BigJon
10-11-2005, 06:12 PM
Ran across a a great article on spike whitetails that ran in Whitetail News awhile back. Thought some of you might find it of interest since it goes into a little greater detail than the average article I see about such things:
Pay Attention to Messages in SHORT SPIKES
By John J. Ozoga
Since body growth among young whitetail bucks takes precedence over antler growth, antler size among yearling (1-year-old) bucks provides a good indicator of deer population health.
If most yearling bucks in a given population are large and healthy, they'll likely sport good-sized, multi-tined antlers. Conversely, a high proportion of small-bodied yearling bucks with short-spike antlers is symptomatic of inadequate nutrition or possibly other consequences of poor herd structure.
In most cases, a high incidence of short-spike antlers in southern deer herds can be attributed to delayed breeding or poor nutrition sometimes associated with infertile soils. In the North, the short-spike phenomenon can usually be linked to inadequate nutrition, often associated with high deer density and social stress.
While genetics certainly is a factor in buck antler development, I believe that hunters, and even some wildlife managers, too often employ the “inferior genetic stock” idea to explain an abundance of stunted, miniature-antlered bucks.
There is no evidence that a “short-spike antler gene” exists. In reality, poor nutrition, late-births, or social stress are more often responsible. It is my view that deer managers are missing the boat when dealing with, and attempting to explain, the frequent occurrence of short-spike yearling bucks in some deer herds they manage. Biologists are not carefully pondering the basic reasons behind such abnormalities, and are not taking advantage of the wealth of information therein.
The 3-inch Rule
In some states, a legally harvested buck must have at least one 3-inch long antler. Generally, this measurement is taken from the base of the skull to the tip of the longest antler, and includes about one-half inch or so of pedicle bone on the skull of the average yearling.
The original intent of such a law probably was to protect buck fawns from harvest. Where the 3-inch antler law prevails, however, short-spike bucks can still be legally harvested by hunters with antlerless deer tags.
Wildlife managers expect to see fewer than 25 percent “spikehorns” among yearling bucks in well-nourished, well-managed whitetail herds. Theoretically, short-spike yearlings should be just about nonexistent. However, you are apt to encounter considerable debate among biologists on this subject.
The Pedicle
Before any deer can grow antlers it must first grow pedicles, or stumps, on which the antlers form. This means that proper development of the pedicle plays a key role in antler growth.
The age at which the pedicle is first distinguishable depends upon the species and the environment. In some species, such as elk and caribou, the rudimentary pedicles appear in the fetus, during the second half of gestation.
In whitetail deer and mule deer, pedicles develop after birth, and don't become pronounced bumps until the fawn is about four or five months old. That's when the healthy young male's testes develop and start producing sufficient quantities of the male sex hormone, testosterone. Elevated levels of testosterone, circulating in the blood, stimulate the laying down of additional bone at the pedicle site.
In order for the pedicles to develop properly, on schedule, a buck fawn must first achieve a certain threshold body weight. Only then can the testes produce enough testosterone to trigger pedicle formation. This means the young male must be born on schedule, in spring, be well-nourished, and grow rapidly. In the absence of testosterone no pedicles form and antlers fail to develop later on.
Infant Antlers
To set the record straight, let’s be sure not to confuse short-spike adult bucks with “button” buck fawns. Contrary to the case among yearlings, buck fawns sporting small polished antlers, usually less than one-half inch long, are indicative of excellent living conditions for deer.
Healthy buck fawns tend to grow prominent antler pedicles by late autumn. Some even develop small, polished antler caps (or “infant” antlers) when six to seven months old. These infant antlers are actually mineralized tips of the pedicles. Growth of the pedicle and these tiny antlers is a continuous process, in that antler growth starts as soon as pedicle growth is complete.
Biologists generally expect about five percent of the buck fawns to achieve polished antler caps by the time they are six to seven months old. However, I believe the frequency of antler-bearing fawns is considerably higher in well-nourished deer populations.
For example, I found that 84 percent of the supplementally fed buck fawns raised in Upper Michigan's square-mile Cusino enclosure achieved polished antlers. Although some rubbed off velvet during the last week of November, most did not polish their little antlers until early December. All had cast their antlers by late February. Therefore, most antler-bearing fawns are probably overlooked wherever deer hunting seasons terminate by December.
At any rate, the message here is rather clear: A high incidence of infant antlers among buck fawns in any herd is indicative of good range nutrition.
Different Types of Short-spikes
One seldom encounters a mature buck with spike antlers shorter than three inches long; most are yearlings. Unhealthy yearlings, or those delayed in sexual maturity, are most likely to exhibit such stunted antler growth. However, the precise reasons for such a predicament will vary greatly from one region of the country to the next, depending upon a host of factors. Even within a given area, short-spike yearlings may be plentiful one year, but scarce the next. Looking closely at why they occur could provide important clues for management practices necessary to remedy the situation.
We see two types of short-spike antlers among yearling bucks: (1) those with a burr, and (2) those without a burr. The burr, also called a cornet, is the flared base of the antler, being especially prominent on the antlers of older bucks. While both of these short-spike conditions are indicative of unfavorable living conditions for deer, they are the result of different troublesome life histories.
Burrless Short-spikes
Short-spike antlers lacking a burr are generally short straight shafts of bone, small but fairly uniform in diameter, with a rounded tip. As in the case of infant antlers, burrless spikes are virtually elongated pedicles. Such a condition suggests the yearling buck did not achieve favorable pedicle development, or may have had no pedicles at all, prior to its first winter. Consequently, it then had to play “catch-up” the next spring, by adding more pedicle bone before growing antlers -- all within a three to four month period.
Therefore, yearling bucks with burrless short-spike antlers are indicative of delayed maturation, due either to the animal's late birth date, or poor nutrition during the first six to seven months of life. In some cases, however, density stress can also result in certain physiological imbalances that interrupt pedicle formation.
Yearling bucks with short burrless spikes tend to be smaller than average for their age, and their delayed antler cycle often results in unusually late shedding of velvet. Because they are sexually retarded, they tend to have low dominance rank and probably seldom breed in the presence of older bucks. Depending upon nutritional conditions within the area where they live, such an animal may or may not overcome its poor start in life. That is, if nutrition remains poor, he more than likely will never become a large-bodied, large-antlered buck, even at maturity. On the other hand, such a stunted individual may compensate somewhat later in life if his nutrition improves sharply.
Burred Short-spikes
We also see very short, sub-legal-sized, spike antlers with a burr, or cornet. These short structures tend to be quite wide at the base, due to the flared cornet, but then come to an abrupt, sharp point. Therefore, they differ greatly in shape from the short burrless spikes, and may also be more stained from rubbing on saplings.
According to George Bubenik, a leading authority on antler development, “We don't really know why and how they (cornets) developed. No experimental study has been so far performed.”
Bubenik notes, however, cornets usually develop during late stages of antler growth. He suggests the reason for the cornet is probably to provide additional protection to the blood vessels around the pedicles during fights.
According to Bubenik, some members of the deer family living in northern environments do not develop cornets until they form their second antlers, probably be-cause of the low level of male hormone production during the usual time of cornet formation. Because a high level of testosterone is dependent upon good nutrition, cornets may not even develop in older under-nourished bucks.
Given what we know about antler development, we can assume that a yearling buck sporting cornet-equipped short-spikes was born on schedule, during May or June, and experienced reasonably good nutrition during his first seven months of life. (Or if he was late-born, he lived in an area of fantastically good nutrition which enabled him to overcome his late-birth disadvantage.) He probably achieved favorable body size by autumn and developed good-sized pedicles prior to winter, and may even have grown “infant” antlers. However, he experienced serious nutritional shortage later in life, either during late winter or the next spring, or possibly during both seasons.
On northern range, well-developed fawns that barely survive their first winter, and then find poor food conditions from March through June, tend to grow this type of short-spike antler. These animals may be fairly large-bodied. If provided good nutrition in subsequent years, they are likely to grow respectable antlers at maturity.
Late-born fawns
Late-born fawns are quite common in southern states, where deer exhibit a long breeding season and heavy buck harvesting often precedes the breeding season. As a result, a shortage of bucks can lead to doe recycling and their breeding later in the season.
Buck fawns born during August and September are less likely to achieve favorable body and antler size by yearling age, and many carry short burrless spike antlers.
Therefore, harvest strategies designed to bring deer herd size and composition in better nutritional and social balances will normally advance breeding dates, improve deer physical condition, and reduce the occurrence of short-spike yearlings produced under such circumstances.
In some areas, however, the combined negative effects of inherent late-birth and poor range nutrition may seriously compromise management efforts to advance maturation rates and improve the physical development of yearling bucks.
Late breeding and late-born fawns are less likely to occur on the northern range, where the breeding season tends to be very short. If late breeding were the primary reason for short-spike bucks in Michigan, for example, then short-spike bucks should be most prevalent in southern parts of the state where a high proportion of the doe fawns breed, because doe fawns typically breed one month later than adult does.
Obviously this is not the case; most short-spike bucks are found in northern Michigan, whereas most pregnant doe fawns occur in southern Michigan.
Conclusions
The frequency and type of short-spike antlers carried by yearling bucks in any given area can vary annually, depending upon a host of factors. A poor acorn crop, unusually early (or late) snow cover, or any disturbance that limits nutritious food and curtails the growth of young deer earlier than normal, or delays their recovery in spring, can set the stage for an abundance of short-spike bucks.
Despite the potential complexity of factors involved, a high incidence of short-spike yearling bucks in any given deer herd normally signals that something is wrong. Generally, the deer population is nutritionally and/or socially out of balance.
The ultimate solution to the short-spike dilemma lies in upgrading the whitetail’s “quality of life” by restoring the herd’s nutritional balance and social harmony. With few exceptions, this can generally be accomplished by increasing the harvest of antlerless deer and allowing more bucks to reach maturity, in conjunction with habitat manipulation designed to improve forage and cover quality for deer.
Pay Attention to Messages in SHORT SPIKES
By John J. Ozoga
Since body growth among young whitetail bucks takes precedence over antler growth, antler size among yearling (1-year-old) bucks provides a good indicator of deer population health.
If most yearling bucks in a given population are large and healthy, they'll likely sport good-sized, multi-tined antlers. Conversely, a high proportion of small-bodied yearling bucks with short-spike antlers is symptomatic of inadequate nutrition or possibly other consequences of poor herd structure.
In most cases, a high incidence of short-spike antlers in southern deer herds can be attributed to delayed breeding or poor nutrition sometimes associated with infertile soils. In the North, the short-spike phenomenon can usually be linked to inadequate nutrition, often associated with high deer density and social stress.
While genetics certainly is a factor in buck antler development, I believe that hunters, and even some wildlife managers, too often employ the “inferior genetic stock” idea to explain an abundance of stunted, miniature-antlered bucks.
There is no evidence that a “short-spike antler gene” exists. In reality, poor nutrition, late-births, or social stress are more often responsible. It is my view that deer managers are missing the boat when dealing with, and attempting to explain, the frequent occurrence of short-spike yearling bucks in some deer herds they manage. Biologists are not carefully pondering the basic reasons behind such abnormalities, and are not taking advantage of the wealth of information therein.
The 3-inch Rule
In some states, a legally harvested buck must have at least one 3-inch long antler. Generally, this measurement is taken from the base of the skull to the tip of the longest antler, and includes about one-half inch or so of pedicle bone on the skull of the average yearling.
The original intent of such a law probably was to protect buck fawns from harvest. Where the 3-inch antler law prevails, however, short-spike bucks can still be legally harvested by hunters with antlerless deer tags.
Wildlife managers expect to see fewer than 25 percent “spikehorns” among yearling bucks in well-nourished, well-managed whitetail herds. Theoretically, short-spike yearlings should be just about nonexistent. However, you are apt to encounter considerable debate among biologists on this subject.
The Pedicle
Before any deer can grow antlers it must first grow pedicles, or stumps, on which the antlers form. This means that proper development of the pedicle plays a key role in antler growth.
The age at which the pedicle is first distinguishable depends upon the species and the environment. In some species, such as elk and caribou, the rudimentary pedicles appear in the fetus, during the second half of gestation.
In whitetail deer and mule deer, pedicles develop after birth, and don't become pronounced bumps until the fawn is about four or five months old. That's when the healthy young male's testes develop and start producing sufficient quantities of the male sex hormone, testosterone. Elevated levels of testosterone, circulating in the blood, stimulate the laying down of additional bone at the pedicle site.
In order for the pedicles to develop properly, on schedule, a buck fawn must first achieve a certain threshold body weight. Only then can the testes produce enough testosterone to trigger pedicle formation. This means the young male must be born on schedule, in spring, be well-nourished, and grow rapidly. In the absence of testosterone no pedicles form and antlers fail to develop later on.
Infant Antlers
To set the record straight, let’s be sure not to confuse short-spike adult bucks with “button” buck fawns. Contrary to the case among yearlings, buck fawns sporting small polished antlers, usually less than one-half inch long, are indicative of excellent living conditions for deer.
Healthy buck fawns tend to grow prominent antler pedicles by late autumn. Some even develop small, polished antler caps (or “infant” antlers) when six to seven months old. These infant antlers are actually mineralized tips of the pedicles. Growth of the pedicle and these tiny antlers is a continuous process, in that antler growth starts as soon as pedicle growth is complete.
Biologists generally expect about five percent of the buck fawns to achieve polished antler caps by the time they are six to seven months old. However, I believe the frequency of antler-bearing fawns is considerably higher in well-nourished deer populations.
For example, I found that 84 percent of the supplementally fed buck fawns raised in Upper Michigan's square-mile Cusino enclosure achieved polished antlers. Although some rubbed off velvet during the last week of November, most did not polish their little antlers until early December. All had cast their antlers by late February. Therefore, most antler-bearing fawns are probably overlooked wherever deer hunting seasons terminate by December.
At any rate, the message here is rather clear: A high incidence of infant antlers among buck fawns in any herd is indicative of good range nutrition.
Different Types of Short-spikes
One seldom encounters a mature buck with spike antlers shorter than three inches long; most are yearlings. Unhealthy yearlings, or those delayed in sexual maturity, are most likely to exhibit such stunted antler growth. However, the precise reasons for such a predicament will vary greatly from one region of the country to the next, depending upon a host of factors. Even within a given area, short-spike yearlings may be plentiful one year, but scarce the next. Looking closely at why they occur could provide important clues for management practices necessary to remedy the situation.
We see two types of short-spike antlers among yearling bucks: (1) those with a burr, and (2) those without a burr. The burr, also called a cornet, is the flared base of the antler, being especially prominent on the antlers of older bucks. While both of these short-spike conditions are indicative of unfavorable living conditions for deer, they are the result of different troublesome life histories.
Burrless Short-spikes
Short-spike antlers lacking a burr are generally short straight shafts of bone, small but fairly uniform in diameter, with a rounded tip. As in the case of infant antlers, burrless spikes are virtually elongated pedicles. Such a condition suggests the yearling buck did not achieve favorable pedicle development, or may have had no pedicles at all, prior to its first winter. Consequently, it then had to play “catch-up” the next spring, by adding more pedicle bone before growing antlers -- all within a three to four month period.
Therefore, yearling bucks with burrless short-spike antlers are indicative of delayed maturation, due either to the animal's late birth date, or poor nutrition during the first six to seven months of life. In some cases, however, density stress can also result in certain physiological imbalances that interrupt pedicle formation.
Yearling bucks with short burrless spikes tend to be smaller than average for their age, and their delayed antler cycle often results in unusually late shedding of velvet. Because they are sexually retarded, they tend to have low dominance rank and probably seldom breed in the presence of older bucks. Depending upon nutritional conditions within the area where they live, such an animal may or may not overcome its poor start in life. That is, if nutrition remains poor, he more than likely will never become a large-bodied, large-antlered buck, even at maturity. On the other hand, such a stunted individual may compensate somewhat later in life if his nutrition improves sharply.
Burred Short-spikes
We also see very short, sub-legal-sized, spike antlers with a burr, or cornet. These short structures tend to be quite wide at the base, due to the flared cornet, but then come to an abrupt, sharp point. Therefore, they differ greatly in shape from the short burrless spikes, and may also be more stained from rubbing on saplings.
According to George Bubenik, a leading authority on antler development, “We don't really know why and how they (cornets) developed. No experimental study has been so far performed.”
Bubenik notes, however, cornets usually develop during late stages of antler growth. He suggests the reason for the cornet is probably to provide additional protection to the blood vessels around the pedicles during fights.
According to Bubenik, some members of the deer family living in northern environments do not develop cornets until they form their second antlers, probably be-cause of the low level of male hormone production during the usual time of cornet formation. Because a high level of testosterone is dependent upon good nutrition, cornets may not even develop in older under-nourished bucks.
Given what we know about antler development, we can assume that a yearling buck sporting cornet-equipped short-spikes was born on schedule, during May or June, and experienced reasonably good nutrition during his first seven months of life. (Or if he was late-born, he lived in an area of fantastically good nutrition which enabled him to overcome his late-birth disadvantage.) He probably achieved favorable body size by autumn and developed good-sized pedicles prior to winter, and may even have grown “infant” antlers. However, he experienced serious nutritional shortage later in life, either during late winter or the next spring, or possibly during both seasons.
On northern range, well-developed fawns that barely survive their first winter, and then find poor food conditions from March through June, tend to grow this type of short-spike antler. These animals may be fairly large-bodied. If provided good nutrition in subsequent years, they are likely to grow respectable antlers at maturity.
Late-born fawns
Late-born fawns are quite common in southern states, where deer exhibit a long breeding season and heavy buck harvesting often precedes the breeding season. As a result, a shortage of bucks can lead to doe recycling and their breeding later in the season.
Buck fawns born during August and September are less likely to achieve favorable body and antler size by yearling age, and many carry short burrless spike antlers.
Therefore, harvest strategies designed to bring deer herd size and composition in better nutritional and social balances will normally advance breeding dates, improve deer physical condition, and reduce the occurrence of short-spike yearlings produced under such circumstances.
In some areas, however, the combined negative effects of inherent late-birth and poor range nutrition may seriously compromise management efforts to advance maturation rates and improve the physical development of yearling bucks.
Late breeding and late-born fawns are less likely to occur on the northern range, where the breeding season tends to be very short. If late breeding were the primary reason for short-spike bucks in Michigan, for example, then short-spike bucks should be most prevalent in southern parts of the state where a high proportion of the doe fawns breed, because doe fawns typically breed one month later than adult does.
Obviously this is not the case; most short-spike bucks are found in northern Michigan, whereas most pregnant doe fawns occur in southern Michigan.
Conclusions
The frequency and type of short-spike antlers carried by yearling bucks in any given area can vary annually, depending upon a host of factors. A poor acorn crop, unusually early (or late) snow cover, or any disturbance that limits nutritious food and curtails the growth of young deer earlier than normal, or delays their recovery in spring, can set the stage for an abundance of short-spike bucks.
Despite the potential complexity of factors involved, a high incidence of short-spike yearling bucks in any given deer herd normally signals that something is wrong. Generally, the deer population is nutritionally and/or socially out of balance.
The ultimate solution to the short-spike dilemma lies in upgrading the whitetail’s “quality of life” by restoring the herd’s nutritional balance and social harmony. With few exceptions, this can generally be accomplished by increasing the harvest of antlerless deer and allowing more bucks to reach maturity, in conjunction with habitat manipulation designed to improve forage and cover quality for deer.