Tyler A. Campbell

• PhD, Forest Resources
• Principal Investigator at East Foundation

The ocelot (Leopardus pardalis) is a wild cat distributed from the southern U.S. to northern South America. In the U.S., ocelots are classified as endangered, and breeding ocelot populations are only found in Texas—a state composed of mostly private lands. Ocelot recovery in the U.S. depends on successful conservation actions on private lands. Unfo...

The Normalized Difference Vegetation Index (NDVI) is a measurement of landscape “greenness” and is used as a proxy for productivity to assess species distributions and habitats. Seasonal levels of productivity have been strongly related to avian population dynamics, suggesting dependence upon biomass production for completing annual life cycle even...

Age classification methods have not been evaluated for free-ranging nilgai antelope (Boselaphus tragocamelus) either on their native or introduced ranges of southern Texas, USA. Our objectives were to 1) determine if cementum annuli aging was a feasible method for aging nilgai, 2) measure the crown-lingual crest heights of nilgai molariform teeth t...

Reintroductions are often needed to recover carnivore populations and restore ecological processes. Felids are common subjects of reintroduction efforts, but published population models informing felid reintroduction plans are uncommon, and poor planning has sometimes caused issues in felid reintroduction programs. In the United States, ocelots (Le...

The resource rule hypothesis predicts that geographic differences in body size among populations of organisms are due to the amount, availability, and quality of food resources. For instance, the body size of large herbivores is often correlated with soil characteristics because better soils produce better forage. In semiarid environments, rainfall...

Simple Summary To better inform nilgai antelope management decisions, basic life history data are needed. We collected reproductive tracts of free-ranging female nilgai from 2018 to 2021 in Southern Texas. We found high pregnancy and twinning rates. Moreover, we found nilgai as young as 1 year old to be pregnant and nilgai as old as 12 years old to...

In the age of global climate change, extreme climatic events are expected to increase in frequency and severity. Animals will be forced to cope with these novel stressors in their environment. Glucocorticoids (i.e. ‘stress’ hormones) facilitate an animal’s ability to cope with their environment. To date, most studies involving glucocorticoids focus...

Competition is a complex ecological process involving individual and community interactions at ecological and evolutionary time scales. Individuals within and between species can compete through two mechanisms: exploitative and interference competition. These mechanisms often co‐occur, making it difficult to develop a mechanistic understanding of c...

Wildlife reintroduction site selection requires the consideration of not only a species' ecology but also socio‐political factors that may impact conservation efforts. These socio‐political dimensions may be especially important for endangered carnivore reintroductions on private lands in the United States, where landowner support for the reintrodu...

Various landscape and environmental factors influence animal movement and habitat selection. Lunar illumination affects nocturnal visual perception of many species and, consequently, may influence animal activity and habitat selection. However, the effects of varying moon stage may differ across taxa. Prey species often reduce activity during highl...

Aim Mitigating the effects of extreme conditions is a mechanism that can structure the activity patterns and habitat selection of a species and may particularly impact species at the extremes of their geographic distribution. Furthermore, changing climate patterns have the potential to influence biotic interactions between species in novel ways. As...

Wildlife depends on specific landscape features to persist. Thus, characterizing the vegetation available in an area can be essential for management. The ocelot (Leopardus pardalis) is a federally endangered, medium-sized felid adapted to woody vegetation. Quantifying the characteristics of vegetation most suitable for ocelots is essential for thei...

Plant species richness is an important property of ecosystems that is altered by grazing. In a semiarid environment, we tested the hypotheses that (1) small‐scale herbaceous plant species richness declines linearly with increasing grazing intensity by large ungulates, (2) precipitation and percent sand interact with grazing intensity, and (3) respo...

Climate change is altering biodiversity of ecosystems worldwide by causing shifts in species’ home ranges, potential extinctions of species, and Extreme Climatic Events (ECEs), such as hurricanes and extreme temperatures. The purpose of this study was to examine effects of two extreme weather events on butterfly populations in the Gulf Prairies and...

Habitat selection by animals is a complex, dynamic process that can vary across spatial and temporal scales. Understanding habitat selection is a vital component of managing endangered species. Ocelots (Leopardus pardalis), a medium-sized endangered felid, overlap in their northern range with bobcats (Lynx rufus) and coyotes (Canis latrans), with a...

Gulf cordgrass (Spartina spartinae [Trin.] Merr. ex Hitchc.) and seacoast bluestem (Schizachyrium scoparium [Michx.] Nash var. littorale [Nash] Gould) are dominant native warm season grasses in the Texas Coastal Prairies and Marshes ecoregion. Mature Gulf cordgrass nutritive value is considered poor for grazing animals, while seacoast bluestem nutr...

Wild pigs (Sus scrofa) are a prolific, invasive species in the United States of America and act as vectors for many pathogens. An emerging pathogen of concern to the USA is African swine fever (ASF), a deadly viral disease affecting swine that is endemic to Africa and has spread to parts of Europe, Asia, and the Caribbean. ASF affects both wild and...

Context Research on large, terrestrial mammals often requires physical captures to attach tags or collars, collect morphological data, and collect biological samples. Choice of capture method should minimise pain and distress to the animal, minimise risk to personnel, and consider whether the method can achieve study objectives without biasing resu...

Context Maintaining landscape connectivity for wildlife has become a conservation priority in response to increasing land development and road networks. Roads affect many wildlife populations worldwide, with the distribution and density of roads having negative impacts on gene flow and landscape connectivity. Objectives We aimed to identify areas...

Net‐wire fencing built to confine livestock is common on rangelands in the Southwestern USA, yet the impacts of livestock fencing on wildlife are largely unknown. Many wildlife species cross beneath fences at defined crossing locations because they prefer to crawl underneath rather than jump over fences. Animals occasionally become entangled jumpin...

Abstract Evaluating temporal trends in habitat and behavioral responses is critical for conservation, yet long‐term monitoring studies are rare. We used a 35‐year dataset (1982–2017) to assess multiscale habitat use and selection by an endangered carnivore, the ocelot (Leopardus pardalis), in South Texas, USA. We used a time series of remotely sens...

The use of scent for communication is widespread in mammals, yet the role of scent-marking in the social system of many species is poorly understood. Nilgai antelope (Boselaphus tragocamelus) are native to India, Nepal, and Pakistan. They were introduced to Texas rangelands in the United States during the 1920s to 1940s, and have since expanded int...

Ecological niche models use presence-only data, which is often affected by lack of true absences leading to sampling bias. Over the last decade, there has been an uptick in the integration of occurrence data from global positioning systems telemetry data in ecological niche models and/or species distribution models. These data types can be affected...

Baseline biodiversity surveys are necessary to assess organismal diversity across spatial and temporal scales. These surveys can be particularly useful for monitoring changes in organismal diversity and pathogen spread in response to climate change. Arthropod vectors such as ticks are susceptible to geographic range shifts with a warming climate, p...

Avian haemosporidian parasites (Haemoproteus, Leucocytozoon, Plasmodium) in Texas are relatively understudied for such a large geographic area with diverse ecoregions. Our study sites in south Texas, located in two adjacent ecoregions, present the opportunity for investigating patterns and possible causes of infections between habitats, and charact...

Formative patterns of vegetation responses to cattle grazing can be difficult to detect because of innate heterogeneity of vegetation communities and grazing patterns, especially in semiarid environments. Nonetheless, some of this heterogeneity can be accounted for using appropriate experimental designs and statistical analyses. Bork and Werner (19...

Bats are difficult to study due to their nocturnal, cryptic, and highly vagile nature. Ongoing advances in acoustic recording hardware and call classification software have made species detection and activity monitoring more feasible. Our objectives were to determine effort necessary to monitor bat assemblages using an occupancy framework and acous...

The jaguarundi (Puma yagouaroundi) is a small felid with a historical range from central Argentina through southern Texas. Information on the current distribution of this re-clusive species is needed to inform recovery strategies in the United States where its last record was in 1986 in Texas. From 2003 to 2021, we conducted camera-trap surveys acr...

The landscape of fear (LOF) hypothesis is a unifying idea explaining the effects of predators on the space use of their prey. However, empirical evidence for this hypothesis is mixed. Recent work suggests that the LOF is dynamic, depending on the daily activity of predators, which allows prey to utilize risky places during predator down times. Whil...

Reducing grass standing crop by grazing may increase forbs and benefit wildlife that depend on forbs. However, precipitation and soil texture also strongly influence forb standing crop. We determined if standing crop of forbs selected by white-tailed deer (Odocoileus virginianus Zimm.) is more strongly influenced by grazing or precipitation. Ungula...

Population monitoring is fundamental for informing management decisions aimed at reducing the rapid rate of global biodiversity decline. Herpetofauna are experiencing declines worldwide and include species that are challenging to monitor. Raw counts and associated metrics such as richness indices are common for monitoring populations of herpetofaun...

South Texas is a highly variable region encompassing multiple habitat types and harboring a wide diversity of organisms. However, the parasite fauna in this region is poorly known, especially for avian ectoparasites such as lice. To better understand avian louse diversity and host associations in South Texas, we examined a total of 507 birds for ch...

Abstract Ecosystem engineers alter, and can be influenced in turn by, the ecosystems they live in. Woodpeckers choose foraging and nesting sites based, in part, on food availability. Once abandoned, these cavities, particularly within areas of high forage, may be crucial to secondary cavity‐nesting birds otherwise limited by cavities formed through...

Simple Summary New or revised techniques are being developed to improve management of expanding populations of invasive wild pigs. In southern Oklahoma, we set out to evaluate the success of various trap types: a conventional corral trap design, drop nets developed for capturing other wildlife, and recently developed suspended traps. Suspended trap...

Simple Summary Wild pigs are the most abundant wild exotic ungulate in the United States. In Texas, particularly, they are abundant and represent a threat to ecosystems, agriculture and humans. Our objective was to apply a landscape-scale analysis of population genetic structure of wild pigs to aid in their management in southern Texas. We used mic...

Aerial surveys are an efficient technique for counting animals over large geographic areas such as rangelands. In southwestern rangelands, aerial surveys are routinely conducted for ungulates, with the implicit understanding that abundance estimates represent an undercount. Distance sampling can correct for visibility bias, but assumes perfect dete...

Understanding how ecosystem engineers influence other organisms has long been a goal of ecologists. Woodpeckers select nesting sites with high food availability and will excavate and then abandon multiple cavities through their lifetime. These cavities are crucial to secondary cavity nesting birds (SCB) that are otherwise limited by the availabilit...

Background The influence of vegetative changes due to livestock grazing on grassland birds is well-recognized because these birds are heavily influenced by vegetative structure. Traditionally, species distribution models (SDMs) use direct variables, resources that the animal consumes or requires to persist in an area (e.g., water) to define and pro...

About 80% of the known breeding population of ocelots (Leopardus pardalis) in the USA occurs exclusively on private ranches in northern Willacy and Kenedy counties in South Texas. These private ranches support several large contiguous undisturbed patches of thornscrub, which is preferred by ocelots. Past studies have indicated ocelots in South Texa...

Sympatric ocelots (Leopardus pardalis) and bobcats (Lynx rufus) in South Texas show substantial overlap in body size, food habits, and habitat use. Consequently, we explore whether temporal niche partitioning may explain ocelot and bobcat coexistence. We investigated the influence of sun angle, lunar illumination, and maximum diurnal temperature on...

Interspecific competition among carnivores has been linked to differences in behavior, morphology, and resource use. Insights into these interactions can enhance understanding of local ecological processes that can have impacts on the recovery of endangered species, such as the ocelot (Leopardus pardalis). Ocelots, bobcats (Lynx rufus), and coyotes...

White-tailed deer ( Odocoileus virginianus) serve as a host for cattle fever ticks ( Rhipicephalus [ Boophilus] microplus and R. [ B.] annulatus; CFTs); therefore, deer are a concern for CFT control programs in southern Texas. Systemic (oral delivery of ivermectin) and topical (permethrin on pelage) treatment devices have been developed for white-t...

Wildlife population monitoring programs are useful for identifying ecological impacts such as those from local management actions and broader scale influences such as climate change. Increasing the number of species monitored improves robustness of the program towards meeting monitoring objectives. In addition, monitoring at multiple spatial scales...

Several habitats may be required for an animal's persistence, and movements within and among these habitats characterise an ani-mal's home range. For species of lizards, variation in home range size is typically best explained by either sit-and-wait or active foraging styles. In this study, we explore movements, home range size, and territoriality...

Patterns of habitat use in animals can vary over time and space in predictable ways. For ectotherms, behavioral cycles are tightly linked to varying temperatures in the environment such that microhabitat availability can constrain individual performance, fitness, and life history. A long history of research on diurnal microhabitat use in lizards ex...

Aim Complex, biotic interactions are notably excluded from species distribution models (SDMs) as they are often difficult to quantify and accommodate in a traditional modeling framework, especially those with a temporal component. The territorial nature of breeding Cactus wren is well-documented and typically involves nest usurping (i.e., destructi...

Woody encroachment has influenced wildlife distributions and, thus, predator-prey dynamics, for many taxa in North American grasslands. In 2015 and 2016, we examined how vegetative characteristics influenced avian nest predator assemblages and nest predation rates in semiarid grasslands of south Texas, where encroachment of woody plant species is c...

Identifying Nilgai antelope using game cameras at latrines in south Texas.

Although the activity patterns of bats are recognized to vary widely, both, temporally and spatially, the underlying drivers for those patterns remain poorly understood. Presently, studies focusing on foraging bat ecology have only generalized activity and influence of the environment (across sampling periods, sampling nights, or seasons). The infl...

The wild pig (Sus scrofa), an exotic and invasive species, has caused great concern at a global scale, particularly within agricultural landscapes. The objective of this study was to determine whether intensive trapping and wild pig removal resulted in a concomitant decrease in damage to rangelands. Removal of 356 wild pigs over 2 years showed an i...

The Greater Roadrunner (Geococcyx californianus) is a medium-sized predatory bird that occurs widely across the southwestern United States. Despite its prevalence in this region, studies examining the nesting and behavioral ecology of this species are limited. In 2015 and 2016, we examined relatively unknown aspects of roadrunner natural history by...

There is growing interest among resource managers in implementing long-term wildlife monitoring. The process to develop such a program may seem daunting, however, because it requires determining the species, metrics, sampling methods, experimental design, and level of effort necessary to achieve the desired power for detecting meaningful changes. F...

Wildlife, both native and introduced, can harbor and spread diseases of importance to the livestock industry. Describing movement patterns of such wildlife is essential to formulate effective disease management strategies. Nilgai antelope (Boselaphus tragocamelus) are a free-ranging, introduced ungulate in southern Texas known to carry cattle fever...

Background The movement behavior of an animal is determined by extrinsic and intrinsic factors that operate at multiple spatio-temporal scales, yet much of our knowledge of animal movement comes from studies that examine only one or two scales concurrently. Understanding the drivers of animal movement across multiple scales is crucial for understan...

The handheld point of care analyzer is a quick and feasible option to obtain hematology data from individuals. The iSTAT-1® was used to evaluate select venous blood analytes obtained via jugular venipuncture from 238 passerine birds from South Texas. These data were used to assess the health of birds in the area while taking into consideration life...

Dung beetles (Coleoptera: Scarabaeidae) play a major role in nutrient cycling, soil aeration, and biological control of pests and parasites that breed in manure. Habitat fragmentation, pesticide usage, and conventional agricultural practices threaten dung beetle diversity, and their conservation is of growing concern. This study from August to Octo...

Cattle fever ticks (CFT), vectors of bovine babesiosis and anaplasmosis, were eradicated from the United States by 1943, but are frequently reintroduced from neighboring border states of Mexico via stray cattle and wildlife hosts including white-tailed deer (Odocoileus virginianus) (WTD) and nilgai antelope (Boselaphus tragocamelus). Nilgai antelop...

Serum samples from 18 axis deer (Axis axis) and 19 fallow deer (Dama dama) were analyzed with an enzyme-linked immunosorbent assay for Neospora caninum antibodies. Two axis (11%) and two fallow deer (11%) were positive for N. caninum antibodies.

Wild pigs ( Sus scrofa ) are causing increasing ecologic and economic damage at a global scale. Because wild pigs can carry ≥65 diseases that affect livestock, their widespread expansion threatens native wildlife and livestock. We screened wild pigs from south-central Oklahoma, US for antibodies against Brucella abortus , pseudorabies virus (PRV),...

Contact rates vary widely among individuals in socially structured wildlife populations. Understanding the interplay of factors responsible for this variation is essential for planning effective disease management. Feral swine (Sus scrofa) are a socially structured species which pose an increasing threat to livestock and human health, and little is...

Management strategies designed to reduce the negative impacts of overabundant Odocoileus virginianus (White-tailed Deer) populations on forest regeneration may be influenced by changes in both population density and timber harvest. However, there is conflicting evidence as to how such changes in per capita resource availability influence home-range...

We harvested 21 fallow deer (Dama dama) and 17 axis deer (Axis axis) in northern Mexico. Two fallow deer were positive for Babesia bigemina and one for Babesia bovis. Amplicons had the expected 170 and 291 base pairs and were identical to B. bigemina (S45366) and B. bovis (M38218), respectively.

By definition, contact denotes the junction of at least two objects. In the context of disease transmission, contact implies interaction with potential to spread disease. Mischaracterization of contacts may result in inaccurate estimates of transmission rates. To collect more-accurate contact data among white-tailed deer (Odocoileus virginianus), w...

Understanding the interrelationship of environmental and biological factors that influence population growth rates of invasive Sus scrofa (Wild Pig) is a requisite for population management of the species. Such information can be used to evaluate various types of population control to ensure that the most cost-effective damage-abatement methods are...

Given the popularity of feeding white-tailed deer (Odocoileus virginianus) in Texas and the increasing amount of corn that is distributed, more information is needed on the impacts of this activity on non-target wildlife. Our objectives were to report visitation, intra- and interspecific contact, and contact rates of wildlife at artificial feeding...

Feral swine (Sus scrofa) are one of the most threatening mammalian pest species in North America owing to the damage they cause to natural habitats and agroecosystems, and the risk of disease transmission they pose to wildlife, livestock, and humans. The long-term (> 1 year) effects of lethal control efforts on feral swine populations at local scal...

Many different types of traps have been developed to increase feral swine (Sus scrofa) capture efficiency. Though not previously compared, gate styles may influence capture success. Our objectives were to report feral swine capture data from 31 trapping campaigns conducted in 17 counties from 2005 to 2011 in Texas, USA, compare capture rates by dem...

Rapidly evolving electronic technology enables wildlife researchers to collect previously unobtainable data. To explore possibilities of using deer-borne cameras (DBCs) to collect behavioral data from an animal's point of view, we constructed DBCs and deployed them on 26 adult male white-tailed deer (Odocoileus virginianus) within a closed populati...

We captured and placed radiotransmitters on 27, 37, and 51 female Rio Grande turkeys (Meleagris gallopavo intermedia) on the Encino, Norias, and Laureles divisions of King Ranch, respectively, in Brooks, Kenedy, and Kleberg counties, Texas. Mean annual sizes of home ranges were 838–5,867 ha, which were larger than most individual holdings of privat...