Elk Research · By Josh Forcier · 8 min read · Updated 2026-09-30
The Elk Forage Maturation Study: Why Green Feed Moves With Elevation and Aspect
What Hebblewhite et al. 2008 says about elk following forage quality, biomass, slope aspect, and elevation.
Hebblewhite, Merrill, and McDermid tested the forage maturation hypothesis in a partially migratory elk population in the Canadian Rockies. Their 2008 Ecological Monographs paper is "A multi-scale test of the forage maturation hypothesis in a partially migratory ungulate population" (DOI: 10.1890/06-1708.1).
For hunters and digital scouters, the study gives a useful way to think about feed: elk are not simply looking for the greenest-looking opening. They are balancing forage quality, forage amount, timing, elevation, and movement costs.
Elk are tracking a moving food window
Young plants can be high quality, but very low biomass may not provide enough intake. Mature forage can offer more volume but lower quality. The forage maturation hypothesis focuses on that middle window where quality and quantity line up. In this study, migrant elk selected that middle window, while resident elk chose the most forage available.
That means feed changes across the season. The best meadow in June may not be the best meadow in September, and the best archery feed may not be the best late rifle feed.
Elevation and aspect help predict timing
The study modeled how the growing season varied across elevation and aspect. South aspects tend to advance earlier and higher elevations delay the start of plant growth, while north aspects keep forage in a different stage later into the season.
On a map, this supports comparing slopes by sun exposure and elevation rather than treating every opening the same. Early seasons often reward attention to cool, higher, or shaded feed pockets that are still attractive, while late seasons may shift value toward sun, snow relief, and accessible calories.
Migratory and resident elk may solve feed differently
The paper compared migratory and resident elk, which is a useful reminder that not every herd uses the same strategy. Some elk move long distances to track forage. Others solve the same problem inside a smaller seasonal range.
For hunting, avoid assuming all elk in a unit leave or arrive at the same time. Search for local feed-security systems too: benches above parks, small openings inside timber, burns near bedding cover, and drainages that hold water and green vegetation longer.
What the study measured
The study followed 119 female elk from the Ya Ha Tinda herd, in and next to Banff National Park, during the 2002, 2003, and 2004 growing seasons. Plant growth started almost 50 days later for every 1,000 meters of elevation gain and 8 days earlier on south aspects than on flat and north aspects, and forage biomass peaked 17.2 days later on north aspects than on flat ground. Migrant elk selected lower forage biomass than residents and were exposed to forage averaging 6.5% higher in digestibility over the summer. The work covered one Alberta herd in three summers, so it cannot tell you what stage the forage in a given meadow will be in on your hunt dates.
How to scout with this study
Build a feed timeline. Mark low south-facing openings, mid-elevation parks, north-facing pockets, burns, riparian strips, and high basins. Then ask which one should be in the right forage stage for your hunt dates.
Compare aspect, elevation, burn age, water, and cover when you mark feed on the map. An opening is more useful when its forage timing fits the hunt and elk have a covered route to it.
Sources and scope
The linked paper reports results for its study animals, location and observation period. The scouting suggestions here are RidgeRead’s interpretation, not field validation of the app or a guarantee of the same behavior elsewhere.