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House mice are among the most widely distributed mammals in the world, and adversely affect a wide range of indigenous biota. Suppressing mouse populations, however, is difficult and expensive. Cost-effective suppression requires knowing how low to reduce mouse numbers to achieve biodiversity outcomes, but these targets are usually unknown or not based on evidence. We derived density-impact functions (DIFs) for mice and small indigenous fauna in a tussock grass/shrubland ecosystem. We related two indices of mouse abundance to five indices of indigenous lizard and invertebrate abundance measured inside and outside mammal-resistant fences. Eight of 22 DIFs were significantly non-linear, with positive responses of skinks (Oligosoma maccanni, O. polychroma) and ground wētā (Hemiandrus spp.) only where mice were not detected or scarce (Woodworthia spp.) were rarely detected where mice were present. A further 9 DIFs were not differentiated from null models, but patterns were consistent with impacts at 5% mouse abundance. This study suggests that unless mouse control programmes commit to very low abundances, they risk little return for effort. Impact studies of invasive house mice are largely restricted to island ecosystems. Studies need to be extended to other ecosystems and species to confirm the universality or otherwise of these highly non-linear DIFs.

Indigenous peoples’ relationships with biodiversity are often poorly recognised in conservation decision-making, but are critical to Indigenous identity and lifeways. These relationships extend to introduced species that are rarely protected under legislation. Kiore (Rattus exulans, Pacific rat) is a species introduced to Aotearoa New Zealand (hereafter Aotearoa) by Māori (the Indigenous people of Aotearoa) as a food source and bio-indicator of ecosystem state. Once common, kiore are now restricted in numbers and range, and widely considered an unwanted organism by conservation managers and some Māori. However, tribal group Ngātiwai wish to safeguard cultural access to remaining kiore on Mauitaha Island. Therefore, the goals of our study were to assess body condition and the reproductive and disease status of kiore on Mauitaha. Of 16 kiore caught, body condition based on body length to mass ratio was similar to that recorded on other islands in Aotearoa. Subcutaneous fat levels were moderate, but lower in individuals with disease inflammation. The results suggest satisfactory population health, but regular monitoring to identify temporal trends in kiore abundance and condition is important for cultural harvesting and long-term population survival. Planning for harvesting by future generations requires transforming conservation biology through Indigenous perspectives, through further assessment of methods, management and agency, examining how Indigenous knowledge and conventional science can be used to balance ecological and cultural trade-offs. Further consideration of ecological habitat and risk is also required for kiore, because the reserve is a single small island, and national conservation priorities focus on native species protection in ecosystems that exclude humans.

Kiore (Pacific rat; Rattus exulans) is both a target for eradication and a taonga or highly valued species in New Zealand, and its abundance and distribution vary considerably throughout the countr...

In the Ross Sea region, most South Polar Skuas (Stercorarius maccormicki) nest near Adelie Penguin (Pygoscelis adeliae) colonies, preying and scavenging on fish, penguins, and other carrion. To derive a relationship to predict skua numbers from better-quantified penguin numbers, we used distance sampling to estimate breeding skua numbers within 1000 m of 5 penguin nesting locations (Cape Crozier, Cape Royds, and 3 Cape Bird locations) on Ross Island in 3 consecutive years. Estimated numbers of skua breeding pairs were highest at Cape Crozier (270,000 penguin pairs; 1099 and 1347 skua pairs in 2 respective years) and lowest at Cape Royds (3000 penguin pairs; 45 skua pairs). The log–log linear relationship (R 2 = 0.98) between pairs of skuas and penguins was highly significant, and most historical estimates of skua and penguin numbers in the Ross Sea were within 95 % prediction intervals of the regression. Applying our regression model to current Adelie Penguin colony sizes at 23 western Ross Sea locations predicted that 4635 pairs of skuas now breed within 1000 m of penguin colonies in the Ross Island metapopulation (including Beaufort Island) and northern Victoria Land. We estimate, using published skua estimates for elsewhere in Antarctica, that the Ross Sea South Polar Skua population comprises ~50 % of the world total, although this may be an overestimate because of incomplete data elsewhere. To improve predictions and enable measurement of future skua population change, we recommend additional South Polar Skua surveys using consistent distance-sampling methods at penguin colonies of a range of sizes.

Cities and urban processes typically have a negative impact on biodiversity via land cover change, high rates of disturbance and high densities of pest species. Increasingly, however, people are being encouraged and empowered to reduce these impacts through urban restoration and backyard conservation initiatives. Internationally, lizards are a common feature of urban biodiversity, but in New Zealand where many species are threatened, little is known about populations of native skinks and geckos in cities. Yet cities may offer unique opportunities for lizard conservation compared with alternatively modified habitats. To explore the potential of cities for the conservation of lizards, we collated knowledge about the current lizard faunas of six New Zealand cities and developed a list of species that would likely have been present in the locations of these cities prior to human settlement. Comparing the two, we found that, although each of the cities has at least one currently urban-dwelling species, the diversity of lizards in all of the cities has declined dramatically since human colonisation. Patterns of species loss in cities reflect those observed across New Zealand more generally; that is, the loss of large-bodied skinks and geckos, probably resulting from predation by introduced mammalian predators, as well as the loss of regionally endemic species. The high diversity of species that are currently, or were historically, present in the locations of New Zealand cities means that urban restoration involving recovery or reintroduction of populations could have significant benefits for lizard conservation and advocacy.

In systems where predation plays a key role in the dynamics of prey populations, such as in Arctic rodents, it is reasonable to assume that differential patterns of habitat use by prey species represent adaptive responses to spatial variation in predation. However, habitat selection by collared (Dicrostonyx groenlandicus) and brown (Lemmus trimucronatus) lemmings depends on intra- and inter-specific densities, and there has been little agreement on the respective influences of food abundance, predators, and competition for habitat on lemming dynamics. Thus, we investigated whether predation affected selection of sedge-meadow versus upland tundra by collared lemmings in the central Canadian Arctic. We first controlled for the effects of competition on lemming habitat selection. We then searched for an additional signal of predation by comparing habitat selection patterns between 12 control plots and one large grid where lemmings were protected from predators by fencing in 1996 and 1997, but not during 5 subsequent years when we monitored habitat use in the grid as well as in the control plots. Dicrostonyx used upland preferentially over meadows and was more numerous in 1996 and 2011 than in other sample years. Lemmus was also more abundant in 1996 than in subsequent years, but its abundance was too low in the exclosure to assess whether exclusion of predators influenced its habitat selection. Contrary to the effects of competition, predation had a negligible impact on the spatial dynamics of Dicrostonyx, at least during summer. These results suggest that any differences in predation risk between the two habitats have little direct influence on the temporal dynamics of Dicrostonyx even if induced through predator-prey cycles.

Lemmings construct nests of grass and moss under the snow during winter, and counting these nests in spring is 1 method of obtaining an index of winter density and habitat use. We counted winter nests after snow melt on fixed grids on 5 areas scattered across the Canadian Arctic and compared these nest counts to population density estimated by mark–recapture on the same areas in spring and during the previous autumn. Collared lemmings were a common species in most areas, some sites had an abundance of brown lemmings, and only 2 sites had tundra voles. Winter nest counts were correlated with lemming densities estimated in the following spring (rs 5 0.80, P , 0.001), but less well correlated with densities the previous autumn (rs 5 0.55, P , 0.001). Winter nest counts can be used to predict spring lemming densities with a log-log regression that explains 64% of the observed variation. Winter nest counts are best treated as an approximate index and should not be used when precise, quantitative lemming density estimates are required. Nest counts also can be used to provide general information about habitat-use in winter, predation rates by weasels, and the extent of winter breeding.

The limestone outcrops of South Canterbury are outstanding landscape features, and many contain remnant native flora and fauna. Three skink species and four gecko species have been found there in subfossil remains. In 2008 the limestone habitats were surveyed to find which lizard species were present and to index their abundance, based on visual observation, artificial cover objects, pitfall traps, and searches of retreat sites. Common skinks (Oligosoma polychroma), McCann's skinks (O. maccanni) and Southern Alps geckos (Hoplodactylus ‘Southern Alps’) were found. Though the jewelled gecko (Naultinus gemmeus) was not found in limestone areas, three small populations were located elsewhere in South Canterbury. The species with the widest distribution and the highest number of sightings was the Southern Alps gecko. The two skink species were not observed living sympatrically. Both were found in low numbers in isolated pockets of suitable habitat. Conservation measures that might benefit these native...

Many bird species endemic to alpine New Zealand are now at critically low densities and restricted in range, making predator‐prey research difficult. We used artificial nests in the Borland Valley, Fiordland National Park, to investigate (1) which introduced species is the most frequent nest predator in the two habitats, (2) whether nest survival differs between habitats, and (3) the utility of artificial nests for guiding conservation management. We used different types of artificial nest in 2 different years and undertook a calibration study of the two types. In 2003, survival of artificial nests containing wax eggs and chicken eggs was high in both habitats. In 2004, survival of artificial nests containing plastilina eggs and chicken eggs was low in both habitats, but was higher in alpine grassland compared with beech forest. Stoats and possums were the most frequent predators (36 and 22% respectively of artificial plastilina nests in alpine grassland and high‐altitude beech forest combined); ...

House mice Mus musculus and other introduced rodents represent a novel source of predation on tree seeds in New Zealand forests. In the northern temperate forests where these rodents are native, spatial and temporal variation in tree seed production can result in dramatic fluctuations in the distribution and abundance of seed predators, with subsequent feedbacks on the distribution and abundance of seedlings. We use neighbourhood models to examine variation in rodent predation on seeds of 4 tree species of the temperate rainforests of New Zealand as a function of 1) spatial variation in local canopy composition and 2) spatial and temporal variation in mouse activity. We placed seeds throughout mapped stands of mixed forests in alluvial valley bottoms and on elevated marine terraces in the Waitutu Forest, South Island. The risk of predation on seeds of 2 dominant

Diabetic foot disease causes more amputations than any other lower limb disease. Management of the diabetic foot requires a thorough knowledge of the risk factors for ulceration and amputation, the most common of which are neuropathy, ischaemia and infection. Amputations are not inevitable, however; early detection and appropriate treatment of ulcers can prevent up to 85% of amputations. This has been demonstrated in the formation of multidisciplinary diabetic foot clinics, which have been shown to reduce the number of amputations across the world. Adherence to a systematic regime of organization, education, screening and intervention can improve communication between patients, GPs, community nursing and diabetes sub-specialists to facilitate appropriate treatment and prevention of complications. The case discussed here demonstrates how inadequate and disjointed management through lack of communication, education and knowledge of diabetic foot disease can lead to complications requiring amputation and debridement.

Summary 1 Angiosperm trees often dominate forests growing in resource-rich habitats, whereas conifers are generally restricted to less productive habitats. It has been suggested that conifers may be displaced by angiosperms except where competition is less intense, because conifer seedlings are inherently slow growing, and are outpaced by faster-growing angiosperm species. Here we investigate whether competition with ferns and deeply shading trees also contributes to a failure of conifers to regenerate in resource-rich habitats. 2 We examined how changes in soil nutrient availability and drainage affected vegetation along the retrogressive stages of a soil chronosequence in southern New Zealand. Vegetation composition shifted from angiosperm-tree dominance on ‘recent’ alluvial terraces (< 24 ky), via coniferous-tree dominance on older marine terraces (79‐121 ky), to coniferous-shrub dominance on the oldest marine terraces (291 ky). Soil drainage deteriorated along the sequence, and N : P leaves and N : P soil indicate increasing Plimitation. Conifer species appear to be adapted to persistence on infertile and poorly drained soils. 3 The floor of the relatively fertile alluvial forests was deeply shaded ( ∼ 1% light transmission) by dense groves of tree-ferns and ground-ferns, and by large-leaved subcanopy trees. Few seedlings of any type were found on the forest floor, even in tree-fall gaps, and establishment was restricted to rotting logs and tree-fern trunks. Angiosperms were particularly successful at colonizing these raised surfaces. 4 Less shade was cast by the conifer-dominated forests on infertile marine terraces ( ∼ 5% light transmission), which lacked tall ferns. There were many opportunities for conifer establishment, with high seedling densities recorded on the forest floor and on logs. By contrast, angiosperm seedlings were mainly restricted to logs. 5 Our results suggest that several mechanisms act in concert to reduce regeneration opportunities for conifers in productive habitats. In particular, we suggest that tall ferns and deep shade are responsible for a restriction of regeneration opportunities in relatively productive forests in New Zealand, diminishing the opportunities for conifers to escape the competitive effects of fast-growing angiosperms. Thus ‘crocodiles’ may alter the outcome of the race between ‘hares’ and ‘tortoises’.

Summary 1 LPBN is a parameterized simulation model of flows of nitrogen (N) in an ecosystem of cyanobacteria, grass and grazers, based on the N dynamics of a grazed Puccinellia lawn in an intertidal marsh on Hudson Bay. This system shows two alternate stable states: (a) lawns that either support a foraging population of lesser snow geese, or are not grazed by geese; and (b) exposed saline sediments that support little or no vegetation. The model represents the flow of N from cyanobacterial fixation, the major N input into the system, to the geese that migrate in autumn; those that do not return represent the major N output from the system. We have modelled N fixation, the transformations of N in the soil, plant growth, lawn regeneration, and goose grazing and grubbing. 2 The model simulates steady-state flows of N similar to those observed in the field at zero and at moderate goose density, and it also simulates the transition to the state of zero plant biomass, a consequence of increased grubbing at high goose density. The simulated steady-state flows are found to be more sensitive to changes in the parameters that describe N fixation and goose biology, than to similar changes in the parameters describing plant biology. 3 Because the model shows the alternate stable states and the transition between them, with values for the state variables that are consistent with field data, we conclude that N dynamics are crucial in determining the stability of the real salt marsh-goose system. The determining factor is the loss of the input of N from fixation when lawn area is reduced because the rate of goose grubbing exceeds that of plant re-establishment.

International audience; Understanding the long-term impacts of invasive mammalian browsers and granivores in mixed forests is difficult due to the many processes potentially affecting the demography of long-lived trees. We constructed individual-based spatially-explicit simulation models of two mixed conifer–angiosperm forests, growing on soils of contrasting phosphorus (P) availability, to investigate how browsing by invasive red deer (Cervus elaphus scoticus) and granivory by invasive rodents (primarily house mouse Mus musculus) might alter forest dynamics. Models were parameterized with field data. Seedling growth and survival rates were estimated inside and outside deer exclosures. Seed predation rates were estimated at high and low rodent densities in mast and non-mast seeding years. For the alluvial terrace forest, which grew on P-rich soil, our model contained 15 tree species dominated by angiosperms; our model of the P-poor marine terrace forest contained 7 species dominated by conifers. The two forest models were used to explore four 500-year scenarios: deer and rodents present, deer present and rodents absent, deer absent and rodents present, and deer and rodents absent. Our field studies revealed that the highest probabilities of seed predation by rodents occurred for two canopy species in mast years and in neighborhoods of high basal area, and that deer browsing had the greatest negative effects on the growth and survival rates of angiosperm seedlings. Our simulation models predicted that the presence of deer and rodents would reduce the abundances of canopy co-dominants, and hence total basal area, in the alluvial terrace forest. The presence of deer increased the dominance of conifers in both forests, but the effects of deer and rodents were much stronger in the alluvial terrace forest. Our study revealed two emergent properties. First, rodent- and deer-induced reductions in seedling abundances did not always translate into reduced sapling and adult tree abundances. Second, when deer changed the abundance of a canopy dominant, other species were affected by altered interspecific competition. We conclude that the effects of invasive deer and rodents will be greatest in forests growing on P-rich soils. Exclusion of deer is predicted to have greater long-term effects on forest dynamics than exclusion of rodents.

The alternative-prey hypothesis predicts that predation on goose eggs will be most severe the year following a lemming peak. We tested this by investigating how predators of goose eggs responded to lemming abundance on the Kent Peninsula, Nunavut, Canada, where nest success of white-fronted geese (Anser albifrons frontalis) and Canada geese (Branta canadensis hutchinsii) fluctuates widely. The main predators of both goose eggs and lemmings are arctic foxes (Alopex lagopus), glaucous gulls (Larus hyperboreus), and parasitic jaegers (Stercorarius parasiticus). Foxes responded functionally to lemming density: in prime goose-nesting areas they spent less time foraging during the peak lemming year than during the increase, and were seen foraging in prime nesting areas less often during the peak than during the decline. However, numbers of fox sightings in the study area during the nesting period did not differ significantly among years. The total response (functional × numerical) of gulls was lowest at the lemming peak and highest during the increase. The total response of parasitic jaegers did not vary significantly among years. Hence, we predicted that the number of nests lost to all predators combined should be lowest at the peak and possibly highest during the increase. During the 3 years of this study, loss of Canada goose nests was lowest at the peak but highest during the decline, and annual losses of white-fronted goose nests varied little. In cycles prior to this study, nest loss was high in declines but not particularly low during peaks. Several factors may alter the functional and numerical responses of predators, obscuring the simple pattern of nest loss predicted by the alternative-prey hypothesis.

We tested whether dispersal of juvenile lemmings occurs at high population densities and whether predation risk affects movements of juveniles. The study was conducted in July and August 1996 on the Kent Peninsula, Northwest Territories, during a peak in the lemming cycle. We fitted 43 juvenile collared lemmings (Dicrostonyx groenlandicus) of the summer generations on a control plot and a predator-exclosure plot with radio transmitters and examined their home ranges and movement patterns. We tested the following hypotheses: (i) extensive juvenile dispersal will occur at high population densities, (ii) male juveniles will move greater distances than females, and (iii) juveniles will move greater distances in the absence of predators. We rejected all these hypotheses. All juvenile collared lemmings remained in the vicinity of their original home ranges. Home-range sizes of all juveniles were similar, the mean size being 100 m2. Mean and maximum distances moved were similar among all juveniles. However, juveniles moved less frequently on the control plot than on the exclosure plot. Juvenile collared lemmings do not disperse at high densities. The lack of dispersal may have been the result of avoidance of confrontations with other lemmings, and may also have been related to delayed breeding, since most juveniles and subadults did not mature in late summer. Differential predation risk or predation mortality may have had no effect on the distances moved by juveniles or may have been masked by strong density effects on both plots.

Neuraxial opioids were first used for labour analgesia in 1980 following the description of spinal cord opioid receptors in 1979. Via these receptors in the dorsal horn, opioids modulate both the visceral and the somatic pain of labour. The onset and duration of action of the individual opioid are determined primarily by its relative lipid solubility. Neuraxial opioids have a local anaesthetic sparing effect, allowing the use of lower concentrations of both agents while maintaining analgesia. As a sole agent, intrathecal opioids can be used to provide analgesia during the first stage of labour, especially in the high-risk parturient. They also have a role in the management of perineal pain and the provision of rapid-onset analgesia. Unfortunately maternal and neonatal side-effects can occur, the most important being respiratory depression.

The first spinal anaesthetic for obstetrics was administered in 1900. Epidural anaesthesia, as a single injection technique, was introduced around the same time, and by the 1950s had become the more popular technique. The use of spinal anaesthesia for Caesarean section has increased since the late 1980s due to the introduction of the pencil-point spinal needles which are associated with a low incidence of headache. Spinal anaesthesia has a number of advantages. It is a reliable, easily learned technique which requires a low dose of local anaesthetic and, hence, has a low risk of toxicity. The quality of the block is better and the onset is more rapid than with epidural anaesthesia. Unlike the epidural, spinal anaesthesia largely remains a single injection technique which has some disadvantages. The side-effect profile of spinal anaesthesia is similar to that seen with epidural anaesthesia. In summary, spinal anaesthesia produces rapid, effective, reliable and safe anaesthesia f or Caesarean section while using low doses of local anaesthetic. This makes it the preferable technique for elective procedures.

Spatial and temporal variation in tree seed production is an important driver of the population dynamics of trees and of mammalian and avian seed consumers. Many studies have documented strong synchrony in production of intermittent large tree seed crops (masting), with cascading effects on the food webs of seed consumers and their predators. We used inverse modeling to characterize spatial and temporal variation in seed production and dispersal by four dominant tree species (two angiosperms and two conifers) over 8 years in southern temperate rainforests of New Zealand. In contrast to expectations from masting theory, there was little evidence of synchrony across species in years of high seed production, and only weak evidence in support of the expectation that temporal variation in seed production within species was strongly bimodal. Contrary to expectation from allometric scaling rules, there was no increase in reproductive effort once tree size (DBH) exceeded a minimum threshold (22–29 cm DBH) in the two angiosperm species. In the conifers, the minimum estimated size threshold for seed production was much higher (42–56 cm DBH), and in one of the species increased faster than linearly with biomass above the threshold size, indicating that the very largest trees in the conifer populations dominated seed production. Of the two species that occurred commonly on both fertile alluvial sites and less fertile uplifted marine terraces, the angiosperm species had higher per capita seed production on the fertile sites, while the conifer had higher per capita seed production (during seed years) on the less fertile sites. Local seed rain from all four species declined steeply with increasing distance from a parent, with peak local dispersal within 6 m of parent trees. This is not surprising given that the species are predominately gravity or animal dispersed with poor adaptations for wind dispersal. A substantial fraction of the input of seeds of all four species could not be attributed to local parent trees, consistent with longer distance dispersal by animals.

Deborah Wilson, recipient of the Lorraine Allison Scholarship for 1997, has designed her doctoral research to answer the following two questions about lemming and goose population dynamics. First, do predators cause the lemming decline? And second, how does the lemming cycle affect predation on goose nest? To this end she experimentally protected an 11-hectare patch of tundra from predators, with a fence to deter large predatory mammals and monofilament fishing line overhead to deter predatory birds. The results of this experiment are reported along with the results of the second part of her study which emphasizes that a decline in abundance of one type of prey may have unexpected deleterious effects not only on its predators but also on other prey species. "These observations may be relevant when outbreaks of disease kill prey animals, or when wildlife managers attempt to remove introduced pest species. To be able to make predictions about the population dynamics of alternative prey, it is necessary to take into account spatial patterns, delayed effects, the foraging behaviour of predators, and interactions among different species of predators."

Context Prey switching by invasive carnivorans to changing food supply could severely impact on endemic prey of conservation importance, but experimental evidence for prey switching in carnivorans is rare. Stoats (Mustela erminea) were introduced to New Zealand and now threaten survival of many native birds, reptiles and invertebrates. Aim Our primary objective was to see whether abundant food caused stoats inhabiting an alpine grassland site to alter the rate at which they preyed upon weta (Orthoptera : Hemiandrus sp.), hares (Lepus europeus), birds and mice (Mus musculus). Methods We used dead rabbits as supplemental food in a before-after-control-impact experiment. Stoat scats were collected from a treatment and non-treatment site before and following food supplementation. Percentage frequency occurrence of the different prey types was assessed for the two sites during each experimental phase. Conclusions Stoats ate fewer ground weta and hares, the two most abundant prey types, when supplemental food was added. In contrast, consumption of mice remained relatively stable at both sites throughout the experiment, and the consumption of birds declined at both sites. Implications Our experiment suggests that stoats may continue to eat scarce endemic prey at similar per capita rates even when alternative prey are available. However, endemic prey that are locally or regionally abundant may be indirectly impacted by fluctuations in alternative prey.

Context. Rodent populations in many parts of the world fluctuate in response to resource pulses generated by periodic high seed production (masting) by forest trees, with cascading effects on predation risk to other forest species. In New Zealand forests, populations of exotic house mice (Mus musculus) irrupt after periodic heavy beech (Nothofagus spp.) seedfall. However, in alpine grasslands, where snow tussock grasses (Chionochloa spp.) also flower and set seeds periodically, little is known about house mouse population dynamics. Aims. Our primary objective was to test for an increase in alpine mouse density following a summer when snow tussocks flowered profusely. We also estimated mouse density in adjacent montane forest over 2 years, and assessed mouse diet, to predict their potential impacts on native species. Methods. Flowering intensity of Chionochloa was assessed by counting flowering tillers on permanent transects (2003–06). Mouse density was estimated with capture–mark–recapture trapping in alpine (2003–07) and forest (2003–04) habitats. Mice were also collected and their stomach contents analysed. Flowering or fruiting of alpine shrubs and herbs, and beech seedfall at forest sites, were also measured. Key results. Chionochloa flowered profusely in austral summer 2005/06. Between autumn (May) and spring (November) 2006, mean alpine mouse density increased from 4 ha–1 to 39 ha–1, then declined to 8 ha–1 by autumn (May 2007). No mice were captured in 768 trap-nights during the following spring (November 2007). Prior to the mouse irruption, mouse density was consistently higher at alpine (0.4–4.0 mice ha–1) than at montane forest (0.02–1.8 mice ha–1) sites (in 2003–04). Alpine mouse diet was dominated by arthropods before mast flowering, and by seeds during it. Conclusions. The density and dynamics of alpine mice in relation to intensive snow-tussock flowering were similar to those in New Zealand beech forest in relation to beech masts. Implications. We predict the timing and duration of periods of heightened predation risk to native alpine fauna, as the result of pulses in mouse density and likely associated pulses in the density of stoats (Mustela erminea), a key exotic predator.

Collared lemmings (Dicrostonyx groenlandicus) fluctuate cyclically in abundance on the Kent Peninsula, Northwest Territories, Canada. We tested whether predation was a necessary limiting factor of the lemming population in summer during the peak and decline phases (1996 and 1997) of the cycle. We reduced predation by means of a fence and an overhead mesh of monofilament line over 11 ha, completed late in the summer of the increase phase (1995). We used mark-recapture and radio-telemetry to investigate differences in demography between this predator exclosure and three control areas. Neither proportions of reproductive animals, nor sex ratio, nor net distances moved between trapping sessions differed significantly between the Exclosure and Controls. Adults were larger in the Exclosure than on Controls throughout the experiment; female juveniles born in the first summer litter of the peak were also larger within the Exclosure by August. Density was much higher in the Exclosure than on Controls in both 1996 and 1997. While density declined in 1997 on Controls, it first declined but then rose in the Exclosure; hence the population decline was reversed within the experimental area. Most mortality was due to predation in all three summers, but survival was significantly higher within the Exclosure only in the decline phase. We conclude that predation was necessary to limit the population in the peak and decline summers, but that the magnitude of the limitation was greater in the decline. Out results demonstrate that predation depresses peak and minimum densities of Dicrostonyx and further shapes the population cycle by extending the duration of the decline.

1 Lesser snow geese feed intensively on graminoid vegetation in intertidal salt marshes at La Perouse Bay, Manitoba. Relatively little grazing occurs in more inland sites, where the same vegetation persists but tidal inundations are infrequent. At some sites geese have grubbed vegetation exposing sediments. 2 Feeding preferences of geese may be linked to the availability of nitrogen for plant growth in the different areas. Total soil nitrogen, exchangeable inorganic nitrogen, net mineralization of nitrogen, together with soil properties, were measured in intertidal and inland sites (both grazed and ungrazed), and in intertidal grubbed sites. Where applicable, rates of net mineralization of nitrogen were compared with aboveground biomass and with the nitrogen content of shoots of graminoids in both grazed and ungrazed (exclosed) swards. 3 All soils were regosolic static cryosols with a thin Ah humus horizon. Most graminoid roots were confined to the top 2 cm of soil, few penetrated deeper than 5 cm. Bulk density of soil 1-2 cm below the surface was 0.87 g cm3 and 0.53 g respectively, in the intertidal and inland marsh, and water content and salinity of soil were higher in the inland marsh. 4 Total nitrogen in soils (0-2 cm below the surface) in the inland marsh was 118 g ? 6g N m-2 compared with 80 + 2 g N m2 in the intertidal marsh. Total soil nitrogen, exchangeable inorganic nitrogen and net mineralization of soil nitrogen were significantly greater beneath intact swards compared with grubbed swards in the intertidal marsh. 5 Seasonal net cumulative amount of nitrogen mineralized in the intertidal marsh (86 days) in 1991 was 0.53 g N m-2 at a soil depth of 1-2 cm. The comparable value for the inland marsh was 0.06 g N m2. In 1992 (54 days) the net amount of nitrogen mineralized in vegetated intertidal sites was 0.18g N m-2 (1-2cm) and in grubbed sites it was 0.06 g N m2. 6 Cumulative above-ground biomass of graminoid species in exclosed plots was greater in the intertidal marsh compared with that in the inland marsh. The amount of nitrogen (as percentage) in above-ground biomass was also higher in plants from the intertidal marsh. 7 Differences in the quantity and quality of vegetation are associated with variation in biogeochemical cycling in soils. Geese exploit patches of vegetation as their primary source of forage where net above-ground primary production is high and plant tissues are rich in nitrogen.

Diagnosis of Cytomegalovirus Infections and Development of Monocional Antibodies Cytomegalovirus (CMV) is a common infection that can cause serious disease in infants who have acquired the virus in utero, in patients immunosuppressed for organ transplantation, and in other individuals who receive chemotherapy or high levels of corticosteroids for treatment of neoplastic and other medical processes. Only 4 years ago, the standard method for detecting CMV infection in the laboratory was the inoculation of diploid fibroblast cell cultures in tubes with subsequent identification of typical cytopathic effects that required an average time period of 7 8 days for recognition (3). Immunologic methods for rapid detection of CMV in clinical specimens waned for lack of high quality homotypic antisera that could produce sensitive and specific results and, importantly, be commercially available. Subsequently, two monoclonal antibodies were prepared against an early and a late antigen of the ADI69 strain of CMV by Shuster et al. at the Mayo Clinic. These monoclonal antibodies provided the key to the development of a rapid test for detection of the virus (10). Since 1973, we have used shell vials to diagnose Chlamydia trachomatis infections. This bacterium is .only 3 4 times larger than the CMV virion; nevertheless, centrifugation of the specimen inoculum at low speed (700 x g) has been shown to enhance the rate and ultimate infectivity of this organism and viruses in susceptible cell cultures. Because we wanted to be able to detect CMV as rapidly as possible after inoculation of cell cultures in the laboratory, we used the monoclonal antibody prepared to an early antigen (72,000 d) to assay for the viral components synthesized after 16 hr incubation by the indirect immunofluorescence test (monoclonal antibody available from DuPont Specialty Diagnostics, Wilmington, DE).

The serologic response to Chlamydia was determined with three sequential serum specimens from 25 renal transplant recipients (RTR) and from 25 blood donors who were matched for age and sex with the study group. Antibodies to Chlamydia were also measured in serum specimens from several other populations. The geometric mean titers (GMT) were significantly higher (P less than 0.05) for infants with pneumonia (1:6927) and women attending a sexually transmitted disease (STD) clinic (1:35) compared with pregnant women (1:25), normal infants, less than 23 weeks of age (1:11), and RTR (1:13). Titer increases of greater than or equal to fourfold were detected in 4 of 25 (16%) RTR, but could not be correlated with clinical pneumonia. Because of the high background prevalence (20% in RTR, 80% in STD patients), combined with low GMT of chlamydial antibody in these groups, the serologic diagnosis of respiratory tract infections in immunosuppressed adults required serial serum specimens.

Modified New York City medium was compared to Hayflick solid medium without methylene blue, using 23 stock strains of Mycoplasma pneumoniae. Time to recovery was the same for both media, never longer than 24 hours. Sensitivity, as measured by colony counts, was significantly greater with Hayflick medium. Modified New York City medium may not be more rapid than Hayflick medium and may not offer significant advantages over the latter.

A fluorescein-labeled monoclonal antibody was compared with the iodine stain for the detection of chlamydial inclusions in McCoy cells grown on cover slips in glass vials. The remainder of the original specimen extracts in 2-sucrose phosphate transport medium from 100 specimens (50 male, urethra; 50 female, cervix), stored at −70°C and previously determined to be culture positive for Chlamydia trachomatis by the iodine stain, were inoculated into vials containing monolayers of McCoy cells. Cover slips were coded and examined microscopically after 40 hr at 35°C. The mean numbers of inclusions detected by iodine and by immunofluorescence were the same. One-half of the specimens had eight or fewer inclusions present. There was a trend indicating that less time was required for microscopic examination of cover slips for chlamydial inclusions with immunofluorescence than with the iodine-staining method. The tagged monoclonal antibody is a high-quality immunodiagnostic reagent for use in the immunofluorescence test; however, our data derived from stored specimen extracts indicate equivalence of detection of inclusions in the glass vial system compared to iodine.

Standard curves for competitive protein binding analysis of steroids are usually arrived at by empirical methods. It is possible from a knowledge of the equilibrium constant, concentration of binding site and radioactive tracer as well as practical inefficiencies of the system, to predict and experimentally confirm standard curves for the estradiol-uterine cytosol assay. This has been done by modifying the mass action equation for the non-ideal conditions that arise in the actual assay. Estimating the error in the bound fraction when tracer only is present allows the 95% confidence interval to be predicted at each hormone concentration on the curve. This estimate of error is used to define a working range and a limit of sensitivity. Because of the complexity of the equations for the relevant variables a computer program has been utilised to solve equations and to provide tabular output for standard curves, error, working range and sensitivity.