The word "elk" is correct in written English.
It refers to a large species of deer found in North America and parts of Europe and Asia.
Example: "While hiking in the national park, we were fortunate enough to see a majestic elk grazing in the meadow."
Alternatives: "wapiti" or "moose" (though moose is a different species).
Park scientists once thought there could never be too many elk; there could be temporary overgrazing, but the range, they insisted, would spring back as soon as the elk died from starvation, revealing a natural equilibrium.
These showed that, over the years, elk have stripped the park of its aspen and willow stands.
Mr Boyce says that Mr Kay's pictures do not tell the whole story: although elk have been hard on these trees in some places, in others their impact is undetectable.
Only two of the nine Yellowstone elk herds winter in the park.
Will visitors really pay to see dying elk and meadows nibbled down to the roots?
Mr Kay claims that aspen in particular have suffered a 95% decline since the park opened in 1872: a serious development because beaver rely on aspen to build their dams, which in turn are vital to keep wetlands going.Park officials say that the elk are only partly to blame.
And Mr Kay himself admits that aspen groves have been deteriorating throughout the west.The feeding of elk outside the park complicates the issue.
The cold and lack of feed that drove bison out of Yellowstone last winter also killed an estimated 6,000 elk.
It is illegal in many states to hunt or scout for elk or deer from the air, but pigs are fair game.
I really feel sick," comments one under the "2013 Pig Killing Highlights" video, complete with perky soundtrack, on Louisiana Hog Control's Facebook page.Traditional hunters think it unsporting when it comes to game species such as elk.
