Time filter

Source Type

Texarkana, TX, United States

McCallum M.L.,117 Linda Lane
Herpetology Notes | Year: 2011

Flood induced road-mortality of wildlife is a poorly studied and understood phenomenon. In 2008, the worst flood since 1973 hit the Arkansas Delta. I previously surveyed road-killed amphibians and reptiles along interstate 40 from West Memphis to Little Rock in 2002 (189.9 km). In 2008, I re-surveyed this road and added surveys of I-44 (28.2 km) and I-30 (218 km) in Arkansas. Turtle mortality on I-30 was 15.5 times greater in 2008 (n = 124) than in 2002 (n = 8). It was 413% higher on I-40 than on I-30. I-440 only had 1 dead turtle. Species composition of road-kills in 2002 was different from in 2008. It appears that the extreme flood of 2008 forced many turtles onto the road for uninvestigated reasons. This movement resulted in unusually high road mortality. This information will be important for conservationists and planners as they deal with the extension of our highway system to serve the public's transportation demands.

I investigated the seemingly haphazard jumping pattern of Blanchard's Cricket Frog (Acris blanchardi) to determine if it was random or patterned. I approached frogs from the front (cranial), back (caudal), and side (lateral) simulating an attacking predator. On average, frogs jumped away at 135.73° (SE = 2.31°) from the direction of attack. I did not distinguish between right and left directions in this study. There were significant differences in the angle of escape among the three attack directions (F2,87 = 17.64, P < 0.001). There were no significant differences in escape angle between frogs that I approached from the front (mean = 130.4°, SE = 2.59°) or the side (mean = 126.3°, SE = 3.75°, Tukey interval: -0.261, 0.626). The angle of escape was not uniform and directional escape was around 120° across all tests. Frontal and side approaches led to escape angles near 120° but attacks from the rear resulted in two modes of escape, at about 180° and 120° from the angle of approach. These frogs have a possible blind spot in the rear of their field of vision that might explain this bimodal escape pattern in rear attacks. The tendency to jump away at an angle rather than strait away from the predator likely represents as an evolutionary compromise between an attempt to maximize angular and linear displacement from the attacking predator. This optimal strategy may demonstrate a fitness and survival advantage. © Firenze University Press.

McCallum M.L.,117 Linda Lane | Brooks C.,Texas A&M University-Texarkana | Mason R.,Texas A&M University-Texarkana | Trauth S.E.,Arkansas State University
Herpetology Notes | Year: 2011

Blanchard's Cricket Frog (Acris blanchardi) and the Northern Cricket Frog (Acris crepitans) are small frogs commonly found along water bodies in eastern North America. We determined growth and seasonal size classes from museum specimens of the Northern Cricket Frog (from Georgia and Florida) and Blanchard's Cricket Frog (from Arkansas and Missouri). We characterized the male and female reproductive phenophases of Blanchard's Cricket Frog using histological technique and gross examination and assessed its age and growth using skeletochronology. Our results show that male and female Blanchard's Cricket Frogs metamorphose in the summer, and snout-vent (SVL) length quickly reaches adult size. Body mass (BM) follows SVL with female BM growing faster than males from spring through oviposition. Male and female reproductive phenophases follow growth patterns. Some males are reproductively viable by late summer. Most ovarian development occurs in the spring and summer with oviposition occurring sometime between late May and June. Growth, reproductive and skeletochronological evidence suggest that very few Blanchard's Cricket Frogs live more than one year. The growth data for the Northern Cricket Frog was insufficient to support either semelparity or iteroparity. As a semelparous species, Blanchard's Cricket Frog may be susceptible to transient and temporary stressors that interfere with reproduction or recruitment.

Mccallum M.L.,117 Linda Lane
Herpetology Notes | Year: 2010

Evaluation of scientists according to their publication counts and the impact ratings of the journals in which they publish is growing in popularity. However, if a scientist is to be rated, it is more logical to assess the citations to its own work. This is especially true considering that fewer than half of the papers published in journals account for over half of the citations to those journals. Therefore, relatively few papers in highly rated journals are actually highly cited. There are numerous metrics used to compare authors based on their citation rates. In this study, I analyzed a random sample of herpetologists appearing on the 2004 membership list of the Societas Europaea Herpetologica. I used linear regression to analyze the influence of career length and publication count on their h-score, g-score, e-score, and m-quotient. I also examined how publication count changes during the career of the average herpetologist. I verified that the h-score increases as career length of a herpetologist gets longer, but I found that the h-scores also become more variable among herpetologists with lengthy careers. The g-score followed the same pattern as the h-score, but the disparity between the h-score and g-score became wider as some papers accumulated more citations than others. The e-score reinforced the belief that h-index scores are more variable among late career herpetologists than early career herpetologists. The m-quotient remained relatively stable throughout a herpetologist's career because it is intended to control for career length. Thus, this metric can be used to compare early and late career herpetologists. Herein, I provide mean scores for each author metric for herpetologists at various career lengths. Hopefully, the data and relationships presented will be useful tools for investigators seeking to understand their development as a herpetologist and for those individuals interested in assessing a herpetologist's performance relative to others in this field.

Discover hidden collaborations