Young Deer Research Articles

Use of different artificial shelter types by farmed red deer ( Cervus elaphus) calves

Young red deer often use natural shelter in a farmed situation. The aim of our study was to determine if certain types or shapes of shelter would be preferred. During the calving season, a group of hinds and calves was kept in a paddock containing a variety of artificial shelters. Sixteen shelters were available, consisting of four shapes at four different locations (centre, side or corner) within the paddock. The four shapes (tunnel, wall, corner and a “seven” shape) provided different combinations of vertical and horizontal surfaces, so that we could determine whether any particular features were preferred. While the calves used the shelters extensively throughout the study, no preference for any particular shape was found overall. However, as the experiment progressed, shelters were used significantly more often; the change was driven primarily by a sharp increase in the use of tunnel shaped shelters ( P<0.05). Of all the shelters, the simple wall design appeared to be used least. Also a significant preference ( P<0.01) for shelters in the centre of the paddock developed toward the end of the experiment. Finally, we found that shelter use increased as the daily maximum temperature increased. These results suggest that farmed red deer readily use shelter and have preferences for certain shelter shapes that change as calves mature. The provision of shelter may improve calf welfare.

Factors causing traffic killings of roe deer Capreolus capreolus in Denmark

In Europe, roe deer Capreolus capreolus is one of the biggest mammal species killed in traffic, and the number of accidents seems to increase. The purpose of our paper is to point out the most important factors causing traffic killings and to suggest conservation measures that may reduce the number of roe deer killings in traffic. Our study is based on data including 115 roe deer killed in traffic at the Kal⊘ estate in East Jutland, Denmark, during 1956–1985. No significant correlation was found between the number of traffic killings of roe deer and mean daily traffic, but the number of roe deer killed in traffic varied significantly over the seasons. The distribution pattern of roe deer/car collision sites was clumped. The risk of being killed in traffic was highest for young and old roe deer. Significantly more adult females, adult males and subadult males than expected were killed in traffic, and significantly more individuals were killed in years when most of the fields next to the roads were left unsown in winter. We suggest that the following measures be taken to prevent traffic killings: increasing areas with winter cereal or wintergreen fields, clearing the vegetation adjacent to roads and reducing car speed in high‐risk areas.

Mortality Profile and Taphonomy : A Look at Huron Deer Procurement

Faunal assemblages that preserve in the archaeological record and reach the desk of zooarchaeologists are not always representative of past subsistence practices and diet. Taphonomic factors affect bone accumulation, deposition and preservation at archaeological sites and these need to be filtered out before conclusions are drawn about human behaviour and the exploitation of faunal resources. In this study, ethnohistoric references to Huron subsistence are confronted with faunal data from a late prehistoric site. The analysis reveals that taphonomic processes have altered bone deposition and preservation of the faunal assemblage, in general, and of the collection white-tailed deer (Odocoileus virginianus) remains, in particular. The mortality profile constructed with the use of NISP counts reveals low relative percentage of young deer in the assemblage. Taphonomic processes, rather than game procurement strategies are invoked as the main causal factor behind such distribution.

Effect of feeding supplements on the intake and live-weight gain of male red deer given silage during winter

AbstractThe live-weight gain (LWG) of young male red deer in New Zealand naturally slows during winter and feeding diets of mainly silage appears to exacerbate this effect. We aimed to quantify the effect of feeding silage on intake and LWG during winter and the ability to improve LWG by feeding supplements, mainly in the form of barley. Seven groups of eight deer were maintained outside in gravelled enclosures and offered silage ad libitum for 94 days during winter. Six groups were given supplements (950 g barley with 50 g rapeseed meal per kg to make all diets isonitrogenous) at rates of proportionately 0·2, 0·4, 0·5, 0·6, 0·7 and 0·9 of the metabolizable energy (ME) intake of the group given only silage (0). The study also examined the effect of the winter treatments on subsequent LWG to slaughter weight whilst grazing on pasture during spring and into summer (102 days).Increasing supplement intake resulted in a decrease in silage dry matter (DM) and ME intake (P&lt; 0·001) and an increase in total ME intake (P&lt; 0·01). The substitution rate for silage DM was 0·84 (s.e. 0·079). LWG during silage feeding was positively related (P&lt; 0·01) to supplement intake with an increase of 6·21 g/day per MJ per day. LWG on pasture was not related to either supplement feeding rate or LWG during winter. LWG over the entire experiment was related (P&lt; 0·01) to supplement feeding rate, with a final difference in live weight of 6 kg between 0 and 0·9 groups.This study has confirmed that the LWG of young male deer is low during winter when given only silage and that feeding supplements increases total ME intake and LWG. The reduced LWG due to silage feeding was not compensated for on pasture during spring and summer, thus delaying the time to reach slaughter weight by approximately 1 month. High proportions of silage in the diet appear unsuitable for young male deer if the aim is to achieve rapid LWG during winter.

Electrophoretic patterns and immunoglobulin G levels in mouflon (Ovis orientalis musimon) and roe deer (Capreolus capreolus).

Serum protein and immunoglobulin G (IgG) levels were measured from 16 healthy mouflons (Ovis orientalis musimon) and from 28 roe deer (Capreolus capreolus) in French and Catalonian populations. Electrophoretic patterns were described for each species. The only significant gender-related difference was increased beta-globulins in French roe deer males. Significantly increased alpha1-globulin levels and decreased IgG levels occurred in the young Catalonian roe deer compared with adults from the same group. Values for total proteins, beta-globulins, gamma-globulin, and IgG were significantly higher in the French roe deer, while albumin and albumin/globulin ratio were higher in the Catalonian roe deer. Both populations had the same relative migration distances of the various protein fractions of the electrophoresis.

Detecting Herpesvirus By Negative Contrast Electon Microscopy in Tissue and Cell Culture From Mule Deer with Infectious Keratoconjunctivitis

Mule deer are infected with a herpesvirus associated with acute infectious keratoconjunctivitis (IKC) or “pink eye”. in December 2000, many young male mule deer in Wyoming had clinical signs of IKC including corneal edema, mucopuvulent conjuctivitis, blepharospasm, and blindness.Conjunctival swab samples from 5 mule deer with IKC were processed for negative contrast electron microscopy (NCEM) at the Wyoming State Veterinary Laboratory (WSVL). Homogenized samples from each deer were centrifuged for 20 minutes at 3440g in a Beckman Avanti J-25 centrifuge (Beckman Instruments Inc., Fullerton, CA, USA). The supernatant from each sample was subsequently centrifuged for 60 minutes at 39,800g. The final pellet was resuspended in 210 μl of sterile deionized microfiltered water. 105 μ1 of the virus suspension was mixed with sodium phosphotungstic acid stain containing 84 μl of 4% aqueous phoshotungstic acid, pH 6.8 with NaOH, 420 μl sterile, deionized microfiltered water, and 21 μl 0.1% bovine serum albumin.

Age-Specific Causes of Mortality among Male White-Tailed Deer Support Mate-Competition Theory

Mate-competition theory predicts that males will invest resources toward intrasexual competition for mates until reproductive benefits are outweighed by costs to future fitness. In populations that have a substantial proportion of mature males, theory predicts that young males will forego reproduction to reduce exposure to mortality that may result from breeding efforts. We examined age-specific mortality of males in a white-tailed deer (Odocoileus virginianus) population in which >50% of the males were ≥3.5 years old to determine whether patterns of male mortality conform to mate-competition theory. Annual mortality rates were relatively stable throughout adulthood (0.26-0.38), but causes of mortality changed with age. Young males (1.5 and 2.5 years old) were most susceptible to human-induced mortality (e.g., hunting and vehicle accidents), whereas males ≥3.5 years old tended to die from non-human causes (e.g., fighting, predation) more frequently than did younger deer. Proportional hazard models also indicated that as antler size increased, likelihood of mortality increased. Age- and cause-specific patterns of mortality in adult male deer from a population with >50% mature males reflected patterns predicted by mate-competition theory. When managing deer populations with high proportions of mature males, it is important to account for shifts in susceptibility to human-induced and natural mortality agents.

Longitudinal studies of Sin Nombre virus in deer mouse-dominated ecosystems of Montana.

Sin Nombre virus (SNV), hosted by the deer mouse (Peromyscus maniculatus), is the primary etiologic agent of Hantavirus pulmonary syndrome (HPS) in North America. To improve our understanding of the epidemiology of HPS in the western United States, we conducted studies of population dynamics and SNV antibody prevalence in deer mouse populations for 6 years on 12 mark-recapture grids in Montana. Monthly numbers of deer mice ranged from zero to over 170 on 1-hectare grids. SNV antibody prevalence was higher than observed in studies in other parts of the United States, averaging 13% (0% to 50%), and peaking in May or June each year. Antibody-positive mice were older (heavier) (78% of positives were adults versus 52% of negatives) and more likely to be males (61% of positives versus 53.4% of negatives). A higher proportion of antibody-positive deer mice of all age-mass classes had scars than did antibody-negative mice. Month-to-month survivorship of antibody-positive adult mice was similar to that of antibody-negative mice, but survival of young antibody-positive deer mice was lower than antibody-negative deer mice. This is the first study to clearly suggest a detrimental effect of SNV infection on deer mice.

II. Remembrances, 1671–1713

Some few remembrances of my misfortunes which have atended me since I were maryed (in my unhappy life), which was 14 of November 16711671, November 14 Thursday, the i4 of November and Childermas or Cross Day and dreadfully rainey, I was in London pryvatly marryed to Mr Percy Freke by Docter Johnson, my Lord Russells chaplin, in Coven Garden Church in London. My husband was the only son liveing of Captaine Aurthur Frek and grandson to Mr William Freke, the only brother of Sir Thomas Frek of Dorshetshire, who was my grandfather, and his son Mr Ralph Freke [was] my own deer father. And my deer mother was Sir Thomas Cullpepers daughter of Hollingburne in Kentt. Her name was Cicelia Cullpeper, who dyed in or about 1649 and left me, the eldest of five daughters, aboutt six or seven years of age and lyes buryed in the chancell att Hollingburne - where lyes six more brothers and sisters of myne which dyed young and my deer sister, the wife of Sir George Choutt, who lived his widow 12 years and dyed of the small pox, as did her only daughter, and are both inter'd in the chancell in Hollingburne. And affter aboutt 6 or seven years being engaged to my deer cosin Mr Percy Frek and all my three surviveing sisters maryed, viz., Cicelia maryed to Sir Georg Choutt in Kentt, Frances marryed to Sir George Norton att Abbots Leigh neer Bristoll, and Judith, my youngest sister, marryed Collonell Roberti Austen of Tenlerden in Kentt, I, the eldest, Elizabetth, as above, was maryed 14 of November 1671 to Mr Percy Frek withoutt my deer fathers consentt or knowledg in a most dreadfull raynie day (a presager of all my sorrows and misfortunes to mee).

Πεφυζοτες ηυτε νεβροι: Genealogy and Poetic Imagery of a Homeric Formula

The formula ~ k } = k m k x k g = r forms part of a simile which has acquired a context-free semantic aura disclosing Homeric eschatological beliefs. The pre-verbal Gestalt which was nascent in the formula ~ k } = k m k x k g = r was that of the terrified, panic-stricken young deer being attacked by some carnivorous predator when they were drinking water. The participles ~ k } = k and k θ m ~ = k determine this framework including two temporally distinct phases of the realization of the Gestalt : confusion and daze before the imminent menace ( k θ m ~ = k ) and panic-stricken flight ( ~ k } = k ). Thus, the ~ = x = notion expresses the concept of dangerous transition and the water imagery connotes destruction, imminent death .

Effect of forage legumes containing condensed tannins on lungworm (Dictyocaulus sp.) and gastrointestinal parasitism in young red deer (Cervus elaphus)

To investigate the effect of feeding forage legumes containing condensed tannins (CT) on internal parasitism, red deer calves were fed either lucerne (Medicago sativa; 0.1 per cent CT), birdsfoot trefoil (Lotus corniculatus; 1.9 per cent CT) or sulla (Hedysarum coronarium; 3.5 per cent CT) and trickle-infected with deer-origin gastrointestinal nematode and lungworm (Dictyocaulus sp.) larvae for 5 weeks, then slaughtered at 7 weeks. There was a significant negative linear relationship between dietary CT concentration and abomasal nematode burdens. No significant differences in faecal egg counts, lungworm burdens or voluntary feed intake were found. Deer fed sulla had higher liveweight gain, carcass weight and carcass dressing-out percentage, higher serum total protein and albumin concentration and lower serum gastrin concentration and faecal lungworm larval count, compared with lucerne-fed deer. Inclusion of sulla in diets for young red deer may reduce the impact of internal parasites and/or reduce the dependence on anthelmintic treatment.

SELECTION OF MULE DEER BY MOUNTAIN LIONS AND COYOTES: EFFECTS OF HUNTING STYLE, BODY SIZE, AND REPRODUCTIVE STATUS

Abstract Predation on mule deer (Odocoileus hemionus) by mountain lions (Puma concolor) and coyotes (Canis latrans) was examined to test effects of hunting style and body size, and for mountain lions reproductive status, on selection of prey. Mountain lions, which hunt by stalking, selected ≤1-year-old mule deer as prey. Body condition of mule deer did not affect prey selection by coyotes or mountain lions, and both predators preyed upon females and older adult deer more often than expected based on the percentage of these groups in the population. Female mountain lions selected female deer, but male mountain lions did not. Female mountain lions without offspring, however, did not differ from male mountain lions in prey selection. Coyotes did not select for young deer. Female mountain lions with kittens were selective for young deer in late summer.

A model for study of lungworm ( Dictyocaulus sp.) and gastrointestinal nematode infection in young red deer ( Cervus elaphus)

A model of sub-clinical parasitism in young red deer, using concurrent trickle infections of lungworm ( Dictyocaulus sp.) and mixed gastro-intestinal (GI) nematodes of deer-origin was evaluated. 20 parasite-free deer calves were artificially reared indoors from 4 days of age. A further five calves were naturally reared on pasture with their dams, treated with anthelmintic and brought indoors at 3–4 months. At 4–4.5 months of age they were individually housed and allocated to five groups ( n=5). Groups were dosed 3× per week, for 9 weeks with 0, 100 and 500, 200 and 1000 (2 groups), 400 and 2000 infective larvae of lungworm and mixed GI nematodes, respectively, cultured from deer faeces. Liveweight and voluntary feed intake measurements and faecal and blood samples were taken weekly. In the fourth week following cessation of trickle infection, deer were euthanased and lung and GI nematodes recovered. Both lungworm and GI nematode infections became patent at Week 4 of infection. Maximum group arithmetic mean faecal egg counts were 100–190 epg. Maximum group arithmetic mean faecal lungworm larval counts were 58–123 lpg. Group arithmetic mean nematode counts at slaughter ranged from 439–806 for GI nematodes and 31–73 for lungworm, respectively. Despite low nematode counts, reduced liveweight gain, voluntary feed intake and serum albumin concentration, elevated serum pepsinogen, gastrin and globulin concentrations and elevated peripheral eosinophil counts and slight haemoconcentration, but no clinical signs, were observed. The reduction in liveweight gain was related to the reduction in voluntary feed intake ( r 2=0.83; p<0.088). Naturally-reared deer had similar liveweight gains, voluntary feed intake and nematode counts to artificially-reared deer. Thus, methods of infection to produce concurrent sub-clinical lungworm and GI nematode burdens for study of sub-clinical parasitism in young deer have been defined.

The effect of age and experience on the reproductive performance and prenatal expenditure of resources in female fallow deer (Dama dama)

In this paper we tested whether prenatal expenditure of resources in fallow deer (Dama dama) is affected by the age and reproductive experience of mothers. The study was carried out on the wild fallow deer population in Doñana National Park in southwestern Spain. Between 1985 and 1996 a total of 60 different females were monitored by direct observation during the fawning season. The exact age of 22 of these females was known, and 59 fawns born of these females were captured. The mother's age had more influence on the fawn's birth mass than the mother's experience did. Fallow deer fawns born of adult multiparous mothers (5-8 years old) were heavier than fawns born of young multiparous mothers (3-4 years old), whereas birth masses of fawns born of primiparous mothers (2-3 years) and young multiparous mothers showed no significant difference. Fawns were born earlier in the breeding season as the mother's age increased. The trade-off required between resources allocated to reproduction and resources available for growth and maintenance may limit reproduction and the possibility of increasing prenatal expenditure by both young primiparous and young multiparous female fallow deer. Sexual dimorphism in birth mass was detected, males being heavier than females, independently of the age and parity of the mothers. This confirms the finding that fallow deer mothers are selected to expend more resources on their male offspring.

Winter Prey Selection by Wolves and Cougars in and Near Glacier National Park Montana

Expansion by wolf (Canis lupus) populations in the western United States creates new opportunities and challenges for researching and managing large mammal predator-prey systems. Therefore, we compared patterns of prey selection between wolves and cougars (Puma concolor) to ascertain the effects of multiple predators on prey and on each other. Because of differences in hunting techniques, we predicted that wolves would kill more vulnerable classes of prey than cougars. Our results did not support this prediction. White-tailed deer (Odocoileus virginianus) composed the greatest proportion of wolf (0.83) and cougar kills (0.87), but elk (Cervus elaphus) and moose (Alces alces) composed a larger proportion of wolf (0.14, 0.03, respectively) than cougar (0.06, 0.02, respectively) kills. Wolves and cougars selected older and younger deer and elk than did hunters. Cougars killed relatively more bull elk (0.74) than did wolves (0.48). Male deer killed by cougars had shorter diastema lengths than did male deer killed by wolves (P = 0.02). Pack hunting by wolves and dense stalking cover may have partially explained the failure to support predictions of the coursing versus stalking dichotomy. Wolves and cougars may be exhibiting exploitation and interference competition that is affecting each others' behavior and dynamics, and that of their prey.

Growth and carcass production of young farmed deer grazing sulla (Hedysarum coronarium), chicory (Cichorium intybus), or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture in New Zealand

Liveweight gain, voluntary feed intake, and carcass production were compared for pure red and hybrid (0.75 red: 0.25 elk) deer calves grazing sulla (Hedysarum coronarium cv. Necton), chicory (Cichorium intybus cv. Grasslands Puna), or perennial ryegrass (Lolium perenne cv. Nui)/white clover (Trifolium repens cv. Huia) pasture from weaning in March to slaughter in December of the same year, at approx one year of age. Organic matter digestibility (OMD) of diet selected was similar for all forages during autumn, but OMD of chicory (88.4%) was greater than both sulla (78.3%) and pasture (83.8%) during spring (P < 0.05). Sulla diet selected contained 5.1% condensed tannin (CT) in autumn and 8.4% CT in spring (P < 0.05); pasture and chicory contained 0.14–0.26% CT. VFI of deer grazing sulla was greater than for deer grazing chicory in autumn (2027 versus 1014 g OM d−1; P = 0.07), but not spring (2029 versus 2251 g OM d−1). In autumn, deer gained 293 g d−1 on sulla, 218 g d−1 on pasture (P < 0.01), and 183 g d−1 on chicory (P < 0.001). In winter, deer gained 150 g d−1 on sulla and 133 g d−1 on pasture. Final liveweight of deer grazing sulla was 106 kg, which was significantly higher than 97 kg for deer on pasture or 95 kg for deer on chicory (P < 0.01). Deer grazing sulla had greater carcass weights (59.9 kg) than deer grazing pasture (52.3 kg) or chicory (52.1 kg) (P < 0.01 hinds; P< 0.05 stags). Hybrid stags had significantly greater carcass weights than red stags (64.1 kg versus 56.3 kg; P < 0.01) and hybrid hinds (52.8 kg; P < 0.001). It was concluded that the increased growth and carcass weight of young deer grazing sulla was caused by a higher feeding value of sulla, with a component of this being increased utilisation of digested nutrients.

Photoperiodic requirements for rapid growth in young male red deer

AbstractWinter growth of young male red deer can be increased by exposure to 16 h of light (L) and 8 h of dark (D) per day (16L: 8D). This study tested the duration of photoperiod required for this growth response, determined if the time to reach slaughter weight can be reduced and monitored plasma IGF-1, prolactin and reproductive development. Fifty male calves were allocated to five equal groups. Four groups were housed indoors and for 33 weeks from the winter solstice (22 June, southern hemisphere) until 11 February were placed under either 16L: 8D (16L), 13·25L: 10·75D (13L), 10·751:13·25D (111) or 8L: 16D (8L) photoperiods. The fifth group of deer (OC) remained outside in a gravelled enclosure. All groups were given a pelleted diet ad libitum. Group food intake was recorded daily, individual live weight was measured weekly and testes diameter and blood samples taken at weekly or 2-week intervals.Plasma prolactin concentrations in 16L increased within 4 weeks of treatment and were different (P &lt; 0·001) between groups from 14 August to 4 September. IGF-1 increased in both 16L and 13L 4 weeks after treatments and then increased further in 16L above that of 13L (P &lt; 0·01). All groups grew at the same rate for the first 7 weeks. 16L then gained more weight (P &lt; 0·001) than the other groups over the next 19 weeks (50·7 kg v. 38·5 for 13L, 35·7 for 11L, 37·0 for 8L and 37·4 for OC; s.e.d. 3·76). Food intake was positively related to growth rate in a similar way among the inside groups (P &lt; 0·001), however there was a higher energy requirement outdoors (P &lt; 0·05). A target live weight for slaughter of 95 kg was reached 7 weeks earlier for 16L than the other groups (P &lt; 0·01). Testes diameter of 16L was larger than in the other groups from 13 November until 24 December (P &lt; 0·001). The growth oflSL slowed from 1 January while that of OC increased and the live weight ofOC was equal to 16L by the end of the experiment. OC also had the largest testes diameter from 5 February onwards (P &lt; 0·01). The live-weight increase in OC was associated with increases in both prolactin and IGF-1 levels.This study confirmed that 16L: 8D stimulates rapid growth of young male red deer during winter for sufficient time to achieve an earlier slaughter date. The live-weight advantage was lost by late summer however. The increased growth rate was mediated by food intake and associated with increases in IGF-1 and prolactin and earlier reproductive development. Photoperiods of 13 h of light per day or less did not stimulate growth and increases in IGF-1 and prolactin were of a lower amplitude than under 16L: 8D.

The efficacy of a pour-on formulation of moxidectin in young red and wapiti-hybrid deer

Aims. To measure the efficacy of a pour-on formulation of moxidectin against lungworm and abomasal parasites in weaner wapiti x red deer and to compare this with its efficacy in weaner red deer. Methods. Six red and six wapiti hybrid deer, naturally infected with lungworm and gastro-intestinal parasites, were treated with pour-on moxidectin at 500 μg/kg body weight and slaughtered 14 or 16 days later, along with six red1 and six wapiti hybrid untreated control deer. Total worm counts were performed on the lungs, abomasum and abomasal digest of each deer. Results. The efficacy of moxidectin pour-on was 100% against adult and immature lungworms (Dictyocaulus viviparus) in red deer, and 100% and 99.7% effective against adult and immature lungworm in wapiti hybrid deer. The efficacy of moxidectin pour-on was 100, 100, 99.9 and 99.9% respectively against adult, fifth stage, late fourth stage and early fourth stage larvae of Ostertagia-type nematodes (assumed to be Ostertagia, Spiculopteragia, Skrjabinagia and Apteragia spp.) in both red and wapiti hybrid deer. Conclusions. The pour-on formulation of moxidectin, at 500 μg/kg body weight, is highly effective against mature and immature lungworms and abomasal nematodes in wapiti hybrid deer and equally effective in red deer.

Digestive rate of Dongtian F1 red Dear in weaning period and growth period

In this paper, 4N-HCLAIA method was adopted to conduct digestive tests in young female and male Dongtian F1 red deer (Cervus elaphus) of rearing seperately in growth period and mixed raising in weaning period in Harbin Specialty Research Institute. Results indicated that digestive rate of crude protein and crude fiber were 95.35% and 73.68% respectively when rational protein content was 26.8% in growth period, Digestive rate was not significantly different between female and male(P>0.05); During weaning period, when rational crude protein content is 22.06%, digestive rate of crude protein and crude fiber were 93.05% and 63.96%, respectively. The tests suggest that higher rational protein can be effective in accelerating growth of young Dongtian F1 red deer during growth period and weaning period(before 10 months old).

Spatial learning and hippocampal volume in male deer mice: relations to age, testosterone and adrenal gland weight

Spatial learning and various physiological parameters were examined in old (57 month), middle aged (38 month), adult (18 month) and young (3–3.5 month) male deer mice ( Peromyscus maniculatus). Performance during acquisition of a water maze task was not significantly reduced for middle aged and adult mice relative to young reproductively active (breeding) mice. Performance was deteriorated in old mice relative to young breeding mice on block 4 of training. Retention of this spatial task, however, was reduced in all three older groups relative to young breeding mice. Corrected hippocampal volume (corrected for brain weight) was reduced only in old mice relative to young breeding mice although absolute volumes of hippocampus were lower in all groups relative to young breeding mice. Old mice also were shown to have lower levels of plasma testosterone and lighter brains relative to young breeding mice. Spatial retention was not deficient in old, middle aged and adult mice relative to a group of young reproductively quiescent male (non-breeding) mice. Young breeding mice displayed better spatial performance and had significantly higher plasma testosterone levels, corrected hippocampal volume and brain weight relative to young non-breeding mice. These results indicate that retention of a spatial task is more sensitive to the age of male deer mice than acquisition of the task. Hippocampal volume, although a gross morphological feature, appears to be sensitive to the effects of ageing in male deer mice. Plasma testosterone levels do not appear to be a crucial factor underlying age-related deficits in retention of a spatial task.