Costs and benefits of aerial 1080 possum control operations using carrot baits to North Island robins (

We monitored the behaviour of 62 radio-collared ferrets and 25 radio-collared cats in dry, tussock grassland habitat in New Zealand's South Island. The total home range of adult male ferrets (102 ± 58 ha, mean ± 1 s.d.) was marginally greater than that of females (76 ± 48 ha), and averaged 90 ± 55 ha. Male ferret core ranges (27 ± 15 ha) were larger than those of females (16 ± 8 ha). Adult cat home ranges were similar between sexes, and were larger and more variable than those of ferrets (225 ± 209 ha). Core range size of cats was similar between sexes and averaged 54 ± 24 ha. The upper 95% confidence limits of the mean home range lengths of adult ferrets and cats were 2.7 km and 5.1 km, respectively, indicating the width of buffer zones where predator control should be extended to protect the boundaries of areas targeted for predator control in dry, tussock grasslands. Although core areas were mostly discrete, home ranges were distributed randomly, and animals that shared space neither avoided nor attracted each other. Little evidence of territoriality may be related to high densities of primary prey. Too few cats were monitored to determine territoriality. Ferrets used at least 9.4 ± 3.2 dens, and cats used 11.5 ± 3.0 dens during the study. Although 71% of dens were used only once, some were used up to nine times. Day time resting by ferrets was mostly solitary. If transmission of bovine Tb occurs between adult ferrets, simultaneous sharing of dens during the day is unlikely to be a significant mode of transmission in this habitat. We were unable to determine the extent of den sharing by cats. Cats occupied den sites with more shrubs and rocks compared with ferrets. Predator control stations in dry tussock grassland habitat may therefore be more effective at killing cats than ferrets if placed in shrubby, rocky areas.     

An assessment of the probability of secondary poisoning of forest insectivores following an aerial 1080 possum control operation

Assays for the toxin sodium monofluoroacetate (compound 1080) were undertaken on arthropods collected from toxic baits after a brushtail possum (Trichosorus vulpecula) control operation in Nothofagus forest in central North Island, New Zealand. The 1080 concentrations measured (mean 57 mu g per g, max 130 mu g per g) are considerably higher than those reported by other researchers who collected arthropods randomly after control operations. These data, together with published information on sensitivities to 1080, as well as diet and consumption rates, were used to calculate the median lethal doses of arthropods that have fed on 1080 baits for a number of vertebrate insectivores found in Nothofagus forest. The results indicate small insectivores that feed on, or close to, the ground (e.g., tomtit Petroica macrocephala, robin P. australis, hedge sparrow Prunella modularis, and the short-tailed bat Mystacina tuberculata) may be vulnerable to secondary poisoning. For instance, a tomtit will receive the median lethal dose of 1080 from 1.32 g (i.e., 14.7% of its daily food intake) of arthropods containing 57 mu g per g of 1080. Because of their greater sensitivity to 1080 poisoning, bats are at much greater risk; a short-tailed bat will receive the median lethal dose of 1080 from as little as 0.04 g (0.7% of its daily food intake) of arthropods containing 57 mu g per g of 1080.     

Plant communities of the Mt Wellington Range,Tasmania

Associations among species of vascular plants in twelve predefined vegetation zones on Mt Wellington, Tasmania, are described. The vegetation zones were based mainly on the dominant species of eucalypt contained therein, following an approach used previously by Martin (1940). The twelve zones were subsequently reduced to a total of six cluster groups using hierarchical classification procedures. Character species, in the sense of the Braun-Blanquet (1928) system of phytosociology, are identified and tabulated for each group. It is suggested that the division of a survey area into zones based upon dominant euealypts may be applicable to the study of vegetation communities in other parts of Tasmania.     

Effects of an aerial 1080 possum poison operation using carrot baits on invertebrates in artificial refuges at Whirinaki Forest Park, 1999– 2002

The effects of an aerial 1080 possum poison operation using carrot baits on invertebrates in Whirinaki Forest Park are described from an un-replicated study of artificial refuges attached to tree trunks. Auckland tree weta (Hemideina thoracica), cave weta (Pharmacus sp. and Isoplectron sp.), cockroaches, spiders and harvestmen, and leaf-veined slugs (Athoracophorus bitentaculatus) were the most frequent occupants, but snails, millipedes, centipedes, flatworms, lepidopteran larvae, glowworm larvae (Arachnocampa luminosa), peripatus, slaters and beetles were also present occasionally. Invertebrate numbers were monitored every second or third month for a year before the poison operation, and for two years afterwards. Numbers of tree weta, cave weta, cockroaches, spiders and harvestmen, and leaf-veined slugs did not decline substantially in refuges in the treatment area relative to those in the non-treatment area immediately after the poison operation. Our results, and those from two other similar studies, suggest that aerial 1080 poison operations are unlikely to have a detrimental effect on invertebrates that occupy cavities above ground.     

Comparing methods for assessing mortality impacts of an aerial 1080 pest control operation on tomtits (

This study aimed to estimate the level of mortality of North Island tomtits (Petroica macrocephala toitoi) during an aerial 1080 possum poisoning operation in Tongariro Forest, New Zealand, and to evaluate transect-based alternatives to banding for monitoring tomtit populations. The operation used 12 g toxic (1080 at 0.15% weight/weight) cereal baits sown at 3 kg/ha. Transects were established at three neighbouring sites; two within the 1080 poison area, and one outside. The re-sighting of 14 out of 15 banded male tomtits at one site within the 1080 operation indicated that mortality was low. This was backed up by results from a before-after-control-impact (BACI) design to analyse density estimates from distance sampling along transects. We analysed the change in counts of territorial males before and after the operation based on the same transect surveys. This also showed little impact of poisoning on tomtits, and indicated that loss rates greater than 8.4% due to 1080 were incompatible with the data (95% one-sided confidence bound). Counts of territorial males gave a much tighter confidence bound than the banding or distance sampling results. Of the techniques applied, the counting of territorial males appears to have the most promise for providing high-precision estimates of short-term impacts, by taking full advantage of the territorial habits of male tomtits in spring. However, distance sampling shows potential for providing the basis for longer-term monitoring of tomtit populations. The transect-based approaches involved substantially fewer resources than banding for estimating short-term impacts, and offer a considerably less-intensive means of longer-term monitoring of tomtits.     

Allometry and sexual selection of male weaponry in Wellington tree weta, Hemideina crassidens

Both male and female Wellington tree weta, Hemideina crassidens,use cavities in trees as diurnal shelters. That these galleriesare often limiting in nature offers males the opportunity toincrease their reproductive success by monopolizing galleriesand the females residing in them. Male H. crassidens, can matureat either the 8th, 9th, or 10th instar, whereas females matureat the 10th instar only, and male head (and mandible) size positivelycovaries with ultimate instar number. It has been suggestedthat males fight for control of galleries by using their enlargedmandibles as weapons, and males with larger mandibles controlgalleries with more females. In the present study, I presenta statistical examination of sexual dimorphism, showing thattraits related to head size are on average significantly largerin males, whereas traits related to body size are on averagesignificantly larger in females. I tested three predictionsaddressing the hypothesis that sexual selection is driving megacephalyin male H. crassidens. First, as predicted, traits related tohead size show a positive allometric relationship with bodysize in males but not in females. Second, adapting a novel statisticaltechnique based on maximum likelihood and bootstrapping revealedthat males, but not females, exhibit a multimodal distributionin head and body size traits. This is likely a consequence ofmales maturing at one of three instars, which results in positivecovariance between the ultimate instar number and morphologicaltraits. Third, as predicted, single adult males with largerheads reside in galleries housing larger groups of adult females.     

Secondary poisoning of stoats after an aerial 1080 poison operation in Pureora Forest, New Zealand

Stoats were monitored by three methods through an aerial 1080 poisoning operation at Waimanoa, Pureora Forest in August 1997. Tracking rates and number of live captures were used as indices of abundance, and radio-transmitters were used to follow individual animals. All 13 stoats with radio-transmitters within the poisoned area died between 2-18 days after the operation. No mustelids were tracked or live-trapped after the operation for three months. Of the radio-tracked stoats that died, rat remains occurred in 67%, passerine birds in 17%, cave weta in 17% and possum in 8%. Residues of 1080 were found in 12 of the 13 dead stoats. Our findings have important implications for the management of threatened species. Stoats are known to be a major factor in the continuing decline of some native birds. Previously, the potential of secondary poisoning to control stoats land other predators) in New Zealand had focused on the use of anticoagulants, as these compounds persist and can accumulate in predators over a longer period. However, our results suggest that secondary poisoning with an acute toxin can also be highly efficient. This may also have greater public acceptability.     

Bait consumption and residual concentrations of diphacinone in the Wellington tree weta (

To investigate the potential for mortality or sublethal effects in the tree weta (Hemideina crassidens) as the result of exposure to baits used for rodent control, and the potential secondary hazard to non-target species, captive weta were offered Ditrac® wax block bait containing the anticoagulant diphacinone. Bait consumption was recorded daily for the first week and then weekly. Weta were sampled in groups of four following 1, 4, 8, 6, 3, and 64 days of exposure to bait and analysed to determine the concentration of diphacinone residues in their bodies. Any changes in feeding behaviour, survival, and bodyweight were recorded. Weta found Ditrac wax block baits palatable even in the presence of natural plant food, showing steady consumption of bait over time. No mortality or weight loss was attributable to the intake of Ditrac bait. All weta that ate bait had detectable diphacinone in their bodies, but did not accumulate diphacinone, i.e. whole-body concentrations did not increase with the amount of diphacinone bait eaten over time. Field use of diphacinone bait is likely to present a low risk of mortality to weta, but the risk posed by secondary diphacinone exposure to non-target species that eat weta requires further investigation.     

Sexually dimorphic immune response in the harem polygynous Wellington tree weta Hemideina crassidens

Abstract Adult males are often less immunocompetent than females. One explanation for this is that intense sexual selection causes males to trade‐off investment in immunity with traits that increase mating success. This hypothesis is tested in the Wellington tree weta (Hemideina crassidens), a large, sexually dimorphic orthopteran insect in which males possess enormous mandibular weaponry used during fights for access to female mates. Field‐collected males have a significantly greater immune response (greater melanotic encapsulation) than females, suggesting that body condition, longevity or an allied trait is important to male fitness, or that females require materials for egg production that would otherwise be used to boost immunity. Although immunity is expected to trade‐off against reproductive traits in both sexes, there is no significant relationship between immune response and weapon or testes size in males, nor fecundity in females.     

Robertsonian translocations and B chromosomes in the Wellington tree weta, Hemideina crassidens (Orthoptera: Anostostomatidae)

Two karyotypes within the species Hemideina crassidens are described, 2n = 15 (XO) and 2n = 19 (XO). These two karyotypes have a NF of 28. The 19-karyotype was found exclusively in the southern part of the species range and the 15-karyotype was found in the north. The differences between the two karyotypes are interpreted as arising from two Robertsonian translocations (fission/fusion). Laboratory matings between weta with the two karyotypes produced viable offspring. During meiosis in F1 intraspecific hybrids metacentric and acrocentric autosomes aligned to form two trivalents, confirming homologies predicted by Robertsonian translocations. The subspecies H. c. crassicruris, (confined to Stephens Island) was found to be polymorphic for a metacentric B chromosome. An unusual association of sex and presence of B chromosome was observed in this island population with Bs found only in male weta.     

Quantification of character-species in vegetation at the tree limit,Brooks Range,Northern Alaska

Quantification of character-species using Dahl's uniformity index is tested on phytosociological data using species composition of tree limit communities on the south slope of the Brooks Range, Northern Alaska as an example. Species in 246 relevés are grouped by minimum spanning tree (MST) analysis. The resulting six species groups are ordinated in a congruent pattern by detrended correspondence analysis along the two main axes of mesotopographic-scale nutrient and moisture gradients. The eutraphent species are restricted to the more fertile sites of the undulating topography in this permafrost area. Uniformity indices are highest for the species in eutrophic sites with average frequencies. In contrast, most oligotraphent species are ubiquitous and occur even within the more eutrophic communities on raised mounds, shallow soils and in the exposed rocky areas. In general, their high frequency and low uniformity indices confirm that they are not useful as characterspecies. Dahl's uniformity index seems to be useful for quantifying a plant's value as a character-species.Abbreviations DCA Detrended correspondence analysis - MST Minimum spanning tree     

Sexual selection and infection by ectoparasites in Wellington tree weta,Hemideina crassidens (Orthoptera: Anostostomatidae)

Abstract Sexual selection can affect the prevalence and intensity of infection of individuals by ectoparasitic mites. According to this theory, males should exhibit greater infection by parasites than females and juveniles should be less infected than adults. In the wild, I investigated whether prevalence and intensity of the chyzeriid mite, Nothotrombicula deinacridae (Dumbleton) differed between the sexes and between developmental stages in Wellington tree weta, Hemideina crassidens. Despite being under strong sexual selection, male tree weta did not exhibit greater parasitism and there was some evidence that adults and juveniles differed in prevalence. The sexual selection hypothesis was not supported in this study.     

Risks to non-target species from use of a gel bait for possum control

The risks to non-target species of a newly developed bait containing either 0.15% 1080 or 0.6% cholecalciferol in a gel matrix were assessed. Very few of them ate gel bait. The safety of the gel bait is further enhanced by its placement in the purpose-designed bait station from which little spillage occurs, and which can be placed so that it is out of reach of most non-target animals. Comparative data show that nontarget species are considerably less susceptible to cholecalciferol than to sodium monofluoroacetate (1080). Risks to non-target species could be further reduced by use of the cholecalciferol form of the bait.     

阿尔泰山萨彦岭4种优势树种径向生长对气候因子的响应

气候变化深刻地影响森林树木的生长,而树种对气候变化敏感度的差异可能影响了气候变化下的森林生态系统响应。因此,研究优势树种间生长对气候变化的敏感度差异,对正确认识气候变化下林分生长动态及分布格局十分重要。基于树木年代学的方法,研究了阿尔泰山萨彦岭西伯利亚落叶松（Larix sibirica）、西伯利亚红松（Pinus sibirica）、西伯利亚冷杉（Abies sibirica）以及西伯利亚云杉（Picea obovata）4种优势树种的径向生长-气候关系。结果显示：（1）西伯利亚冷杉径向生长与上一年10-11月、当年1-9月的干旱指数、2-4月的降水显著正相关,与1月的平均温和最高温呈显著负相关关系,与当年4、6月份的水汽压正相关;（2）西伯利亚落叶松径向生长与上一年8月和当年8月的平均温、最高温以及当年8月的最低温显著负相关,而与当年6月的最低温则正相关,与8月份的水汽压显著负相关;（3）西伯利亚红松径向生长与3月降水、7月最低温、上一年10月的水汽压显著正相关;（4）西伯利亚云杉径向生长与6月平均温、最高温、水汽压正相关,与上一年10-11月、当年2-4月和9月的干旱指数正相关,同时与3、4月的降水量显著正相关。西伯利亚冷杉和西伯利亚云杉、西伯利亚云杉和西伯利亚落叶松、西伯利亚云杉和西伯利亚红松对于特定气候因子表现出相似的响应结果,与年表间相关性的结果一致。但差异也是明显的,西伯利亚冷杉和西伯利亚云杉对区域水分变化敏感,而西伯利亚落叶松和西伯利亚红松主要对区域温度变化敏感。综上所述,气候变化下,该区域优势树种对气候变化响应的差异可能导致区域林分动态和格局的改变,因此,多树种径向生长-气候关系研究有助于正确反映森林动态。研究结果可以为区域森林管理与生态保护工作提供理论依据。     

Effects of environment and grazing disturbance on tree establishment in meadows of the central Cascade Range,Oregon, USA

Abstract. Within the last century there has been widespread establishment of trees in mountain meadows of the Pacific Northwest. We reconstructed patterns of tree invasion at 17 meadow sites in the central Cascade Range of Oregon, USA -sites representing diverse physical environments and vegetation types and experiencing different histories of recent anthropogenic disturbance (sheep grazing). Spatial distributions and age structures of invasive tree populations were analysed with respect to climatic records and grazing history. Patterns of establishment varied considerably among meadows, reflecting strong differences in environment and grazing history. In montane hydric meadows, tree establishment was spatially clumped beneath large old trees and on elevated microsites; however the timing of invasion differed between sites with stable versus fluctuating water tables. In upland mesic/dry montane meadows, timing of invasion corresponded with cessation of sheep grazing (early 1940s) and the onset of wetter summers (mid 1940s). In the subalpine zone, climate and aspect interacted to produce contrasting histories of invasion on north- and south-facing slopes. Establishment on north-facing slopes, concentrated in heath-shrub communities, coincided with regional warming (ca. 1920–1945) when snowpacks were lighter and melted earlier. Recruitment of trees onto south-facing slopes occurred later, when conditions were wetter (1945–1985). In many environments, the spatial distribution of recruitment suggests that once trees have established, autogenic factors become increasingly important as individual trees or groups of trees alter the physical or biotic conditions that once inhibited establishment. Knowledge of the factors that influence invasion, and of their varying importance across gradients in environment and vegetation, is critical to predicting future changes in these dynamic systems.     

Reproductive and physiological costs of repeated immune challenges in female Wellington tree weta (Orthoptera: Anostostomatidae)

Fitness‐related traits, such as immunity and reproduction, are typically condition dependent, and are predicted to trade off against each other because they share a pool of energy and resources. It is generally assumed that the resources and energy required for immune processes and reproduction is contained in the body fat; however, few studies quantify the effect of an immune insult on fat load. I tested the hypothesis that if mounting an immune response is physiologically costly in terms of consuming limited resources from body fat, and reproduction also relies on these resources, then an immune challenge should cause a reduction in fat load and an associated decline in reproduction. I tested this hypothesis by assaying the fat content of female Wellington tree weta (Hemideina crassidens) after repeated challenges with lipopolysaccharide (LPS), and counting the number of oviposited eggs in addition to assaying the egg protein content, a possible measure of egg quality. In line with my prediction, immune‐challenged females had significantly smaller fat loads and laid significantly fewer eggs than saline‐injected controls. Moreover, the protein content of the eggs laid by immune‐challenged females was significantly lower than that of controls. My experimental results show that an immune challenge with a non‐pathogenic stimulant increases fat consumption, which in turn limits the resources available for reproduction. These findings support the hypothesis that reproduction and immunity are condition dependent, and are traded off against each other. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 38–46.