Nature is a ruthless taskmaster! For Utah’s wildlife, particularly native upland nesting birds such as the sage-grouse, that have only a few nesting seasons during their lifetime, those that are most attuned to environmental change are the ones that prosper. To survive, native birds must nest and hatch their young during brief windows when food is most plentiful.
This winter has provided Utah landscapes a temporary respite from a decade long drought. The moisture provided by snowmelt and spring rains fuels seasonal flush of nutrient rich green groceries. This flush, known as the green wave, tracks both temperature and moisture up mountain slopes. Mule deer and elk follow the green wave during their spring seasonal migrations.
For most native wildlife, spring is also the birthing season. Mule deer, elk, and sage-grouse synchronize birthing to match the period half way between the start of spring and the peak of the growing season, which provides increasingly highly nutritious food on a daily basis.
Sage-grouse broods follow the elevational wave of the green groceries to maximize forage quality through the brood-rearing season. For sage-grouse that have survived the winter feeding on sagebrush, spring is a time to recoup energy reserves and enhance nutrition for the demands associated with egg production and nesting. Newly hatched sage grouse chicks are highly vulnerable to predation, As such, they require high protein foods to grow and rapidly develop flight abilities. A diet of just sagebrush is just not enough. The green wave also provides ready availability source of animal protein, such as crickets, spiders, and ants, to support chicks through these critical first weeks of life.
Researchers at Utah State University used satellite imagery from NASA to map the green wave They used the imagery to measure the timing, magnitude, and duration of the growing season. Even given all the variability in weather, land-use, and disturbances, sage-grouse initiated nesting precisely half way between the start and peak of the growing season regardless of where they lived in Utah. This window captures the period when food resources are increasing and diversifying on a daily basis.
So, what does this mean for Utah’s wildlife? Unfortunately, the arid ecosystems of the West are changing. The conservation of sage-grouse and all native wildlife depends on minimizing disturbances while maximizing wildlife access to the green wave.
More information at Utahcommunitybasedconservation.org
