Amounts Of Bait Research Articles

Diurnal and nocturnal scavenger communities differ at two shallow-water depths in an Irish marine lough

We report on still/video photographic studies in 2018/9 of diurnal and nocturnal benthic scavenging on carrion in shallow water (2 m and 12 m depths) within Lough Hyne (a biodiverse Irish sea lough) using natural light during replicated 6 h daytime deployments and dim red light (630 nm) during 6 h deployments at night. In 2018 at 2 m depth in the North Basin, bait was present throughout day-time deployments, showing little evidence of scavenging; scavenger species' richness and abundance were low. At night, baits disappeared or were skeletonised; they were scavenged by a significantly more abundant and species-rich scavenger guild. At 12 m depth in the same basin, baits were removed or skeletonised during day and night. This confirmed our hypothesis that scavengers avoid well-lit very shallow water during the day, probably to avoid predation. Multivariate analysis of 2018/19 still photo data (12 m depth) revealed pronounced and statistically significant separate clustering of day, night and basin abundance/species data, although overall species' richness values did not differ significantly. These analyses together reflected differences in species’ compositions associated with contrasting sediments, flow regimes and night/day. Nephrops norvegicus, Pagurus bernhardus and Crangon crangon were only found in the low flow rate North Basin; Homarus gammarus, Trigla sp., Callionymus lyra, Agonus, Tritia reticulata and Marthasterias glacialis were only found in the high flow rate South Basin. Most scavenger species foraged in both day and night (though in different proportions). However, prawns (Palaemon serratus) only appeared at night. Small mobile scavenging fish, small crabs and prawns arrived at baits within seconds to minutes, as did locally-abundant slow movers (e.g. anemones (Anthopleura ballii), whelks (T. reticulata)). These times are shorter than recorded in earlier studies in deeper water. Larger crustaceans (e.g. Cancer pagurus, H. gammarus) took tens of minutes to hours before arrival; similar times have previously been recorded in deeper water. Large crustacean scavengers (C. pagurus, Maja squinado, H. gammarus) took substantial quantities of bait during long feeding bouts, but catsharks (Scyliorhinus canicula) often took similar quantities in a few seconds. All of the dominant scavenger species are broad-spectrum omnivores; only one obligate scavenger species (Tritia reticulata) was present (only in South Basin) and consumed negligible quantities of bait.

Diets of scaup occupying baitfish and sportfish farms in eastern Arkansas

Although not typically associated with eating fish, lesser scaup (Aythya affinis) and greater scaup (Aythya marila) have recently been reported consuming large quantities of bait- and sportfish produced on Arkansas commercial aquaculture facilities. During winters 2016–2017 and 2017–2018, we collected 529 lesser scaup and 19 greater scaup foraging on golden shiner (Notemigonus crysoleucas), fathead minnow (Pimephales promelas), goldfish (Carassius auratus), sunfish (Lepomis spp.), and other sportfish production ponds to investigate the diet composition of scaup. We compared lesser scaup diet between years, among temperature categories (Low, Medium, High), and among pond types using PERMANOVAs to investigate foraging dynamics. Lesser scaup diets differed between winters, and between Low and both Medium and High temperature categories. Only traces of fish were detected in scaup in winter 2016–2017, but fish comprised 18% of birds' overall diet in winter 2017–2018. Chironomidae was the most common prey item in lesser scaup during both winters, occurring in 86% and 68% of diets in winter 2016–2017 and 2017–2018, respectively. Chironomidae comprised 40% of lesser scaup diet by weight in winter 2017–2018, but 71% in winter 2016–2017. Similar to lesser scaup, Chironomidae was the most commonly occurring prey item in greater scaup, which occurred in 88% of the diets, or composed 74% of their overall diet. Fish comprised about 13% of the overall diet of greater scaup. We suspect that scaup increasingly exploited fish in colder winters, perhaps because of the birds' increased energy demands, prey availability, and ease of capture, or some combination of these.

Bait-subsidized diets and their effects on ovigerous North American lobsters (Homarus americanus)

Ovigerous American lobsters (Homarus americanus) display a protracted period of ovary maturation and maternal care when incubating their eggs, potentially influencing offspring fitness. Lobsters consume a wide range of food items; however, trap bait may comprise a larger proportion of their diet in some fished areas compared to non-fished areas, and the long-term consequences of a bait-based diet remain largely unexplored in lobsters. We tested the hypothesis that disproportionate amounts of bait in the diets of pre-ovigerous females affect the quality of their ovaries and eggs. We held pre-ovigerous lobsters (n = 29) over a period of ~ 300 days (range = 270–378) and fed them diets of herring bait, natural prey items (crab, mussel, urchin, macroalgae), or a combination of both diet types. Nutritional status, measured as biweekly blood indices and total glucose levels, suggest differences between lobsters fed a natural or combination diet and lobsters fed a bait-based diet (ANOVA; P < 0.05). We found that bait diets contained more protein (58.5%) and lipids (31.6%) compared to natural diets (34.5 and 13.2%, respectively) and lipid levels in ovaries and eggs significantly correlated with each other for all treatments (r = 0.76, n = 15, P = 0.028). Histopathological analysis indicates that ovaries contained more variable maturation in starved lobsters or those fed with bait, with some animals showing delayed gonad maturation. Results suggest that a varied diet promotes the overall fitness of ovigerous lobsters and the associated reserves that are used for ovarian development and subsequent oocyte formation.

Comparison of mixing methods and associated residual levels of zinc phosphide on cabbage bait for rodent management

Zinc phosphide is a toxicant that is used extensively for rodent management throughout many parts of the world. Some rodent species, such as Belding's ground squirrels (Urocitellus beldingi Merriam, 1888), often avoid zinc phosphide grain baits, leaving green vegetation such as cabbage as the only viable carrier for rodenticides. However, to date, ambiguity has existed as to the most appropriate mixing strategy for zinc phosphide-coated cabbage baits, and it is unknown how rapidly zinc phosphide degrades on these green carriers. Following laboratory and field-enclosure trials, we detected no significant difference in mean zinc phosphide concentrations or variability in zinc phosphide concentrations between mechanical and hand mixing strategies. However, the use of a mechanical mixer was determined to be the more practical option given that it is quicker and requires less effort for mixing large quantities of bait, it minimized worker exposure to phosphine, and because it yielded mean concentrations that were closer to target values. Both the moisture content of cabbage and zinc phosphide concentrations diminished over time, resulting in a fairly minimal window of exposure for non-target wildlife. Field investigation of this exposure risk, as well as an assessment of efficacy of zinc phosphide-coated cabbage baits for Belding's ground squirrel management, are warranted.

Pindone residues in rabbit tissues: implications for secondary hazard and risk to non-target wildlife

Context Pindone is used to control rabbits in Australia and New Zealand, but the secondary non-target risks presented by pindone-poisoned rabbits are poorly known. Aims We aimed to generate new data on residual concentrations of pindone in poisoned rabbits for use in a review of the secondary poisoning risks posed to non-target animals in New Zealand. Methods Laboratory rabbits were offered pellet bait containing 0.25 g kg–1 pindone in three trials to simulate a range of bait uptake scenarios: single exposure and low or high chronic exposure. Residual pindone concentrations measured in body tissues of laboratory rabbits that had ingested known exposures of pindone were compared with those in wild rabbit carcasses collected after three pindone-baiting operations. Residues in the faeces of some laboratory rabbits were also measured. Key results Highest concentrations of pindone residues were in the liver and fat tissue of poisoned rabbits, with consistently lower concentrations in muscle tissue. A dose–response relationship between pindone exposure and liver residue concentrations was found only at the highest chronic exposures. Rabbit carcasses collected after field-baiting operations had generally higher pindone residue concentrations than did laboratory rabbits that had ingested known lethal amounts of bait. Unmetabolised pindone was excreted in rabbit faeces. Conclusions The occurrence of the highest residual pindone concentrations in rabbit liver was consistent with the known tissue distribution of anticoagulants in mammals; however, the co-occurrence of similar-range pindone concentrations in rabbit fat has not been previously described. Re-ingestion of soft faecal pellets (caecotrophy) in rabbits that have eaten pindone bait may function as a secondary exposure to increase or prolong their oral exposure to pindone. Some rabbits poisoned following field pindone-baiting operations are likely to have consumed well in excess of a lethal amount of bait. Implications Concentrations of residual pindone in fat and liver of poisoned rabbits suggest that secondary poisoning hazard to some non-target predators and scavengers is high. The lack of field-based assessments of the non-target impacts of pindone is a marked information gap that needs to be addressed.

Efficacy of Germinated Cereals as Bait Carrier for Zinc Phosphide and Bromadiolone against Field and Commensal Rodent Pests: A Laboratory Evaluation

Both sexes of rodent pests such as Bandicota bengalensis, Millardia meltada, Mus booduga, and Rattus rattus were subjected to toxicity tests (acute rodenticide: 1.5% and 2% zinc phosphide and chronic rodenticide: bromadiolone (0.005%), under no-choice and choice tests) by using their preferred germinated cereals, namely, paddy, pearl millet, and finger millet, as bait base, individually. The results indicated that the poison baits in the germinated cereals induced all the chosen four species of rodent pests to consume greater quantities of bait perhaps due to the bait carrier’s palatability and texture. Besides these, the chosen three germinated cereals proved themselves that they are also capable of acting as suitable bait base for both selected rodenticides in bringing maximum mortality among the tested rodent pests under both no-choice and choice tests. Therefore, these germinated cereals may be recommended as a bait carrier for both zinc phosphide (2%) and bromadiolone (0.005%) poisons for the control of all these four species of rodent pests under field conditions. However, this requires field based trials with rodenticides for making a final recommendation.

A little bait goes a long way: The influence of bait quantity on a temperate fish assemblage sampled using stereo-BRUVs

Baited remote underwater video systems are becoming a widely adopted tool for sampling fish assemblages. One of the outstanding knowledge gaps associated with this technique is the effect of different quantities of bait on the fish assemblages sampled. We investigated how different quantities of bait (0g, 200g, 1000g or 2000g of crushed pilchards, Sardinops sagax) influenced the relative abundance and species richness of a temperate, Western Australian reef fish assemblage sampled with baited remote underwater stereo-video systems (stereo-BRUVs). The presence of bait significantly increased the relative abundance and numbers of fish species sampled, with few differences between the three quantities of bait. Trends in fork length were identified between bait quantities for some species. For example, juvenile stage Coris auricularis (a protogynous labrid) were significantly larger in the unbaited treatment, whereas males of the same species were significantly smaller at unbaited treatments. This pattern was interpreted as being the result of intraspecific competition and the dominance of larger males in the presence of bait. When bait was present, fish were significantly closer to the stereo-BRUVs. However, there was again no difference between the three baited treatments.At this location in temperate Western Australia, stereo-BRUVs with 200g of bait are as effective at sampling the temperate reef fish assemblage as stereo-BRUVs set with greater quantities of bait. In our study, the numbers of high trophic level species recorded were low. In areas with abundant high trophic level fishes, such as tropical reef systems, greater quantities of bait may be required to prevent it being quickly depleted by intense feeding.

Optimising Bait for Pitfall Trapping of Amazonian Dung Beetles (Coleoptera: Scarabaeinae)

The accurate sampling of communities is vital to any investigation of ecological processes and biodiversity. Dung beetles have emerged as a widely used focal taxon in environmental studies and can be sampled quickly and inexpensively using baited pitfalls. Although there is now a wealth of available data on dung beetle communities from around the world, there is a lack of standardisation between sampling protocols for accurately sampling dung beetle communities. In particular, bait choice is often led by the idiosyncrasies of the researcher, logistic problems and the dung sources available, which leads to difficulties for inter-study comparisons. In general, human dung is the preferred choice, however, it is often in short supply, which can severely limit sampling effort. By contrast, pigs may produce up to 20 times the volume. We tested the ability of human and pig dung to attract a primary forest dung beetle assemblage, as well as three mixes of the two baits in different proportions. Analyses focussed on the comparability of sampling with pig or human-pig dung mixes with studies that have sampled using human dung. There were no significant differences between richness and abundance sampled by each bait. The assemblages sampled were remarkably consistent across baits, and ordination analyses showed that the assemblages sampled by mixed dung baits were not significantly different from that captured by pure human dung, with the assemblages sampled by 10% and 90% pig mixes structurally most similar to assemblages sampled by human dung. We suggest that a 10:90 human:pig ratio, or similar, is an ideal compromise between sampling efficiency, inter-study comparability and the availability of large quantities of bait for sampling Amazonian dung beetles. Assessing the comparability of assemblage samples collected using different baits represents an important step to facilitating large-scale meta-analyses of dung beetle assemblages collected using non-standard methodology.

Elimination of Subterranean Termite (Isoptera: Rhinotermitidae) Colonies Using a Refined Cellulose Bait Matrix Containing Noviflumuron When Monitored and Replenished Quarterly

Using a quarterly (3-mo) monitoring and bait-replenishment interval, 122 subterranean termite colonies throughout the United States were baited with a refined cellulose bait matrix containing 0.5% noviflumuron. All colonies were eliminated in less than 1 yr after initiation of baiting as determined by long-term monitoring and genetic markers. Sixty-three percent of the colonies were eliminated during the first quarter after the initiation of baiting and 77% of colonies were eliminated after consuming two bait tubes or less. This suggests that a single baiting cycle and bait installed in response to a single active monitoring device were sufficient to eliminate the majority of colonies. Although termites temporarily abandoned stations after depleting bait, workers resumed feeding when baits were replenished. Colonies that consumed large amounts of bait before elimination foraged into multiple stations, thus allowing adequate amounts of bait to sustain feeding. The time to eliminate termite colonies with bait replenished quarterly was similar to that previously reported for laminated cellulose bait replenished monthly. Our data support the conclusion that extending the bait replenishment interval from monthly to quarterly for bait tubes with refined cellulose containing 0.5% noviflumuron did not adversely impact colony elimination.

Palatability and efficacy of rodent baits for eradicating house mice (Mus musculus) from Gough Island, Tristan da Cunha

Context Introduced house mice (Mus musculus) are a serious predator of seabird chicks at Gough Island, resulting in declining populations of several threatened species. This has prompted the preparation of plans to eradicate mice from Gough and other islands. However, relatively little is known about the palatability and efficacy of rodent baits for house mice, as most studies have focussed on rats (Rattus spp.). Aims The study’s aim was to test the palatability of non-toxic forms of two commercially available rodent pellet bait formulations (Pestoff® 20R and Final®) and a new pellet bait formulated specifically for mouse control (Pestoff® 20M) to house mice on Gough Island. We also tested the efficacy of toxic Pestoff 20R and Final pellets containing 20 and 25 ppm of the anticoagulant toxin brodifacoum. Methods Five trials with 50 mice housed in individual cages and kept at ambient temperature and light cycles, were undertaken during the year. Palatability of bait pellets was measured over five days and compared with a non-toxic control food (standard ‘rodent pellets’ sourced from a pet food supplier). Toxic bait trials were run for 25 days with bait administered at 1, 2 and 10 g for a 24-h period and at 20 g per day for 72 h. Key results All three baits were highly palatable; however, mice showed the greatest preference for Pestoff 20M and 20R, consuming a larger mass of bait. Estimated oral LD50 values of brodifacoum for Gough mice were 0.44 mg kg–1 and the average time to death following exposure was 5.5 days (range 0–16 days). Two mice (~1% of those tested) survived after apparently ingesting doses of brodifacoum estimated to be 5 and 10 times the oral LD50 values, potentially indicating a lower susceptibility to brodifacoum in some individuals, although subsequent exposure at higher doses resulted in mortality. Conclusions The results of this study confirmed that house mice on Gough Island find bait pellets highly palatable and that brodifacoum is an effective toxin with LD50 values and time to death within the same range (0.4 to 0.52 mg kg–1 and 5.2 days) as other studies, indicating no major difference in the susceptibility of Gough mice to this poison. Implications We recommend that bait manufacturers produce formulations designed to be attractive to mice and consider the use of higher concentrations of brodifacoum to increase the likelihood of all mice obtaining a toxic dose when small quantities of bait are consumed, although higher toxin concentrations must be balanced against the increased risks to non-target species. Eradication operations targeting mice should undertake more than one bait drop to ensure any individuals surviving the initial drop have access to sufficient toxic bait to cause mortality upon second or subsequent exposure.

Relative quantity judgment by Asian elephants (Elephas maximus)

This study investigated whether Asian elephants can make relative quantity judgment (RQJ), a dichotomous judgment of unequal quantities ordered in magnitude. In Experiment 1, elephants were simultaneously shown two baskets with differing quantities of bait (up to 6 items). In Experiment 2, elephants were sequentially presented with baits, which could not be seen by elephants in their total quantities. The task of elephants was to choose the larger quantity in both experiments. Results showed that the elephants chose the larger quantity with significantly greater frequency. Interestingly, the elephants did not exhibit disparity or magnitude effects, in which performance declines with a smaller difference between quantities in a two-choice task, or the total quantity increases, respectively. These findings appear to be inconsistent with the previous reports of RQJ in other animals, suggesting that elephants may be using a different mechanism to compare and represent quantities than previously suggested for other species.

A New Sampling Protocol for the Endangered American Burying Beetle, Nicrophorus americanus Olivier (Coleoptera: Silphidae)

The endangered American burying beetle, Nicrophorus americanus Olivier, presently occurs in small and widely scattered areas on the periphery of its former range. As part of the recovery plan for this insect implemented by the U.S. Fish and Wildlife Service (USFWS), we conducted surveys in Nebraska to ascertain its presence. Additionally, we examined various trapping methods and procedures in the course of our survey work. We compared the effectiveness of different trap designs, trap placement, timing of trapping, types and amounts of bait, and monitoring traps. We also developed methods to reduce beetle mortality in traps. Our work offers more effective sampling procedures for N. americanus and suggests the current USFWS sampling protocol should be modified. New procedures include larger traps, moist soil substrate, a soil berm to the edge of the trap, longer trapping season, and increased distances between traps. A moist soil substrate, in combination with a shade-giving rain cover, precludes the necessity of servicing all traps by 9 AM each day (as mandated in the current protocol), a task that is logistically difficult or impossible if there are many traps. The sampling procedures we have identified as most appropriate for N. americanus will also improve sampling for other silphid species.

Seasonal Patterns in Bait Consumption by Feral Pigs (Sus Scrofa) in the Hill Country of South-Eastern Australia.

Both fermenting wheat and bran/pollard pellets were readily accepted as bait throughout the year by feral pigs (Sus scrofa) in Namadgi National Park, Australian Capital Territory. Birds mainly ate wheat bait, particularly during winter. Other animals occasionally fed on both types of bait, mainly during autumn and winter. Covering baits with forest-floor litter did not significantly affect their discovery and consumption by pigs or by other animals. The proximity of the pigs to the bait line and their appetite for bait appeared to be the main factors responsible for seasonal differences in bait consumption. Trail-baiting campaigns against pigs in similar hill country areas are likely to be more effective during late autumn than other seasons because more pigs are likely to be close to the trails then and more quickly find and eat greater quantities of bait.

Bait Consumption by the European Rabbit in Southern England

The consumption of nontoxic, sliced carrot baits by 10 free-living European rabbit (Oryctolagus cuniculus) populations was investigated using Rhodamine B dye and fluorescent acetate floss fibers as bait markers. Total bait consumption was highest after 5-8 days of exposure. Increases in consumption between the 3rd and 8th days resulted from bait consumption by greater numbers of rabbits rather than increases in the amounts eaten by individuals. The data suggest that the more widely ranging individuals began consuming bait earlier than others. The average daily bait consumption/individual after 8 days of exposure varied between 216 and 346 g/kg body weight. The proportion of individuals eating bait was inversely related to the distance of their burrows from bait. There were no significant differences (P > 0.05) between sexes or among age classes in the proportions of animals consuming bait. Males ate significantly more (P < 0.001) bait than females. Adults ate significantly less (P < 0.05) bait than animals <9 months of age. It is concluded that sliced carrot bait could be used effectively as a vehicle for toxicants to control rabbit populations in Britain, provided that its presence does not substantially reduce bait consumption. A toxicant concentration considerably lower than that employed in Australia and New Zealand could be used because of the large amounts eaten by individual rabbits, thereby substantially reducing the risk to nontarget wildlife. J. WILDL. MANAGE. 51(2):386-392 The European rabbit is a major pest of agriculture in Great Britain. This problem is likely to increase as the effects of myxomatosis on rabbit numbers wane and improved methods of rabbit management become necessary (Ross and Sanders 1984). Toxicants have been successfully used to control rabbits in both Australia and New Zealand (Oliver et al. 1982 a,b). However, distributing toxic baits for rabbits is currently illegal in Britain. The study reported here forms part of an investigation into a baiting method that would be acceptable in Britain if a suitable toxicant (humane, low risk to nontarget species, and efficaceous) was available. The rabbit is a grazing animal and consumes large quantities of food relative to its body size. This suggests that low concentrations of toxin could be used effectively (if its presence does not constrain bait acceptance), hence reducing the risk to many nontarget species that would be unable to consume sufficient bait to receive a lethal dose. In these circumstances an effective baiting technique must involve consumption of large amounts of bait by a high proportion of a given rabbit population. Changes in these parameters with increasing length of exposure to nontoxic, sliced carrot bait, equivalent to a period of prebaiting prior to the use of toxin, have been investigated using 2 bait markers, Rhodamine B dye and fluorescent acetate floss fibers (Cowan et al. 1984). In addition, variations in patterns of bait consumption have been considered in relation to age, sex, and the distance of rabbit warrens (interconnected burrow systems with multiple entrances) from bait points. We thank landowners, C. A. Swan, T. Steele, L. M. Lelliott, G. Lambourne; and other Minist. Agric., Fish., and Food staff for access to the study sites and assistance in the field and laboratory; J. Bell for valuable discussion on the use of bait markers; A. Hart for statistical advice; and W. A. Rees and J. Ross for constructive criticism of earlier drafts of this paper.

Varying Amounts of Bait Influences Numbers of Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae) Caught in Cucurbitacin Traps

Traps utilizing powdered squash that contains cucurbitacins have shown promise as a reliable method of monitoring adult corn rootworm populations. This study describes the influence of varying amounts (0.05, 0.5, 5.0, and 50.0 mg/trap) of squash bait, either with or without cucurbitacins, on the catch of western corn rootworm, Diabrotica virgifera virgifera LeConte, and northern corn rootworm, D. barberi Smith and Lawrence, adults. Total number of beetles captured increased with increasing amounts of bait both without and with cucurbitacins, but the increase was greater with the latter bait. Additionally, as the amount of bait was increased, the male–female ratio increased, especially for the western species in the cucurbitacin treatments.

Field trials of a new sub-acute rodenticide flupropadine, against wild Norway rats (Rattus norvegicus).

Fifteen experimental treatments with rodenticidal baits containing 0.1, 0.15 or 0.2% flupropadine were conducted on farmsteads against Rattus norvegicus infestations. Eight treatments were completely successful and the others gave kills ranging from 36 to 72% in 28 days. Treatments with 0.1 and 0.15% flupropadine were less successful against large infestations than against small ones. Flupropadine was most successful at 0.2% but still gave incomplete kills on farms where abundant alternative food was available. The compound was more effective than acute poisons in achieving complete control of Norway rat infestations, but was less reliable in doing so than anticoagulants. On the other hand, many flupropadine treatments gave quicker control and used smaller quantities of bait than anticoagulant treatments.

The utilisation of poison hoppers designed for grey squirrel ( Sciurus carolinensis Gmelin) control

The grey squirrel is recognised as a pest species of economic importance but the justification of the view appears to be founded on local areas of severe damage. Despite evidence that damage may not be alleviated by squirrel population destruction, Warfarin poisoning was introduced as an alternative to trapping. The utilisation by wildlife of a poison hopper designed for grey squirrel control was investigated by automatic photography. Results confirmed that a number of species may feed from the grain presented via the hopper. However, the majority of the bait was removed during the hours of darkness when grey squirrels were not active. It is a conservative estimate that between 55 and 65% of the grain entered the environment via animals other than squirrels. In addition, the removalof bait by night visitors resulted in the accumulation of large quantities of bait at and around the entrance to the hopper tunnel. This increased accessibility to the potentially poisoned bait by animals other than squirrels. Until such time as evidence is produced to show these results as exceptional, it can only be concluded that fears expressed over the lack of specificity of this method of control are justified.