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Amy Yackel

Publications and source records attributed to Amy Yackel.

7 recordsLinked to original sources
USGS2018

Evaluating airsoft electric guns for control of invasive brown treesnakes

Firearms are often used in lethal control of invasive vertebrates, but safety and regulatory aspects limit the circumstances under which they can be used. During August 2016 at the Brown Treesnake Project laboratory on Guam, we evaluated hobby‐grade Airsoft Electric Guns (AEGs)—a lower powered, less‐hazardous, and less‐regulated alternative to firearms—for capture and control of small animals, with specific emphasis on invasive brown treesnakes ( Boiga irregularis ). Tests of AEGs differing in power with ammunition (plastic pellets) masses ranging from 0.20 to 0.39 g, fired at gelatin blocks from distances of 4, 8, and 12 m, showed that heavy ammunition is of overriding importance for maximizing lethality: 0.39‐g pellets penetrated more deeply at 12 m than did 0.20‐g pellets at 4 m. Inspection of tissue damage in brown treesnake carcasses subjected to fire with the 0.39‐g ammunition from the same distances suggested that injuries sustained by a direct hit from 12 m would often be lethal, and snakes would be unlikely to survive multiple hits from automatic fire discharged at approximately 17/s. Limited trials with live snakes helped us to understand behavioral responses in a snake hit by ≥1 pellets, including distance traveled over time. Based on these factors, we assessed the risk that a snake injured by pellet fire might evade subsequent capture by rapid responders in the proximity. We also discuss ethical considerations and regulatory advantages of using AEGs. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Wildlife Society Bulletin↗
USGS2018

Modeling the distributions of tegu lizards in native and potential invasive ranges

Invasive reptilian predators can have substantial impacts on native species and ecosystems. Tegu lizards are widely distributed in South America east of the Andes, and are popular in the international live animal trade. Two species are established in Florida (U.S.A.) - Salvator merianae (Argentine black and white tegu) and Tupinambis teguixin sensu lato (gold tegu) – and a third has been recorded there— S. rufescens (red tegu). We built species distribution models (SDMs) using 5 approaches (logistic regression, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy) based on data from the native ranges. We then projected these models to North America to develop hypotheses for potential tegu distributions. Our results suggest that much of the southern United States and northern México probably contains suitable habitat for one or more of these tegu species. Salvator rufescens had higher habitat suitability in semi-arid areas, whereas S. merianae and T. teguixin had higher habitat suitability in more mesic areas. We propose that Florida is not the only state where these taxa could become established, and that early detection and rapid response programs targeting tegu lizards in potentially suitable habitat elsewhere in North America could help prevent establishment and abate negative impacts on native ecosystems.

Scientific Reports↗
USGS2016

Extremes of heat, drought and precipitation depress reproductive performance in shortgrass prairie passerines

Climate change elevates conservation concerns worldwide because it is likely to exacerbate many identified threats to animal populations. In recent decades, grassland birds have declined faster than other North American bird species, a loss thought to be due to habitat loss and fragmentation and changing agricultural practices. Climate change poses additional threats of unknown magnitude to these already declining populations. We examined how seasonal and daily weather conditions over 10 years influenced nest survival of five species of insectivorous passerines native to the shortgrass prairie and evaluate our findings relative to future climate predictions for this region. Daily nest survival ( n = 870) was best predicted by a combination of daily and seasonal weather variables, age of nest, time in season and bird habitat guild. Within a season, survival rates were lower on very hot days (temperatures ≥ 35 °C), on dry days (with a lag of 1 day) and on stormy days (especially for those species nesting in shorter vegetation). Across years, survival rates were also lower during warmer and drier breeding seasons. Clutch sizes were larger when early spring temperatures were cool and the week prior to egg-laying was wetter and warming. Climate change is likely to exacerbate grassland bird population declines because projected climate conditions include rising temperatures, more prolonged drought and more intense storms as the hydrological cycle is altered. Under varying realistic scenarios, nest success estimates were halved compared to their current average value when models both increased the temperature (3 °C) and decreased precipitation (two additional dry days during a nesting period), thus underscoring a sense of urgency in identifying and addressing the current causes of range-wide declines.

Ibis↗
USGS2016

Vulnerability of shortgrass prairie bird assemblages to climate change

The habitats and resources needed to support grassland birds endemic to North American prairie ecosystems are seriously threatened by impending climate change. To assess the vulnerability of grassland birds to climate change, we consider various components of vulnerability, including sensitivity, exposure, and adaptive capacity (Glick et al. 2011). Sensitivity encompasses the innate characteristics of a species and, in this context, is related to a species’ tolerance to changes in weather patterns. Groundnesting birds, including prairie birds, are particularly responsive to heat waves combined with drought conditions, as revealed by abundance and distribution patterns (Albright et al. 2010). To further assess sensitivity, we estimated reproductive parameters of nearly 3000 breeding attempts of a suite of prairie birds relative to prevailing weather. Fluctuations in weather conditions in eastern Colorado, 1997-2014, influenced breeding performance of a suite of avian species endemic to the shortgrass prairie, many of which have experienced recent population declines. High summer temperatures and intense rain events corresponded with lower nest survival for most species. Although dry conditions favored nest survival of Burrowing Owls and Mountain Plovers (Conrey 2010, Dreitz et al. 2012), drought resulted in smaller clutch sizes and lower nest survival for passerines (Skagen and Yackel Adams 2012, Conrey et al. in review). Declining summer precipitation may reduce the likelihood that some passerine species can maintain stable breeding populations in this region of the shortgrass prairie.

Conference Paper↗
USGS2016

Phrynosoma hernandesi (Greater Short-Horned Lizard). Commensalism

Commensalism is a relationship between two organisms whereby one benefits without negatively affecting the other. Like other horned lizards, Phyrnosoma hernandesi feeds primarily on ants, but will take other insects (Powell and Russell 1983. Can. J. Zool. 62:428–440). Here we describe apparent com-mensalism between P. hernandesi and Lark Buntings (Calamo-spiza melanocorys).

Herpetological Review↗