College of Agricultural and Environmental Sciences
Department of Wildlife, Fish and Conservation Biology
University of California - Davis
1055 Academic Surge
One Shields Ave
Davis, CA 95616
E-mail: jtveon@ucdavis.edu
Current Research
Coming Soon!!!
Past Research
Mallard body mass variation during the winter in the Lower Mississippi Alluvial Valley of Arkansas and Mississippi
- In Prep for Submission
North American waterfowl face the challenge of needing to maintain their body mass during the winter as weather conditions become harsh and food resources become increasingly scarce. I am currently analyzing body mass trends in relation to land management and rice production from mallards sampled throughout the Lower Mississippi Valley of Arkansas over the next two Arkansas duck hunting seasons (2019-2020 and 2020-2021). I am working with public land hunters, hunting clubs, and duck processing businesses to sample body mass in hunter-harvested mallards. I will also combine our novel waterfowl body mass data with data collected from the 1970's to early 2000's in order to analyze waterfowl body mass trends over time.
Toxoplasmosis is a coccidian protozoan parasitic disease in mammals, birds, and reptiles. It is caused by Toxoplasma gondii (T. gondii) and primarily affects the nervous system. The only known definitive hosts are species of the Felidae (feline) family. Preliminary analyses have shown upwards of 80% prevalence of T. gondii within hunter-harvested waterfowl species. I am currently collaborating on a project with Dr. Rick Gerhold's lab at the University of Tennessee College of Veterinary Medicine analyzing blood serology and tissue samples of duck hearts I collect from hunter-harvested mallards. This project aims to determine the prevalence and transmission rates of the T. gondii parasite within wintering waterfowl species of Arkansas. This project will also help address gaps in the literature regarding transmission of T. gondii to waterfowl from feral cats.
Toxoplasma prevalence and transmission rates in waterfowl
- In Prep for Submission
Disturbance of wintering waterfowl by traffic noise
- In Review
Wetlands are highly impacted by land-use changes associated with threats like agriculture and urbanization. However, one threat that receives less attention is that of anthropogenic noise. Waterfowl could be at risk for disturbance by automobile noise due to the spread of transit networks into rural areas. In this project, I tested the response of wintering waterfowl through a playback experiment using traffic noise at 75 dB in wetland habitats of Arkansas from January through March 2018. Our results suggest that traffic noise disturbs waterfowl by causing them to avoid areas of open water that are near the noise source. This finding highlights the importance of considering anthropogenic noise when selecting sites for new wetlands or regulating existing waterfowl habitat.
Influence of human development and predators on patterns of Virginia opossum (Didelphis virginiana) occupancy, abundance, and activity
- In Review
As human development increases across the globe, wildlife are either pushed out of developed areas or adapt to survive in these novel, human-dominated landscapes. Many mammalian mesopredators, such as the Virginia opossum (Didelphis virginiana), have adapted to living alongside human development and take advantage of human-subsidized food, water, and shelter. Understanding how dominant and subordinate mesopredators co-exist across natural and developed areas will provide valuable insight into how urban wildlife communities are structured. Our objective was to evaluate how Virginia opossum occupancy, abundance, and activity was associated with both human development and the relative abundance of their predators. We found that opossum occupancy was positively associated with an index of human activity (anthropogenic sound), but at very high levels of housing density, opossum occurrence decreased. Opossum in heavily forested areas were more likely to be detected in areas with higher predicted anthropogenic sound. In areas with a high density of human housing, opossum relative abundance increased even in situations where predator abundance also increased. However, at low or moderate levels of housing density, opossum abundance did not increase although predator abundance did. Opossum shifted their activity to being active earlier in the evening in the presence of high predator abundance. These results confirm that the Virginia opossum is a successful urban-exploiter. Future research should evaluate if the association of Virginia opossum with urban areas is a direct result of human subsidized resources and/or reduced mortality caused by altered predator-prey dynamics.
Influences of landscape composition on non- breeding mallard (Anas platyrhynchos) body condition and harvest in east Arkansas
- In Review
Overwintering waterfowl with a higher body condition index are thought to be more likely to survive the winter and have increased productivity during the following breeding season. Body condition index in waterfowl should reflect the resources available to them locally. Here, we analyze the relationship of landscape composition on mallard (Anas platyrhynchos) body condition using a mass by wing length index (BCI) within the Lower Mississippi Alluvial Valley of Arkansas. We measured hunter-harvested mallards during the 2019-2020 and 2020-2021 duck hunting seasons. We found that mallards collected from areas with high proportions of water cover, woody wetlands, and open water within a 30-km radius had higher BCI. Conversely, we found that mallards collected from areas with higher proportions of herbaceous wetlands or human disturbance had lower BCI. Management actions focused on maintaining water levels for waterfowl to access food resources, while providing ample habitat that allows for resting, loafing, and other life cycle events free of human disturbance, will most likely increase BCI in mallards wintering in the Lower Mississippi Alluvial Valley.
Wildlife associates of nine-banded armadillos (Dasypus novemcinctus) burrows in Arkansas
Published 05/2022
Nine-banded armadillos (Dasypus novemcinctus) are mainly found in the southeastern United States, but have been expanding their range northward for more than a hundred years. However, little is known about how their existence in novel areas may be altering the landscape and species diversity around them. I am currently working with colleagues in my lab at the University of Arkansas to deploy game cameras at nine-banded armadillo burrow locations across Arkansas. We will analyze the photos to assess the surrounding area species diversity and burrow commensalism. This research will develop a better understanding of the role nine-banded armadillo burrows play within varying ecosystems of Arkansas.
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View Dr. Brett DeGregorio's website here.
The northern bobwhite quail has been declining in the southeastern United States over the last 20 years. Evidence suggests the reasons for the decline are region specific. In this project, I assisted in the development of an occupancy model used to determine what variables correlate with the presence of quail within different ecoregions of Arkansas. Our results confirmed previous research that the variables that affect quail oocupancy are locality specific. This project aims to give management agencies insight into what variables to consider when managing northern bobwhite quail populations in Arkansas.
Read Here
Northern bobwhite occupancy patterns on multiple spatial scales across Arkansas
Published 12/2021
Nine-banded armadillo (Dasypus novemcinctus) activity patterns are influenced by human activity
Published 11/2021
Nine-banded armadillo's have an active period of about 6 hours per day. Activity can be affected by dietary needs, thermoregulatory benefits, and weather. The time in which armadillos are active can greatly influence the density and type of food they acquire, as well as their survival. As nine-banded armadillos are increasingly expanding their range north, they may become increasingly exposed to a varying degree of human disturbances along rural and urban gradients. This study aimed to analyze armadillo activity at undisturbed sites (no human foot traffic or dog walking) and disturbed sites (where foot traffic and dog walking is allowed). Our results indicated that nine-banded armadillos are likely shifting to nocturnal activity patterns in the presence of human disturbance. Although the exact reasons for this shift remain unknown, our result further highlights the potential effects of nonlethal human presence on wildlife behavior.
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View Dr. Brett DeGregorio's website here.
Read Here
Coronaviruses (CoVs) are single-stranded RNA viruses that pose a threat to livestock, household pets, and humans. Avian CoVs are a group of viruses that contain infectious bronchitis viruses. Previous research has shown that healthy wild birds can serve as a vector for CoVs between domestic and wild birds. However, little is known about CoVs in wintering waterfowl. I am currently assisting Dr. Kris Forbes and his lab here at the University of Arkansas to collect fecal samples from hunter-harvested waterfowl in the Arkansas Delta. This research aims to gain a better understanding of the prevalence of CoVs in wintering waterfowl populations of Arkansas.
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Result update 05/2020: No coronaviruses were found in waterfowl samples
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View Dr. Kris Forbes' website here.