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Loggerhead Shrike Detectability And Occurrence In Coastal South Carolina Urban Areas, Michelle Krauser May 2022

Loggerhead Shrike Detectability And Occurrence In Coastal South Carolina Urban Areas, Michelle Krauser

Electronic Theses and Dissertations

Grassland birds, such as the loggerhead shrike (Lanius ludovicianus), are threatened by extensive land-use change, including urbanization. Loggerhead shrikes have been declining since the early 1900s and are rare or extirpated in portions of their former range. Obtaining reliable population estimates of loggerhead shrikes is important to identify demographic trends and ensure conservation decisions are based on an accurate assessment of their current status. Imperfect detection, or the inability to detect every shrike during a survey, can result in biased population estimates. Estimating detection probability is labor-intensive and requires assumptions that are difficult to satisfy in most field studies. Understanding …


Detectability And Impact Of Repetitive Surveys On Threatened West African Crocodylians, Michel N. Ahizi, Christine Y. Kouman, Allassane Ouattara, N’Dri Pascal Kouamé, Azani Dede, Emilie Fairet, Matthew H. Shirley Nov 2021

Detectability And Impact Of Repetitive Surveys On Threatened West African Crocodylians, Michel N. Ahizi, Christine Y. Kouman, Allassane Ouattara, N’Dri Pascal Kouamé, Azani Dede, Emilie Fairet, Matthew H. Shirley

All Faculty

West African crocodylians are among the most threatened and least studied crocodylian species globally. Assessing population status and establishing a basis for population monitoring is the highest priority action for this region. Monitoring of crocodiles is influenced by many factors that affect detectability, including environmental variables and individual- or population-level wariness. We investigated how these factors affect detectability and counts of the critically endangered Mecistops cataphractus and the newly recognized Crocodylus suchus. We implemented 195 repetitive surveys at 38 sites across Côte d’Ivoire between 2014 and 2019. We used an occupancy-based approach and a count-based GLMM analysis to determine the …


Weather And Exposure Period Affect Coyote Detection At Camera Traps, Anastasia E. Madsen, Lucia Corral Hurtado, Joseph J. Fontaine Mar 2020

Weather And Exposure Period Affect Coyote Detection At Camera Traps, Anastasia E. Madsen, Lucia Corral Hurtado, Joseph J. Fontaine

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Abstract Camera traps are an increasingly popular means to monitor wildlife populations. However, like other techniques for measuring populations, camera traps are subject to sources of error that may bias population estimates. Past studies accounting for detection error have failed to account for a simple but potentially widely pervasive source of environmental error: weather conditions. Using 5,108,416 photographs from 804 scent‐lured camera traps deployed in western Nebraska, USA, during spring and autumn of 2014 and 2015, we analyzed the relationship between weather conditions (barometric pressure, wind speed, precipitation, and temperature) and coyote (Canis latrans) detection probability. Using binomial …


A Presence-Absence Survey To Monitor Montezuma Quail In Western Texas, Cristela Gonzalez Sanders, Fidel Hernández, Leonard A. Brennan, Andrew N. Tri, Robert Perez Nov 2017

A Presence-Absence Survey To Monitor Montezuma Quail In Western Texas, Cristela Gonzalez Sanders, Fidel Hernández, Leonard A. Brennan, Andrew N. Tri, Robert Perez

National Quail Symposium Proceedings

Developing an effective monitoring program for Montezuma quail (Cyrtonyx montezumae) is challenging because the technique must be practical for surveying vast, remote landscapes while accounting for the species’ low detectability. We used call-back surveys within a presence–absence framework to estimate occupancy and detection probability of Montezuma quail and used this information in conjunction with habitat data to develop an estimated probability of occurrence map for the species. We established survey points at 4 sites in western Texas (n = 20–30 points/site) and conducted 5 repeat surveys/season during June–August 2007 and 2008. We documented abiotic conditions (temperature, time …