Bias associated with baited camera sites for assessing population characteristics of deer

Abstract

Camera surveys often involve placing bait in front of the camera to capture animals more frequently, which could introduce biases in parameter estimates. From September 2008 to March 2009, we monitored cameras placed at random, along game trails, and at feed stations to determine if camera placement influenced measures of population demographics in a herd of white‐tailed deer (Odocoileus virginianus). There was no time period in which cameras placed at feed stations provided sex ratio and recruitment estimates similar to those acquired from randomly placed cameras. Trail‐based camera surveys provided population estimates similar to those from random sites and may provide a feasible alternative to using baited camera stations. © 2011 The Wildlife Society.

Detection Probabilities of Ungulates in the Eastern Swaziland Lowveld

“…We would caution managers from translating spotlight counts into population estimates for stocking rates or other purposes but if they do we would suggest doubling their estimated abundance for very coarse and conservative estimates . We believe a better approach would be to use spotlight data in conjunction with other monitoring methods such as vegetation monitoring, camera surveys, or a variety of other methods (Kraaij & Milton 2006;Ditchkoff 2007;McCoy et al 2011) focused on conditions of the grassland savanna. Additionally, although perhaps cost prohibitive, use of thermal imagers seems to provide a less biased estimate of detection probabilities for ungulates, thus managers could potentially consider thermal imaging for surveying ungulates in African savanna.…”

Accessing camera trap survey feasibility for estimating Blastocerus dichotomus (Cetartiodactyla, Cervidae) demographic parameters

“…Despite the fact that white-tailed deer males can travel twice as far as females in a day (Webb et al, 2010) no bias was observed in detectability by sex or recapture rates for males and females (Roberts et al, 2006;Watts et al, 2008). McCoy et al (2011), highlighting that the main reason for sexual bias corresponds to different responses to bait attraction. Studies that do not use bait have determined sex ratios using camera traps without further discussion (Shields et al, 2012;Ikeda et al, 2013).…”

Monitoring population density and activity pattern of white-tailed deer (Odocoileus virginianus) in Central Mexico, using camera trapping

“…We did not use bait in the study, as it is subject to controversy (Mccoy et al 2011). Some argue that using bait may overestimate the number or sex of deer, by attracting individuals from other territories (Jacobson et al 1997, Roberts et al 2006.…”

“…The most commonly used monitoring techniques rely on indirect methods, such as track and pellet-group counts (Mooty and Karns 1984, Mandujano 2005, Ortíz et al 2005, Reyna-Hurtado and Tanner 2007, Sánchez-Rojas et al 2009). However, these methods are sensitive to habitat, terrain conditions, and the need for trained personnel; further, they do not provide information regarding age structure or sex ratio (Novak et al 1991, Smallwood and Fitzhugh 1995, Mccoy et al 2011). On the other hand, aerial counts, spotlight surveys, thermal imaging, as well as direct counts on foot or in vehicles, are costly, as well as being restricted to open zones and specific seasons (Jacobson et al 1997, Dellafiore et al 2003, Roberts et al 2006, Collier et al 2007).…”

“…Nowadays, camera trapping is used to estimate densities and activity patterns of mid-sized and large mammals ( Van-Schaik and Griffiths 1996, Maffei et al 2002, Pinto and Andriolo 2005, Tobler et al 2009, MonroyVilchis et al 2011a. Camera traps are beneficial for a variety of reasons; being noninvasive, abundance data are obtained in short sampling periods, and the financial costs are lower than the traditional method of capturing and recapturing the individuals (Karanth 1995, Jacobson et al 1997, Soria-Díaz et al 2010, Mccoy et al 2011.…”