Matching Items (3)

Using Bag of Words Approach for Classifying Native Arizona Snakes in Images as Venomous or Non-Venomous

Description

Uninformed people frequently kill snakes without knowing whether they are venomous or harmless, fearing for their safety. To prevent unnecessary killings and to encourage people to be safe around venomous

Uninformed people frequently kill snakes without knowing whether they are venomous or harmless, fearing for their safety. To prevent unnecessary killings and to encourage people to be safe around venomous snakes, a proper identification is important. This work seeks to preserve wild native Arizona snakes and promote a general interest in them by using a bag of features approach for classifying native Arizona snakes in images as venomous or non-venomous. The image category classifier was implemented in MATLAB and trained on a set of 245 images of native Arizona snakes (171 non-venomous, 74 venomous). To test this approach, 10-fold cross-validation was performed and the average accuracy was 0.7772. While this approach is functional, the results could be improved, ideally with a higher average accuracy, in order to be reliable. In false positives, the features may have been associated with the color or pattern, which is similar between venomous and non-venomous snakes due to mimicry. Polymorphic traits, color morphs, variation, and juveniles that may exhibit different colors can cause false negatives and misclassification. Future work involves pre-training image processing such as improving the brightness and contrast or converting to grayscale, interactively specifying or generating regions of interest for feature detection, and targeting reducing the false negative rate and improve the true positive rate. Further study is needed with a larger and balanced image set to evaluate its performance. This work may potentially serve as a tool for herpetologists to assist in their field research and to classify large image sets.

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Date Created
  • 2017-05

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The Relationship Between Vertebral Osteology and Microhabitat and Prey-capture Methods in Snakes

Description

Vertebral osteology varies greatly among snake species. This variation may be related to specialization in microhabitat and prey-capture. Radiographs of eight preserved male specimens were taken in order to analyze

Vertebral osteology varies greatly among snake species. This variation may be related to specialization in microhabitat and prey-capture. Radiographs of eight preserved male specimens were taken in order to analyze the vertebral length and morphology of snakes which exhibit extreme characteristics in microhabitat utilization and prey-capture methods (highly arboreal, effective constrictor). This group includes two representatives each from four major families within Serpentes: Boidae, Pythonidae, Viperidae, and Colubridae. The four boids and pythons are effective constrictors, while the four vipers and colubrids are non-constricting. One specimen of each pair is highly arboreal, while the other is terrestrial. Findings support previous research in that constrictors had larger total numbers of vertebrae than non-constrictors. When average maximum adult length and morphology of axial musculature was taken into consideration, however, flexibility gained by vertebral number alone does not theoretically confer a mechanical advantage during constriction, at least among the specimens examined. All arboreal specimens had tails with a greater number of vertebrae than their con-familial terrestrial counterpart, implicating greater flexibility in the caudal region as an important characteristic for arboreality across taxa. Examination of segments of 10 vertebrae revealed that the greatest vertebral elongation occurred at the midpoint of the thoracic region. Reduction in size and length of tail vertebrae appears to occur independently of thoracic vertebrae. Colubrids, specifically, demonstrated a unique caudal vertebral elongation pattern which could potentially be advantageous for quick locomotion. These results indicate that caudal morphology may be more important in behavioral specialization than previously thought.

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Date Created
  • 2016-12

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Environmental Perceptions: An Analysis of Snake Populations Surrounding Phoenix Neighborhoods and Resident Survey Responses

Description

Urban encroachment into traditional snake territories has long been underway; likely increasing snake sightings in urban neighborhoods. With increasing overlap, I ask if the perceptions of snakes are actually influencing

Urban encroachment into traditional snake territories has long been underway; likely increasing snake sightings in urban neighborhoods. With increasing overlap, I ask if the perceptions of snakes are actually influencing urban residents to say that snakes are a significant problem in their neighborhood today? I was interested in finding out whether or not there would be a positive correlation between the perception of snakes being a problem within a neighborhood and the actual number of sightings recorded. To address this, I used survey responses from 2017 regarding the risk perception of snakes from twelve neighborhoods within Maricopa County. These responses were then compared to the number of snake sightings within those same neighborhoods over a span of ten years using community science data from iNaturalist. The average results of the people who took the survey perceived that snakes were not a problem in their neighborhood. It was also found that in the outlying areas closer to natural snake habitat (desert preserves), a positive correlation between a higher survey response and a higher number of snake sightings could be seen. Overall, the conclusion of the data revealed that the perceptions of residents did not align with the actual number of snake sightings.

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Date Created
  • 2021-05