HABITAT SELECTION AND AVOIDANCE BEHAVIOR OF FEMALE GREATER SAGE-GROUSE RAISING YOUNG IN AN OIL AND GAS FIELD
Christopher P. Kirol and Bradley C. Fredy
First published 09 November 2023
Using individual-based habitat selection analyses to understand the nuances of habitat use in an anthropogenic landscape: a case study using greater sage-grouse trying to raise young in an oil and gas field.
In the early 2000’s, coalbed-methane development was in full boom with companies drilling around 3000 wells per year in the Power River Basin, in northeastern Wyoming. With the development of some 30,000 wells, came the construction of thousands of miles of new roads, pipeline corridors, overhead power lines and hundreds of waste-water storage reservoirs, all of which crisscrossed Greater Sage-grouse sagebrush shrubland habitat in northeastern Wyoming. Twenty-three years later only a small portion of coalbed-methane wells have been reclaimed, even though many of them are no longer producing gas. The network of thousands of miles of overhead power lines also largely remain. Many of these lines feeding power to wells that are no longer producing or have been abandoned (“orphaned wells”).
Greater Sage-grouse populations are gauged by annual counts of males at communal Sage-grouse displaying sites, known as leks. Sage-grouse return to these leks year after year in the spring. These annual lek counts have shown that average male lek attendance in northeastern Wyoming has decreased significantly over time and decreased by about half over the last 30 years. During this same timeframe many Sage-grouse leks have become inactive.
A recently published study, sought to explore habitat use and movements of female Sage-grouse raising young in this oil and gas landscape. To accomplish this, the authors fit GPS transmitters on female Sage-grouse in northeastern Wyoming that gathered high-frequency location data (a GPS location every 4 hours).
Chick survival is critical to population persistence in Sage-grouse and a large amount of research has shown that Sage-grouse chick survival is lower in fragmented sagebrush landscapes which is likely due to chicks being more vulnerable to predation in these landscapes. The intent of this study was to understand how females trying to raise chicks responded when they encountered infrastructure, like overhead power lines and wells, and converted habitat, like roads and pipeline corridors. These hens are trying to lead their chicks to food (insects and forbs), needed for the chicks to grow and survive, while at the same time, trying to keep their chicks hidden from mammal and bird predators.
The researchers found that Sage-grouse hens with chicks demonstrated strong avoidance of power lines and waste-water reservoirs, both of which are widespread in the Powder River Basin. However, the hens were not avoiding the 3 m tall coal-bed natural gas well structures unless these wells were at high densities. The authors suggest that the avoidance of power line corridors and reservoirs by female Sage-grouse raising young is likely a response to predation risk. Power lines are tall structures that can provide perches for hunting raptors or ravens and reservoirs are areas where many mammal predators congregate, like striped skunks that establish home ranges around water bodies. The data shows that hens with chicks were spending most of their time in sagebrush cover and not using converted habitat, such as roads and pipeline corridors. Older hens were showing stronger avoidance of infrastructure and converted habitat than first-year hens, which suggests hens are learning to avoid these areas. The primary issue with avoidance of infrastructure and converted habitat is that it dramatically shrinks the amount of habitat that is available to female Sage-grouse and their chicks. This is known as functional habitat loss. This research emphasizes the importance of removing overhead power lines, reclaiming waste-water reservoirs and the need to reestablish sagebrush shrubs on converted surfaces, such as pipeline corridors, so they may again provide habitat for Sage-grouse hens and chicks.