Antler size provides an honest signal of male phenotypic quality in roe deer

Identifying factors shaping secondary sexual traits is essential in understanding how their variation may influence male fitness. Little information is available on the allocation of resources to antler growth in territorial ungulates with low sexual size dimorphism. We investigated phenotypic and environmental factors affecting both absolute and relative antler size of male roe deer in three contrasting populations in France and Sweden. In the three populations, we found marked age-specific variation in antler size, with an increase in both absolute and relative antler size between yearling and prime-age stages, followed by a decrease (senescence) for males older than 7 years. Antler size increased allometrically with body mass. This increase was particularly strong for senescent males, suggesting the evolution of two reproductive tactics: heavy old males invested particularly heavily in antler growth (potentially remaining competitive for territories), whereas light old males grew small antlers (potentially abandoning territory defense). Finally, environmental conditions had little effect on antler size: only population density negatively affected absolute antler size in one of the three populations. Antler size may therefore provide an honest signal of male phenotypic quality in roe deer. We discuss the implications of these results in terms of territory tenure and mating competition.     

The effect of artificial photoperiodicity and antiandrogen treatment on the antler growth and plasma levels of LH, FSH, testosterone, prolactin and alkaline phosphatase in the male white-tailed deer

1. Artificial extension of day-length in adult male white-tailed deer during the autumn induced: (a) premature casting of antlers, early onset of the new antler growth and out of season mineralization, (b) early elevation of plasma levels of prolactin, LH, FSH, testosterone and alkaline phosphatase and (c) out of season hair molt. 2. Intramuscular administration of the antiandrogen cyproterone acetate immediately after velvet shedding induced: (a) dramatic reduction of testosterone levels in plasma, (b) premature casting in bucks with fully mineralized antlers and (c) renewal of bone rebuilding activity in incompletely mineralized antlers which resulted in blockage of casting.     

Regrowth of amputated velvet antlers with and without innervation

The influence of removing portions of the growing antler of yearling red deer stags on subsequent regeneration of the antler in the same season was studied. The influence of the innervation of the antler on such regeneration was the subject of a further study. When the top 0.5-1 cm was removed from antlers 9-17 cm long, growth was slightly reduced in that season. When the antler/pedicle length was reduced to 6-10 cm in antlers 16-38 cm long, branched antlers regrew in 11 out of 13 cases provided the amputation was carried out early in the growing season, i.e., before mid-December. Denervated antlers were shorter, lighter, and of different shape compared with controls, but they were of similar density. Denervation was confirmed histologically. Cleaning of velvet and casting of antlers following castration were unaffected by denervation. It would appear that although nerves affect the size and shape of the antler, they are not essential to the actual control of antler growth and regeneration.     

Assessing the intensity of sexual selection on male body mass and antler length in roe deer Capreolus capreolus: is bigger better in a weakly dimorphic species?

Little is known about traits under sexual selection in territorial mammals with low sexual size dimorphism. We examined the potential for sexual selection on male body mass and antler length in the European roe deer Capreolus capreolus, a territorial ungulate in which males are less than 10% heavier than females. Independently, both body mass and antler length (irrespective of age) had a positive effect on male yearly breeding success. However, when corrected for body mass, antler length at a given mass only had a slight effect on male breeding success. This suggests that: (1) ‘bigger is better’ and (2) sexual selection is responsible for at least part of the observed variation in body mass and antler length in roe deer. High body mass and large antlers may be advantageous to males for two reasons: (1) they enhance fighting ability and dominance, so allowing males to defend better their territory and hence access mates, and (2) they attract females because they are honest signals of male phenotypic quality. This suggests that, even in weakly dimorphic ungulate species, sexual selection may lead to a marked influence of body mass on male breeding success, as long as body mass is also strongly selected in females.     

Access to mates in a territorial ungulate is determined by the size of a male's territory, but not by its habitat quality

1. Territoriality is commonly associated with resource defence polygyny, where males are expected to gain access to females by anticipating how resources will influence female distribution and competing for resource-rich sites to establish their zone of dominance. 2. We tested this hypothesis in European roe deer (Capreolus capreolus) by simultaneously assessing the influence of resources on female distribution and the influence of female distribution on male distribution and breeding success using paternity analyses. 3. Females did not fully distribute themselves among male territories in relation to resources. As a result, relative female abundance in a male's territory depended on territory size, but not on its habitat quality. In turn, relative female abundance in a male's territory determined, at least partially, his breeding success. 4. Interestingly, male territory size, and hence access to females, was partly determined by male body mass (all males) and by residual antler size (subadults only). The latter result suggests that large antlers may be important to young males for establishing their first territory, which is then usually retained for all subsequent reproductive seasons. 5. To conclude, although territoriality of male roe deer has certainly evolved as a tactic for ensuring access to mates, our results suggest that it does not really conform to a conventional resource defence polygyny strategy, as males seem to gain no obvious benefit from defending a territory in an area of high habitat quality in terms of enhanced access to mates. 6. This may explain the stability of male territories between years, suggesting that male territoriality conforms to an 'always stay' and 'low risk-low gain' mating strategy in roe deer.     

Effects of environmental conditions, human activity, reproduction, antler cycle and grouping on fecal glucocorticoids of free-ranging Pampas deer stags (Ozotoceros bezoarticus bezoarticus)

In this study, a commercial enzyme immunoassay (EIA) was validated in detecting glucocorticoids in Pampas deer feces, in order to investigate the influence of several factors on the adrenocortical function. Fecal samples, behavioral data and information concerning male grouping and antlers status were collected at a monthly basis during a 1 year period from free-ranging stags living at Emas National Park, Brazil (18 degrees S/52 degrees W). The results revealed that concentrations of fecal glucocorticoids in winter were significantly higher than those corresponding to spring and summer. In addition, dry season data presented higher levels than during the wet season. Significant difference was found between fecal levels of breeding stags in summer and nonbreeding stags, whereas no difference was observed between breeding stags in winter and nonbreeding stags. On the other hand, males from areas with frequent human disturbance exhibited higher glucocorticoid concentrations and flight distances than individuals from areas of lower human activity. Males with antlers in velvet had elevated levels compared with animals in hard antler or antler casting. Also, we found that glucocorticoid levels were higher in groups with three or more males than in groups with only one male. The flight distances showed positive correlation with fecal glucocorticoid. These data indicate that fecal glucocorticoid provides a useful approach in the evaluation of physiological effects of environment, inter-individuals relationship and human-induced stressors on free-ranging Pampas deer stags.     

Do Antlers Honestly Advertise the Phenotypic Quality of Fallow Buck (Dama dama) in a Lekking Population?

Size and symmetry of secondary sexual traits are supposed to be honest signals of male phenotypic quality in vertebrates. Antler size and symmetry, male quality and mating success have not been fully demonstrated to be correlated in cervids. Such correlations can be particularly intriguing in the case of species adopting costly mating strategies, which imply territorial defence without feeding. In these cases, body condition appears to be crucial at the onset of the rut, and large and symmetrical antlers may be borne by successful males. For these reasons, during four consecutive years, we analysed growth rate, size and symmetry of 26 fallow bucks’ antlers in relation to individual mating strategy and success in a lekking population. Territorial (T) males, which gained higher mating success in the lek, showed a faster antler growth (about 10 g/d per antler) than non‐territorial (NT) males (3.6–5.2 g/d per antler) during the velvet period, and this was likely because of optimized foraging strategies. At the onset of the rut, when antler growth was completed, T males had larger antlers than NT males. Possibly because of worsened body conditions, NT males showed a pronounced antler directional asymmetry, while T males did not. However, no direct link between antler symmetry and mating success was found, thus confirming the ambiguous role of antler asymmetry as an indicator of fitness. The faster the antler growth, the larger its final size and the higher its beholder’s mating success. Our results confirmed that, like groaning and scent marking, antler size reflects social status and dominance in male fallow deer, and therefore represents an honest advertisement of phenotypic quality.     

Fighting behaviour in territorial male roe deer <Emphasis Type="Italic">Capreolus capreolus</Emphasis>: the effects of antler size and residence

In all areas where they have been studied, male roe deer are believed to have a territorial mating system, although few quantitative studies have been conducted and there remains considerable debate about the function of male roe deer territories. We observed 139 aggressive interactions between male roe deer in Storfosna Island (Norway) during one territorial season (March–August). We recognised seven rank levels of escalation according to the potential danger of the behaviour. On the basis of the number of escalation levels included in the interactions, the complexity of the fights was also scored. We recorded the presence of other individuals during the interaction, the age, the antler size, the territorial status and the residency status of the two contestants and tested how these variables affected escalation, complexity and outcome of the fights. Most of the interactions ended with low levels of escalation, and physical contact occurred only in fights between two territorial bucks. The escalation was also affected by the difference in antler size index (the bucks escalated more when the difference in antler size was smaller) and increased with an increasing number of female deer present during the interaction. The resident buck won in 81% of the fights. When it drew or lost, it was generally both inferior in age and antler size, and the duration and escalation of the interactions were higher. However, even when a fight was lost, no territory loss occurred. These results are consistent with the evolutionary game theory and the proposed low risk–low gain strategy of roe deer bucks.     

Role of oestradiol in the regulation of the seasonal antler cycle in female reindeer, Rangifer tarandus.

Reindeer (or caribou), Rangifer tarandus, is the only extant species of deer in which females as well as males normally develop antlers that are cast and regrown each year. This study investigated the role of ovarian oestradiol in the regulation of the seasonal antler cycle in female reindeer. Ovariectomized Norwegian reindeer living outdoors in northern Norway (69 degrees N) were treated with continuous-release subcutaneous Silastic implants containing oestradiol, which maintained the blood concentrations of oestradiol within the physiological range for the mating season from June to October-November. The treatment with oestradiol induced the synchronized maturation of the antlers and rapid cleaning of the velvet-like skin in August-September in the ovariectomized reindeer, a pattern very similar to that observed in ovary-intact controls living under the same conditions. The removal of the steroid implant in October-November caused the premature casting of the antlers in early winter in two of five animals, while the remainder cast at the normal time in spring; this response was seen whether the animals had received one or two oestradiol implants in autumn. The antlers developed by the ovariectomized, oestradiol-treated females were significantly heavier and carried more branches than the ovariectomized animals without oestradiol replacement, and were marginally heavier than the antlers of intact controls. These results support the view that oestradiol is the biologically active steroid secreted by the ovary in intact female reindeers that induces the normal development of the antlers. Oestradiol stimulates the growth and mineralization of the antler bone, the cleaning of the velvet, and suppresses the casting of the hard antlers. This endocrine control ensures that the hard antlers, which function as weapons, are retained throughout the autumn and winter when the females are normally pregnant and when competition between females over food in the snow is most intense; hence there is a reproductive advantage to explain the evolution of antlers in females.     

Should I Stay or Should I Go Now: Late Establishment and Low Site Fidelity as Alternative Territorial Behaviors

In species in which males defend territories for breeding, males may differ in territorial behavior; alternative behaviors among territorial males are not well understood. In our long‐term study of partially‐migratory song sparrows, we have observed that most territorial males establish territories before females begin nesting and remain site‐faithful both within and between breeding seasons; however, some males establish territories later in the season (late establishers) and/or change territory locations either within or between seasons (movers). Whether late establishment or moving are equally successful strategies for territory defense, or best‐of‐bad‐job options, is not known. Here, we compare the frequencies of these behaviors to demographic variables over a 9‐yr period and compare lifetime tenure and early season nesting success for males who differ in site fidelity and timing of territory establishment. Across years, late establishing was negatively correlated with the return rate of previously territorial males; moving was positively correlated with the number of occupied territories at the start of the breeding season (territory density). While moving was independent of number of years on territory, late territory establishment only occurred in a male’s first year as a territory holder. Of 88 males, 25% established their first territory late, primarily in undefended space; 31% moved. Late and early establishers did not differ in lifetime tenure; movers, however, had longer lifetime tenure than site‐faithful males. Among early establishers, movers and non‐movers did not differ in the number of successful early nests/year or number of young fledged/year; among late establishers, however, movers had significantly higher early nesting success by both measures. Late establishers who moved had higher early season nesting success and higher early season nesting success/year than site‐faithful early establishers. Thus, individual variation in the timing of territory establishment and site fidelity may be facultative alternative territorial strategies.     

Relationship between dominance and antler cycle in white-tailed deer<Emphasis Type="Italic">Odocoileus virginianus</Emphasis>

We tested the hypothesis that there is a negative correlation between rank and order of casting antlers in white-tailed deerOdocoileus virginianus (Zimmermann, 1780) and that dominant individuals will start antler regrowth and velvet shedding earlier than subordinates. We assessed dominance relationship among 14 bucks (1.5 to 7.5 years-of-age) confined in a 0.6 ha enclosure and related hierarchal position to timing of antler casting, initiation of antler regrowth, and initiation of velvet shedding. During 66 observation sessions we recorded 2833 agonistic interactions. Bucks developed an unstable hierarchy with relatively frequent changes in rank, particularly in the upper half of the hierarchy. Antler casting dates were positively correlated with age and wins and losses of agonistic encounters; correlations with body mass approached significance. When age was eliminated as a confounding factor by partial correlation, no significant relationship between antler casting date and other characteristics occurred, except losses. When body mass was eliminated by partial correlation, the relationship between casting date and losses was more pronounced. Timing of antler regrowth was negatively correlated with age, body mass, rank and wins, while positively correlated with losses. The start of velvet shedding was negatively correlated with rank position. Our results are in apparent contrast with previous studies. However, our experimental group contained more individuals in a confined area than is typical for the species. Whitetails may be more susceptible to social stress in captivity than more gregarious species such as red deer, resulting in variable responses to rank position.     

Effect of antiandrogen cyproterone acetate on the development of the antler cycle in Southern pudu (Pudu puda)

The antler cycle of pudu is similar to other cervids, but unlike most boreal deer, male Southern pudu (Pudu puda) exhibits two seasonal peaks of LH and testosterone. In that respect, pudu is similar to roe deer. Whereas the antler cycle in some deer species, such as roe deer or white-tailed deer, is very sensitive to variation of testosterone, in other cervids, such as fallow deer or reindeer, a blockade of androgens with cyproterone acetate (CA) has little or no effect on the timing of the antler casting. In order to test the sensitivity of pudu antlers to variations of androgens, CA (administered 2x weekly at 50 mg/buck) was injected intramuscularly for 3 weeks in 5 adult male pudu, starting February 19 (late summer). Four other males of similar age served as controls. The experiment was performed at the University of Concepcion, Chile, latitude 36.6 degreeS. Blood samples were taken once a week between January 19 and April 3. In CA-treated bucks, the antlers were cast approximately 3 weeks after the initiation of CA treatment and a new antler growth began almost immediately. The antlers reached about 5 cm in length, before ceasing to grow at the end of April, when they became mineralized and were subsequently polished. CA had no effect on the already declining levels of LH. Plasma levels of testosterone in controls increased from February 15, whereas in CA-treated bucks remained depresses until March 21. It is concluded that similarly to white-tailed deer, the antler cycle of Southern pudu is very sensitive to manipulation of androgen levels.     

Intra- and Inter-seasonal Variation in the Socio-Spatial Behavior of Adult Male Collared Lizards, Crotaphytus collaris (Reptilia, Crotaphytidae)

When individuals maintain strong inter‐seasonal philopatry to the same territories, males may be able to re‐establish territory occupancy without intense intra‐sexual aggression, and instead spend more time courting females early in the reproductive season. Furthermore, when some males have prior experience defending the same territories, it may be necessary for young males to exhibit higher levels of aggression because they are establishing a territory for the first time. We tested these hypotheses by examining within‐season (1992 and 1997) temporal variation in the social behavior of adult male collared lizards of known age and prior territorial experience in a population where inter‐season philopatry to territories is high. Contrary to expectations, the frequency of aggression exhibited by males with and without prior territorial experience did not differ. The frequency of intra‐sexual aggression was higher in 1992 than in 1997, perhaps because male competitors were more abundant in 1992. Although there was an interactive effect of year, male display and patrol were low at the beginning of the reproductive season in Apr. and May, reached peaks during midseason in June, and then decreased as reproduction ended in July. The size of territories showed a similar pattern, with males defending larger areas in June. Our data support the philopatry hypothesis in that the establishment of territories occurred without high levels of aggression early in the season, perhaps because territory boundaries have been well defined by high rates of patrol and advertisement during the middle of the previous season. Inter‐sexual interactions were most frequent in June rather than at the beginning of the reproductive season. Adult females are producing their second clutches and yearling females are producing their first clutches in June. The high rate of inter‐sexual encounters in June supports the hypothesis that males allocate more time to courtship when females are receptive because there are more reproductively active females at this time. The temporal pattern of activities in adult Crotaphytus collaris appears to function as a compromise between competing intra‐ and inter‐sexual social demands on males, allowing males to maximize mating opportunities as well as maintain future access to productive territories.     

Influence of photoperiod on the seasonal pattern of secretion of luteinizing hormone and testosterone and on the antler cycle in roe deer (Capreolus capreolus).

Annual variations in concentrations of luteinizing hormone (LH) and testosterone in plasma were analysed in relation to the antler cycle in six adult male roe deer exposed to a natural photoperiod (latitude 46 degrees 10'N) and in four adult males maintained in a constant short-day photoperiod (8 h light: 16 h dark) for a year, from the winter solstice at which time both groups of animals had antlers in velvet. The animals were sampled, every 15 min for 2 or 4 h at intervals of one month for a year. Under both natural and experimental conditions, LH concentrations were high from January to March, but in the experimental conditions they decreased between April and May-June, whereas in the natural conditions they increased. Plasma LH concentration was lowest between July and November in animals under natural photoperiod, whereas under 8 h light:16 h dark photoperiod a second increase in plasma LH occurred between August and September. Between March and August, concentrations of plasma testosterone increased under natural photoperiod, whereas under experimental photoperiod there was a biphasic pattern of plasma testosterone with peaks between February and May and between September and November. Under natural photoperiod, antlers were cast in November, 369 +/- 6 days after the previous antlers were cast. Under experimental photoperiod, antlers were cast after 193 +/- 10 days, and a new set developed. The sexual cycle of the male appears to be initiated by an endogenous rhythm in winter and is then maintained by hormonal changes resulting from increasing photoperiod in spring.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endocrine control of antler growth in red deer stags

Observations of body weight, testis size, antler status, plasma testosterone and prolactin were made on 12 red deer stags during their first 2 years of life. Six of the stags were fed to appetite throughout the study (Group A) and 6 were fed a 70% restricted diet during each winter (Group B). In addition 6 of the stags , 3 from each group, were studied in more detail; LH and testosterone were measured either after a single injection of LH-RH or in samples taken at frequent intervals over a period of 8 or 24 h. During the study the stags became sexually mature, developed first their pedicles and then antlers and showed at least one complete cycle of casting and regrowth of the antlers . The stags in Group A developed their testes and pedicles about 2 months earlier than did those in Group B. Pedicle initiation was associated with increasing plasma testosterone levels in response to changes in LH secretion, and antler development occurred when testosterone levels were low or decreasing. Cleaning of the velvet was associated with high levels of plasma testosterone. Antler casting occurred when plasma testosterone concentrations were low or undetectable and prolactin levels were high or increasing. The relationship between LH and testosterone varied during the study; in spring when the testes and antlers were growing, relatively high levels of LH were associated with only small peaks of testosterone, yet in summer, when antler growth was complete and the antlers were clean of velvet, low LH concentrations were associated with large peaks of testosterone.     

Seasonal antler cycle in a herd of pampas deer (Ozotoceros bezoarticus) in Uruguay

To describe the yearling antler cycle of pampas deer bucks (Ozotoceros bezoarticus) 22 bucks and 72 antler cycles have been studied in a semi-captive population. Date of individual antler cast, first day on which the brow and the trez tine were observed, and day of the velvet shedding were registered. Time intervals (days) between first and second antler casts, between first antler cast and the brow tine observation, between brow and trez tines observation and from first antler cast to velvet shedding were calculated. The brow and the trez tine were first observed 22.8±0.6 and 45.9±0.9 days after the first antler cast. Velvet shedding was observed 103.3±2.1 days after the first antler cast. Both antlers casts were observed earlier in adult cycle bucks than in first antler bucks, although the interval between both casts was not different. The interval from the brow tine observation to the trez tine observation was shorter in first antler cycle bucks than in adults. As in other deer species, antler cycle was seasonal, but persistence of cycle-to-cycle antler growth well into adulthood is different from what occurs in most deer species.     

Territory Availability at Different Spatial Scales does not Affect Fighting Investment in Males of the Lycaenid Butterfly Strymon mulucha

In territorial species, rivals investment in fights over territories may increase when the availability of suitable areas for defense is low. This should occur because low territory availability may increase the costs to maintain and acquire territories. Although such process occurs in small spatial scales (local scale), territory availability in larger scales (regional scale) may also affect fighting investment, as losers should incur additional dispersing costs to find new territories. In this study, we used males of the hilltopping butterfly Strymon mulucha to evaluate the hypothesis that males should invest more in territorial fights when the costs to find new territories are higher (both at local and at regional scale). We timed male–male contests for territories located in 12 hilltops and measured male density per territory in each hilltop (local scale). We also quantified the distance between hilltops containing suitable areas for territories (regional scale). Male–male contests lasted 21 s on average, and copulations did not occur during the observations. The duration of contests was unrelated to the male density per territory or to the distance among hilltops, indicating that the investment in fights was unaffected by the availability of territorial sites, independent of the spatial scale. As male–male contests in S. mulucha are longer than the mean contest duration in other butterfly species and mating is extremely rare, we suggest that the value of each territory may be high enough to favor males that always invest as much as possible in contests.     

Reproductive strategies and the influence of date of birth on growth and sexual development of an aseasonally-breeding ungulate: Reeves' muntjac (Muntiacus reevesi)

Unlike most species of deer, Reeves' muntjac does not have a seasonal reproductive cycle. Births are equally distributed throughout the year and, irrespective of season of birth, females start breeding when they have reached a minimum body weight of about 10 kg. A significantly smaller proportion of females is born in the autumn/winter than the spring/summer, but there is no effect of maternal age or condition on foetal sex ratios for first or subsequent pregnancies. Whilst aseasonal breeding increases female productivity, males are only able to hold territories encompassing the ranges of a number of does for a relatively short period of time. It is argued that for muntjac there is much less inter-sexual variation in lifetime reproductive success than for seasonally-breeding polygynous cervids. Hence, although muntjac are sexually dimorphic and polygynous, females do not invest preferentially in male offspring.
Young males can be fertile from 36 weeks of age, when their first antlers are still in velvet. Whilst season of birth has no effect on the rate of sexual development in females, it does for males, with autumn-born male fawns attaining sexual maturity earliest. This accelerated development occurs in the period following independence from the mother, and there is no evidence of a maternal cost in producing male fawns. Since the canine tusks are the main weapons for intra-sexual conflict, there could be clear gains in terms of reproductive success for males that attain sexual maturity, adult weight and adult tusk size quickly, even though their first antlers are much smaller than those of older bucks. The hypothesis is presented that, for muntjac, the majority of a male's lifetime reproductive success is achieved relatively early in life when the canine tusks are in pristine condition, and that bucks lose their territories, and associated access to oestrous does, once the canines are broken.     

The role of male territories in the mating system of the Yellow-shouldered Widowbird Euplectes macrourus

The territorial system and breeding biology of the Yellow-shouldered Widowbird Euplectes macrourus (Ploceidae) was investigated in western Kenya. Yellow-shouldered Widowbirds had a resource-defence polygynous mating system: males defended large (mean = 0.95 ha) territories and built the coarse framing for the nests in tall grass. Males had up to five females nesting per territory. Females provided nearly all parental care except for a territorial male seen feeding a fledgling: the first observation of paternal care in the wild for this genus. There was considerable variation in territory size, but the cause of this variation remains unknown: territory size was not related to potential indicators of territory quality, such as grass height and abundance, did not relate to male morphology (mass, size and ornament size) or territorial behaviour (boundary displays and singing) and did not affect female preferences. Although resources (territories and nests) were defended by the males, observations that males frequently fed outside their territories and formed communal roosts during the breeding season suggest that this species represents a transitional stage between typical resource-defence polygyny and lek breeding.     

Serum testosterone (T) and 5-alpha-dihydrotestosterone (DHT) in male fallow deer (Dama dama L.): seasonality and age dependence

1. Seasonal levels of testosterone (T) and 5-alpha-DHT (DHT) were determined by RIA in serum of seven adult male fallow deer living under outdoor conditions (G?ttingen, FRG; 51.32 degrees NL). 2. The study, spread over six consecutive years, reveals the following seasonal T changes: Minimum concentrations in November or December, around antler casting and at early antler growing phase; increasing levels in the course of late antler development (mineralization) with relatively high values around velvet shedding; peak levels occurring during onset of rutting period followed by a sharp decrease after the rut; and distinct and oscillating T peaks during late winter and spring. 3. For the first time DHT levels were measured in male cervidae. Surprisingly, large values of DHT were found and occasionally levels were higher than T concentrations, but without a significant annual periodicity. 4. In some individuals maximum DHT values were found shortly before and during the rut. 5. During several months of the annual cycle individual T and DHT profiles showed opposite relationships, particularly during antler growing phase and shortly before antler casting. 6. Around rut the size of T peak levels depends on animal age.