The REAL Reason...

Behavioural ecologists examine animal behaviour from an evolutionary perspective and try to understand both the ultimate causation of a behaviour and the proximate causation of that same behaviour. The ultimate causation concerns itself with the survival value of a behaviour and how that behaviour will contribute to the reproductive fitness (think in terms of "genes left to next generation") of the animal. Proximate causation is the "here and now" immediate motivation that drives the behaviour (so, for example, an animal is motivated to eat or forages because simply because it is hungry).

The ultimate causation of male wild sheep - such as Bighorn Sheep and Dall Sheep - to engage in head-butting clashes is very well-studied. In the simplest terms, the victors "win" the right to mate with more of the receptive females (thus ensuring more of their genes are represented in the next generation than those "subordinate" sheep that lost the butting contest).

But what is the proximate causation of the head-butting? What motivates the sheep to rear up and charge at its competitor and violently clash heads? Well...this image holds the key to understanding this complex behaviour. Turns out the rams are rude as heck and stick their tongues out at their competitors. And, those competitors have very short fuses (AKA bad tempers). Mystery solved! 

Subject: Male Dall Sheep (Ovis dalli) taunting a rival?
Location: Southwest Yukon Territory, Canada
Camera: Nikon D5
Lens: Nikkor AF-S 300mm f4 PF prime lens. Hand-held. VR on and in “Sport” mode.
Exposure: 1/1250s @ f6.3; ISO 100. No compensation from matrix-metered exposure setting.
Crop: None - this is full frame

A whole lot more info about this shot - including a 2400 pixel version it - can be found on my website using the link immediately below.

http://www.naturalart.ca/galleries/latest/

Comments and critiques welcomed - probably best to view the larger version prior to doing so!

Cheers...

Brad

PS: Like all wildlife images on my website and that I post on NPN, the subject is fully wild and completely unconstrained. Besides the potential impact of my presence, nothing has been done to intentionally alter or affect the ongoing behavior of the subject and, of course, there has been no use of any form of bait or other form of wildlife attractants (including vocalizations).