Geology topics

Robert A. McCleery

Publications and source records attributed to Robert A. McCleery.

12 recordsLinked to original sources

USGS2026

Not so fatal attraction: Captive female Burmese Python lures do not improve wild python detection

The ongoing invasion of Python bivittatus (Burmese Python; henceforth, Python) across the Greater Everglades Ecosystem (GEE) has led to near total collapse of the affected mammal community over the past few decades. Management efforts to eliminate Pythons and control their spread have been hampered by the Python's low detectability, which may be improved by using a lure. In controlled settings, male Pythons show an attraction to the scent from reproductively active females. To test the effectiveness of using reproductively active female Pythons as a lure for attracting wild male Pythons in the field, we conducted a paired experiment with wild-caught female Pythons in pens and empty control pens. We monitored Python visitation at all sites using camera traps, which resulted in >3,000,000 photographs that we filtered to 4 independent detections of Pythons using AI software. Python detection was low at sites with female Pythons (3 observations) and control sites (1 observation) over 90 days at 12 sites. Stress associated with captivity may have halted reproductive females from producing pheromones, eliminating the chemosensory cue that lures males. Identifying and implementing husbandry techniques to reduce stress in wild-caught female Pythons could improve the effectiveness of this technique. Little is currently known about the chemical ecology of Pythons, and pheromonal communication in particular, and further research in this area could aid in the identification and production of effective, low-cost lures to increase detection and removal of this invasive species.

Florida↗

USGS2025

Mammalian scent lures fail to increase detections of invasive Burmese pythons (Python bivittatus)

Burmese pythons ( Python bivittatus ) are large constricting snakes native to Southeast Asia that have invaded the Greater Everglades Ecosystem in South Florida, USA. Pythons have caused precipitous declines in native mammals and are exceedingly difficult to detect using traditional methods such as scout snakes, detection dogs, and visual surveys. Live mammal lures have previously been used to attract pythons, with rabbits outperforming rodents in increasing detection. While live mammal lures can increase python detection and identify hotspots of python activity, ensuring animal welfare and logistical challenges limit their utility. As part of this study, field experiments were conducted to determine if mammalian lures, derived from rabbits (feces, urine, and hair) could replace live mammals and increase the detection of pythons. We ran trials for 84 days from June to September 2022 for 21 paired plots across three study sites in the Greater Everglades. We monitored two groups, the treatment (i.e., rabbit scent) and control (i.e., soil) with camera traps on a 1-minute time lapse. We detected 11 pythons during our study, but there was no difference between controls with soil ( n = 7) and treatments (n = 4). However, we did find that scent lures increased native snake detection. This pattern was best explained by an increased number of rodents at the scent lures. Our experiment indicates that mammalian scent lures alone are insufficient to attract pythons. Since live mammals can attract pythons, but scent lures cannot, future studies could examine if a multi-faceted lure combining several stimuli (i.e., heat, visual, movement) might increase python detection.

Florida↗

USGS2025

Object detection-assisted workflow facilitates cryptic snake monitoring

Camera traps are an important tool used to study rare and cryptic animals, including snakes. Time-lapse photography can be particularly useful for studying snakes that often fail to trigger a camera's infrared motion sensor due to their ectothermic nature. However, the large datasets produced by time-lapse photography require labor-intensive classification, limiting their use in large-scale studies. While many artificial intelligence-based object detection models are effective at identifying mammals in images, their ability to detect snakes is unproven. Here, we used camera data to evaluate the efficacy of an object detection model to rapidly and accurately detect snakes. We classified images manually to the species level and compared this with a hybrid review workflow where the model removed blank images followed by a manual review. Using a ≥0.05 model confidence threshold, our hybrid review workflow correctly identified 94.5% of blank images, completed image classification 6× faster, and detected large (>66 cm) snakes as well as manual review. Conversely, the hybrid review method often failed to detect all instances of a snake in a string of images and detected fewer small (<66 cm) snakes than manual review. However, most relevant ecological information requires only a single detection in a sequence of images, and study design changes could likely improve the detection of smaller snakes. Our findings suggest that an object detection-assisted hybrid workflow can greatly reduce time spent manually classifying data-heavy time-lapse snake studies and facilitate ecological monitoring for large snakes.

Florida↗

USGS2025

Navigating new threats: Prey naivete in native mammals

1. Invasive predators pose a substantial threat to global biodiversity. Native prey species frequently exhibit naïveté to the cues of invasive predators, and this phenomenon may contribute to the disproportionate impact of invasive predators on prey populations. However, not all species exhibit naïveté, which has led to the generation of many hypotheses to explain patterns in prey responses. These hypotheses primarily fall into two categories: system-centric hypotheses related to biogeographic isolation (BIH) and species-centric hypotheses, like the arche type similarity hypothesis (ASH). 2. We tested the predictions of these hypotheses by assessing the response of the common raccoon ( Procyon lotor ) and hispid cotton rat ( Sigmodon hispidus ), two native mammal species with divergent snake predation histories, to the cues of the invasive Burmese python ( Python bivittatus ) in the Florida Everglades (USA). Using giving-up densities (GUDs), we assessed the responses of both cotton rats and raccoons to life-size replicas of Burmese pythons and two North American predators eastern diamondback rattlesnakes ( Crotalus adamanteus ) and coyotes ( Canis latrans ). 3. Although cotton rats increased their GUD in the presence of all three predators relative to the novel-object control, raccoons only increased their GUD in coyote treatments. 4. These results align with the predictions of the ASH but not the BIH, and mirror observed patterns of population declines in invaded areas of the Florida Everglades. 5. More broadly, our findings suggest that naïveté may contribute to the vulnerability of some species to invasive predators even in large continental systems

Florida↗

USGS2024

Ecological function maintained despite mesomammal declines

Mid-sized mammals (i.e., mesomammals) fulfill important ecological roles, serving as essential scavengers, predators, pollinators, and seed dispersers in the ecosystems they inhabit. Consequently, declines in mesomammal populations have the potential to alter ecological processes and fundamentally change ecosystems. However, ecosystems characterized by high functional redundancy, where multiple species can fulfil similar ecological roles, may be less impacted by the loss of mesomammals and other vertebrates. The Greater Everglades Ecosystem in southern Florida is a historically biodiverse region that has recently been impacted by multiple anthropogenic threats, most notably the introduction of the Burmese python ( Python molurus bivittatus ) . Since pythons became established, mesomammal populations have become greatly reduced. To assess whether these declines in mesomammals have affected two critical ecosystem functions—scavenging and frugivory—we conducted experiments in areas where mesomammals were present and absent. We did not observe significant differences in scavenging or frugivory efficiency in areas with and without mesomammals, but we did observe significant differences in the communities responsible for scavenging and frugivory. Despite the observed evidence of redundancy, the changes in community composition could potentially lead to indirect consequences on processes like seed dispersal and disease dynamics within this ecosystem, emphasizing the need for further study.

Florida↗

USGS2024

Mammalian lures monitored with time-lapse cameras increase detection of pythons and other snakes

Background Enhancing detection of cryptic snakes is critical for the development of conservation and management strategies; yet, finding methods that provide adequate detection remains challenging. Issues with detecting snakes can be particularly problematic for some species, like the invasive Burmese python ( Python bivittatus ) in the Florida Everglades. Methods Using multiple survey methods, we predicted that our ability to detect pythons, larger snakes and all other snakes would be enhanced with the use of live mammalian lures (domesticated rabbits; Oryctolagus cuniculus ). Specifically, we used visual surveys, python detection dogs, and time-lapse game cameras to determine if domesticated rabbits were an effective lure. Results Time-lapse game cameras detected almost 40 times more snakes ( n = 375, treatment = 245, control = 130) than visual surveys ( n = 10). We recorded 21 independent detections of pythons at treatment pens (with lures) and one detection at a control pen (without lures). In addition, we found larger snakes, and all other snakes were 165% and 74% more likely to be detected at treatment pens compared to control pens, respectively. Time-lapse cameras detected almost 40 times more snakes than visual surveys; we did not detect any pythons with python detection dogs. Conclusions Our study presents compelling evidence that the detection of snakes is improved by coupling live mammalian lures with time-lapse game cameras. Although the identification of smaller snake species was limited, this was due to pixel resolution, which could be improved by changing the camera focal length. For larger snakes with individually distinctive patterns, this method could potentially be used to identify unique individuals and thus allow researchers to estimate population dynamics.

Florida↗

USGS2023

Compensatory mortality explains rodent resilience to an invasive predator

Invasive Burmese pythons ( Python bivittatus ) in the Everglades of Florida, United States, have drastically reduced populations of mammals, yet populations of some rodents appear unaffected by the invasion. To understand this pattern, we radio-tagged cotton rats ( Sigmodon hispidus ) in areas of high and low python occurrence densities (hereafter occurrence) and quantified the effects of python occurrence, seasonality, and sex on their survival and cause-specific mortality. Cotton rat survival was not influenced by difference in python occurrence (hazard ratio = 1.32, 95% CI = 0.77–2.26, P = 0.30). However, cotton rats were at greater risk from mortalities caused by mammals in areas of low python occurrence. In areas with elevated python occurrence, we attributed most cotton rat mortalities to birds of prey (48.6%) and reptiles (non-python = 24.3%, python = 16.2%). Where python occurrence was relatively low, we attributed cotton rat mortalities to native reptilian (28.6%), avian (35.7%), and mammalian predators (35.7%) with no python-related deaths. In total, pythons were responsible for 11.8% of all cotton rat mortalities. Finding no difference in the survival of cotton rats, despite differences in the causative agents of mortality, suggests that predation pressure from an invasive predator was compensatory for cotton rat population dynamics. This type of compensatory mortality is common for small mammals and helps explain why mammal communities in python-invaded portions of the Greater Everglades Ecosystem are increasingly dominated by cotton rats and other rodents.

Journal of Mammalogy↗

USGS2023

Burmese pythons in Florida: A synthesis of biology, impacts, and management tools

Burmese pythons ( Python molurus bivittatus ) are native to southeastern Asia, however, there is an established invasive population inhabiting much of southern Florida throughout the Greater Everglades Ecosystem. Pythons have severely impacted native species and ecosystems in Florida and represent one of the most intractable invasive-species management issues across the globe. The difficulty stems from a unique combination of inaccessible habitat and the cryptic and resilient nature of pythons that thrive in the subtropical environment of southern Florida, rendering them extremely challenging to detect. Here we provide a comprehensive review and synthesis of the science relevant to managing invasive Burmese pythons. We describe existing control tools and review challenges to productive research, identifying key knowledge gaps that would improve future research and decision making for python control.

Florida↗

USGS2021

Native mammals lack resilience to invasive generalist predator

Invasive predators have caused catastrophic declines in native wildlife across the globe. Though research has focused on the initial establishment, rapid growth, and spread of invasive predators, our understanding of prey resilience to established invasive predators remains limited. As a direct result of invasive Burmese pythons ( Python molurus bivittatus ), medium- to large-bodied native mammals decreased drastically across much of southern Florida as early as 2003. By 2014, most of these mammal species were exceedingly rare within the core invasion area, while pythons expanded outward to newly invaded areas. We used python observations to delineate the core python invasion area from the more recently invaded invasion front, and we compared changes in mammal occurrence from 2014 to 2019 between these two areas. We surveyed mammal communities using camera traps and scat surveys and used these observations to quantify the changes in occurrence among mammal species. As expected, occurrence of medium- and large-bodied mammals declined within the invasion front. However, contrary to our expectation, we observed little evidence of resilience among mammals within the invasion core. Of the 15 species detected in 2019, invasive black rats were the only species to increase in occurrence within the invasion core. Additionally, we observed declines in occurrence among native rodents within the invasion core, which were previously thought to be resistant to the effects of pythons. The continued presence of invasive pythons appears to be shifting the diverse mammal communities of southern Florida to one primarily composed of invasive species.

Florida↗

USGS2017

Urbanization may limit impacts of an invasive predator on native mammal diversity

Aim Our understanding of the effects of invasive species on faunal diversity is limited in part because invasions often occur in modified landscapes where other drivers of community diversity can exacerbate or reduce the net impacts of an invader. Furthermore, rigorous assessments of the effects of invasive species on native communities that account for variation in sampling, species-specific detection and occurrence of rare species are lacking. Invasive Burmese pythons ( Python molurus bivittatus ) may be causing declines in medium- to large-sized mammals throughout the Greater Everglades Ecosystem (GEE); however, other factors such as urbanization, habitat changes and drastic alteration in water flow may also be influential in structuring mammal communities. The aim of this study was to gain an understanding of how mammal communities simultaneously facing invasive predators and intensively human-altered landscapes are influenced by these drivers and their interactions. Location Florida, USA. Methods We used data from trail cameras and scat searches with a hierarchical community model that accounts for undetected species to determine the relative influence of introduced Burmese pythons, urbanization, local hydrology, habitat types and interactive effects between pythons and urbanization on mammal species occurrence, site-level species richness, and turnover. Results Python density had significant negative effects on all species except coyotes. Despite these negative effects, occurrence of some generalist species increased significantly near urban areas. At the community level, pythons had the greatest impact on species richness, while turnover was greatest along the urbanization gradient where communities were increasingly similar as distance to urbanization decreased. Main conclusions We found evidence for an antagonistic interaction between pythons and urbanization where the impacts of pythons were reduced near urban development. Python-induced changes to mammal communities may be mediated near urban development, but elsewhere in the GEE, pythons are likely causing a fundamental restructuring of the food web, declines in ecosystem function, and creating complex and unpredictable cascading effects.

Florida↗

USGS2016

Invasive pythons, not anthropogenic stressors, explain the distribution of a keystone species

Untangling the causes of native species loss in human-modified systems is difficult and often controversial. Evaluating the impact of non-native species in these systems is particularly challenging, as additional human perturbations often precede or accompany introductions. One example is the ongoing debate over whether mammal declines within Everglades National Park (ENP) were caused by either the establishment of non-native Burmese pythons ( Python molurus bivittatus ) or the effects of other anthropogenic stressors. We examined the influence of both pythons and a host of alternative stressors—altered hydrology and habitat characteristics, mercury contamination and development—on the distribution of the marsh rabbit ( Sylvilagus palustris ), a once common mammal in ENP. Distance from the epicenter of the python invasion best explained marsh rabbit occurrence in suitable habitat patches, whereas none of the alternative stressors considered could explain marsh rabbit distribution. Estimates of the probability of marsh rabbit occurrence ranged from 0 at the python invasion epicenter to nearly 1.0 150 km from the invasion epicenter. These results support the hypothesis that invasive pythons shape the distribution of marsh rabbits in southern Florida. The loss of marsh rabbits and similar species will likely alter trophic interactions and ecosystem function within the Everglades, an internationally important hotspot of biodiversity. Further, our results suggest that non-native species can have profound impacts on mainland biodiversity.

Florida↗

USGS2015

Marsh rabbit mortalities tie pythons to the precipitous decline of mammals in the Everglades

To address the ongoing debate over the impact of invasive species on native terrestrial wildlife, we conducted a large-scale experiment to test the hypothesis that invasive Burmese pythons ( Python molurus bivittatus ) were a cause of the precipitous decline of mammals in Everglades National Park (ENP). Evidence linking pythons to mammal declines has been indirect and there are reasons to question whether pythons, or any predator, could have caused the precipitous declines seen across a range of mammalian functional groups. Experimentally manipulating marsh rabbits, we found that pythons accounted for 77% of rabbit mortalities within 11 months of their translocation to ENP and that python predation appeared to preclude the persistence of rabbit populations in ENP. On control sites, outside of the park, no rabbits were killed by pythons and 71% of attributable marsh rabbit mortalities were classified as mammal predations. Burmese pythons pose a serious threat to the faunal communities and ecological functioning of the Greater Everglades Ecosystem, which will probably spread as python populations expand their range.

Florida↗