e at Texas A&M University-Kingsville studied the effects of supplemental feeding on fawn weights. They weighed 42 fawns contained within both supplemental-fed and non-fed 200-acre enclosures. The researchers found that supplemental feeding resulted in fawn weights that were 14 to 47% higher than weights of fawns from enclosures where supplement was not provided. Interestingly, fawn weights were lowest in the enclosure with the highest deer density and highest in the enclosure with the lowest deer density.
The two Michigan researchers mentioned above, John Ozoga and Louis Verme, also found that supplementation greatly increased deer numbers, by improving both fawn production and survival, and by increasing buck survival during the post-rut.
Feeding Fawns and Does
Unfortunately, fawn production and survival could no doubt be further improved with supplementation if it were easier to get feed to fawns and does. At typical feeder densities of around one feeder per 200 to 500 acres, few if any fawns will access feeder sites. This is especially true if the feeder sites are fenced to exclude feral hogs and javelinas. Relatively few does will access these sites as well if timed-release feeders are used due to buck dominance at this style of feeder.
A recent study in Colorado involving mule deer supports the above concerns. Chad Bishop and his co-workers fed manufactured protein pellets to deer during winter and spring only, by placing the pellets directly on the ground in two-to-three-pound piles spread out along primitive roads within the study area. They reported that survival rates of fetuses and newborn fawns, overwinter survival of older-aged fawns, and adult doe survival all increased as a result of the supplemental feeding.
When Is The Best Time To Feed?
The short answer, in south Texas at least, is that supplemental feed should be provided year-round. A supplemental feeding program should be designed to cover two different stress periods. The first stress period is based on the native habitat and occurs whenever the quantity or quality of the native forage is in some way lacking. Results of deer carrying capacity studies at Texas A&M University-Kingsville indicate that late summer is the most stressful time of the year for deer in south Texas. These researchers found that the carrying capacity of the habitat reaches its low point, or “bottleneck,” during July and August. In other words, the native habitat will support only a certain number of deer. This “maximum” number of deer is set by the number that can be supported when the habitat reaches it’s lowest nutritional point, which is late summer. Therefore, this two-month period is a critical time to provide supplemental feed.
The study conducted by Zaiglin and DeYoung verified the importance of supplemental feeding during late summer, which is when they found that consumption, peaked. In their study, supplemental feed consumption was also inversely related to the crude protein levels of the native habitat. Larry Varner, Lytle Blankenship, and Greg Lynch collected and analyzed the nutritive content of 26 different plant species eaten by deer on the Chaparral Wildlife Management Area. They found that crude protein levels were highest in spring, at intermediate levels during fall and winter, and at lowest levels during summer. In a study conducted on the Welder Wildlife Refuge, Thadis Box found that the two periods of lowest forage production were winter (January-February) and late summer (July-September).
Based on the above, ranchers and managers in south Texas should provide supplement during January through February and again during July through September in order to cover the two times of the year when the native vegetation is most likely to be lacking in quantity or quality. Obviously, droughts can also result in less than optimum forage conditions at other times. Therefore, your supplemental feeding program should include periods of drought as well.
The second stress period is based on the deer themselves and occurs when deer are physiologically stressed due to incre