bluuebunny/crossref_metadata_2025_split huggingface dataset:
ADVANCES IN APPLIED ECOLOGICAL TECHNIQUES A novel mark–recapture technique and its application to monitoring the direction and distance of local movements of rangeland grasshoppers (Orthoptera: Acrididae) in the context of pest management
Authors: Narisu  , Lockwood Jeffrey A. , Schell Scott P. 
Published: March 2003

Summary 1. Rangeland grasshopper movement was studied in Wyoming, USA, with respect to the biological and ecological factors (population density, developmental stage and weather) influencing net displacement and directionality. 2. A novel adaptation of the mark–recapture method was developed to monitor grasshopper dispersal. The method used fluorescent powder and resighting marked grasshoppers in the field with ultraviolet light, rather than physical recapturing of individuals. 3. Rangeland grasshoppers exhibited a strong tendency for directional movement. Adult grasshoppers demonstrated a significant tendency for dispersal in a north‐westerly direction across a range of population densities (5–8, 10–15 and ≥ 18 grasshoppers m–2). Although not a definitive explanation, weather might have influenced this behaviour, as the grasshoppers consistently moved upwind. 4. The mean displacement of grasshoppers in a 36‐h period ranged from 2·3 m in nymphs to 3·7 m in adults, with the distance of displacement being positively correlated with population density. 5. An understanding of grasshopper movement in terms of directionality and displacement has immediate applicability to reduced agent–area treatments for rangeland grasshopper management.
Survey of badger Meles meles damage to agriculture in England and Wales
Authors: Moore Niall , Whiterow Anne , Kelly Paul , Garthwaite David , Bishop Julie , Langton Steve , Cheeseman Chris 
Published: March 2003

Summary 1. In response to reported increases in badger numbers and associated agricultural damage, a questionnaire survey of 3600 land owner/occupiers was conducted in 1997 to determine the extent and significance of badger damage in England and Wales. We assess the significance of badger‐induced damage and highlight problem regions, farm types and specific crops to allow targeting of future research efforts at amelioration. (This survey investigated alleged badger damage to agriculture but did not address the role of badgers in the transmission of bovine tuberculosis.) 2. The return rate of the questionnaire was 55·1% (n = 1982) and 150 of the responses were ground‐truthed. 3. Almost 30% of those land owner/occupiers who responded reported that badger damage had occurred in the previous 12 months, and 57% reported an increase in damage during the past 5 years. 4. Badger damage was widespread, but its incidence was highly dependent on region and farm type. The most frequently reported damage (25·5%) resulted from badgers’ burrowing activities (especially those causing damage to fences). Crop damage was also frequently reported (21·2%), with wheat, forage maize and vines being damaged most frequently. 5. Ground‐truthing showed that incorrect attribution to badgers of damage was negligible and that the majority of respondents had assessed correctly the extent and cost of badger damage, except for predation on livestock where most ‘evidence’ was circumstantial. 6. Most reported damage was of little economic consequence to individual land owners/occupiers; however, approximately 5% estimated that they had incurred costs of over £1000. 7. Assuming that the questionnaires returned were a random subset of those distributed, the mean estimated national cost was £41·5 million per annum (62% of which was due to burrowing activity). Assuming that all the non‐respondents had no damage, the estimate was £21·5 million per annum. 8. Future research into management options for damage limitation should be targeted at the areas and situations of most significant damage. These are primarily burrowing damage and direct crop damage to wheat, maize, vines, fruit and vegetables. The region suffering the most intense damage was the south‐west of England. The highly seasonal nature of the damage to some crops will allow preventative action to be taken at the most appropriate times. Predation by badgers on livestock is considered a small‐scale and unproven problem.
Effects of surgically imposed sterility on free‐ranging rabbit populations
Authors: Twigg Laurie E. , Lowe Tim J. , Martin Gary R. , Wheeler Amanda G. , Gray Garry S. , Griffin Sandra L. , O’Reilly Catherine M. , Robinson David J. , Hubach Peter H. 
Published: March 2003

Summary 1. Demographic changes in response to surgically imposed female sterility were monitored in 12 free‐ranging rabbit populations in south‐western Australia over a 4‐year period. This was part of a research programme aimed at examining the potential for virally vectored immunocontraception to limit the abundance of rabbits (e.g. using a recombinant myxoma virus) and other mammalian pests. Sterility levels were 0%, 40%, 60% and 80% of all females in year 1, with a similar proportion of female recruits sterilized surgically in subsequent years. 2. There was a significant decrease in rabbit productivity with increasing sterility level. This was overcome by increased survival of kittens and adults on the high‐sterility sites, such that the base‐level numbers of rabbits were maintained, and mean annual rates of increase (r) were near zero for all treatments in all years. However, in the high‐sterility populations this compensation was insufficient to overcome the effects of sterility totally, and there was a marked decrease in the seasonal peaks in rabbit abundance for these treatments. 3. Survival and recruitment were dependent upon the level of sterility, and consequently the density of rabbits, with greatest survival of adult rabbits occurring on the 80% sites. Survival of sterile females was greater than that of other adults, probably because of their increased ability to maintain body condition during times of low pasture biomass (summer drought). Thus two density‐dependent processes were identified: the first was operating through increased survival of juvenile rabbits, the second through increased adult survival, particularly sterilized females. 4. Because the proportional impact of immigration was greater (i.e. immigrants constituted a greater proportion of the population) and emigration was less, from the 80% sites, the effects of sterility may have been underestimated on these sites. 5. The abundance of European rabbit fleas, a vector of myxomatosis, was significantly lower on the 80% sites, but this did not appear to affect the transmission of myxoma. Myxomatosis occurred as an annual epizootic in three of four years, with > 90% of rabbits on site after each epizootic testing positive for myxoma antibodies. 6. To achieve a sustained long‐term reduction in rabbit abundance, 60–80% of female rabbits would need to be prevented from breeding. This could be achieved by a recombinant strain of myxoma provided the strain retained good transmissibility and all infected rabbits became sterile for life.
Interactions between nutrient status and weevil herbivory in the biological control of water hyacinth
Authors: Heard Tim A. , Winterton Shaun L. 
Published: March 2003

Summary 1. Despite the widespread release of effective biocontrol agents, water hyacinth remains the world’s most problematic aquatic weed, particularly in eutrophic waterbodies. However, understanding of the interaction between control and trophic status is still incomplete. 2. Growth of water hyacinth plants was measured at two water nutrient concentrations (high and medium) and in the presence and absence of two insect biocontrol agents in a large circulating hydroponic system in a glasshouse. 3. At the high nutrient concentration (1·6 mg l−1 N and 1·0 mg l−1 P), plants multiplied more quickly, attaining greater biomass. Both insect species reduced plant growth at both nutrient concentrations. Neochetina bruchi, however, performed better than N. eichhorniae at the high nutrient concentration by inflicting more damage on the plants and reducing biomass by a greater extent. 4. Insect damage reduced the concentrations of nitrogen and phosphorus found in plants growing in high nutrient water but not in medium nutrient water (0·4 mg l−1 N and 0·025 mg l−1 P). 5. The developmental and reproductive performance of N. bruchi was determined at both nutrient concentrations. Water hyacinth plants grown at higher nutrient concentration were superior hosts to N. bruchi than plants grown at medium concentrations. Net reproductive rate and intrinsic rate of increase were significantly greater at the high concentrations. Greater damage by N. bruchi to water hyacinth at the high nutrient concentration was due to the greater production of offspring, and hence greater larval damage. 6. We predict that water hyacinth problems will be greater in eutrophic waterbodies, where N. bruchi will be a superior biocontrol agent to N. eichhorniae. In low‐nutrient waterbodies, local nutrient enrichment of water may assist the establishment of control agents. These results illustrate the importance of wider ecological factors on the success of biological control.
How environmental stress affects density dependence and carrying capacity in a marine copepod
Authors: Sibly Richard M. , Williams Timothy D. , Jones Malcolm B. 
Published: March 2003

Summary 1. Management of the effects of stress on populations – for instance in ecotoxicology – requires understanding of the effects of stressors on populations and communities. Attention to date has too rarely been directed to relevant ecological endpoints, such as carrying capacity and density dependence. Established procedures are instead based on measuring the Life Tables of individual organisms exposed to differing concentrations of a pollutant at low population density, but this approach does not take into account population effects that may occur through interactions between individuals. Here we introduce an approach that allows direct measurement of the effects of stressors on carrying capacity and density dependence. 2. Using the marine copepod Tisbe battagliai Volkmann‐Rocco, we report replicated experiments establishing the effects of 100 µg L−1 pentachlorophenol (PCP) in combination with varying diet and food concentrations. Population density was measured as population biomass in 10 mL volumes. Diet was either the alga Isochrysis galbana Parke (here designated ‘poor diet’) or a mix of two algal species (I. galbana and Rhodomonas reticulata Novarino: ‘good diet’). Each was given at three food concentrations (520, 1300 and 3250 µgC L−1), selected on the basis that at low population density these cover the range between limited and maximal population growth. 3. Carrying capacity increased linearly with food concentration. On the poor diet the increase was 1·2 μg L−1 for each μgC L−1 increase in food concentration. On the good diet the increase was 2·3 μg L−1/μgC L−1 in the absence of PCP, and 1·9 μg L−1/μgC L−1 with PCP. Maximum carrying capacity was in the region of 60–80 μg per 10 mL volume. Population growth rate (pgr) decreased linearly with population biomass when the latter was plotted on a logarithmic scale. Increasing biomass reduced pgr by 1·70 week−1 for each unit increase in log10 biomass. Increasing food concentration and improving diet both increased pgr, but did not affect the slope of the density‐dependent relationship. Presence or absence of PCP had no effect except that at some higher food concentrations non‐PCP populations initially increased faster than PCP populations, and at high concentration on the good diet the effect of density‐dependence was decreased in PCP populations. 4. The results show that a stressor's effects at high population density may differ from its effects at low density, and emphasizes the importance of finding new protocols, such as those introduced here, with which to study the joint effects of a stressor and population density. Managers and researchers of threatened species, harvested species and pest species need to know the joint effects of stressors and population density, in order to be able to predict the effects of stressors on carrying capacity and on the course of recovery from environmental perturbations.
Effects of spring drought and irrigation on farmland arthropods in southern Britain
Authors: Frampton Geoff K. , Van Den Brink Paul J. , Gould Philip J. L. 
Published: March 2003

1. Information is lacking on how possible future changes in the seasonal occurrence and intensity of precipitation in Europe will affect the arthropod community of arable farmland.2. We used a novel experimental approach to investigate the responses of farmland arthropods to spring precipitation in a spring‐sown legume. Replicated plots were subjected to spring drought (plots shielded from rainfall), actual rainfall (reference) and spring irrigation. Shielding plots extended an existing drought to 58 days.3. The response of epigeic arthropods was investigated using principal components analysis (PCA) and principal response curves (PRC). Temporal changes in treatment effects at the community level were more clearly displayed by PRC than by PCA, while PRC improved the interpretation of individual species' responses. PRC analysis has potential for wider application in ecological experiments and monitoring.4. Short‐term manipulation of precipitation in May affected the arthropod community for at least 97 days, despite exceptionally high rainfall in June. The effects of drought on the abundance of herbivores, mycophages, omnivores and predators were negative, while those of irrigation were positive. There were no differences in the responses of beneficial and pest taxa.5. In addition to their intrinsic importance, these findings illustrate that spring weather might affect the availability of arthropod prey for insectivorous wildlife. Food availability has been implicated in the population declines of several insectivorous farmland birds.6. The difficulty of manipulating rainfall in a temperate climate precludes realistic field studies of how farmland arthropods respond to precipitation. We suggest that automated rain shielding of experimental plots provides a technique for wider application in drought studies.
Effects of agricultural intensification on the breeding success of corn buntings Miliaria calandra
Authors: Brickle Nick W. , Harper David G.C. , Aebischer Nicholas J. , Cockayne Simon H. 
Published: March 2003

1. Corn buntings Miliaria calandra have declined steeply in Britain and north‐western Europe since the mid‐1970s; changes in farming practice are believed to have been partly responsible. 2. We studied nesting corn buntings on the South Downs in west Sussex between 1995 and 1997 to examine the possible effects of agricultural intensification on breeding success. The abundance of invertebrates around individual nests was sampled by sweep‐netting in July. 3. Corn buntings provisioning nestlings foraged in grassy margins more than any other habitat relative to their availability within the maximum foraging range. The other habitats used more than expected were spring‐sown barley, unintensified grass and set‐aside. Those used less than expected included winter‐sown wheat and intensively managed grassland. The invertebrates most commonly fed to chicks were more abundant in foraging areas than elsewhere. Their density was negatively correlated with the number of insecticide applications both when cereal fields only were considered and when all foraging habitats were included. 4. The lower the abundance of chick‐food invertebrates close to nests, the greater the distance from the nest at which parents foraged, and the longer such trips were in duration. The weights of nestlings, corrected for age using tarsus length, were positively correlated with the abundance of chick‐food invertebrates. 5. The probability of nest survival was negatively correlated with the abundance of chick‐food invertebrates close to the nest, apparently as a result of an increased risk of predation. 6. Agricultural intensification in Britain, including the increased use of pesticides, has led to a widespread decrease in the availability of chick‐food invertebrates on lowland farmland. If our results are typical of corn buntings in an arable environment, this decrease correlates with reduced breeding success. Depending on the mortality rates for fledged chicks and older birds, this reduction may have contributed to the corn buntings' decline and may hamper recovery. 7. Farming practices that increase invertebrate availability ought to benefit breeding corn buntings. Large‐scale measures such as set‐aside and the spring‐sowing of cereals (especially if undersown with grass) depend heavily on overall agricultural policy. Small‐scale initiatives might therefore be more feasible; these include the provision of grassy margins or beetle banks and selective spraying of headlands.
Relationships between livestock management and the ecological condition of riparian habitats along an Australian floodplain river
Authors: Amy Jansen , Robertson Alistar I. 
Published: March 2003

Summary

Grazing by introduced ungulate livestock is a major form of land use over large parts of Australia. Due to the tendency of stock to concentrate around water, riparian zones and wetlands are heavily impacted by grazing. However, little is known about how effects on riparian habitats vary spatially and with management regimes. We investigated how livestock affected riparian habitats on the Murrumbidgee River in south‐eastern Australia.
A rapid appraisal index of the ecological condition of floodplain riparian habitats was developed. This measured habitat continuity and extent, vegetation cover, bank stability, soil structure, quantity of fallen debris, dominance of natives vs. exotics, and the presence of indicative species. The method could be readily adapted for use on other floodplain rivers with extensive riparian habitats.
Riparian condition was scored at 138 sites along 620 km of the Murrumbidgee River on private properties (n = 77), in State Forests (n = 27) and on Crown Land (n = 34). Riparian condition declined significantly with increasing grazing intensity and also with distance upstream in the upper half of the floodplain.
Stocking rate, distance upstream, relative periods of paddock rest and grazing, proportion of bank accessible to stock, and the presence of off‐river water in the paddock, accounted for 76% of the variance in riparian condition.
Most riparian habitats on the Murrumbidgee River and other rivers in the Murray‐Darling Basin are privately owned. Thus exclusion of the grazing industry from the riparian zone is not practical. However, lowered stocking rates, particularly in the upper parts of the catchment, resting of paddocks to allow recovery from grazing, and the provision of off‐river watering points could all be used to improve riparian habitats.
Exotic plants are ubiquitous, occurring even where grazing has been excluded for many years. Thus restoration of riparian habitats will require weed removal even in areas not used by livestock.
Identifying rice fields at risk from damage by the greater flamingo
Authors: Tourenq Christophe , Aulagnier Stéphane , Durieux Laurent , Lek Sovan , Mesléard François , Johnson Alan , Martin Jean‐Louis 
Published: March 2003

Summary

Since the early 1980s, greater flamingos Phoenicopterus ruber roseus have been reported to cause damage to the rice fields of the Camargue, south‐eastern France.
We tested whether some rice fields had landscape features that were more attractive to flamingos than others, using data from the period 1993–97 and from 1978 different paddies. Discriminant function analysis (DFA), logistic regression (LR) and artificial neural networks (ANN) were used to identify the environmental variables best explaining flamingo incursions.
The most accurate models (LR) gave 75% prediction success and used as predictors the surface area of rice fields, the presence of contiguous damaged fields, the presence of wooded margins and the distance to natural marshes.
Our study suggests that it is possible to identify accurately fields at risk from damage in order to concentrate scaring methods. We also suggest that planting hedges should be promoted, and wood cutting discouraged, in high‐risk areas. Following our study a programme of planting of hedges by the Natural Regional Park of the Camargue started at the beginning of 2000.
Our work reveals how presence–absence modelling can have clear applications in managing important species that sometimes cause negative impacts locally.
Refuge habitats modify impact of insecticide disturbance on carabid beetle communities
Authors: Lee Jana C. , Menalled Fabián D. , Landis Douglas A. 
Published: March 2003

SummaryCarabid beetles are polyphagous predators that can act as biological control agents of insect pests and weeds. While current agricultural practices often create a harsh environment, habitat management such as the establishment of within‐field refuges has been proposed to enhance carabid beetle abundance and impact. We examined the joint effects of refuge habitats and insecticide application on carabid activity density (parameter of population density and relative activity) and species composition in a cornfield.Our 2‐year study comprised four treatments: (i) −refuge/−insecticide; (ii) +refuge/−insecticide; (iii) −refuge/+insecticide; (iv) +refuge/+insecticide. Refuge strips consisted of grasses, legumes and perennial flowering plants. ‘−Refuge’ strips were planted with corn and not treated with insecticide.Before planting and insecticide application, carabid activity density in the crop areas was similar across all treatments. Insecticide application immediately reduced carabid activity density and altered community composition in the crop area.Refuge strips had significantly higher activity density of beetles than −refuge strips before planting and during the summer.During summer, as new carabids emerged and insecticide toxicity declined, the presence of refuge strips influenced carabids in the adjacent crop area. Carabid activity density within crop areas previously treated with insecticide was significantly higher when adjacent to refuge strips. Also, carabid communities within insecticide‐treated crop areas were affected by the presence or absence of a refuge strip.The presence of refuge strips did not consistently augment carabid numbers in crop areas where insecticide was not applied. One explanation may be that insecticides decreased the quality of crop habitat to carabids by depletion of prey and direct mortality. However, subsequent rebounds in prey density and the absence of competing predators may make these areas relatively more attractive than unperturbed crop habitats to carabid colonization from refuges.This study demonstrates that refuges may buffer the negative consequences of insecticide application on carabids in adjacent fields. Diversifying agro‐ecosystems with refuge habitats may be a viable strategy for maintaining carabid populations in disturbed agricultural landscapes to keep pests below outbreak levels.