a protective function in the noisy subterranean setting. Alternatively, novel features of the geomyid ear simply might be the result of heterochrony. Hyrtl's (1845) treatise on auditory mor­ phology in an array of mammalian species constituted the first report of a stapedial footplate possessing an unusual bullate form. In this configuration, the footplate, rather than being fiat, bulges convexly far into the vestibule of the inner ear. Hyrtl (1845) reported this morphology for the ring-tailed possum Phalangista cookii (= Pseudocheirus peregrinus; Petauridae), a scansorial arboreal marsupial (Nowak and Paradiso, 1983). Subsequent anatomical in­ vestigations revealed the highly convex sta­ pedial footplate in only two other families of mammals, Geomyidae and Heteromyi­ dae. Geomyids are highly fossorial herbiv­ orous rodents occurring in North and Cen

D. J. Schmidly 2002. Texas Natural History: A Century of Change. Texas Tech University Press, Lubbock, xv + 534 pp. ISBN 0-89672-469-7, price (hardcover), $39.95. About 3 decades ago, the Texas state tourism bureau promoted the state as a “land of contrasts.” A visitor to Texas could experience a wide range of landscapes, all within the borders of just 1 state. The tourism bureau, however, was not the 1st to recognize the vast ecological diversity of Texas. C. Hart Merriam perceived this richness late in the 19th century and chose Texas as 1 of the states where the United States Bureau of Biological Survey could conduct such a survey (Bailey 1905). The introductory chapter of Schmidly's book is of as much interest to a biological historian as to a mammalogist. This historical account was developed from exhaustive search and study of records housed in the Library of Congress, National Archives, National Museum of Natural History, and Philadelphia Academy of Natural Sciences. Chapter 1 begins with a brief account of the formation of the U.S. Biological Survey, focusing on the career of its founder (Merriam) before addressing the Texas survey. From 1889 through 1906, a dozen “survey contributors” invested 2,185 “man days” of field effort; of these, the best known to mammalogists were Vernon Bailey, Ned Hollister, and A. H. Howell. More than 20 black and white photographs show many expedition participants in portrait, field, and museum settings. Additional photographs depict habitat and “typical night's captures” of small mammals. Louis Agassiz Fuertes, famed biological illustrator, produced a portfolio of mammal sketches from Trans-Pecos Texas; several of these are reproduced in Chapter 2. Excerpts from conespondence and field journals offer insight into activities of and field conditions experienced by field investigators. The important role of local naturalists and of farmers, ranchers, and woodsmen in this effort is acknowledged and described. Schmidly briefly describes life zones, biotic provinces, and ecological regions of Texas and plots the localities …

Cranial morphology and dental features (orientation of enamel bands and of tooth scars) were examined in osteological specimens of four species of Ctenomys ( C. magellanicus, C. maulinus, C. mendocinus , and C. opimus ) with the objective of understanding possible relationships between skull morphology, chewing direction, and subterranean lifestyle. Similarity of skull shape suggested that the four species studied chew in the same direction. Orientation of tooth scars and of enamel bands on the upper cheek teeth predicted an oblique angle of chewing, ca. −55 to −60°. In comparison to pocket gophers, the broadest-skulled Ctenomys are about as narrow as the narrowest-skulled geomyids. We suggest that broad skulls are not requisite for a fossorial lifestyle. Rather, skull morphology in subterranean rodents might be related to reception of substrate-borne vibrations.

Geographic distribution and variation were examined in cranial and dental morphology of Geomys personatus in coastal southern Texas and Tamaulipas, Mexico. Unsuitable soils, waterways and a composite of physiographic features were used as criteria for dividing the samples for analysis. Geomys personatus appears to be restricted to fine sands, loamy fine sands, fine sandy loams and sandy loams. The history of coastal processes in the region suggests widespread distribution of G. personatus across a broad sandy plain exposed during lower sea levels of the late Wisconsinan glaciation. Subsequent rise of sea level at the end of this glaciation flooded the river valleys, forming present-day bays and leading to the disjunct distribution seen at present. Patterns of geographic variation, interpreted with reference to the geological history of the area and to modern distribution of soils, generally do not correspond with locations of physiographic features, including waterways that prob- ably now serve as isolating features. Rather, morphological variation corresponds better with soils composition without regard to geographic location.

There is an extensive Pleistocene record, from early Irvingtonian to present, of pocket gophers (genus Geomys) in Florida. Evolutionary trends include the widening of lower cheekteeth and the expansion of the retromolar fossa; these changes resulted in progressively more efficient mastication. Other trends in dental characters include the loss of enamel from the posterior face of P4 and a change in the occlusal shape of M3 from elongate and bilophate to subtriangular. Mandibular and dental features distinguish early and middle Irvingtonian samples from late Irvingtonian to modern samples, which are referred to the extant Geomys pinetis. The new species may be diagnosed both quantitatively from mandibular characters and qualitatively from characters of the upper dentition.

Pocket gophers of the tribe Geomyini are subdivided into three groups according to cranial morphology. Merriam (1895) stated that the mode of mastication corresponds to gross skull shape, with generalized and dolichocephalic forms chewing propalinally and platycephalic forms chewing obliquely. To test these conclusions, we examined different dental and cranial features from those used by Merriam in examples of the three skull types. Dental evidence (tooth scar orientation and alignment of teeth and enamel blades) indicates that propalinal chewing characterizes all three skull types; this conclusion is contrary to that inferred from differences in cranial morphology. We suggest that discordance of these two lines of evidence reflects the dual role in pocket gophers of masticatory and fossorial adaptations in determining the shape of the skull.

The roost environment is a factor determining the survival and mortality rates in newborn bats. We compared mortality in two species of bats that shared a common roost but that differed in developmental strategies. The precocial species, Tadarida brasiliensis, appeared to exhibit less preweaning mortality than did the altricial species, Myotis austroriparius. Pre-weaning mortality in M. austroriparius was most pronounced shortly after birth. Many North American bat species produce a single precocial offspring each year, a demographic response related to the brevity of the season during which offspring can be produced and reared (Tuttle and Stevenson, 1982), restricted food supply (Humphrey, 1975), or aerodynamic constraints (Myers, 1978). The southeastern brown bat M. austroriparius however, commonly produces altricial twins (Foster et al., 1978). Central Florida populations of M. austroriparius do not hibernate and are therefore exposed to in-flight mortality factors over a larger portion of the year than other temperate Myotis. Maternity roosts of M. a. austroriparius are generally found in limestone caves over water where pre-weaning mortality is significant because females cannot retrieve fallen young from the water (Rice, 1957). Thus, twinning is thought to be an adaptive response to a high annual mortality of M. austroriparius (Foster et al., 1978). In contrast, female free-tailed bats, T. brasiliensis, give birth to a single precocial young each year (Pagels and Jones, 1974; Sherman, 1937), and generally roost in man-made structures throughout the year in Florida (Bain, 1981). Roost mortality is unknown in the Florida Tadarida populations, but was estimated at 1.8% for Texas cave populations (Davis et al., 1962). We monitored mortality in an attic-dwelling colony of M. austroriparius and T. brasiliensis during the spring and summer of 1983. These data supplement information provided for M. austroriparius by Foster et al. (1978), and compare mortality in two species, M. austroriparius and T. brasiliensis, under identical roost conditions.

Three lines of evidence were used independently to predict directionality of chewing in the nine extant species of Thomomys pocket gophers. Cranial morphometrics identified T. bulbivorus and T. bottae as having the broadest (platycephalic morphology) and narrowest (dolichocephalic) skulls, respectively, in the genus. Using Merriam's (1895) skull-shape approach, chewing in T. bulbivorus was predicted to be transverse/oblique, whereas T. bottae was expected to chew propalinally. Orientation of tooth scars and enamel bands suggested that all nine Thomomys species studied chew propalinally. To determine whether skull morphology or dental features were better indicators of directionality of chewing, live specimens of T. bulbivorus and T. bottae were collected and their chewing modes evaluated by external observation and cineradiography both species (and presumably all members of the genus) chew propalinally. Therefore, dental features better reflect masticatory mode than does skull morphology.

Colonies of pocket gophers (Geomys pinetis pinetis) in the St. Johns River basin of eastern peninsular Florida occur in uplands which generally correspond to islands emergent from the Pamlico Sea of the latest Sangamonian interglacial. The uplands presently occupied by G. pinetis are isolated by intervening unsuitable habitats and by the St. Johns River. Cranial morphometrics were used to evaluate the pattern of geographic variation among populations of modern G. pinetis in the St. Johns River basin and to examine the influence of the river as a dispersal barrier. Significant variation was found among samples on the E side, the W side, and on opposite sides of the St. Johns River. Results are interpreted in light of historical biogeography of the Quaternary Period; the distribution of pocket gophers in peninsular Florida has been significantly affected by changes in eustatic sea level.