The Effects of Commercial Harvest on the Density and Demography of Aquatic Turtles in Arkansas

The United States is home to the second highest concentration of turtle species in the world, after Asia. As of 2018, there are 57 turtle species recognized within the US, 40% of which are listed as threatened or endangered, with the primary threats to population persistence identified as over-consumption and/or habitat loss. Within the US, the Mississippi Alluvial Valley (MAV) region represents the second highest turtle species richness, after the Mobile River Basin. The MAV region of Arkansas is one of the least regulated in terms of commercial aquatic turtle harvest and has undergone large-scale habitat conversion from bottomland hardwood forest wetlands to agriculture, yet little is known about freshwater turtle populations within this region. As awareness of the plight of turtles worldwide increases and studies continue to find current levels of commercial harvest unsustainable, biologists and conservation organizations have begun petitioning states to close or strictly regulate commercial turtle harvest. Baseline data on turtle populations in the MAV of Arkansas is lacking. We conducted a three-year capture-mark-recapture (CMR) study of turtle community composition, density, and demography in agricultural ditches and aquaculture ponds of eastern Arkansas, two abundant wetland habitats which are often targeted by commercial turtle harvesters. We captured and marked over 4,000 individual turtles of nine species including red-eared sliders (Trachemys scripta; N = 2695), spiny softshell turtles (Apalone spinifera; N = 640), common musk turtles (Sternotherus odoratus; N = 508), eastern mud turtles (Kinosternon subrubrum; N = 81), common snapping turtles (Chelydra serpentina; N = 56), river cooters (Pseudemys concinna; N = 11), southern painted turtles (Chrysemys dorsalis; N = 7), Mississippi map turtles (Graptemys pseudogeographica kohnii; N = 7), and alligator snapping turtles (Macrochelys temminckii; N = 2). We found that harvest severely reduces density of red-eared sliders and spiny softshell turtles in both pond and ditch systems for up to two years post-harvest and potentially causes shifts in community composition detectable for years after the initial removal event. We found no differences in turtle species richness or diversity between harvest status in ponds, but harvested ditches had higher mean Simpson’s diversity and species richness. There were relatively few consistent differences in density or demography within ditches, likely because the dynamic hydrology of ditches results in frequent immigration and emigration. Recently harvested aquaculture ponds had lower densities of red-eared sliders and spiny softshell turtles than unharvested ponds and were missing size cohorts, persisting for at least 5 years after harvest. Using supervised classification in a GIS, we delineated 22,317 ha of aquaculture ponds and more than 18,350 linear km of agricultural ditches occurring in the MAV. Based on our density calculations, we estimate that more than 2 million red-eared sliders and 427,000 spiny softshell turtles occur in ditches and aquaculture ponds of the region. Overall density of sliders was greater in ditches, with approximately 65% of our extrapolated abundance existing in this habitat type, while spiny softshell turtles are far more common in ponds, with only about 17% of our extrapolated abundance occurring in ditches across the MAV. Our density estimates were moderate compared to other reports in the literature. These turtles are clearly utilizing these habitats, sometimes occurring at high densities, yet they are not limitless. Harvest can reduce their populations and managers must take this into account

Analysis of Spiny Softshell Turtle Distribution and Abundance in Four Rivers Systems in Eastern Montana

The spiny softshell turtle (Apalone spinifera) is designated as a species of concern in the state of Montana due to a lack of knowledge regarding their conservation status, loss of habitat connectivity and anthropogenic changes in hydrology.  Information on population abundance, and basic population structure for these turtle species is necessary to better understand how climatic changes, human responses to these changes, and other disturbances influence this neglected faunal component of freshwater ecosystems.  To examine differences in subpopulations exposed to different environmental factors, spiny softshell turtles were studied in four river systems in south eastern Montana.  Over two years a total of 328 spiny softshell turtles (283 females, 41 males and four juveniles) were captured and tagged in the Bighorn, Clarks Fork, Musselshell and Yellowstone Rivers. The proportion of males to females across all four rivers was 86.28% females and 12.5% males. Based on a method adapted from the von Bertalanffy growth model by Plummer and Mills (2015), the length of the female spiny softshell turtles were correlated to known ages from other studies and broken into four age cohorts (juvenile, subadult, reproductive adult, mature adult). Numbers of turtles in each cohort were found to be significantly different between the four rivers p < 0.00001.  The Musselshell and Yellowstone Rivers had a more even distribution of age classes with the Musselshell having notably less mature adult turtles.  Differences in hydrology, such as temperature, and the timing and magnitude of spring pulse flows on these four rivers may explain the observed spiny softshell turtle demographic structures

Analysis of Spiny Softshell Turtle Distribution and Abundance in Four Rivers Systems in Eastern Montana

The spiny softshell turtle (Apalone spinifera) is designated as a species of concern in the state of Montana due to a lack of knowledge regarding their conservation status, loss of habitat connectivity and anthropogenic changes in hydrology.  Information on population abundance, and basic population structure for these turtle species is necessary to better understand how climatic changes, human responses to these changes, and other disturbances influence this neglected faunal component of freshwater ecosystems.  To examine differences in subpopulations exposed to different environmental factors, spiny softshell turtles were studied in four river systems in south eastern Montana.  Over two years a total of 328 spiny softshell turtles (283 females, 41 males and four juveniles) were captured and tagged in the Bighorn, Clarks Fork, Musselshell and Yellowstone Rivers. The proportion of males to females across all four rivers was 86.28% females and 12.5% males. Based on a method adapted from the von Bertalanffy growth model by Plummer and Mills (2015), the length of the female spiny softshell turtles were correlated to known ages from other studies and broken into four age cohorts (juvenile, subadult, reproductive adult, mature adult). Numbers of turtles in each cohort were found to be significantly different between the four rivers p < 0.00001.  The Musselshell and Yellowstone Rivers had a more even distribution of age classes with the Musselshell having notably less mature adult turtles.  Differences in hydrology, such as temperature, and the timing and magnitude of spring pulse flows on these four rivers may explain the observed spiny softshell turtle demographic structures

Analysis of Spiny Softshell Turtle Population Structures in Five River Systems in Eastern Montana

 The spiny softshell turtle (Apalone spinifera) is designated as a species of concern in the state of Montana due to a lack of knowledge regarding their conservation status, loss of habitat connectivity and anthropogenic changes in hydrology. Information on population abundance and basic population structure for this species is necessary to understand how altered hydrological regimes and catastrophic events may affect this highly aquatic species. Spiny softshell turtles were studied in five river and creek systems in southeastern Montana. Over three years a total of 553 spiny softshell turtles were captured. The proportion of females to males captured across all five systems was not significantly different between creeks and rivers, with a total of 89.69% females and 10.31% males. We developed four length / age classes (juvenile, sub-adult, reproductive adult, mature adult) based on reported age cohorts from other studies. Numbers of spiny softshell turtles in each cohort were found to be significantly different between the five systems p < 0.00001. The Musselshell and Yellowstone Rivers and Pryor Creek had evidence of juvenile age classes and a more even distribution of age classes than the other systems. The Bighorn River had mostly larger adults and the Musselshell River lacked significant numbers of mature adults. Average seasonal water temperatures, timing and magnitude of spring pulse flows, ice cover and scour in winter, and abundance of open gravel bars, should be examined as possible factors which may explain the observed differences in spiny softshell turtle demographic structures on these five systems

Snapping Turtle Populations and Movements in South-central Montana

Snapping turtle (Chelydra serpentina) populations were surveyed on a number of tributaries and other water bodies in south eastern Montana along the Yellowstone River in 2016 and 2017. While records exist from incidental observations, systematic surveys for snapping turtles have not previously been conducted in Montana. Little is known about their population density and specific habitat requirements in northern parts of their range. Anthropogenic changes in land use and hydrology may affect nesting sites and hibernacula and thus snapping turtle vital rates, while also impeding metapopulation connectivity or recolonization after localized extinctions. Eighty two snapping turtles (including nine recaptures) were recorded primarily in small creeks, ponds and lakes. Only one snapping turtle was captured on the Yellowstone River though many were found in small tributaries. When analyzed separately capture success rates were significantly different amongst five creeks (p < .05) with a higher proportion of males in all populations (p < .05). Afteridentifying several creeks with larger numbers of snapping turtles present we fitted turtles over 8 kg with radio transmitters, beginning June 2017. Movements of radio-tagged individuals were recorded at least monthly to determine average distances moved. Maximum river miles moved per turtle were averaged (females = 0.83 miles and males = 1.21 miles). Low numbers of females could indicate higher female mortality related to risks during nesting such as crossing roads. Snapping turtle abundance was highest in creeks dominated by cattle grazing or agricultural uses. Creeks with lower abundance were dominated by urbanization and higher density of road crossings, potentially leading to increased mortality and lower hatchling success rates

Wildlife associates of nine-banded armadillo (Dasypus novemcinctus) burrows in Arkansas

The Nine-banded Armadillo (Dasypus novemcinctus) is a widespread burrowing species with an expanding geographic range across the southeastern and midwestern United States. Armadillos dig numerous, large burrows within their home ranges and these burrows are likely used by a diverse suite of wildlife species as has been reported for other burrowing ecosystem engineers such as Gopher Tortoises (Gopherus polyphemus), Desert Tortoises (Gopherus agassizi), and Black-tailed Prairie Dogs (Cynomys ludovicianus). We used motion-triggered game cameras at 35 armadillo burrows in 4 ecoregions of Arkansas and documented 19 species of mammals, 4 species of reptile, 1 species of amphibian, and 40 species of bird interacting with burrows. Bobcat (Lynx rufus), Coyote (Canis latrans), Eastern Cottontail (Sylvilagus floridanus), Gray Fox (Urocyon cinereoargenteus), Gray Squirrel (Sciurus carolinensis), Northern Raccoon (Procyon lotor), Virginia Opossum (Didelphis virginiana), and unidentified rodents (mice and rats) were documented using burrows in all four ecoregions. We documented wildlife hunting, seeking shelter, rearing young in, and taking over and modifying armadillo burrows. The rate of use was highest in the Mississippi Alluvial Valley, a landscape dominated by agriculture, where natural refugia may be limited and rodents are abundant. Armadillo burrows are clearly visited and used by numerous wildlife species to fulfill various life stage requirements, and this list will likely expand if more attention is devoted to understanding the role of armadillos burrows. Armadillos are important ecosystem engineers, and their ecological role warrants more investigation and attention as opposed to only being viewed and managed as agricultural and garden pests

Nine-banded armadillo (Dasypus novemcinctus) activity patterns are influenced by human activity.

As the human footprint upon the landscape expands, wildlife seeking to avoid human contact are losing the option of altering their spatial distribution and instead are shifting their daily activity patterns to be active at different times than humans. In this study, we used game cameras to evaluate how human development and activity were related to the daily activity patterns of the nine-banded armadillo (Dasypus novemcinctus) along an urban to rural gradient in Arkansas, USA during the winter of 2020-2021. We found that armadillos had substantial behavioral plasticity in regard to the timing of their activity patterns; >95% of armadillo activity was nocturnal at six of the study sites, whereas between 30% and 60% of activity occurred during the day at three other sites. The likelihood of diurnal armadillo activity was best explained by the distance to downtown Fayetteville (the nearest population center) and estimated ambient sound level (both indices of human activity) with armadillos being most active during the day at quiet sites far from Fayetteville. Furthermore, armadillo activity occurred later during the night period (minutes after sunset) at sites near downtown and with higher anthropogenic sound. Anecdotal evidence suggests that the observed activity shift may be in response to not only human activity but also the presence of domestic dogs. Our results provide further evidence that human activity has subtle nonlethal impacts on even common, widespread wildlife species. Because armadillos have low body temperatures and basal metabolism, being active during cold winter nights likely has measurable fitness costs. Nature reserves near human population centers may not serve as safe harbors for wildlife as we intend, and managers could benefit from considering these nonlethal responses in how they manage recreation and visitation in these natural areas

Northern Bobwhite Occupancy Patterns on Multiple Spatial Scales Across Arkansas

Abstract: Northern bobwhite Colinus virginianus populations have been rapidly declining in the eastern, central, and southern United States for decades. Land use change and an incompatibility between northern bobwhite resource needs and human land use practices have driven declines. Here, we applied occupancy analyses on two spatial scales (state level and ecoregion level) to more than 5,000 northern bobwhite surveys conducted over 6 y across the entire state of Arkansas to explore patterns in occupancy and land use variables, and to identify priority areas for management and conservation. At the state level, northern bobwhite occupied 29% of sites and northern bobwhite were most likely to occur in areas with a high percentage of early successional habitat (grassland, pasture, and shrubland). The statewide model predicted that northern bobwhite were likely to occur (≥ 75% predicted occupancy) in < 20% of the state. Arkansas is comprised of five distinct ecoregions, and analyses at the ecoregion spatial scale showed that habitat associations of northern bobwhite could vary between ecoregions. For example, early successional habitat best predicted northern bobwhite occupancy in both the Arkansas River Valley and Ozark Mountains ecoregions, and other habitat associations such as the proportion of herbaceous habitat and hay-pasture habitat, respectively, further refined predictions. Contrastingly, richness of land cover classes alone best predicted northern bobwhite occupancy in the Ouachita Mountains ecoregion. Ecoregion-level models were thus more discerning than the state-level model and should be more helpful to managers in identifying priority conservation areas. However, in two of five ecoregions, surveys too rarely encountered northern bobwhite to accurately predict their occurrence. We found that likely occupied northern bobwhite habitat lay primarily on private properties (95%), but that numerous public entities own and manage land identified as suitable or likely occupied. We conclude that management of northern bobwhite in Arkansas could benefit from cooperation among state, federal, and military partners, as well as surrounding private landowners and that ecoregion-specific models may be more useful in identifying priority areas for management. Our approach incorporates multiple landscape scales when using remote sensing technology in conjunction with monitoring data and could have important application for the management of northern bobwhite and other grassland bird species

Nocturnal basking in freshwater turtles: A global assessment

Diurnal basking (“sunning”) is common in many ectotherms and is generally thought to be a behavioural mechanism for thermoregulation. Recent studies have reported the occurrence of nocturnal basking in a few distantly-related species of freshwater turtles, but the true extent of this behaviour is unknown, and it may be underreported due to sampling biases (e.g., not surveying for turtles at night). Therefore, we initiated a global, collaborative effort to systematically document and quantify basking activity (diurnal and nocturnal) across a wide range of freshwater turtle species and locations. We conducted camera trap or manual surveys in North America, the Caribbean, Europe, Asia, Africa, the Seychelles, and Australia. We collected 873,111 trail camera photographs (25,273 hrs of search effort) and obtained data on 29 freshwater turtle species from seven families. Nocturnal basking was documented in 13 species, representing six families (Chelidae, Emydidae, Geoemydidae, Kinosternidae, Pelomedusidae, and Trionychidae), including representatives in Central America, Trinidad and Tobago, Africa, the Seychelles, Asia, and Australia. Nocturnal basking was restricted to tropical and sub-tropical locations, suggesting that environmental temperature plays a role in this behaviour. However, the primary factors driving nocturnal basking are yet to be determined and may vary geographically and by species. The frequency and duration of nocturnal basking varied among species and seasons, but nocturnal basking events were often substantially longer than diurnal events. This is the first study to document a widespread occurrence of nocturnal basking, and our results suggest that nocturnal basking may be a common, although overlooked, aspect of many species’ ecology