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The Relationship Between Mast Crops and Deer Harvest:

by: By Lindsay Thomas Jr., QDMA

In the 2004 hunting season, many states in both the North and the South experienced above-average mast crops. At the same time, hunters in many states are saying that the 2004 hunting season was a poor one for harvest success and overall deer sightings. In some areas, fewer sightings last season is seen as evidence of a reduced deer population and even overharvest of does. However, several studies including new research out of West Virginia suggest strongly that deer harvests, for a number of possible reasons, are always lower when mast crops are heavy.

In a 2004 issue of the Wildlife Society Bulletin, four biologists with the West Virginia Division of Natural Resources (DNR) and a statistics professor at West Virginia University published the results of their analysis of 22 years of mast-crop surveys along with big-game harvest statistics in West Virginia. Many prior studies had established that food abundance is linked to movement levels and patterns in wildlife, including deer, so the West Virginia researchers predicted they would find a negative correlation between mast crops and deer harvest — when mast crops are heavy, deer harvests are lower.

Their database for the mast crop came from annual surveys conducted each August from 1980 through 2002. For the surveys, DNR and Division of Forestry personnel around the state sampled mast crops at a range of elevations and rated the crops as abundant, common or scarce. They recorded data for nine species of hard-mast trees, mostly oaks, and nine species of soft-mast producers, including crabapple, grapes, black cherry and apple. Overall, these surveys pointed to widely fluctuating mast supplies from season to season. The best crops during the survey period came in 1983, 1984, 1989 and 1998. Mast failures occurred at five-year intervals during the survey, with the worst years being 1982, 1992, 1997 and 2002.

The mast survey information was then compared against eight different big-game combinations, including total white-tailed deer harvest, buck harvest, doe harvest, archery whitetail harvest, muzzleloader whitetail harvest, plus turkey season and bear archery and gun seasons. Each was compared to five different mast combinations: all oaks, oak and hickory, all hard mast, all hard mast plus black cherry, and soft mast.

Negative relationships between mast crops and deer harvest were plainly seen in the data, bearing out the predictions of the researchers. Of all the mast combinations, bumper crops of oak mast were most strongly related to the total deer harvest — deer harvests were lower in years with heavy oak mast crops. Oak mast was also seen as having a strong negative correlation with the archery deer harvest and the harvest of antlerless deer. The combination of oak and hickory mast had a moderate negative correlation to whitetail harvests, and the correlation was less clear for “all hard mast” and the “hard mast plus black cherry” combinations, except in the case of the archery deer harvest. For archers, the combination of all hard mast plus black cherry was strongly tied to harvest success.

Interestingly, the researchers saw no correlation worth mentioning between soft-mast crops and whitetail harvest success of any kind, not even archery, even though the West Virginia archery season opens in mid-October when some soft mast is still available.

No mast combination, not even oak mast, had a significant correlation to the harvests achieved during the annual, two-week buck-only season beginning the Monday of Thanksgiving week. The researchers hypothesized that high hunter numbers and heavy hunting pressure during the first three days of the buck-only season (the most popular three days of deer season each year) were enough to overcome the mast-crop factor in bumper years. With so many hunters in the woods for a short period of time, it did not matter if bucks were not concentrated around moderate or scarce food supplies.

However, for the week-long antlerless hunting season that followed the buck-only season, the correlation in heavy oak-mast years re-emerged. Then it diminished again for the week after that, the muzzleloader season.

The West Viriginia researchers concluded that it was reasonably safe for West Viriginia DNR to make predictions about deer harvests each year based on the August mast-crop surveys. If oak mast is heavy, hunters can expect less concentration of deer feeding activity, less use of food plots while mast supplies last, less deer movement and more man hours required to bring home meat for the freezer.


About the Author: Lindsay Thomas Jr. is the managing editor of Quality Whitetails magazine, the journal of the Quality Deer Management Association.