It is known that yearling bucks move out, even if the habitat is good. Thus, there are probably social pressures that are the cause. A 1992 study suggested that female relatives (including the mother) of the yearling buck drive him away, and in so doing reduce the chance for inbreeding. This same study showed that fawns orphaned before they reached one year of age had lower dispersal rates than those that stayed with their mother longer than one year. Hmmm. Mother present, bucks disperse. Mother absent, fewer disperse. Not only that, orphaned bucks had higher survival rates, probably because they didn’t have to leave their home range. This study then has ramifications for deer management. Remove the mothers via a harvest and you could end up with more bucks on your property.
But hold on. Another larger and more recent study done on the eastern shore of Maryland, contradicts this. In this study they observed that bucks orphaned as fawns and non orphaned bucks dispersed at the same rate. (Note, this doesn’t mean the above study was wrong, it just means that we got two different results in two different situations.) The Maryland study also found that the yearling buck-adult doe aggressive interactions were the same for those bucks that dispersed and those that stayed. From this they concluded that dispersal was not caused by maternal aggression as earlier research had showed.
The data here also showed that before quality deer management (where higher numbers of adult does are harvested, and small-antlered bucks are not harvested) there was an average per year total of 39 emigrants and 31 immigrants ... a net loss of eight yearling bucks per year via dispersal. Researchers believe this is because survival of young bucks living outside the area was low due to heavy hunting pressure, leaving fewer deer available to move into the area. After quality deer management an average of 26 bucks walked away and 37 bucks moved in ... a net gain of eleven bucks. The gain was attributed to the fact that fewer young bucks dispersed from the area. Researchers observed that 70 percent of yearling bucks walked away from their birth areas before quality deer management, while 55 percent did so after quality deer management.
Finally they noted that those bucks that dispersed were involved in more sparring activities with other yearling bucks than those that did not leave their birth places, before and after quality deer management. And they noted less sparring in general after quality deer management. What does this mean?
All young bucks push and shove, and in so doing, they learn who is dominant. However, it’s rare for a young buck to spar with an older buck. Thus, the researchers suggested that dispersal is caused by breeding competition between young bucks. That there is less sparring after quality deer management reflects that there are more old bucks around, and the little guys leave these bigger bucks alone. In addition, the presence of older bucks reduces the sparring between the yearling bucks. And it is this lower rate of sparring between yearlings that reduces dispersal rates after quality deer management.
The bottom line is that if you remove more adult does and protect the young bucks on your property, you get less dispersal, and thus will have more bucks. Just another reason to harvest more adult does.
QDM reduces buck dispersal?
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