Whitetail Insider

Does with Antlers?

By: Christopher S. DePerno, Ph.D. and Jonathan A. Jenks, Ph.D.

A few years ago – specifically, during the 2002 Minnesota deer-hunting season, Tom Schneider of Willmar, Minnesota harvested a 13-point, non-typical antlered deer. The animal had polished antlers (velvet rubbed off), female genitalia, an udder and teats. This animal, coupled with other reports of hunters harvesting antlered female deer, created tremendous publicity focusing hunter attention on these unusual, ‘pseudotrophys’. But what is known of this phenomenon, how common are they, and what causes them to occur?

What is known about antlered females? Antlers in white-tailed deer are composed of bone and grow from pedicels on the frontal part of the skull. The pedicels are the ‘buttons’ generally present on male white-tailed deer less than 6 months of age (i.e., fawns). Annual antler growth begins in mid-March to April and is dependent on the interaction of the hormone, prolactin, that is controlled by the pituitary gland in the brain, testosterone from the testes and increasing daylight. During early development, the growing antlers are composed of blood vessels and nerves and covered with a hairy skin called ‘velvet’. Antler growth continues through August or September, when testosterone, which accompanies the mating season and is the most important stimulant to antler growth, is released causing the velvet to die and the bone to harden. The velvet is eventually rubbed off and the antlers become polished.

By late December or early January, the supply of testosterone declines and a separation layer is formed between the antler and pedicel. The antlers drop off shortly thereafter. In March or April, an increase in prolactin and daylight stimulates the process to begin again.

Except in caribou, females of the deer family generally do not develop antlers. However, the scientific literature contains numerous reports of female deer with antlers and this phenomenon is not as uncommon as many may believe. In fact, reports of female deer with antlers go back more than a century and refer not only to white-tailed deer, but also to female black-tailed deer and mule deer.

Generally, reports of females with antlers involve velvet covered pedicels or small velvet-covered spikes with occasional branching. These females are fertile and can carry and raise fawns. Reports of females with hard polished antlers have also been documented in the scientific literature and researchers have experimentally produced antlers in female deer in captivity. An antlered doe

How common are antlered females?

During a 4-year study of hunter-killed deer in Pennsylvania, 47 antlered female deer were reported out of 162,000 antlered deer killed or about 1 antlered doe per 3,500 antlered deer. Researchers were able to fully analyze 34 of the 47 antlered females and reported that 28 had antlers in velvet and 6 had polished antlers; the 6 with polished antlers were later determined to be cryptorchid males (males with developmental defects that cause the testes to fail to descend into the scrotum).

Results of studies vary by region and researchers have estimated that overall, 1 in every 1,000 to 1 in 6,000 white-tailed deer females produce antlers. One region where antlered females appear to be very common is Alberta, Canada, where, in 1985, a study documented that 8 of 517 adult females (or about 1 in 64) had antlers, none of which were polished. The reasons for the high number of antlered females in this region may be because every harvested deer was examined or there may be a genetic predisposition for female antler growth.

What causes antlers to grow on female deer?

Researchers from around the country have conducted postmortem examination of many antlered female deer carcasses. Results indicate that female deer with antlers in velvet were either reproductively functional females with corpora lutea (functional ovaries with evidence of a previous birth), reproductively functional females without corpora lutea, females with complete but malformed reproductive tracts, or true hermaphrodites.

True hermaphrodites have both ovaries and testes present, however, one of the sex organs is generally more developed than the other. Generally, hermaphrodites with ovaries more developed then testes will have antlers in velvet. Conversely, if the testes are more developed the antlers will be polished.

Postmortem research on females with polished antlers have contrasting results. The majority of these animals are either cryptorchid males, males with malformed reproductive tracts, hermaphrodites with male organs more developed than female organs or pseudohermaphrodites. Pseudohermaphrodites are animals with external female genitalia but internal male reproductive organs.

Externally, pseudohermaphrodites have a vulva, clitoris, udder and teats of normal proportions and no external scrotum or penis. Internally, these animals usually have smaller than normal testes that may contain active sperm, epididymis, shorter than normal vas deferens, male ampullae, underdeveloped cervix, and a vagina. Importantly, in pseudohermaphrodites the testes (although undescended) are present and functional; therefore, testosterone would be present to terminate the velvet, resulting in polished antlers similar in size and shape to that of a normal male deer. This combination of normal sized antlers, external female genitalia and smaller than normal internal male genitalia make it very difficult for hunters to distinguish sex.

The physiological process of antler development helps to explain how antlers can develop in female deer. An initial surge of testosterone is necessary for antler development to be initiated resulting in buttons or antlers in velvet. Researchers have noted that females may have a surge of testosterone because of a first pregnancy, degenerative conditions to the ovaries or adrenal glands, or tumors. A simple hormonal imbalance in reproductively functional females can cause the initial surge of testosterone necessary for the growth of antlers in velvet. However, for the velvet to die and the antlers to become polished a second surge of testosterone is necessary. Because they lack the second surge of testosterone necessary to terminate the life of the velvet, reproductively functional females have antlers in velvet. Similarly, because they have a second surge of testosterone necessary to terminate the growth of the velvet, deer identified as females with polished antlers are actually reproductively malformed males.

In conclusion, the general consensus within the scientific literature is that true antlered white-tailed deer females are usually reproductively functional, may or may not have given birth to young, retain the velvet and may never shed the antlers. Conversely, deer identified as females with polished antlers are usually misidentified males, hermaphrodites, cryptorchids (males with testes that fail to descend into the scrotum) or pseudohermaphrodites.

Therefore, without being able to examine the internal organs of the ‘Schneider’ 13-point non-typical deer harvested in Minnesota, we were unable to determine if this deer was a reproductively functional female. However, the scientific research clearly indicates that females with well-developed polished antlers are infertile and either true hermaphrodites or pseudohermaphrodites. Hence, this animal, because of the size, shape and fact that the antlers were polished, likely was a pseudohermaphrodite with female external genitalia and an udder with teats, but with small, internal, functional testes.

If you happen to harvest what you suspect is an antlered doe save the internal organs, contact your local wildlife manager or veterinarian and ask them for a thorough professional examination of the animal. You may be surprised at what they find.

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