STAG BEHAVIOR

During the period in which antlers are in velvet stags do not normally engage in any sexual behavior. If stags or bucks are competing while their antlers are in velvet they will normally do so by rising on their hind legs and engaging in boxing activity. However, the presence of hinds in estrus outside the normal breeding season will induce a full range of mounting and mating activity. Normally hinds would not be in estrus at this time, but this type of behavior has been seen when hinds are brought into estrus out of season by artificial hormonal means, or when animals have been transferred across the equator and have not yet adjusted to the new photoperiod. Resumption of rutting behavior occurs late in winter if a female loses a conceptus and begins to cycle again, or begins estrous cyclicity particularly late.²

The behavior of stags changes quite abruptly at about the time that antler velvet is shed and antlers become fully calcified. Wapiti gestation is about 2 weeks longer than that of red deer and fallow deer, and so the changes occur that much earlier (for more on the relationship of antlers to reproduction see Chapter 133).³ They take place, in mature males, about 3 to 4 weeks before the onset of the rut (mating season) itself. Younger males start rutting behavior a little later than mature adults. The behaviors at this time include antler rubbing or thrashing, wallowing, preputial palpitation with or without urine spraying, bugling or roaring, dominance displays, and sparring in wapiti and red deer.⁴ At this time, stags become extremely aggressive toward one another and often toward humans in a farming environment. Antler rubbing and thrashing serve to both mark territory and remove the dried velvet tissue on the surface of the hard antler. The thrashing may be accompanied by rubbing of the neck on vegetation, fence posts, or other wooden structures and is probably a form of scent marking. At this time, in male-only mobs, the fighting mode changes from boxing to a complex of displays that may culminate in clashes that involve the use of the head. In single sire mating mobs fighting is not seen, but fence pacing with parallel walking displays projected at males across fence lines, or at people, are common. Males will also face directly up to people at fence lines and carry out head threats that involve a rapid dip. If stags (also called bulls in wapiti) are placed in adjacent paddocks, fighting through the wire will occur.

In Cervus males the underside of the belly, the forelegs, and the neck are often darkly stained during the rut and for a period thereafter. This is due to the frequent spraying of fluid from the penis, usually accompanied by preputial palpitation, that is known in elk as “thrash urination,” and which is almost certainly used as a scent marker.^4,⁵ The urethra at the tip of the elk’s penis points upward, which allows for a spray that is almost at right angles to its long axis.⁶ This ensures that the entire belly and neck can efficiently be scented. The smell of the fluid, and the smell of the stag himself, is particularly strong at this time of year.^4,⁶ When this fluid has been collected it has not been shown to contain sperm.⁷ Thrashing is sometimes accompanied by wallowing. If there is a convenient wet or damp spot, a stag will often choose it for a wallow. He will scrape with his feet in the ground, sometimes will use his antlers, and often will urinate as well. He will then usually roll in the wallow and cover both his belly and neck with the mixture.^4,⁶

On deer farms stags have usually been “placed” or “joined” with hinds just before velvet cleaning, or very soon after it occurs in order to take advantage of the well-recognized “stag effect.” It has been shown that the stag’s rutting behavior advances the onset of estrus if introduced to the female about 3 weeks before onset of estrous cyclicity in the absence of stags.^6,⁸ The array of behaviors described serves to stimulate and synchronize the hinds during the phase of transition between the anestrus period of summer and the active breeding season. Hinds may go through a silent heat and both hormonal activity and follicular wave activity increase until an ovulatory cycle occurs.¹ A “dormitory effect” is also recognized to occur among hinds, and silent heat may further synchronize estrus among a group of hinds, thus shortening the rut and calving period.

The intensity of stag behavior increases gradually until the animals are in full-blown rut. The rut is defined as the period of maximum reproductive activity.² It is timed to meet the evolutionary pressures that have dictated parturition onset to meet the optimal forage availability in the following year.

Sparring

Sparring encounters, when antlers are engaged and pushing matches occur, are a common feature of the rut in free-ranging animals. They are most intense in mature individuals and are unusual if males are of different ages. However, they are usually preceded by a series of ritualized behaviors during which males size one another up. Stags may break off an encounter before engaging in physical contact.⁷

Vocalization

The calling sound made by rutting males is known as roaring in red deer, and bugling in wapiti. By the onset of the rut mature stags have been calling for at least 2 or 3 weeks. Stags will call whether or not they are placed with hinds. If the weather is cool (<10° C) during the day, calling may occur as often as twice a minute throughout the 24-hour day, but if temperatures exceed 20° C the frequency declines during the middle of the day. The sounds are most commonly heard before 9 AM and after 5 PM.^4,⁹ In red deer frequency increases to as many as eight roars per minute preceding a fight.⁹ In red deer it has been shown that the frequency of roaring may affect the success that a stag has in maintaining his harem.⁹ It is rare to hear a yearling wapiti bugle at all.

Heterosexual Behavior

Hinds tend to move into rutting areas held by dominant stags over this period. While they are nonestrous, hinds remain subordinate to the stag, displaying characteristic submissive behaviors whenever approached. These behaviors include a head lowering and neck stretching posture associated with jaw chattering. Hinds will often run short distances to avoid the stag. Stags frequently display to hinds, particularly if they appear to be moving outside the stag’s rutting area. Such displays include standing side-on to the hind with chin raised. The stag will often raise and stamp a front foot, emitting a deep guttural bark at the same time. This is usually sufficient to direct the hind back to the core rutting area or to join the other hinds. The stag will frequently wander among resting and grazing hinds, sniffing each hind’s perianal region for signs of impending estrus. Hind urine is often tested with displays of flehmen.^6,¹⁰

In natural mating systems wapiti and red deer hinds form groups of several animals and these are “rounded up” by rutting stags. The amount of time spent herding females increases steadily from the time that velvet is cleaned off, and within about 2 weeks has become a major activity.⁴ Rutting bulls will spend up to 40% of their time herding their females on farms, even chasing them away from water or feed troughs.⁶ Most of the herding behavior is seen in the early morning up to 9 AM or in the evening as during the hottest part of the day stags and hinds may spend up to 60% of their time resting. The threat employed by stags that are herding hinds is usually extension of the head and neck such that the head is level with or slightly below the shoulders. This posture, held while the stag runs toward a hind that is trying to leave the herd, often stimulates the hind to rejoin the group, whereupon herding activity ceases.⁴

Yearling males may not show full rutting behavior for as much as a month later than older ones and may be seen making homosexual mounts, but they are capable of breeding if older males are not present.^2,^11,¹²

Throughout the rut the stags can be seen periodically checking the hinds, both by smelling their perineal regions or faces and by sniffing their urine and performing “flehmen,” or lip curl.¹⁰ The stag may walk among a group of resting hinds carrying out these checks and if a hind is coming into estrus the stag will pay more attention to her, sometimes separating her from the herd.

The hinds show little overt behavior related to reproduction in the period preceding the peak of the rut. Only the most vigilant observer will be able to detect when a hind is in heat. There is little or no vulval swelling, and although it does occur, hind mounting of other hinds is unusual. The well-known research team on the island of Rhum have reported that red deer hinds give off a distinctive odor during the time that they are in estrus.² The interaction of a hind with the stag is the best indicator of her reproductive state. Hinds may exhibit different behavior if they are kept separate from stags.¹³ They would approach fences separating them from the male, frequently reaching through to lick him, while he became agitated and ran along the fence bugling frequently. Hinds approaching estrus may spend an increasing amount of time paying attention to the stag, or there may almost no interaction between them until the moment of coitus.¹³

The range of behaviors that are engaged in by elk and red deer have been extensively studied by many observers. One of the earliest “textbook” references was published in 1576 and is an account by Turbevile of many aspects of hunting and the biology of deer.¹² A section of his chapter on the “Vault of Hartes”^* bears quoting as it cannot be much improved upon today.^† The second paragraph quoted contains what is probably the most lyrical description of flehmen ever penned:

Harts do beginne to Vault about the middeft of September, and their Rut doth continue about two monethes, and the older that they be, the hottere they are, and the better beloued of the Hyndes. The old harts go fooner to vault than the yong, and they are fo fierce and fo proude, that vntil they haue accomplyfhed their luft, the yong Harts dare not come neare them, for if they do, they beate them and dryue them away. The yong Deere haue a maruellous craft and malice, for when they perceiue that the olde Hartes are wearie of the Rut and weakened in force, they runne vppon them, and eyther hurt or kyll them, caufing them to abandon the Rut, and then they remayne maifters in their places.

Hartes doe muche foner kyll each other when there is fcarcitie of Hyndes, for if there be Hyndes plentie, then they feparate them felues in one place or other. It is a pleafure, to beholde them when they goe to Rutte and make their vaute. For when they smell the Hynde, they rayfe their nofe vp nto the ayre, and look aloft, as though they gaue thankes to nature which gaue them fo great delight.

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