We studied understory vegetation response to complete overstory mortality in a xeric oak (Quercus) forest in Oklahoma to determine the magnitude of changes in understory species composition, richness, cover, and biomass. Graminoid species showed the largest increases in species richness, cover, and biomass following forest canopy decline, mainly attributable to C4 species. The increase in richness of forb species might have been due to the large number of annuals with light, wind-disseminated seeds. Woody and legume species did not respond to forest canopy decline, but their capacity to sprout following disturbance ensured their continued presence. Although graminoid and forb species increased dramatically in response to forest canopy decline, woody plants might eventually recover and produce a forest canopy similar to the canopy before forest decline, unless prevented by annual prescribed burns.

Channel Island foxes (Urocyon littoralis) live on six of the eight California Channel Islands, and each island is inhabited by a distinct subspecies. Until recently, four of these subspecies were listed under the Endangered Species Act as endangered. Although three of the four subspecies have been delisted, and one subspecies was downlisted to threatened, all subspecies are still vulnerable because of small population sizes and potential threats from predation and disease. Consequently, information on reproductive behavior for each subspecies, including the San Clemente Island fox (Urocyon littoralis clementae), is important for understanding fox population dynamics. We determined reproductive status of 28 island foxes through observations of radio collared yearlings and adults with or without juveniles between 25 February and 8 October 2009. We found a greater number of adult foxes than yearling foxes and a greater number of female foxes than male foxes observed with juveniles. Also, there was a significantly greater probability of observing adult female foxes with juveniles than yearling males with juveniles. Only 1 of 28 radio collared foxes exhibited either polygamous or “helper” behaviors. Parturition started approximately 2 months earlier than historically recorded for other Channel Island fox subspecies. Our results suggest that in future studies of reproductive success more effort should be placed on monitoring adult females than yearling males. If emergence from dens continues to occur earlier than previously recorded, the current recommended time period for trapping (20 June–31 January) might need revision to exclude January to reduce stress to pregnant females. If all foxes have similar probabilities of transmitting disease on a given contact with juveniles, our data suggest that it may be appropriate to focus more vaccination efforts on females than males and adults than yearlings because they contact juveniles more frequently.

In 1989 a mark–recapture study of a free-ranging urban population of Pantherophis obsoletus inhabiting the 38.5-ha grounds of the Dallas Zoo (Dallas, Texas) was undertaken and has continued until the present time. Seasonal activity occurred from late February through December. To understand and evaluate further the geographic variation of the seasonal activity of the eastern rat snake complex, we combined data on the seasonal activity of P. obsoletus from our long-term study with those from five other populations previously studied in Texas, Illinois, Kansas, and Maryland and Ontario, Canada. There was a highly significant linear reduction in length of the activity season with increasing latitude. We also describe significant changes in population size and body condition of the snakes during a 26-year study period at the Dallas Zoo and discuss possible factors causing the changes.

Before this study, researchers had not systematically surveyed the Río Conchos, a tributary of the Rio Grande located in northern Mexico, for freshwater mussels. The Texas hornshell, Popenaias popeii, an endangered species under the United States Endangered Species Act, occurs in the main stem of the Rio Grande near its confluence with the Río Conchos. The Texas hornshell's proximity to the Río Conchos prompted us to survey to determine whether P. popeii also occurs within the Conchos basin. Additionally, previous researchers described the Conchos disk, Disconaias conchos, from the Río Conchos but, to date, no one has reported live individuals of this species. The goal of this study was to determine the status of mussels within the Río Conchos basin and to provide a baseline for future monitoring efforts. We qualitatively surveyed 11 sites within the Río Conchos basin in May 2018. In total, we found two live individuals of the paper pondshell, Utterbackia imbecillis, at one site in the Río San Pedro, a tributary of the Conchos River, and as shells of recently live individuals at two sites in the Río Conchos. We found D. conchos as relict shells only at three sites, two in the Río Conchos and one in a tributary of the river at Coyame. The lack of live or fresh-dead material suggests that D. conchos is extinct. We also found live individuals of nonnative Asian clams (Corbicula spp.) at 10 sites. Sand and gravel mining, high organic pollution, and inadequate instream flows were evident throughout the basin and might explain the general absence of mussels.

Western chicken turtles (Deirochelys reticularia miaria) spend most of the year estivating on land, but researchers know little about their choice of estivation locations, and understanding their terrestrial requirements is important for conservation efforts. Therefore, we used radio telemetry to examine the estivation locations of nine males and four females. We followed six of those males and three of those females for 2 years, and two males and one female for 3 years. We examined site fidelity and compared the habitat features of their estivation locations to the habitat available in the area. We found that males exhibited site fidelity across years, but females generally did not. We also found that D. r. miaria selected sites that contained small-mammal burrows, leaf litter, and <25% vegetative ground cover. There was no evidence of selection for sites with or without slopes. Because this species relies on estivation sites with specific characteristics, protecting suitable habitat is an important part of conservation efforts. This study can help to guide those efforts.

A record flood in 2015 resulted in widespread disturbance of the Blanco River riparian corridor with extensive loss of vegetation through floodplain stripping. The riparian forest along the Blanco River is slowly recovering via two primary pathways—natural regeneration from the seedbank and through resprouting of damaged trees. We conducted a study of woody riparian vegetation along the Blanco River to quantify the composition of the recovering forest community and the proportion of trees that are regenerating by resprouting vs. seedbank colonizers. The study captured overall compositional and density patterns as well as comparisons among three geomorphic settings including instream channel bars, the riverbank and near-channel lower elevation floodplain, and the higher-elevation floodplain to upland terraces. Seedlings represented 90% of the density and only 2% of the biomass; in contrast, resprouted trees represented 10% of the density and 98% of the biomass. Fast-growing pioneer species such as sycamore (Platanus occidentalis) and black willow (Salix nigra) were dominant nearest the river channel while facultative and upland species such as pecan (Carya illinoiensis) and hackberry (Celtis spp.) dominated plots higher on the floodplain. Seedlings were far more numerous than resprouts, and seedling density was highest in plots along the riverbank and closest to the channel.

Mexican forest ecosystems are exposed to a great variety of natural disturbances such as fire, which is a key disturbance process influencing tree survival and regeneration. Nevertheless, forest fires are one of the primary causes for which a large portion of the forest in Mexico is lost. Thus, the objectives of this research were to determine (1) the pattern of occurrence of forest fires, and (2) their relationship with precipitation and atmospheric circulation patterns. We reconstructed the historical forest fire regime from fire scars of 22 sample trees in a coniferous forest stand on the mountain Cerro El Potosí in southern Nuevo León, Mexico. Frequent surface fires characterized the site. The mean fire return interval for all fires was 11 years and for the more-widespread fires (those that scarred ≥25% of all samples) was longer (15.7 years). The Superposed Epoch Analysis indicated as not statistically significant the role of dry years as well for the subsequent wet conditions for the period from 1881 to 2004.

In the United States, mourning doves (Zenaida macroura) are harvested more than all other game birds combined. In the Lower Rio Grande Valley of South Texas, mourning doves nest in citrus and remnant woodland habitats, both of which are decreasing in the region. The objectives of this study were to compare nest survival between woodland and citrus land cover types and to model the influence of habitat characteristics and observer disturbance on nest survival. In 2016, we located 100 nests in four citrus groves (n = 21) and two woodlots (n = 79) in Hidalgo and Cameron counties, Texas. We monitored nests every 3 days and collected nest site vegetation measurements. We used logistic-exposure and Akaike information criterion model selection to determine which environmental and temporal variables best predicted nest survival. Candidate models included temporal variables and nest concealment variables such as overhead cover, side cover, distance to foliage edge, and vertical density below the nest. We found considerable differences in the vegetation structure between citrus and woodland sites. Density of vegetation below the nest was the best predictor of survival. Our results suggest that nest survival is higher in citrus groves likely because of increased cover below, to the side, and above nests. Although not considered native habitat, citrus groves might mitigate the loss of native woodland for mourning doves. Thus, the conversion of citrus agriculture to urban areas and row cropping should trouble wildlife managers in the region. Breeding mourning dove populations may be negatively affected by the loss of citrus and woodland land cover that has occurred over the last 50 years.

The lower Rio Grande Valley of Texas (LRGV) contains a unique, subtropical, semiarid floodplain with most of the few remaining Tamaulipan thorn forests in the United States. Less than 2% of Tamaulipan thorn forest remains, with urban and agricultural conversion potentially threatening diverse plant and animal communities native to the habitat. We performed vegetative community surveys and conducted a comprehensive survey of terrestrial snail communities in intact (refugia sites, minimally altered in recent times) and altered (previously cleared and regrown or restored) Tamaulipan thorn forest habitats of the LRGV. In a comparison of intact and altered sites that have comparable vegetation (paired sites), we found that intact sites had a less species-rich snail community than their altered counterparts, but this difference was not statistically significant. This counterintuitive result, in part reflects the fact that the most species-rich, intact snail communities (i.e., Sabal Palm Forest) have no altered (restored or regrown) counterparts and so were not included in the paired comparisons. A nestedness analysis supports this, finding that these unique intact sites, which have the highest species richness and no comparable restored sites, contain the largest pool of species in South Texas. Species richness of snails significantly correlated with a precipitation gradient. A general linear model incorporating mean canopy cover, mean plant height, plant abundance, and plant species richness shows a significant correlation with snail communities. This study is the only comprehensive survey of the snail communities of the lower Rio Grande Valley.

Many causes of mortality have been reported for the peregrine falcon (Falco peregrinus), but there are no published descriptions of fence mortalities for this species. We report on a recently deceased juvenile peregrine falcon that was found ensnared on the top strand of a barbed-wire fence on 24 August 2018 in Hale County, Texas. The cause of mortality was determined to be from exposure after being ensnared by a barb on the fence, a previously undescribed cause of fence-related mortality for the species. This mortality illustrates the novel hazard that fencing and other such structures pose to wildlife, and highlights problems with using barbed fencing because it increases the risk of mortality due to ensnarement and exposure in addition to the risk of blunt-force trauma from collision.

We observed black phoebe (Sayornis nigricans) nests, breeding pairs, and juveniles in Cameron County, Texas, in 2017. Our first confirmed nesting records in Cameron County document a continued eastward range expansion by black phoebes.

Specimens of the invasive red-rim melania snail, Melanoides tuberculata, were observed in concrete drainage ditches throughout Jefferson County, Texas, from May 2018 to September 2019. The species appears to be well established in this artificial habitat, with a population disjunct from other established areas in central Texas and southeastern Louisiana. This occurrence in Jefferson County is likely the result of an aquarium release event independent of other release events for this species and subsequently spread by tropical storm activity.

Opuntia species express great intraspecific morphological variability. All reproductive structures, cladodes (stem segments), and spines respond to macroenvironmental and microenvironmental variation and all of these form from areoles (axillary buds). However, little is known about areole response to light and temperature differences. In this study, I determined whether Opuntia areole numbers and spacing respond to environmental conditions. Terminal cladodes of Opuntia littoralis (Cactaceae) were sampled in Southern California. Data were collected for pad length, pad width, number of areoles on one pad face, number of areoles on the other pad face, and the distances to the nearest areole from the center one on one pad face and on the other for each pad for each of the four orientation groups (N-S, E-W, NW-SE, or NE-SW) for a total of 24 variables. Two-way analysis of variance, related-samples Wilcoxon signed rank tests, and Pearson product-moment correlation identified relationships across and between variables. Results show that areoles are a rather stable feature with regard to environmental variation; there were only small differences on cladode faces oriented in opposite directions. Areoles do not show the more dramatic responses to environmental variation typically seen on the structures borne from those areoles (such as cladodes and spines).