Because antler growth depends fundamentally on health and nutrition as well as age and size, antlers are among the most plastic of all bones. You might be able to appreciate this fact from this photo (courtesy Jon McGowan) showing diversity in English Roe deer Capreolus capreolus, yet even the diversity shown here is far from comprehensive.
Roe deer actually have particularly odd antlers. In addition to a prominent coronet (the roughened ‘lip’ at the antler’s base that separates it from the bony pedicle), and brow, back and top tines (or points) arranged along the rack, they sport weird gnarly spicules termed pearls at the antler base. The distribution, size and extent of these pearls is highly variable, as you can see from the photo.
Roe usually possess three points per antler. Exceptional individuals have been recorded with very long top points and no back points. Such individuals are able to stab an opponent with greater effect that is usual and there have been cases in which individuals have broken into the skull of a competitor. Normal roes may stab competitors anyway if they’re unlucky enough to fall over and become pinned on their sides, but such events are rare. On the subject of rare things, antler plasticity sometimes means that you get real freaks, like the Roe deer shown here with coalesced antlers. Very weird, and very rare. Whether this individual could function normally in sparring and fighting I have no idea.
Incidentally, moose antlers have recently been shown to play a possible role in hearing as the massive palmate antler surfaces seem to act as parabolic reflectors (Bubenik & Bubenik 2008): do note that this may only apply to moose, not to most or all deer.
Went to a neat talk by Dominic Couzens the other day (his most recent book is titled 100 Birds To See Before You Die). Would talk about it but don’t have time. In fact, still haven’t had time to do any proper article-writing recently, just too busy with other stuff.
Refs – –
Bubenik, G. A. & Bubenik, P. G. 2008. Palmated antlers of moose may serve as a parabolic reflector of sounds. European Journal of Wildlife Research 54, 533-535.