Is Male-biased Collision Mortality of Whooping Cranes (Grus americana) in Florida Associated with Flock Behavior?

Abstract

We estimate that from 500 million to possibly over 1 billion birds are killed annually in the United States due to anthropogenic sources including collisions with human-made structures such as vehicles, buildings and windows, power lines, communication towers, and wind turbines; electrocutions; oil spills and other contaminants; pesticides; cat predation; and commercial fishing by-catch. Many of the deaths from these sources would be considered unlawful take under federal laws such as the Endangered Species Act, Migratory Bird Treaty Act, and the Bald and Golden Eagle Protection Act. In this paper, we summarize this literature and provide the basis for the mortality projections for many of the apparent significant sources. Most of the mortality projections are based on small sample sizes, and on studies typically lacking adjustments for scavenging and searcher efficiency biases. Although the estimates for each source often range by an order of magnitude, the cumulative mortality from all these sources continues to be a concern.

Reactions of Sandhill Cranes Approaching a Marked Transmission Power Line

“…Nonhunting mortality of sandhill cranes is poorly understood (Gerber et al 2014) beyond observations that predation is a primary cause of mortality on breeding grounds (Olsen 2004;Nesbitt et al 2008), and collisions with power lines are an important cause of mortality during migration and wintering Morkill and Anderson 1991;Murphy et al 2009). Collisions with power lines also cause mortality of species of conservation concern such as whooping crane (Miller et al 2010;Folk et al 2013;Stehn and Haralson-Strobel 2014), sarus crane Antigone antigone (Sundar and Choudhury 2005), and blue crane Anthropoides paradiseus . Because sandhill crane is ecologically and physiologically similar to other crane species, but more abundant than some at-risk species, this species can serve as a model to facilitate assessment of the effectiveness of collision mitigation measures for crane species in general (Morkill and Anderson 1991;Brown and Drewien 1995).…”