The relative effect of top-down versus bottom-up forces in regulating
and limiting ungulate populations is an important theme in ecology.
Untangling these effects is important for basic understanding of trophic
dynamics and is critical for effective management. We integrated two
independent sources of observations to compare the drivers of moose
abundance across 55 replicated populations. Across populations, moose
declined by nearly 20% over 20 years. At high density, moose were
regulated by intraspecific competition. Predation primarily limited
population growth, except at low density, where it was regulating.
Harvest was largely additive and potentially contributed to population
decline. Our results provide strong evidence for density dependent
predation, highlighting that population dynamics are context dependent
and vary strongly across gradients in climate, forest type and predator
abundance. Consequently, management of moose would be optimized by
taking different strategies across populations in accordance with their
population trajectories and abundance of predators.