192 research outputs found

    Economic Analysis of Base Acre and Payment Yield Designations Under the 2002 U.S. Farm Act

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    The 2002 Farm Act provided farmland owners the opportunity to update commodity program base acres and payment yields used for calculating selected program benefits. Findings in this report suggest that farmland owners responded to economic incentives in these decisions, selecting those options for designating base acres that resulted in the greatest expected flow of program payments. Decisions of farmland owners in South Dakota, in upland cotton area, and in the Heartland region support the payment-maximization argument. In general, landowners favored maximizing payments over aligning base acres to current or recent plantings. Farmland owners with high-payment base acres, such as rice and cotton, held on to these base acres and, whenever possible, expanded them. Analogously, landowners with low-payment commodity base acres, such as oats and barley, switched to higher payment commodities whenever possible.base, 2002 Farm Act, direct payments, counter-cyclical payments, production flexibility contract payments, base acres, program yields, Agricultural and Food Policy, Farm Management,

    Movement patterns of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) linked to habitat structure and prey availability

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    Patterns of movement and habitat use by adult crown-of-thorns starfishes (Acanthaster spp.) will have a major bearing on their distribution, reproductive capacity, and impacts on coral assemblages and reef ecosystems. The spatial and temporal scales over which crown-ofthorns starfish move will also have important implications for the scales at which they will be most effectively managed. Movement patterns of crown-of-thorns starfish have been studied previously, though mostly over small distances (metres) and limited timeframes (minutes to hours). This study reports on explicit studies that measured the movement rates and movement patterns of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) at a range of temporal and spatial scales. In the first instance, we measured the instantaneous movement rates of starfish (n = 218) across different substrates; sand, coral rubble and consolidated carbonate pavement. This study was conducted in a large (5m diameter) tank, using video recordings that were then analysed to determine the mean and maximum rates of movement over successive 15-second intervals. To assess movement patterns of A. cf. solaris in the field, short-term tagging and movement studies were undertaken at Rib Reef, in the central GBR. All starfish (n = 357) recorded on semi-permanent transects were individually tagged using numbered pieces of flagging tape. The precise position of each starfish (where detected) was then recorded during successive surveys during day and night for up to 4 days. To further scale-up movement studies for crownof-thorns starfish we tagged 50 crown-of-thorns starfish using V7 (69KHZ) acoustic transmitters, at Lodestone Reef or Big Broadhurst Reef. The position of these starfish relative to acoustic receivers deployed 50-200m along the edge of the reef was recorded (at 3-minute intervals) for up to 8 months. Passive acoustic monitoring was intended to provide greater insights into longer-term (weeks to months) and larger-scale (kilometres) patterns of movement for crown-of-thorns starfish, but provided much less resolution regarding fine-scale movements of individual starfish. Instantaneous measures of movement capacity for A. cf. solaris (in aquaria) showed that these starfish are capable of moving at 20-35 cm per minute, and move fastest over sand. Despite their capacity for movement, field-based studies suggested that crown-of-thorns starfish actually move very little at scales of days to weeks, and even months. For starfish that were tagged with temporary visual markers, the minimum displacement distance recorded for the majority of starfish (88.0%) was <2m throughout the course of the study. Moreover, starfish that did move to feed (mostly at night) often returned to the same resting location between feeding bouts. Similarly, starfish tagged with acoustic transmitters for up to 6 months were only ever detected on adjacent receivers with large overlap in their ranges, suggesting that all starfish remained within 50-100m of where they were initially found and tagged for up to 6- months. The frequency and duration of passive detections varied greatly among individual starfish tagged with transmitters, with detections peaking in early hours of the morning. While this study shows that it is possible to effectively tag crown-of-thorns starfish, both over short and longer time-frames, there were considerable logistical challenges to documenting occasional large-scale, and presumably quite rapid, displacement of individual starfish. It is clear that crown-of-thorns starfish generally move very little and remain within localised areas (even returning to the same sheltering location between successive feeding bouts) of moderate to high coral cover. However, Acanthaster spp. are also capable of moving large distances when necessary, presumably when coral prey are locally depleted. It will be important to understand the nature and scale of both modes of movement to effectively manage population irruptions of crown-of-thorns starfish. Documenting the incidence and rates of movement during these infrequent events remains a priority for future research

    Threatened but not conserved: flying-fox roosting and foraging habitat in Australia

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    Conservation relies upon a primary understanding of changes in a species' population size, distribution, and habitat use. Bats represent about one in five mammal species in the world, but understanding for most species is poor. For flying-foxes, specifically the 66 Pteropus species globally, 31 are classified as threatened (Vulnerable, Endangered, Critically Endangered) on the IUCN Red List. Flying-foxes typically aggregate in colonies of thousands to hundreds of thousands of individuals at their roost sites, dispersing at sunset to forage on floral resources (pollen, nectar, and fruit) in nearby environments. However, understanding of flying-fox roosting habitat preferences is poor, hindering conservation efforts in many countries. In this study, we used a database of 654 known roost sites of the four flying-fox species that occur across mainland Australia to determine the land-use categories and vegetation types in which roost sites were found. In addition, we determined the land-use categories and vegetation types found within the surrounding 25 km radius of each roost, representing primary foraging habitat. Surprisingly, for the four species most roosts occurred in urban areas (42-59%, n = 4 species) followed by agricultural areas (21-31%). Critically, for the two nationally listed species, only 5.2% of grey-headed and 13.9% of spectacled flying-fox roosts occurred in habitat within protected areas. Roosts have previously been reported to predominantly occur in rainforest, mangrove, wetland, and dry sclerophyll vegetation types. However, we found that only 20-35% of roosts for each of the four species occurred in these habitats. This study shows that flying-fox roosts overwhelmingly occurred within human-modified landscapes across eastern Australia, and that conservation reserves inadequately protect essential habitat of roosting and foraging flying-foxes

    Body-size dependent foraging strategies in the Christmas Island flying-fox : implications for seed and pollen dispersal within a threatened island ecosystem

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    Background: Animals are important vectors for the dispersal of a wide variety of plant species, and thus play a key role in maintaining the health and biodiversity of natural ecosystems. On oceanic islands, flying-foxes are often the only seed dispersers or pollinators. However, many flying-fox populations are currently in decline, particularly those of insular species, and this has consequences for the ecological services they provide. Knowledge of the drivers and the scale of flying-fox movements is important in determining the ecological roles that flying-foxes play on islands. This information is also useful for understanding the potential long-term consequences for forest dynamics resulting from population declines or extinction, and so can aid in the development of evidence-based ecological management strategies. To these ends, we examined the foraging movements, floral resource use, and social interactions of the Critically Endangered Christmas Island flying-fox (Pteropus natalis). Methods: Utilization distributions, using movement-based kernel estimates (MBKE) were generated to determine nightly foraging movements of GPS-tracked P. natalis (n = 24). Generalized linear models (GLMs), linear mixed-effect models (LMMs), and Generalized linear mixed-effects model (GLMMs) were constructed to explain how intrinsic factors (body mass, skeletal size, and sex) affected the extent of foraging movements. In addition, we identified pollen collected from facial and body swabs of P. natalis (n = 216) to determine foraging resource use. Direct observations (n = 272) of foraging P. natalis enabled us to assess the various behaviors used to defend foraging resources. Results: Larger P. natalis individuals spent more time foraging and less time traveling between foraging patches, traveled shorter nightly distances, and had smaller overall foraging ranges than smaller conspecifics. Additionally, larger individuals visited a lower diversity of floral resources. Conclusions: Our findings suggest that smaller P. natalis individuals are the primary vectors of long-distance dispersal of pollen and digested seeds in this species, providing a vital mechanism for maintaining the flow of plant genetic diversity across Christmas Island. Overall, our study highlights the need for more holistic research approaches that incorporate population demographics when assessing a species’ ecological services

    Molecular species identification, host preference and detection of myxoma virus in the Anopheles maculipennis complex (Diptera: Culicidae) in southern England, UK.

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    BACKGROUND: Determining the host feeding patterns of mosquitoes by identifying the origin of their blood-meals is an important part of understanding the role of vector species in current and future disease transmission cycles. Collecting large numbers of blood-fed mosquitoes from the field is difficult, therefore it is important to maximise the information obtained from each specimen. This study aimed to use mosquito genome sequence to identify the species within Anopheles maculipennis sensu lato (An. maculipennis s.l.), identify the vertebrate hosts of field-caught blood-fed An. maculipennis s.l. , and to test for the presence of myxoma virus (Poxviridae, genus Leporipoxvirus) in specimens found to have fed on the European rabbit (Oryctolagus cuniculus). METHODS: Blood-fed An. maculipennis s.l. were collected from resting sites at Elmley Nature Reserve, Kent, between June and September 2013. Hosts that An. maculipennis s.l. had fed on were determined by a PCR-sequencing approach based on the partial amplification of the mitochondrial cytochrome C oxidase subunit I gene. Mosquitoes were then identified to species by sequencing a region of the internal transcribed spacer-2. DNA extracts from all mosquitoes identified as having fed on rabbits were subsequently screened using PCR for the presence of myxoma virus. RESULTS: A total of 94 blood-fed Anopheles maculipennis s.l. were collected, of which 43 (46%) provided positive blood-meal identification results. Thirty-six of these specimens were identified as Anopheles atroparvus, which had fed on rabbit (n = 33, 92%) and cattle (n = 3, 8%). Seven mosquitoes were identified as Anopheles messeae, which had fed on cattle (n = 6, 86%) and dog (n = 1, 14%). Of the 33 An. atroparvus that contained rabbit blood, nine (27%) were positive for myxoma virus. CONCLUSIONS: Results demonstrate that a single DNA extract from a blood-fed mosquito can be successfully used for molecular identification of members of the An. maculipennis complex, blood-meal identification, and for the targeted detection of a myxoma virus. This study shows that An. atroparvus has a strong feeding preference for both healthy and myxoma-infected rabbits, providing evidence that this species may play a significant role in the transmission of myxomatosis among wild rabbit populations in the United Kingdom (UK)

    Relative efficacy of three approaches to mitigate Crown‑of‑Thorns Starfish outbreaks on Australia’s Great Barrier Reef

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    Population outbreaks of Crown-of-Thorns Starfish (COTS; Acanthaster spp.) are a major contributor to loss of hard coral throughout the Indo-Pacific. On Australia’s Great Barrier Reef (GBR), management interventions have evolved over four COTS outbreaks to include: (1) manual COTS control, (2) Marine Protected Area (MPA) zoning, and, (3) water quality improvement. Here we evaluate the contribution of these three approaches to managing population outbreaks of COTS to minimize coral loss. Strategic manual control at sites reduced COTS numbers, including larger, more fecund and damaging individuals. Sustained reduction in COTS densities and improvements in hard coral cover at a site were achieved through repeated control visits. MPAs influenced initial COTS densities but only marginally influenced final hard coral cover following COTS control. Water quality improvement programs have achieved only marginal reductions in river nutrient loads delivered to the GBR and the study region. This, a subsequent COTS outbreak, and declining coral cover across the region suggest their contributions are negligible. These findings support manual control as the most direct, and only effective, means of reducing COTS densities and improving hard coral cover currently available at a site. We provide recommendations for improving control program effectiveness with application to supporting reef resilience across the Indo-Pacific

    DECOUPLED PAYMENTS IN A CHANGING POLICY SETTING

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    The studies in this report analyze the effects of decoupled payments in the Federal Agriculture Improvement and Reform (FAIR) Act on recipient households, and assess land, labor, risk management, and capital market conditions that can lead to links between decoupled payments and production choices. Each study contributes a different perspective to understanding the response of U.S. farm households and production to decoupled income transfers. Some use new microdata on farm households collected through USDA's Agricultural Resource Management Survey (ARMS), initiated in 1996, and its predecessor survey. These data are used to compare household and producer behavior and outcomes before and after the FAIR Act. Other studies use applied or conceptual models to characterize the impact of introducing decoupled payments. Collectively, the chapters represent an early stage in the empirical analysis of decoupled payments. The studies address many aspects of the payments' household impacts but remaining issues call for additional analysis. As the analytical paradigm changes with the evolution of farm programs, the development of appropriate data and models will improve our understanding of farm program impacts on the behavior and well-being of U.S. farm households, and the agricultural sector.Agricultural and Food Policy,

    Body Size and Substrate Type Modulate Movement by the Western Pacific Crown-Of-Thorns Starfish, Acanthaster solaris

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    The movement capacity of the crown-of-thorns starfishes (Acanthaster spp.) is a primary determinant of both their distribution and impact on coral assemblages. We quantified individual movement rates for the Pacific crown-of-thorns starfish (Acanthaster solaris) ranging in size from 75–480 mm total diameter, across three different substrates (sand, flat consolidated pavement, and coral rubble) on the northern Great Barrier Reef. The mean (±SE) rate of movement for smaller (diameter) A. solaris was 23.99 ± 1.02 cm/ min and 33.41 ± 1.49 cm/ min for individuals \u3e350 mm total diameter. Mean (±SE) rates of movement varied with substrate type, being much higher on sand (36.53 ± 1.31 cm/ min) compared to consolidated pavement (28.04 ± 1.15 cm/ min) and slowest across coral rubble (17.25 ± 0.63 cm/ min). If average rates of movement measured here can be sustained, in combination with strong directionality, displacement distances of adult A. solaris could range from 250–520 m/ day, depending on the prevailing substrate. Sustained movement of A. solaris is, however, likely to be highly constrained by habitat heterogeneity, energetic constraints, resource availability, and diurnal patterns of activity, thereby limiting their capacity to move between reefs or habitats

    Precipitation Augmentation for Crops Experiment: Phase II, Exploratory Research, Year 1

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    NOTE: Appendix referenced on page 7-2 of the main report was not included in the original scan of the report, nor in the print copy in the University Library. The appendix was acquired from Nancy Westcott in 2019, and it is incomplete, lacking "Appendix B - Examples of Products Generated by the Forecasting/Nowcasting System"published or submitted for publicationis peer reviewedOpe

    Close-kin mark-recapture informs critically endangered terrestrial mammal status

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    Reliable information on population size is fundamental to the management of threatened species. For wild species, mark-recapture methods are a cornerstone of abundance estimation. Here, we show the first application of the close-kin mark-recapture (CKMR) method to a terrestrial species of high conservation value; the Christmas Island flying-fox (CIFF). The CIFF is the island's last remaining native terrestrial mammal and was recently listed as critically endangered. CKMR is a powerful tool for estimating the demographic parameters central to CIFF management and circumvents the complications arising from the species’ cryptic nature, mobility, and difficult-to-survey habitat. To this end, we used genetic data from 450 CIFFs captured between 2015 and 2019 to detect kin pairs. We implemented a novel CKMR model that estimates sex-specific abundance, trend, and mortality and accommodates observations from the kin-pair distribution of male reproductive skew and mate persistence. CKMR estimated CIFF total adult female abundance to be approximately 2050 individuals (95% CI (950, 4300)). We showed that on average only 23% of the adult male population contributed to annual reproduction and strong evidence for between-year mate fidelity, an observation not previously quantified for a Pteropus species in the wild. Critically, our population estimates provide the most robust understanding of the status of this critically endangered population, informing immediate and future conservation initiatives
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