Cool-dry Season Research Articles

Steroid Levels and Reproductive Cycle of the Galápagos Tortoise,Geochelone nigra,Living under Seminatural Conditions on Santa Cruz Island (Galápagos)

The Galápagos Islands are home to 11 subspecies of large terrestrial tortoises (Geochelone nigra). All Galápagos tortoises are considered endangered and approximately 12,000 animals still exist. Until now, the reproductive cycle of the Galápagos tortoise has been studied only in captive animals, and no data from free-ranging tortoises have been available. During a one-year period, blood samples were collected from male and femaleG. nigraliving under seminatural conditions on Santa Cruz Island, Galápagos. Plasma steroid hormones were measured by radioimmunoassays (RIAs). In males, plasma testosterone and corticosterone increased a few months before the onset of the mating season. Peak levels were observed while most copulations occurred and environmental temperatures were highest. Both testosterone and corticosterone showed low levels during the cold and dry nesting season and high levels during the hot and rainy mating season. In females, testosterone and corticosterone also rose during the hot and rainy mating season. Both hormones peaked during the second half of the mating season and decreased during the cooler dry season. Female estradiol levels increased at the onset of the mating season, reaching the highest level at the peak of the mating season, which coincided with the highest annual temperatures measured. Estradiol slowly decreased within the next months and rapidly dropped at the onset of the nesting season when temperatures decreased. Progesterone levels were high close to the time of ovulation and showed clearly elevated levels at the beginning of the nesting season after some females had laid their first clutch. Progesterone decreased during the nesting season, when ambient temperatures began to decrease, and reached minimal levels in the postbreeding period shortly before the onset of the next mating season. There were significant annual variations in plasma testosterone in both males and females. Plasma corticosterone was generally higher in males than in females and varied throughout the year in both sexes.

Female Reproduction in Two Species of Tropical Horseshoe Bats (Rhinolophidae) in Zimbabwe

Female reproduction was studied in sympatric populations of two species of African horseshoe bats in a seasonal tropical environment of central Zimbabwe. Both Rhinolophus simulator and its largest African congener, R. hildebrantii , were monotocous and monestrous, and reproduction was highly seasonal. In 3 consecutive years, R. simulator gave birth consistently later (15–20 days) than R. hildebrantii , and early embryonic development was retarded in the smaller R. simulator . Copulations occurred during June and July of the cooldry season, and both species gave birth to single offspring during separate synchronized periods of parturition at the start of the wet season. Lactation in both species coincided with the period of maximal rainfall, but the weaning period of R. hildebrantii was distinctly long.

Interrelationship between ectoparasites and wild rodents from Tijucas do Sul, state of Paraná, Brazil.

Sixteen species of ectoparasites were collected from 50 wild rodents, from August 1990 to August 1991, in an area of Araucaria augustifolia forest, in the municipality of Tijucas do Sul, State of Paraná, Brazil. Ectoparasites infested 98% of the rodents, with the highest indices of infestation found in the drycool season. Species that occurred in single or multiple infestations were recorded. Ectoparasite/host associations were significant (p < 0.01) for Gigantolaelaps wolffsohni/Oryzomys nigripes, Polygenis pradoi/Oxymycterus sp. and Amblyopinus sp./Oxymycterus sp. The following represent new host records: Polygenis (Polygenis) tripus from Akodon serrensis and Hoplopleura sciuricola from Sciurus aestuans. New geographic records are given for two species of flea and one sucking lice.

Seasonal patterns of deaths in Matlab, Bangladesh.

Deaths exhibit a seasonal pattern in most parts of the world. Analyses of deaths for the years 1972-1974 from the vital registration system of Matlab, Bangladesh, published in this journal 17 years ago, showed sinusoidal seasonal patterns. As death rates have declined in other nations, the seasonal pattern is attenuated. Death rates have declined substantially in Bangladesh in the past two decades. Thus, the present study examines monthly counts of deaths from Matlab data for a period 15 years later and tests the hypothesis of a decrease or shift in seasonality over time. Trigonometric regression models were fit to monthly data by age and cause of death from the Matlab vital registration system for the years 1982-1990. A total of 20,328 death records were available for analyses. In the recent period significant sinusoidal seasonal patterns are found in all but one of the age and cause of death groups. Total deaths peak in the winter as do neonatal deaths but post-neonatal and child deaths are maximum in April and July respectively. Among cause groups, injury deaths (mostly attributed to drowning) show the greatest seasonal swing. The time of peak has only shifted for one age group--neonates--since the 1972-1974 period. The magnitude of the seasonal swing has declined significantly only for the neonatal age group and injury cause of death group. Marked seasonal patterns of deaths persist in the Matlab area of Bangladesh even as the level of mortality has declined.

THE USE OF LEAF APPEARANCE RATES ESTIMATED FROM MEASUREMENTS OF AIR TEMPERATURE TO DETERMINE HARVEST INTERVALS FOR TEA

The effects of temperature (13–20 °C) and potential soil water deficit (0–350 mm on the leaf appearance rates of six contrasting clones of tea (Camellia sinensis) were studied over twenty-five months to provide guidance to tea growers in southern Tanzania on the choice of harvest intervals. Within the fully irrigated treatments (potential soil water deficit &lt;65 mm) the mean time period between a shoot unfurling its second and third true leaf (a phyllochron) ranged from 5.8–7.9 d during the warm–wet season to 11–19 d during the cool-dry season. Between 61 and 79% of the weekly variation in the mean leaf appearance rate (1/phyllochron) for each clone could be explained by an asymptotic relation with the mean air temperature. Building on research in India which has suggested that appropriate harvest intervals for tea can be derived from measurements of leaf appearance rates, a simple procedure is described for determining harvest intervals from the daily mean air temperature. Corrections to account for the effects of drought and clonal differences in responses to temperature are also explained.

ザンベジ川氾濫原の水収支と水田の純用水量の推定

The analysis of the meteorological data and soil moisture observed in the cool-dry season at the Zambezi river flood plain and Mongu meteorological station shows that water supply from groundwater covers almost two-third of the actual evapotranspiration rate in the objective development area and amounted to 1mm/d.The potential evapotranspiration rates in this area after the development as paddy field were estimated at more than 6mm/d for hot-dry season. These rates can be considered as a proper rate, because in this area there is a lot of fair or partly cloudy days with low humidity in hot-dry season. It was found that net radiation had direct effect upon the evapotranspiration rate. So if it is needed to get more accurate rate for paddy field, the estimation of net radiation based on the albedo, changed the value for soil surface conditions as growing stage of paddy rice, would be more important.Estimated from the water budget and the potential evapotranspiration rate as paddy field in this area, daily rates of the net water requirement for the year 1994 were ranged between 6mm/d and 14.5mm/d, and indicated larger rates in the dry season from April to October than in the wet season from November to March.In this study, the percolation loss was estimated in the verification paddy field from the water budget equation. At place where all terms of the water budget are not available, the value of percolation loss should be carefully decided based on the water supply from groundwater.

Diets of Hartebeest and Roan Antelope in Burkina Faso: Support of the Long-Faced Hypothesis

Diets of hartebeest ( Alcelaphus buselaphus ) and roan antelope ( Hippotragus equinus ) were assessed at the Nazinga Game Ranch in southern Burkina Faso, West Africa. Microhistological analysis of feces indicated that dietary overlap was high during the rainy ( X = 73.7%) and cool-dry (68.2%) seasons, low during the hot-dry season (48.2%), and lowest during the last month of the hot-dry season (31.5%). As the hot-dry season progressed and food presumably became less available, diets of the two antelopes diverged. Hartebeest maintained a high percentage of grass in their diet, but roan antelope switched from being predominantly grazers (>95% grass) to mixed feeders (<50% grass). As grass feeders, both antelopes have skeletal features that facilitate acquisition and grinding of highly fibrous diets, but 11 of 12 mass-relative indices of the skull morphology of hartebeest exceeded those of roan antelope. Because of those differences in skull morphology, and in keeping with the “long-faced” hypothesis, hartebeest were apparently more capable than roan antelope of acquiring and masticating scarce regrowth of perennial grasses when availability of forage was lowest. Such divergence within a single foraging class of African bovids, such as grass feeders, should reduce competition and perpetuate coexistence.

Field studies on the ureogenic gulf toadfish in a subtropical bay. I. Patterns of abundance, size composition and growth

Opsanus beta abundance in Biscayne Bay, Florida, varied significantly depending on site and season. O. beta catch per unit effort (cpue) was highest in southern study sites which tended to provide the combination of shallow mean depth, nocturnally high levels of dissolved oxygen, and Thalassia‐dominated substrate. Significant seasonal differences in abundance were restricted to the three sites where O. beta cpue tended to be highest; two of these sites shared the same pattern of in crease during the cool‐dry season (November‐April), followed by a return to lower levels during warm‐wet season (May‐September). Dramatic seasonal abundance increases could not be ascribed to large influxes of immature fish. Rather, size composition data suggested sexually mature individuals moved seasonally among habitats, possibly for reproductive purposes. Modal analysis of length‐frequency data followed by nonlinear regressions yielded preliminary values for the von Bertalanffy growth parameters K and t0, given that Lσ= 300 mm. Possible reasons for O. beta growing slower and attaining a smaller maximal size than its temperate congener, O. tau, are discussed.

Stargrass Response to Lime and Phosphogypsum

Stargrass (Cynodon spp.) is an important forage in tropical Florida and other tropical regions of the world. Lime is believed to be a major input needed for stargrass production. A field study was conducted on a Pomona fine sand (sandy, siliceous, hyperthermic, Ultic Haplaquod) to determine the response of stargrass to lime and phosphogypsum and to determine if lime application levels can be reduced below the current agronomic recommendations for commercial growers (pH = 6.0). Treatments consisted of a check (0 tons lime or phosphogypsum/acre) and five rates of dolomitic limestone (0.5, 1.0, 1.5, 2.0, and 3.0 tons/acre) and two rates of phosphogypsum (1.0 and 2.0 tons/acre) in a randomized complete block design with four replications. Dolomitic lime increased stargrass dry matter (DM) yields quadratically in all 3 yr with yield maximizing when 2 ton/acre of dolomitic lime was applied. Application of dolomitic lime increased soil pH, soil Ca, and soil Mg linearly in the Ap soil horizon. Soil pH ranged from 4.6 to 6.0 and exchangeable Al ranged from 10.4 to 18.1 ppm for the Ap horizon for the 3.0 and 0 ton lime/acre treatments, respectively. Application of phosphogypsum resulted in increased yields in spite of the increase in soil acidity. Stargrass roots penetrated the spodic horizon regardless of phosphogypsum or lime rates. This study demonstrates the importance of dolomitic lime or phosphogypsum for stargrass production in low pH soils and that the recommended rate of lime application may be reduced without affecting forage production. Research Question Stargrass, a warm season perennial forage, is becoming one of the most popular grasses throughout the tropics. It produces high quality forage that, when properly managed for grazing, results in good animal performance. With the exception of N, soil acidity may be the major factor limiting stargrass growth and production. The purpose of this study was to evaluate the Florida lime recommendations for stargrass production and to determine whether the recommended levels of lime could be reduced without harmful effects on stargrass production. Literature Summary Stargrass is demonstrating excellent potential as a high quality forage in tropical USA and many other tropical regions of the world. Because this grass has high yield potential, insect and disease resistance, persistence, and high forage quality, both dairy and beef cattle producers are increasing their acreage planted to stargrass. Stargrass has the unique ability to produce forage during saturated soil conditions in the warm season (70 to 95°F) and in the cool-dry season (50 to 70°F). Dairy farmers find stargrass grown under high fertility and harvested frequently will persist for many years, yielding high quality forage when harvested for hay or haylage on a 4-wk schedule. Since many soils in the tropical regions of the world are strongly acid, studies have to be conducted on defining the lime requirement needs for optimum stargrass production. Study Description A 3-yr field study was conducted on a strongly acid, infertile spodosol at Ona, FL, to determine the response of six rates of incorporated dolomitic lime (0, 0.5, 1.0, 1.5, 2.0, and 3.0 tons/acre) and three rates of phosphogypsum (0, 1.0, and 2.0 tons /acre) on stargrass production and soil chemical characteristics Applied Questions What are the minimum calcium and pH requirements for stargrass production? Stargrass yields increased quadratically with increasing rates of dolomitic lime. Incorporated dolomite of 2.0 tons /acre increased soil pH from 4.6 to 5.5 in the Ap horizon and increased stargrass yields by 100%. Addition of lime above 2.0 tons/acre did not significantly affect yields (Fig. 1). Addition of 2.0 tons/acre of phosphogypsum resulted in a 50% increase in stargrass production (Fig. 1). Results of this study demonstrate the importance of dolomitic lime or phosphogypsum for stargrass production. Based on this study it would appear that dolomitic lime is essential for stargrass production and that the lime recommendations for stargrass could be reduced in Florida spodosols without seriously affecting the crop yield. Figure 1Open in figure viewerPowerPoint Influence of dolomitic lime and phosphogypsum on stargrass production.

Field simulation of wet and dry years in the Chihuahuan desert: soil moisture, N mineralization and ion-exchange resin bags

Irrigation and rain-out shelters were used to simulate precipitation patterns of wet and dry years in the northern Chihuahuan Desert. Irrigation provided approximately double the long-term average monthly precipitation. Rain was excluded during the wet season, July-October, to simulate a dry year. N net mineralization in laboratory incubations was undectable at calculated water potentials less than -1 MPa. Witb increasing moisture, mineralization gradually rose to the highest observed rates near field capacity. There was no mineralization maximum at moisture contents below field capacity. Irrigation significantly increased the water potential and rainfall exclusion reduced water potentials to less than-8 MPa. The general absence of important irrigation effects may have resulted from the high natural precipitation during the experiment or because irrigation inputs were insufficient to increase microbial activity during very dry periods. Precipitation exclusion reduced ion capture during the warm-wet season. After allowing precipitation inputs to resume, NH4+-N capture was increased in the cool-dry seasons of both 1987–1988 and 1988–1989. NH4+-N capture more than doubled that predicted from the overall covariance of moisture input and ion capture, suggesting increased availability of N. An unusually hot, dry period in May and June 1989 was followed by a threeto fourfold increase in the warm-wet season NO3−+NO2−N capture compared to 1988. These data suggest that short droughts of about 3 months in length (both simulated and natural) increased N availability relative to moisture availability.

Seasonal Changes in Thermoregulation by the Frillneck Lizard, Chlamydosaurus Kingii, in Tropical Australia

The frillneck lizard Chlamydosaurus kingii is an arboreal lizard that is a conspicuous component of the reptile fauna of the wet—dry tropics of northern Australia during the wet season. During the dry season, however, they are secretive, and a previous study revealed that during this season they remain perched in trees and have field metabolic rates only 28% of the wet season levels. Body temperatures (Tb's) of the lizards were measured by ratio telemetry throughout the day during the wet and dry seasons. The midday Tb's during the wet season high (grand mean = 36.7°C) and typical for heliothermic lizards, but the dry season midday Tb's were significantly lower (grand mean = 32.8°C). Microclimatic data and physical characteristics of the lizards were used in a biophysical model to calculate the operative temperatures (Te) of lizards in the shade, in the sun on a horizontal plane, and normal to the sun at each hour of the day for the two seasons. The Te's revealed the physical possibility for the lizards to achieve much higher Tb's during the dry season than were measured. Thus, the lower Tb's in the dry season represent a shift in preference rather than an inability to attain a high Tb's during the cooler dry season. Inspection of the Tb's and Te's revealed that although the lizards remained cooler in the dry season, they did not thermoregulate at the lowest possible Tb's. During both seasons the lizards basked in the sun early and late in the day, but during the dry season the lizards stopped intensive basking at a Tb °4°C lower than in the wet season. An index of the extent to which the lizards exploit the available thermal environment indicates that they thermoregulate carefully in both seasons. Tb's were also measured in a laboratory thermal gradient during both seasons, and the Tb's selected during the dry season were significantly lower than those selected in the wet season. This suggests that the seasonal shift in thermal preference is acclimatization response or an endogenous seasonal cycle rather than a response to a simple thermal cue. The lower Tb's in the dry season result in a conservation of energy and water during a season when these resources are relatively scarce. However, the fact that the lizards do not thermoregulate at the lowest possible Tb's suggests that the dry season Tb's represent a compromise between conservation of resources and the ability to perform other functions such as escape predators and/or digest food.

Spacing behaviour and habitat use of axis deer (Axis axis) in lowland Nepal

A total of 17 axis deer (Axis axis) (12 females, 5 males) were radio-instrumented in Bardia National Park in lowland Nepal, and 1921 locations of females and 605 locations of males were obtained during the 2-year study period. Both the annual home ranges (135 ± 33 and 204 ± 38 (SD) ha for females and males, respectively) and the seasonal home ranges were quite small compared with those reported in another study in Nepal. We present evidence that this difference is due to a more fine-grained habitat mosaic in Bardia. Males used larger areas than females in the monsoon and the hot part of the dry season. The deer were sedentary, with a mean seasonal home range overlap between 49 and 86%, and seasonal occupancy centres were all located less than 1300 m apart. Mean seasonal home range size (68 and 110 ha for females and males, respectively) was smallest in the cool part of the dry season. The rutting period did not seem to have any major effect on the ranging behaviour, as neither males nor females increased home range size from the pre-rut to the rutting period. The deer used riverine forest preferentially during the cool-dry and hot-dry seasons, whereas sal forest was the preferred habitat during the monsoon and the cool-dry season. Grasslands were preferentially utilized by females at night during the hot-dry season, presumably because of improved forage quality following cutting and burning. Males were more associated with riverine and sal forest than were females, while females used grassland areas more than males did.

Temperature-Determined Outcrossing Ability in Wild Populations of a Simultaneous Hermaphrodite Snail

Phally, a genital polymorphism found in some species of self-compatible simultaneous hermaphrodites, presents an opportunity to examine environmental and genetic influences on mating system traits. Both aphallics and euphallics can self-fertilize, but aphallics cannot donate sperm because they do not develop a functional penis and prostate. Previous studies of the freshwater gastropod Bulinus truncatus (Mollusca: Pul- monata) suggest that in at least some laboratory populations, phally is determined by temperature during egg and hatchling stages, with colder temperatures favoring the de- velopment of euphally. Here we provide evidence for temperature-influenced phally de- termination in natural populations of B. truncatus in northern Nigeria. The prevalence of euphally across 49 populations ranged from 0 to 81%. Levels of euphally increased sig- nificantly both within and across sites as temperatures decreased during the dry-cool season. Across sites, time of year (date) was the strongest single predictor of proportion of euphallics. When the effects of time of year were controlled for, there was a significant negative correlation between temperature during phally development and proportion of euphallics. In addition, maximum water temperature during the 1st wk of the study predicted pro- portions of euphallics in the next snail generation. A laboratory study of snails from three of these populations demonstrated that temperature sensitivities differed between popu- lations: one population that remained 100% aphallic over the course of field observations showed only low levels of temperature sensitivity in the laboratory, while a population that tripled in proportion of euphallics in the field showed strong levels of temperature sensitivity. Furthermore, individuals within populations varied in their temperature sen- sitivities. These results are discussed in light of the adaptive significance of labile phally determination.

Problem crocodiles, Crocodylus porosus, at Nhulunbuy, Northern Territory: an assessment of relocation as a mangaement strategy

Since 1986 the Conservation Commission of the Northern Territory has operated a programme to remove 'problem' saltwater crocodiles from waters in and adjoining the township of Nhulunbuy. Over a period of five years, 52 different saltwater crocodiles (44 male) were captured. Most (48) were released at remote sites designated by the traditional Aboriginal owners of the surrounding lands. Release distances from the township varied from 17 to 282 km (by coastline). Many crocodiles (47.9%), including those released at the most distant sites, returned to, and were subsequently recaptured at, the township. Total capture rates (initial captures and recaptures pooled) varied seasonally, with fewer crocodiles being caught in the cooler dry season. During the wet season capture rates remained high, but relatively fewer 'new' crocodiles were caught. Probability of recapture could not be related to distance and direction of release from the township, nor size and sex of the released crocodile. Frequency of capture of individual crocodiles (1-8 times) was also unrelated to these variables. The high rates of return indicate that relocation is unlikely to be an effective strategy for managing humancrocodile interactions, at least in areas where potential release sites already support saltwater crocodile populations near carrying capacity.

Distribution and seasonal dynamics of Rhodophyta in the Preto River basin, southeastern Brazil

Distribution and seasonal dynamics of freshwater Rhodophyta were investigated in the Preto River basin, located in northwestern Sao Paulo State, southeastern Brazil. Twenty-two sites were sampled, six monthly during one year, four bimonthly during two years, and 12 twice (hot-rainy and cool-dry seasons) during the study period (May 1989 through March 1991). Red algal representatives were found in 19 sites (86.4%). Four species occurred in the basin with varying frequencies:Batrachospermum delicatulum (54.5%),Compsopogon coeruleus (36.4%),B. bicudoi (13.6%) andB. virgatum (4.5%). In addition, ‘Chantransia’ stage of the batrachospermalean species was found in 17 sites (77.3%).B. bicudoi, B. virgatum andC. coeruleus occurred only in large stream segments (≥ 3-order), generally in the main river, whereasB. delicatulum was more frequent in small streams (≤ 3-order). The stream variables most closely related to the species distribution in the basin were specific conductance, pH and oxygen.B. bicudoi andB. delicatulum showed a marked seasonality: gametophytes were observed from late fall to early spring, while the ‘Chantransia’ stage generally occurred throughout the year.C. coeruleus was observed throughout the year in most sites, but the populations were generally more abundant from late fall to early spring. The combination of lower temperature and reduced turbidity resulting in increased illumination to the benthic algae during the dry winter months promotes the gametophytic growth of the batrachospermalean species, whereas current velocity was found to be the most influential stream variable forC. coeruleus. The persistance of the ‘Chantransia’ stage throughout the year as well as its tolerance to wider environmental conditions are key factors in the efficiency of the batrachospermalean life history strategy in lotic ecosystems.

Phenotypic Variation in Australian Eurema Species

Australian butterflies in the tropical pierid genus Eurema (the grass yellows) exhibit seasonal phenotypic changes in both size and colour pattern. In four of the five species, smaller adults were present during the summer and autumn wet season than during the cooler winter-spring dry season. The fifth species, E. hecabe, showed the reverse pattern, being largest when it first appeared late in the wet season and becoming smaller as the dry season progressed. When reared in the laboratory, however, all five species produced larger adults when reared at lower temperatures, and at least two of the species also produced larger adults at shorter photoperiods. In the case of E. hecabe, juvenile overcrowding and resource limitation may prevent the potential size increase during the cooler dry season from occurring. All five species had darker markings during the cooler dry season, and in two of them, E. herla and E. laeta, there was also a change in the ground colour of the underwing from yellow to pink or brown. The darker markings may serve a thermoregulatory function, as in other pierids, but the change in colour probably functions to allow E. herla and E. laeta, which diapause as adults during the dry season, to be more cryptic as the grasslands they occupy dry off and change colour. In all species except E. herla, the range of variation in dark markings observed in the field could be reproduced in the laboratory by varying the temperatures and/or photoperiods at which the juvenile stages were reared (darker individuals were produced at lower temperatures and shorter photoperiods). The change in ground colour in E. herla and E. laeta, however, was not reproduced in laboratory rearings, either by changing photoperiod and temperatures, or by rearing animals at low humidities, suggesting that an additional cue may be needed to induce this shift in phenotype.

Ectoparasites in rodents of the urban region of Belo Horizonte, MG. III. Fleas, Anoplura and Acari indices in Rattus norvegicus norvegicus

The total and specific indices of fleas, lice and mites were determined for ectoparasites on Rattus norvegicus norvegicus capture in urban areas of Belo Horizonte, Minas state, Brazil, from June 1980 to September 1982. In view of the limiting or critical values attributed to flea indices above all the "cheopis" index, proposed by several authors as a complementary measure for bubonic plague surveillance, the community of Belo Horizonte would have been exposed to this infection. The annual total indices ranged from 0.3 to 2.4 and the prevalent flea was Xenopsylla cheopis (99.2%), with the highest indices coinciding with the late dry-cool season. On two occasions, in this period, the community would have remained highly exposed to infection, since the index-limits were superseded: 8.8 (October 1980) and 6.2 (September 1982). It is suggested that preventive measures, such as protection against rat insecticide treatment may be efficiently applied in the late dry-cool season, or previous to the rainy season, before the elimination of rats. Reports on indices of lice and mites are important as they may establish index-limits for certain infections exclusive to rodents.

Ectoparasites of rodents of the urban region of Belo Horizonte, MG. II. Variations of the infestation indices in Rattus norvegicus norvegicus

The indices of infestation by the mites Echinolaelaps echidninus and Laelaps nuttalli, the louse Popyplax spinulosa and the flea Xenopsylla cheopis, obtained monthly, from June 1980 to September 1982, on Rattus norvegicus norvegicus in the city of Belo Horizonte, Minas Gerais state, Brazil were related to seasonal period, sex of the host and area of capture. Mites and insects showed different behaviour in relation to these factors. Only the fleas and lice exhibit significant association between the rodents' infestation and the seasonal period, or between the infestation and the rodents' sex or else a variation of the distribution by the three main areas of capture. The fleas showed the highest indices of infestation in the warm-rainy season (October to March) while the infestation by the lice was more prevalent in the dry-cool season. The climatic factors most related with the hosts' infestation were, in decreasing order, rainfall, temperature and relative humidity. Fleas and lice preferentially infested male rodents, being infestation by X. cheopis highly significant.

Cottonseed meal and molasses as sources of protein and energy for cattle offered low quality hay from pastures of the North Coast of New South Wales

Cottonseed meal and molasses, regarded as sources of protein and energy for cattle, were included with a basal ration of low quality pasture hay and fed to beef cattle in an experiment that contained two periods of 50 d each. The hay was made from a pasture consisting predominantly of Rhodes grass (Chloris gayana). The pasture site was on the North Coast of New South Wales with a subtropical climate and an area where cattle lose liveweight during the winter or cool-dry season. The experiment aimed at determining whether the intake of hay, and liveweight of cattle, could be increased by supplements of either cottonseed meal or molasses or both. The experimental design was based on a response-surface with 12 treatment combinations. Twenty-four Hereford steers, aged about 26 months and having a mean liveweight of 315 � 28 kg were used. They were offered the low quality hay (435 g digestible organic matter (DOM)/kg dry matter (DM); 7.3 g nitrogen (N)/kg DM) in amounts expected to be 15% greater than that eaten. Fixed amounts of the energy supplement (undiluted molasses) were offered in separate containers at 0,0.5, 1.3 and 2.1 kg/d. Cotttonseed meal (930 g organic matter (0M)lkg DM) was added to the hay to raise the N content of the ration from the 7.3 g N/kg DM of the basal ration (A) to 14.1 (B), 19.4 (C) and 25.7 (D) g N/kg DM. Steers on ration C ate 19.3% more hay (P c 0.05) than steers on ration A; steers on rations B and D ate 11.0 and 14.5%, respectively, more hay than steers on ration A ( P &lt; 0.10). Molasses had no significant effect on hay intake, but as did cottonseed meal, it increased steer liveweight. Final liveweight (LW: kg) was a function of the initial liveweight (IW: kg) and of the amount of supplements eaten (kg/d) for both cottonseed meal (CSM) and molasses (Mol). LW = 16.7(+ 11.0) + 5.9(+ 2.0)Mol + 38.3(� 5.6)CSM - 9.2(� 2.0)CSM2 + 0.88(� 0.03)IW; Residual standard deviation � 8.7. N balance, and excretion of N in faeces and urine, were increased (P &lt; 0.05) by cottonseed meal but not by molasses supplements. Liveweight change (LWC: g/d) was a function of N balance (NB: g/d). LWC = - 1 08.3(� 48.0) + 19.7(� 2.1 4)NB; Residual standard deviation � 243. Liveweight change was also a function of the digestible organic matter intake (D0MI:gld) from the total ration. LWC = - 996(� 104) + 0.364(� 0.032)DOMI; Residual standard deviation � 182. The results highlight the limitation to cattle growth imposed by the low N intake from the pasture hay, and a consequent low intake of DOM. They suggest that cottonseed meal is a suitable source of protein for cattle on the North Coast although in districts growing sugar cane economics may favour the use of molasses as an energy source provided that some protein is added to it

A climate index and mule deer fawn survival in Montana

A sign of deviation type of index was used to convert standard temperature and precipitation data into a readily used form for the study of deer population dynamics. Statistically significant correlations between the climate index and mule deer fawn survival were demonstrated for four different mule deer populations in Montana. These correlations led to reasonable biological hypotheses delineating the linkage between climate and fawn survival in each of the four areas. The correlations support the frequent observations in the wildlife literature concerning the importance of summer and winter range. They also suggest that human activities may interact with climate in a manner which affects deer fawn survival. In general, in these areas, fawn survival was favored by relatively warm-moist summer, warm-dry winter and cool-dry hunting season weather. The apparent affect of spring weather was variable. Fawn survival in two areas was enhanced by cool-dry summer weather. This reversed response could be the result of human use of the areas, including livestock grazing. It is concluded that this index of climatic fluctuations can be a versatile and useful tool in assessing the impact of climate upon deer populations. In general, weather can be described as a strong biasing factor even when direct effects cannot be consistently demonstrated.