Aerial Surveys for Estimating Wild Turkey Abundance in the Texas Rolling Plains

Abstract

: Aerial surveys have been used to estimate abundance of several wild bird species including wild turkeys (Meleagris gallopavo). We used inflatable turkey decoys at 3 study sites in the Texas Rolling Plains to simulate Rio Grande wild turkey (M. g. intermedia) flocks. We evaluated detectability of flocks and errors in counting flock size during fixed‐wing (Cessna 172) aerial surveys using logistic and linear regression models. Flock detectability was primarily influenced by flock size and vegetative cover, and errors in counting flock size were primarily influenced by size of flocks. We conducted computer simulations to evaluate the accuracy and precision of fixed‐wing aerial surveys and examined power to detect trends in population change. Our simulations suggested abundance estimates from fixed‐wing aerial surveys may be underestimated by 10‐15% (2.0‐4.8% CV). Power analyses suggested that fixed‐wing aerial surveys can provide sufficient power (>0.80) to detect a population change of 10‐25% over a 4‐5‐year period. We concluded fixed‐wing aerial surveys are feasible on ecoregion scales.

Detectability of lesser prairie‐chicken leks: A comparison of surveys from aircraft

“…We also found that lek detectability increased with lek size. Butler et al (2007) reached a similar conclusion, reporting that flock size of wild turkeys ( Meleagris gallopavo ) played an important role in aerial survey detectability.…”

“…Beyond platform, we had a balanced model set including distance from the transect to the lek, survey date, lek type, lek size, and the platform × distance interaction as covariables. The platform × distance interaction was necessary because a strip approximately 100‐m wide was not viewable directly below the fixed‐wing aircraft causing a suspected difference in the slope of detection functions between the fixed‐wing aircraft and the helicopters (Butler et al 2007). We used SPSS® 16.0 (SPSS, Inc., Chicago, IL) to analyze the data and Akaike's Information Criterion corrected for small sample size (AIC c ) to evaluate the model set.…”

“…Calculating precise distances was possible because we surveyed areas with known coordinates at the center of each lek. In an applied setting, it would be necessary to use laser range‐finders from helicopters or streamers on struts from fixed‐wing aircraft to obtain distances to leks (Guenzel 1997; Butler et al 2007, 2008). We generated a standardized survey date value by assigning the day of our earliest survey date, 8 March, as standardized date value zero and consecutively numbered until our latest survey date, 17 May, which received a value of 70.…”

An approach for using off-the-shelf object-based image analysis software to detect and count birds in large volumes of aerial imagery

“…They are commonly used to survey waterbirds (Kingsford and Porter 2009), as well as raptors (Good et al 2007) and upland game birds (Butler et al 2007). Bird identification and counts are performed either in real time by airborne observers or using on-board cameras to collect aerial imagery that is reviewed and analyzed later.…”

Point-Based Mark-Recapture Distance Sampling

“…Detection heterogeneity due to variation in vocalizations or visual cues is difficult to model and mark-recapture data will likely be dominated by the most detectable birds that were detected by both observers. This heterogeneity effect will typically increase with distance and models using only mark-recapture are likely to conclude that detection probability does not decrease with distance (Alldredge et al 2006;Butler et al 2007).…”