Fertility Control in Free-Ranging Elk Using Gonadotropin-Releasing Hormone Agonist Leuprolide: Effects on Reproduction,Behavior, and Body Condition

ABSTRACT Overabundant elk (Cervus elaphus) populations have become a significant problem in many areas of North America. This is particularly true for protected areas where high densities of elk can cause long-term ecological degradation. When lethal control is not acceptable in these environments, resource managers must often consider alternative methods for reducing the size of resident elk populations. A potential management alternative is controlling the fertility of female elk. A promising new approach to wildlife contraception involves the use of biodegradable implants containing the gonadotropin-releasing hormone (GnRH) agonist leuprolide. During fall 2002-spring 2004, we compared pregnancy rates, reproductive behavior, daily activity patterns, and body condition of 17 free-ranging female elk treated with a leuprolide formulation with 17 untreated females, in Rocky Mountain National Park, Colorado, USA. After treatment, the pregnancy rate of treated elk was 0%, whereas 79% of control elk became pregnant. The effects of treatment were reversed the subsequent year with the pregnancy rate of treated females 100% compared with 91% for controls. Reproductive behaviors were similar for treated and control elk during the breeding and postbreeding seasons; treated elk did not exhibit postrut reproductive behaviors. Moreover, we found no differences in daily activity patterns of experimental groups during the breeding or postbreeding seasons. Treated elk did not show improved body condition over pregnant females. Instead, treated females catabolized proportionately more body fat during winter after treatment and at a higher rate than pregnant control elk. However, this effect was reversed the next spring with no difference in body fat between treated and control elk. We conclude from this experiment that leuprolide, administered as a controlled release formulation, offers a safe and effective method of controlling fertility in free-ranging female elk. However, practical application is limited by treatment duration and the need to treat females before the breeding season.     

Body condition during pregnancy and lactation and reproductive efficiency of mares

In Experiment I, 32 mares were equally allotted to the following treatments: mares fed to A) high body condition from 90 days prepartum to foaling and maintained in high body condition to 90 days postpartum, B) high body condition from 90 days prepartum to foaling and allowed to lose body condition to 90 days postpartum, C) lose body condition from 90 days prepartum to foaling and maintained in low body condition to 90 days postpartum, and D) lose body condition from 90 days prepartum to foaling and allowed to gain weight after foaling to attain a high level of body condition by 90 days postpartum. After three cycles, pregnancy rate at 30 days postovulation was lower (P<0.05) in C mares (50%) than in those in the other three groups (100%). Maintenance of pregnancy to 90 days was also reduced (P<0.05) in C mares (25%) when compared with A, D (both 100%) and B mares (88%). Foal growth to 90 days of age was similar in all treatments. In Experiment II, 927 mares were evaluated for body condition and monitored for reproductive performance. Pregnancy rate was lower (P<0.05) and number of cycles/conception was higher (P<0.05) for barren and maiden mares entering the breeding season in thin condition and for pregnant mares foaling in thin condition (condition score less than 5.0) when compared with mares with a higher level of condition. Also, onset of estrus and ovulation appeared to be delayed in barren and maiden mares entering the breeding season in thin condition. Breeding efficiency was enhanced in mares entering the breeding season or foaling at a condition of 5.0 or above. Initial excess stores of body fat enhanced fertility. There were no detrimental effects of excess body fat stored in late gestation.     

Seasonal field analyses of water and fat content in the long-lived millipede Polyzonium germanicum (Diplopoda, Polyzoniidae)

Two hundred and seventy-nine Polyzonium germanicum individuals of various stadia were collected seasonally in winter, late spring-early summer (the breeding period) and early autumn. Fresh weight, dry weight and defatted dry weight were determined for each specimen. Seasonal changes in water content and fat content, expressed as percentages of defatted dry weight, were analysed in relation to body size and sex. Changes in water content were more pronounced in the smallest individuals (juveniles), whereas changes in fat content were more pronounced in the largest (adults). Seasonal fluctuations in water and fat content were similar in both sexes despite the sexual dimorphism of body weight. The results suggest the following relationships within the species life-cycle: (i) water content increases during the warm months (up to 295% for juveniles in early autumn), which coincides with the moulting period, (ii) Fat content increases subsequently to moulting; overall maxima are reached in early autumn (population mean = 62–5%), as well as in early summer for the young, (iii) Both water and fat content decrease (to about 150% and 50%, respectively) in winter; however, there is no evidence of starvation–at least in ovigerous females which increase in dry weight during that season, (iv) Fat content strongly decreases (below 30% in the largest specimens) in adults of both sexes during the breeding period.     

Annual patterns in reproduction and perirenal fat of hares (Lepus europaeus) in sub-alpine Canterbury, New Zealand

The aim of this paper was to describe how the age, sex and reproductive state of hares affected the amount of fat found around their left kidney. A total of 2208 hares ( Lepus europaeus ) was shot and autopsied over 13 years from sub-alpine grasslands in Canterbury, South Island, New Zealand. Adult females may be pregnant from July to mid-March. Adult males' testis weights were highest from July to January, and some fertile males may have been present in all months but April. The amount of perirenal fat in adults increased in autumn, peaked in early winter, and decreased thereafter to low levels through spring and summer. Autumn fat deposition in males was not clearly related to reproductive state in individuals, although it coincided with seasonal testicular development. Autumn fat deposition in females may have been caused in part by the cessation of lactation, but, like that in males, the increase was also part of an endogenous pattern. Fat utilization in winter was related to breeding. In males, utilization coincided with reproductive activity and the amount of perirenal fat remained consistently low throughout the breeding season. In females, net fat utilization was associated with lactation but this was balanced to some extent by fat deposition induced by pregnancy. Females simultaneously lactating and pregnant were in finer balance between utilization and deposition. Other factors, such as the number of embryos and the stage of gestation, altered the fat balance in these hares. Fat was also deposited as a 'yolk-sac' in embryos.     

Body fat in pregnant rats at mid- and late-gestation

Carcass fat content was estimated in fed 12- and 19-day pregnant rats and fed and 48 hour starved virgin females following both specific gravity determination and direct gravimetry of extracted lipids. No change in body fat accumulation was found in 12-day pregnant rats whereas in 19-day pregnant animals it increased significantly. A significant correlation was also found when the percentage of carcass fat was plotted against specific gravity considering values from all subjects. Results indicate that in spite of reported maternal anabolic changes in the rat at midgestation fat accumulation occurs later in pregnancy when the mother has the highest food intake, which makes available sufficient substrates to support both fetal growth and body lipidic deposition.     

THE ANNUAL CYCLE IN A TROPICAL WET FOREST HUMMINGBIRD COMMUNITY

In the Caribbean lowlands of Costa Rica, rainfall is moderately seasonal, although even in the driest month over 100 mm of rain usually fall. Flowering of hummingbird food plants shows a peak in the dry season (February-April) and another in the early wet season (July-September), with a severe flower shortage at the end of the rains (November-December). The dry season peak involves largely canopy epiphytes, the wet season peak large herbs of light gaps and edges and forest understory plants. This study examines the responses of the associated community of 22 species of hummingbirds (of which 13 breed, and 12 are common for at least parts of most years) to these spatial and temporal patterns of resource availability. Nearly all common breeding species show a peak of reproductive activity in the dry season, coinciding with the first flowering peak, followed by a discrete moulting season that coincides with the wet season peak of flowering. Of the three species with extended breeding seasons, the two species of hermit, Phaethornis, show moult-breeding overlap to varying degrees on an individual basis. In a number of species moult and breeding appear antagonistic. The annual peak of body weight and fat deposits in all species occur during the second flowering peak, approximately corresponding to the moult. The annual minima of body weight and fat occur in the lean season and the breeding season respectively. The lack of concordance of these two possibly reflects the use of muscle protein as a nutrient source during the lean season. Several species show pronounced habitat shifts through the year, with the sexes sometimes occupying different microhabitats, especially during the dry season. At least five species show pronounced seasonal migrations, largely or entirely leaving La Selva for part of the year. Overall hummingbird numbers are greatest early in the rainy season, lowest in the lean season, with the non-hermits (Trochilinae) showing a more pronounced annual cycle of numbers than the hermits (Phaethorninae). Comparisons with other tropical lowland hummingbird-flower communities are made with respect to the roles of flowers as proximate and ultimate factors regulating the annual cycles and affecting the population biology of the birds.     

Cold exposure does not decrease serum leptin concentration,but increases energy intake and thermogenic capacity in pregnant Brandt's voles (Lasiopodomys brandtii)

In most mammals, maternal body mass and fat mass increase during pregnancy due to hyperphagia. These physiological changes provide the fetus with energy and nutrients and prepare the mother for the high energetic demands of lactation. In the present study, metabolic changes in response to cold and pregnancy were examined in female Brandt's voles (Lasiopodomys brandtii). At 23±1 °C, the voles increased body mass and deposited body fat during pregnancy. However, at 5±1 °C pregnant voles did not deposit body fat even though energy intake increased above the level in the warm. Serum leptin concentration increased during pregnancy and was not influenced by cold exposure. Thermogenic capacity, as indicated by uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT), increased in cold-exposed pregnant voles. The number and mass of fetuses were not affected by cold exposure. Our data may indicate the importance of an increased serum leptin concentration for a successful outcome of the pregnancy and also the independence of leptin secretion from body fat in pregnant voles. It also implies the need to develop central leptin resistance with respect to control of energy balance for pregnant voles.     

Impaired basal and noradrenaline-induced iodothyronine 5'-deiodinase activity in brown adipose tissue from pregnant and lactating rats

Basal iodothyronine 5'-deiodinase activity is lowered in brown fat from 20-day pregnant, 5 and 15-day lactating rats when compared with virgin controls. Acute noradrenaline treatment caused a seven fold increase in 5'-deiodinase activity in brown fat from virgin control rats. Late pregnant and lactating rats showed a reduction in noradrenaline-induced 5'-deiodinase activity in brown adipose tissue and the maximum impairment was observed in 15-day lactating rats. Lowered 5'-deiodinase activity in brown fat during late pregnancy and lactation correlates with the known reduction in the thermogenic activity of the tissue during these situations and agrees with the proposal that the rate of 3,5,3'-triiodothyronine generated in situ because of thyroxine 5'-deiodination could be an essential event related to thermogenesis in brown fat. Even though the relationship between 3,5,3'-triiodothyronine generation in the tissue and the specific thermogenic mechanisms of brown fat is unknown, present results indicate a close link between the thermogenic and 5'-deiodinase activities in physiological situations when brown adipose tissue needs to adapt to a low activity, such as that of the breeding cycle.     

Elevational range and timing of breeding in the birds of Ladakh: the effects of body mass, status and diet

We studied the effects of body mass, status (resident or migratory) and diet on the breeding elevation range and timing of reproduction of the birds in the Trans-Himalayan region of Ladakh, northwestern India. Most of breeding birds of Ladakh are Palearctic or breed at high elevations in the mountains. There is a small proportion of Oriental species, and no bird is endemic to this region. We found that heavier birds tended to start their egg-laying earlier than lighter ones. Since body mass is related to the length of incubation and nesting periods, it would appear that one result of this phenomenon is that the time of peak demand for food for most birds coincides with peak food abundance in summer. Status affected the elevation of the breeding range, with resident birds tending to breed at higher elevations than summer visitors. Residents and summer breeders also differed significantly in their diet composition, with the former feeding mainly on plants and seeds, and the latter feeding on molluscs, insects and worms.     

State-dependent male mating tactics in the grey seal: the importance of body size

The purpose of this study was to examine the importance of bodysize and body composition as determinants of conditional matingtactics exhibited in male grey seals. We combined behavioralobservations with measures of energy expenditure and successon 42 known-age individuals during the breeding seasons of 1997–2001at Sable Island, Canada. Males with a large body mass arrivedat the breeding grounds with more body fat and body energy andcatabolized less body protein than smaller males. Males consumed1.9 ± 0.2 MJ day^–1, and those with a smaller percentageof body fat had higher rates of food energy intake. The amountof body energy on arrival was positively correlated with theduration of the breeding period. Males that exhibited the primarymating tactic of consortship were heavier, had absolutely morebody fat and body energy, and sustained breeding longer thanthose males that did not exhibit the primary tactic. Amongstall males, body mass showed a quadratic relationship with thenumber of female consorts mated and the estimated number ofpups sired. Thus, intermediate-sized males mated with the mostconsorts and achieved the highest success. Intermediate bodysize may be optimal during breeding due to greater agility inmale combat. Body size was an important determinant of matingtactics used by male grey seals. A large body size providedan energetic advantage of greater endurance while an intermediatebody size may provide greater competitive ability in acquiringconsortships.     

Travel schedules to the high arctic: barnacle geese trade-off the timing of migration with accumulation of fat deposits

On their way from the wintering area to the breeding grounds in Spitsbergen, barnacle geese Branta leucopsis stage on islands off the coast of Norway. The aim of this study was to describe when the geese migrate in relation to the body stores deposited and explore questions related to the concept of optimal migration schedules and on the possible mechanisms involved. We estimated fat stores by repeated assessments of the abdominal profile index of individually marked females throughout staging. Reproductive success was derived from observations of the same individuals later in the annual cycle. Females arriving late, or with low fat stores at arrival, achieved higher fat deposition rates, probably by spending more time foraging. But they were unable to match final fat scores of birds that arrived earlier or with larger fat stores. Reproductive success was correlated with the timing of migration and individuals departing at intermediate dates achieved highest success. The exact date of peak reproductive success depended on the size of fat stores accumulated, such that low-quality birds (depositing less fat) benefited most from an early departure to the breeding grounds. Observations in the breeding colonies showed that these birds did not initiate a nest earlier but they spent a longer time in Spitsbergen before settling. The length of stay in Norway was close to the prediction derived from an optimisation model relating spring events to eventual breeding success. Poorest performing birds stayed longer than expected, perhaps depositing more fat to avoid the risk of starvation. Two possible mechanisms of the timing of migration were contrasted and it seemed that the geese departed for migration as soon as they were unable to accumulate any more fat stores.     

Lipid levels in the South Island pied oystercatcher (Haematopus ostralegus finschi)

Wing lengths and some major body components were compared among the sexes and age classes of a sample of 48 South Island pied oystercatchers (Haematopus ostralegus finschi). Immature males were significantly lighter in wet weight and fat‐free weight than either immature females or adults, and were significantly lighter than adults in lean dry weight. No statistical differences were found in wing length, total lipids, or fat measure for birds in this sample. In a larger sample of 182 birds, fat measure varied similarly in the age classes, from a low in autumn to a peak in spring just before vernal migration. Massive pre‐migratory fattening typical of many small passerines does not occur in this species, but even so the average fat reserves in spring adults are sufficient for an approximate flight range of 2140 km, well in excess of need. It is hypothesised that the amount of fat deposited before vernal migration is a compromise between the energy cost of acquiring and transporting extra fat and the advantages of arrival at the breeding grounds with sufficient fat reserves for early achievement of breeding condition.     

The effect of nutrition on the seasonality of reproduction in ewes

The beneficial effects of nutrition on reproduction in sheep have been described, particularly on ovulation rate. However, the relationships between nutrition and reproductive seasonality are not well known. This review will deal with the effects of body fat or food intake on sexual and hypothalamic/pituitary activity in sheep, mainly focused on Mediterranean genotypes. Although only severe malnutrition can significantly extend the length of the seasonal anestrous period, the level of fat reserves can play a significant role on reproductive seasonality delaying the onset of seasonal anoestrus, particularly on the Mediterranean environment. The effect of overfeeding on LH secretion has also been reported, specially at short term. Several experimental approaches have elucidated that both high body fat and food intake are able to modify the sensitivity of the hypothalamus to oestradiol negative feedback during seasonal anoestrus, with those effects being associated to a reduced amount of NPY mRNA and to an increase of plasma insulin, glucose and leptin concentrations, particularly in the late scenario. However, the highest receptivity to nutritional stimulation in terms of increasing LH occurs when ewes are subjected to a photoperiodic state of early anoestrus or late breeding season rather than under a photoperiod characteristic of the end of anoestrus or the beginning of the breeding season.     

Body weight, gonad development and moult in the Tawny owl (Strix alum)

Gonad development, moult and seasonal changes in body weight and composition in the Tawny owl Strix aluco were studied by examining the carcasses of 369 owls (mostly road casualties) supplemented by 112 weights of live birds. In breeding females laying was preceded by the accumulation of fat and to a lesser extent protein which meant that they weighed more at this time (February/March) than at any other. Females declined in weight after laying but were still heavy during incubation. In contrast, males and non-breeding females did not increase in weight before the start of the breeding season. Juveniles reached or even exceeded adult weight well before independence due to the deposition of fat. Even after the exclusion of diseased or contaminated individuals, 9·4% of the birds examined were identified as starving; most of these were in the autumn and were probably newly-independent young wandering in search of territories. In both sexes gonad maturation was of brief duration coinciding with the period (mid-March to mid-April) in which eggs are normally laid. Ovarian growth was biphasic. In the three months prior to the breeding season ovarian condition in different birds was positively correlated with body weight and it appeared that the largest ovarian follicles of females in poor condition failed to attain the size from which rapid growth to final ovulation occurs. in males testis size in the breeding season was correlated with pectoral muscle weight (an index to protein condition) but not body weight. The majority of adults commenced wing moult in June. The average duration of primary moult was estimated to be 77 days. Healthy birds replaced the primaries of both wings at the same rate but most diseased birds moulted asymmetrically and/or out of season. First-year birds renewed their body feathers between September and November. In the Tawny owl territory establishment, breeding and moult are temporally separated.     

Seasonal changes in condition, reproduction and fecundity in the wild European rabbit (Oryctolagus cuniculus)

A total of 1248 rabbits ( Oryctolagus amiculus ) were shot on farmland in Cambridgeshire, UK over a period of three years. This provided pooled estimates of changes in reproductive and body condition and of fecundity during the annual cycle. Both males and females showed a significant annual cycle in reproductive condition as indicated by changes in the size of the gonads and accessory glands of reproduction. No females were pregnant during October, November and December, but males with active spermatogenesis were found during every month of the year. The distribution of pregnancies through the year showed that the reproductive season varied greatly between individuals. Peak fecundity occurred during April, May and June. On average, each female conceived 23.9 and suckled 17.2 young per breeding season. Proportionately more young died during the early stages of the reproductive season. The body weight of adult males, but not of females, varied seasonally. Body condition (kidney fat index) in adults was maximal at the start of the breeding season and minimal at the end.     

Seasonal changes in density, demography and body composition of small mammals in a southern temperate forest

Eleven small mammal species (nine rodents and two shrews) were recorded in 16 months of trapping in the Karkloof Forest, Natal. Total densities varied seasonally, ranging from 60.7 animals/ha in the dry autumn and winter to 29.1 animals/ha at the onset of the rains in spring and early summer. Peaks in breeding coincided with high body fat and water content in the five common species during summer: in winter, when body fat and water levels were low, there was no breeding. This may be related to poor food quality at this time. Annual changes in density, breeding season and juvenile recruitment of Rhabdomys pumilio, Mastomys natalensis and Myosorex varius are the same as recorded in conspecific populations from other habitat types and do not seem modified by the habitat stability of the forest environment. Of the five common species, only Grammomys dolichurus , one of the few forest-associated small mammals in southern Africa, and Graphiurus murinus demonstrated stable, K-selectéd life-history styles.     

Estimation of the biological age in taiga tick females (Ixodes persulcatus:Ixodidae) by the fat reserves in organism

The method of estimation of the biological age in non-feeding tick females by the level of adipose inclusions in the cells of the midgut and fat body is developed. In order to estimate the fat reserves in non-feeding females, alive ticks were dissected and fragments of their internal were vitally stained with the pregnant solution of sudan III in 70 % ethanol. Three age-specific groups were established: I, young females whose intestines and fat body were filled with fat inclusions; II, mature females whose fat reserves were partially expended; III, old females having isolated fat inclusions in their midgut and fat body.     

Assessing the heritability of body condition in birds: a challenge exemplified by the great tit Parus major L. (Aves)

The definition and measurement of body condition are central to many ecological and evolutionary studies, yet the fundamental issue of whether variation in condition is inherited genetically remains unresolved. Furthermore, confusion has been caused through diverse uses of the word 'condition' itself. In this paper, we introduce the terms 'broad-sense condition' and 'narrow-sense condition' in an attempt to reduce this confusion. Because of the difficulty of measuring condition, field biologists use the mass relative to body size as a convenient index of condition. Such indices have also been used to estimate die heritability of condition. Using data from a wild great tit Parus major population, we demonstrate that a condition index may still contain residual variance that is due to body size. Hence, using a condition index to study the heritability of condition can give misleading results because that residual variance may itself be heritable. To avoid this problem, direct measures of condition, such as reserve tissues, should be used. We provide the first heritability estimates of direct measures of condition of full-grown birds in a wild population by the regression of mean offspring (both in winter, and when breeding) on mean parent (when breeding) values of two reserve tissues, fat and pectoral muscle, which are independent of body-size. A great tit's fat and muscle reserves in winter were significandy correlated with their respective values when the birds bred. However there was no evidence that the level of fat reserves in winter resembled those of the parents (when breeding), more than expected by chance. Slight resemblances between parents and offspring were detected for muscle in winter and for fat reserves when breeding. Muscle size in the breeding season provided stronger evidence for the inheritance of condition.     

Body condition of shorebirds upon arrival at their Siberian breeding grounds

Arctic breeding shorebirds carry substantial body stores on their long-distance migrations from their non-breeding grounds. Upon arrival at the breeding area the remains of these stores can be used for egg formation, insurance against poor feeding conditions or rebuilding organs. We quantified body condition (body mass, total body water, lean body mass and fat mass estimated using the deuterium dilution method) in seven shorebird species caught upon arrival in the Siberian Arctic. Arrival condition was compared with incubation condition in a subset of species. After correction for structural size, body mass was significantly lower at arrival than during incubation in most of the species (but 3–18% above lean mass). Fat index (fat mass/lean mass) varied between 5.1 and 13.2%. Fat stores were estimated to enable survival for 0.6 days for the smallest and 2.5 days for the largest species. We discuss possible functions of arrival stores: insurance, egg-formation or rebuilding organs. G. H. Visser: Deceased.     

The induction of autophagy in isolated insect fat body by β-ecdysone

The fat body in Calpodes undergoes sequential organelle specific autophagy as a first step in the cell remodeling process necessary for metamorphosis to the pupa. This autophagy begins at about 36 hr before pupation and coincides with a critical period after which an isolated abdomen will pupate without further influence from the prothoracic glands. This suggested that autophagy might be induced by ecdysone. Fat body taken before the critical period and cultured in a medium containing β-ecdysone undergoes autophagy. Fat body from the same animal maintained in hormone-free medium retains the pre-critical period morphology with no autophagy. Autophagy is therefore directly induced by β-ecdysone. Fat body taken soon after the critical period continues with the autophagic sequence in hormone-free medium. Therefore the entire autophagic sequence is induced and does not require the continuing presence of hormone. Protein storage granule formation and cell dissociation, which occur in fat body at metamorphosis, are also induced by β-ecdysone.