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Rubs

Nobody really knows the biological reason for signpost rubs, but they do appear to be "pheromone wicks" where bucks leave the scent from their forehead glands on the tree. Each subsequent deer that visits the rub sniffs and licks these pheromones. Exactly what these pheromones do is the question. It has been known for years that older more dominant bucks produce different pheromones than younger subordinate bucks, and the presence of an older buck in the herd reduces testosterone production in young bucks, lessening their desire to breed (a good thing biologically). I remember one study with deer in several acre enclosures where a real signpost rub was cut down and placed in the enclosure with young bucks. Having the signpost where the young bucks could interact with it had the exact same result as actually having a dominant buck in the enclosure - the young bucks testosterone production immediately declined. So it appears that signpost rubs serve the same purpose as having a dominant buck actually in the area. Deer appear to use signpost rubs to spread their "chemical influences" (pheromones) around without having to be close by.

For me, an even bigger question is "What is the difference chemically between a signpost rub and a scrape?" Both are primarily buck-to-buck communication devices, helping to establish and spread social hierarchy, but also appear to help time estrus in female groups. So why the two different behaviors, and what different chemicals are involved?
 
BSK said:
I don't think the size of rubbed signposts are misleading at all, except for the fact once created every buck in the area will work them, including little yearling spikes. Hunters see or get a picture of a little spike working the huge signpost and think, "See, big rubs mean nothing." Actually, some big old buck created that signpost, so having it around means there are some big, old bucks around.
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I was talking more about regular rubs. I do have 3 cedar trees on my property that get rubbed every year. I have owned the property for 4 years and found those trees the first time I walked the property. I have placed cams on them but always too late. There are deer of all sizes and ages that travel through my property so I am sure they all hit those rubs at some point.
 
My mistake Tanelson43. One thing I can guarantee, little rubs mean nothing. Every buck of every age and size makes little rubs. Seeing one doesn't mean a young buck made it.
 
BSK said:
For me, an even bigger question is "What is the difference chemically between a signpost rub and a scrape?" Both are primarily buck-to-buck communication devices, helping to establish and spread social hierarchy, but also appear to help time estrus in female groups. So why the two different behaviors, and what different chemicals are involved?
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I don't see them necessarily being primarily buck-to-buck communication. They're both certainly initiated by bucks and most aggressively used by bucks, but with scrapes I see at least as much doe activity as I do bucks. It's 100% two way communication.....with some caveats. Before breeding takes place I see does rub their faces on licking branches, and often they urinate or defecate while doing so. I've even seen them pause in place for a little while so they could defecate at the scrape. However, after they get bred they tend to ignore scrapes. It always seems to be the oldest does first, with younger does being interested further into the season, and fawns staying interested all the way through. So it appears that a doe's interest in the scrape is reliant, as you say, on her estrus cycle. Up until she's bred it has been my observation that she actively communicates through the scrape almost as if she's reporting her current status to the buck(s).

Coincidentally(or not), when the matriarch does begin ignoring scrapes is also about when I notice a drop in scrape activity and soon after a turnover of bucks. Bucks that were around pre-rut through first phase of breeding largely disappear and new bucks begin showing up. Same thing repeats with younger does but it seems less intense and is drawn out until things trickle off completely. I see two rotations of bucks in fall & winter. The latest rotaton seems to always be at the end f season or after it's already closed. I always see a new big boy or two show up looking for girls after season is over, thinking to myself that I wish they were around during season. There's some kind of complex dynamic happening that I recognize but don't really understand. It's as if they're purposely diversifying genetics.

With rubs it's different. I only know of a few true legit sign post rubs, or at least busy ones, so I can't comment much because I don't know much. But of the ones I have had the pleasure of monitoring, I see does interact with them. They don't rub their heads like the bucks do, but they stop to take a whiff. They stick their noses right to the rub. I have no idea if they're leaving scent by doing that or communicating back to the bucks, but it's apparent the does are interested in the rubs. Whether the bucks are communicating something to them or only toward other bucks I don't really know. But the does do indeed pay attention. My stance for now, based on my limited knowledge, is that sign post rubs serve more as a "sign in" station for bucks while scrapes are social media dating sites.
 
Research shows that signpost rubs and scrapes (the actual scrape itself) are primarily buck-to-buck communication devices that help establish social pecking order and dominance status. However, that doesn't mean they don't also play a role with male-female communication. In signpost rub research, females were photographed sniffing and licking signpost rubs, which means they are picking up whatever pheromones are being deposited. Does were even photographed backing up to signpost rubs and rubbing their butts on them. What this means is unknown. As for scrapes (the actual scrape on the ground), they are created by bucks under traditional licking branches that are maintained year-round primarily by does. Does will completely ignore the scrape on the ground until their hormones begin to change as the breeding season approaches. In fact, I've found that does primarily ignore the scrape on the ground - only continuing to work the overhanging limb - until about 5 days before they come into estrus. Up until that time, the scrape itself, which may have been opened a month to month and a half earlier, is only worked by bucks, hence is primarily a buck-to buck communication device.

But again, signpost rubs and scrapes do play a role in estrus timing. In the north estrus timing is so critical to fawn survival that estrus timing is deeply genetically ingrained into the population. However, in the Southeast, lacking severe winter and early spring conditions, estrus timing is more fluid. Signpost rubs and scrapes appear to keep estrus somewhat earlier and definitely more tightly timed. A tightly timed estrus ensures the genetic diversity that makes whitetails such a uniquely successful species. When all of the females in a local does social group come into estrus around the same time, one buck cannot breed all of these does. This means that although all of the females in the group are related on the female side, each will produce an offspring from a different father. Again, ensuring maximum genetic diversity within localized populations.
 

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