Bird Attack Research Articles

Opposite latitudinal patterns for bird and arthropod predation revealed in experiments with differently colored artificial prey.

The strength of biotic interactions is generally thought to increase toward the equator, but support for this hypothesis is contradictory. We explored whether predator attacks on artificial prey of eight different colors vary among climates and whether this variation affects the detection of latitudinal patterns in predation. Bird attack rates negatively correlated with model luminance in cold and temperate environments, but not in tropical environments. Bird predation on black and on white (extremes in luminance) models demonstrated different latitudinal patterns, presumably due to differences in prey conspicuousness between habitats with different light regimes. When attacks on models of all colors were combined, arthropod predation decreased, whereas bird predation increased with increasing latitude. We conclude that selection for prey coloration may vary geographically and according to predator identity, and that the importance of different predators may show contrasting patterns, thus weakening the overall latitudinal trend in top‐down control of herbivorous insects.

Influence of Pre-Harvest Bagging on Fruit Quality of Mango (Mangifera indica L.) cv. Langra

Fruits are susceptible to insect pest infestations, bird attack, various pathogens, and mechanical damages, all of which can reduce their commercial value and thereby cause significant yield and economic losses. The objective of this study was to control mango pests and diseases as well as to improve the fruit quality of mango through bagging technology. An investigation was performed during the year 2016 from March to July for safe mango production by applying minimum use of pesticide entitled studies on influence of bagging on physico-chemical properties and shelf life of mango cv. Langra. The mango fruits were bagged at marble stage (40 days from fruit set) with different types of bags which constituted the various treatments viz: T1: Brown paper bag; T2: White paper bag; T3: Polythene bag T4: Muslin cloth bag; T5: No bagging (control). Bagging with brown paper bag and white paper bag improved fruit retention, weight of fruit, diameter of fruit, pulp weight, total soluble solids, ascorbic acid, percent of citric acid, reducing sugars and β-carotene at harvest and ripe stage over control. Brown paper bag changed fruit color. In all cases good quality, cleaner, disease and insect free fruits were harvested. The sensory qualities in fruits of brown, white and muslin cloth bags were improved over control. Pre-harvest bagging also reduced occurrence of spongy tissue and the incidence of mealy bugs. These results indicate that fruit bagging can improve fruit quality through reduction in disease and insect-pest attack and shelf life of mango cv. Langra.

Solar Powered Soil Condition Activated Irrigation System with Automated Bird Repellant

Irrigation plays a very important role in agriculture. Not all geographical regions utilize irrigation which is an important activity that is expensive. For the regions where irrigation is used, it commonly amounts to significant energy consumption. Traditional methods of farming are time-consuming and can only be efficient on a small scale. This project was implemented to make irrigation progressively inventive, easy to use, more efficient and cheaper than the current irrigation system and to solve traditional farming problems like an attack on crops by bird thereby increasing agricultural productivity. This system incorporates a soil moisture sensor to guarantee the application of water to soil adequately. It uses a PIR sensor and a buzzer to solve the problem of attack on crops by birds. This project is powered by a solar panel which is one of the cheapest form of renewable energy and environmentally friendly. The main objective of this project is to upturn the agricultural productivity of the nation by automating the irrigation process. Bird attacks on farmlands are also responsible for destroying a vast amount of crops. One of the traditional problems of agriculture is that farmers frequently neglect to water their plants; it can be as a result of inattentiveness or because of the fact that the farmers are far from home. The utilization of the soil moisture sensor limits the human presence. The microcontroller utilizes the real-time readings of the sensors and automates the irrigation and bird repellent process. From the results, it was observed that the irrigation time was higher in totally dry clay compared to partially wet clay and wet clay respectively. For clay, the irrigation time is in order of magnitude dry clay > partial wet clay > wet clay of the irrigation other soil samples. For the loamy soil, the dry soil was higher. It follows the same trend as the clay in magnitude. It can be found in sandy soil that the wet sample was higher than the totally dry and partially wet sandy soil in terms irrigation time

Effects of habitat, leaf damage and leaf rolling on the predation risk of caterpillars in the tropical rain forest of Borneo

AbstractAddressing what affects predation among caterpillars, we conducted an experiment in a Bornean rain forest on 212 clay models of Tortricidae caterpillars (the herbivore) and 53 trees of Kopsia pauciflora (the host), located either in the open or under closed canopies. We predicted that the frequency of predatory attacks towards caterpillars increases (1) in canopy gaps and (2) on leaves damaged by herbivory, but (3) decreases among caterpillars that wrap their body in leaves. Each plant with caterpillar models was consecutively allocated to one of four treatments: caterpillars artificially rolled in leaves vs caterpillars on unrolled leaves, and caterpillars on artificially damaged vs undamaged leaves. Each time, caterpillar models were placed on the plants for 48 h, and then replaced with new models that were subjected to a new treatment. On average, our caterpillar models had a 21% chance of being attacked per 24 h. More attacks were performed by insects (81.6%) than birds. The attack frequency did not depend on the canopy cover or on leaf damage, but decreased among models rolled in leaves. This pattern was mainly attributable to insect attacks, which were also more frequent than bird attacks. Overall, the Tortricidae caterpillars seem to suffer comparable predation rates in the open and under closed canopies irrespective of the herbivory damage of leaves, but their leaf-rolling behaviour might reduce predation.

Factors Affecting Hot Pepper Production: The Case of Gursum District, Oromia Regional State, Ethiopia

Hot pepper is one of the vegetable crops which serves as spices, vegetables, cash crop and ensures food security as a result of its income generating crop. But this crop is devastating by different factors which reduce its production and quality. Therefore, this study intended to undertake factors affecting hot pepper production in Gursum district with the objectives of identifying factors affecting hot pepper production, and analyze linkages of its production with the household’s expenditures. The study used 150 households as sample respondents and collected primary data from them and secondary data from secondary sources, then analyzed data by mean, percentage and frequency. As a result, the finding shows that the factor affect the production of hot pepper are low price, second disease, lack of improved seed, lack of pesticide, knowledge management, lack of market access, lack of land and others like bird attack respectively. Moreover, the finding linked hot pepper production with household expenditures and found household expenses their income from hot pepper on purchasing grain, school fees, clothing, health care, festivities and others like dowry respectively. Therefore, the government and other stakeholder should focus on negotiating the market price of hot pepper and other factors hindering hot pepper production. Keywords : Hot pepper, Gursum, cash crop DOI : 10.7176/FSQM/87-04 Publication date :May 31 st 2019

Phytotoxicity of Cypermethrin Pesticide on Seed Germination, Growth and Yield Parameters of Cowpea (Vigna unguiculata)

The experiment was carried out at Federal College of Forestry Jos, in Jos North Local Government Area of Plateau State to determine the phytotoxicity of cypermethrin pesticide on seed germination, growth and yield parameters of cowpea. Cypermethrin is popularly used by farmers as a means of treating seeds before planting to prevent insect, pest and birds attack. Randomized Complete Block Design (RCBD) involving 5 treatments T0 as control (No cypermethrin used), T1 with 0.25% cypermethrin (0.25ml of cypermethrin in 99.75ml of water), T2 with 0.50% cypermethrin (0.50ml of cypermethrin in 99.50ml of water), T3 with 0.75% cypermethrin (0.75ml of cypermethrin in 99.25ml of water) and T4 contained 1.00% cypermethrin (1.0ml of cypermethrin in 99.00ml water). Data was collected on radicle length, plumule length, number of leaves, number of branches, stem girth, number of seeds/pod, 100 seed weight, pod length and dry matter. Data collected was subjected to analysis of variance (ANOVA) at 5% level of significance using SPSS 23 and where significance was declared, Duncan Multiple Range Test (DMRT) was used to separate the means. The result of the research indicates that significance difference occurs in the radicle length (P<0.05) in which T1 has the highest mean value. The stem girth shows a significance difference with T0 having the highest mean value (7.32) at P<0.05. The result for the number of branches and the number of leaves shows significance difference with T0 having the highest mean values 39.15 and 101.65 respectively at P<0.05 level of significance. The yield parameters shows a significance difference for number of seeds/pod, 100 seed weight, pod length, as well as the total dry matter. The highest mean values for the yield parameters are observed in T0 with mean values 18.52, 18.53, 16.35 and 68.35 for number of seeds/pod, 100 seed weight, pod length and total dry mass respectively. Alpha amylase enzyme activity was observed to be higher at lower concentration of the cypermethrin (T1) on day 2 (2.75) but the increase in the enzyme activity tilted towards the highest concentration (T4) on day 3 and day 4 with mean value 2.70 and 3.10 at 5% level of significance.

Yield loss in sunflower cultivars due to bird attack

Bird attacks on the sunflower may hinder its exploitation in the Brazilian semi-arid region. The aim of this study was to evaluate the effects of different levels of protection (0, 33, 66 and 100%) of the capitula of eight sunflower cultivars, evaluated in randomized blocks with sub-divided plots and four replications. The cultivars were allocated in the plots and the levels of protection in the sub-plots, by covering the capitula with caps of non-woven fabric after physiological maturity. The most frequent bird species was the Paroaria dominicana. The Aguara 06 cultivar was the most productive and most tolerant to bird attack, followed by the Helio 250, CF 101 and Charrua cultivars. There was a positive correlation between yield loss (YL) due to birds and the flowering period, YL and the period for physiological maturity, YL and capitulum diameter, YL and stem diameter, YL and plant height, YL and the angle of the capitulum with the stem, and between YL and the distance of the capitulum from the ground. A negative correlation and the absence of correlation were seen between YL and the number of leaves, and between YL and distance of the capitulum to the stem respectively. The effects of protecting the capitula were similar for grain yield in the cultivars under test. Use of the caps was efficient, since an increase in the proportion of protected capitula determined an increase in grain yield, number of grains per capitulum and 1000-grain weight. These increases continued up to a certain proportion, after which there was a decrease in the three characteristics.

Assessment of farmers’ perceptions of production constraints, and their trait preferences of sorghum in western Ethiopia: implications for anthracnose resistance breeding

ABSTRACTSorghum, Sorghum bicolor (L.) Moench is an important food security crop widely grown by smallholder farmers in sub-Saharan Africa (SSA), including Ethiopia. In SSA, the potential of sorghum production and productivity has not been realised due to an array of constraints. Colletotrichum sublineolum disease is one of the main biotic constraints causing significant yield losses. The objectives of this study were to assess farmers’ perception, preferences and constraints to sorghum production and productivity in western Ethiopia, and to identify key drivers for anthracnose resistance breeding. A participatory rural appraisal study was undertaken in six selected districts in the East Wellega and West Shewa Administrative Zones in Ethiopia. Data were collected through structured questionnaires involving 165 respondent farmers. Further focus group discussions were held with 180 farmers and development agents. Sorghum is the third most preferred cereal crop after Eragrostis tef and Zea mays in western Ethiopia. About 79% of interviewed farmers cultivated sorghum during the study season. Farmers perceived that sorghum production is constrained by anthracnose disease, bird attack, loose smut and covered smut diseases. The most important farmer-preferred traits in sorghum varieties in the study areas were anthracnose resistance and tolerance to bird attack. Breeding sorghum varieties with the farmer-preferred traits is an important consideration to enhance productivity and adoption of improved sorghum cultivars in western Ethiopia.

English

Classification of sorghum [Sorghum bicolor (L) Moench] breeding material based on multiple crucial characters is important towards the possible formation of homogeneous groups of genotypes and groups that can be exploited in the identification of parents for use in a breeding program. The objective was to determine the morphological characters that distinguish desirable breeding material and group the genotypes of sorghum according to similarity. Principal component analysis (PCA) and cluster analysis were used to establish the relationships among germplasm and the Shannon Diversity index was used to quantify the level of diversity. The experiment involving 26 sorghum genotypes was conducted at Sussundenga Research Station across two seasons and laid out in a 13 × 2 alpha lattice design with four replications. Cluster analysis grouped genotypes into four clusters based on 15 evaluated traits. Five principal components cumulatively accounting for 58.5% of the total variation were estimated from the PCA analysis. The results showed that genotypes 150B, IS 14257R, LARSVYT 46B, TX 631B, TX 630B and 8601B were the early maturity while for late maturity genotypes were MA 6B, A 6352R, ICSA 19B and MZ 30R. The genotypes IS 7179R, SPL 9B, A 6353R, SPL 38B, SDS 6013R and MZ 2R showed a potential for grain yield improvement. Other genotypes presented potential for drought tolerance and birds attack. The multivariate analyses clearly showed the grouping of the genotypes according to the characters outlined in the study. These results have implications in selecting parents for use in sorghum breeding program. Key words: Cluster analysis, diversity index, principal component analysis and sorghum improvement.

Predation by avian insectivores on caterpillars is linked to leaf damage on oak (Quercus robur)

Birds that are foraging in tree canopies can cause a substantial decrease in arthropod numbers. Trees may benefit from avian insectivores attacking insect herbivores. In a field study, we tested whether the intensity of bird predation on caterpillars is linked quantitatively to leaf damage caused by insect herbivores, a hypothesized relationship that previously was poorly investigated. Artificial caterpillars were placed in the lower part of oak trees (Quercus robur) in urban and suburban sites across the city of Gothenburg, Sweden. Two days later, we recorded the survival: the pooled predation rate was 11.5% (5.7% day−1). Mean predation rate per tree was 10.4%. Mean leaf damage, i.e. leaf area eaten by insect herbivores, per tree was 5.7% but there was large variation between trees. We found a significant negative relationship between survival probability of caterpillars and leaf damage in an analysis using a mixed model logistic regression. This suggests that caterpillars are at high risk of bird attacks in trees with a high degree of leaf damage and avian insectivores may increase the foraging effort in the foliage of such oak trees. Our findings concerning the quantitative relationship between the predator–prey interactions and plant damage suggested tentatively that the survival probability of caterpillars decreases rapidly at 15–20% leaf damage in lower part of oak canopies. Furthermore, our findings add credence to the idea of using artificial caterpillars as a means to obtain standardized comparisons of predation rates in various habitats.

Parasite-infected sticklebacks increase the risk-taking behaviour of uninfected group members

Trophically transmitted parasites frequently increase their hosts' risk-taking behaviour, to facilitate transmission to the next host. Whether such elevated risk-taking can spill over to uninfected group members is, however, unknown. To investigate this, we confronted groups of 6 three-spined sticklebacks, Gasterosteus aculeatus, containing 0, 2, 4 or 6 experimentally infected individuals with a simulated bird attack and studied their risk-taking behaviour. As a parasite, we used the tapeworm Schistocephalus solidus, which increases the risk-taking of infected sticklebacks, to facilitate transmission to its final host, most often piscivorous birds. Before the attack, infected and uninfected individuals did not differ in their risk-taking. However, after the attack, individuals in groups with only infected members showed lower escape responses and higher risk-taking than individuals from groups with only uninfected members. Importantly, uninfected individuals adjusted their risk-taking behaviour to the number of infected group members, taking more risk with an increasing number of infected group members. Infected individuals, however, did not adjust their risk-taking to the number of uninfected group members. Our results show that behavioural manipulation by parasites does not only affect the infected host, but also uninfected group members, shedding new light on the social dynamics involved in host–parasite interactions.

BIRD ATTACK OCULAR INJURIES.

To report 30 patients with bird attack-related eye injuries. This study was performed among patients coming to Farabi Eye Hospital, Tehran, Iran, from 2010 to 2015 with a history of bird attack causing eye injury. The inclusion criteria were a history of bird attack by pecking causing eye injury and having treatment and follow-up record for at least 6 months after treatment. The primary eye examinations included a full ophthalmic examination including evaluation of uncorrected visual acuity and best-corrected visual acuity (BCVA), anterior segment slit lamp biomicroscopy, and photography. For all patients with penetrating injury, primary repair was undertaken. Thirty patients (10 females and 20 males) with a mean age of 23.3 ± 18.5 years entered the study. The most common zone of injury was zone 1 (P < 0.001), and lensectomy was not needed in majority of patients (P < 0.001). The most common bird causing the injury was mynah (P < 0.001). Those patients with baseline BCVA of less than 20/200 or those with endophthalmitis had statistically worse final BCVA after treatment. Patients attacked by mynah bird had significantly better pretreatment uncorrected visual acuity and BCVA. The most common bird causing the eye injury among the sample of patients from Iran was mynah, which differs with previous studies indicating the rooster attack as the most common cause of eye injury. The authors also found that the most common zone of injury was zone 1, and the presence of endophthalmitis and lower baseline BCVA were significant risk factors for worse visual outcomes.

English

Twenty locally generated hybrids of Sun flower (Helianthus annuus L.) hybrids were evaluated in two seasons (2012 and 2013) for yield and yield components at Khordunia area, Blue Nile State under rain fed conditions. A randomized complete block design with six replications was used for laying out the field experiments. The seeds were sown in the second and third week of July in the first and second seasons, respectively in plots 6 × 3 m2. Each plot was divided into four ridges 70 cm apart and 6-m long. Three seeds were sown in holes of 20 cm distance along the ridge then thinned into one plant per hole three weeks after sowing. Weeding was practiced three times to control weeds. Rains were recorded during autumn at Khourdunia area. Fertilizers were not applied. The heads of the sample were bagged during the seed filling period using paper bags to avoid birds attack. Data were collected on the following characters: Days to 50% flowering, days to maturity, plant height, stem diameter, head diameter (cm), number of seeds/head, percentage of empty seed, 1000-seed weight (g), seed yield/plant (g) and seed yield (t/ha). Phenotypic, genotypic, and environmental variances were determined. The results in season 2012 revealed highly significant differences among the undertaken hybrids for plant height, stem diameter, head diameter, empty seed %, 1000-seed weight, seed yield/pant and seed yield (t/ha), whereas only two characters were significant in 2013. These were empty seed% and 1000-seed weight. Key words: Sunflower, seed yield, genetic variability, genetic advance, heritability.

Predation pressure by birds and arthropods on herbivorous insects affected by tropical forest restoration strategy

Recovery of animal‐dependent ecosystem functions is a key component of ecological restoration on degraded tropical forest lands. One of these functions, regulation of herbivorous insects by predators, shapes tropical communities through cascading trophic effects. An improved understanding of how predation pressure on herbivorous insects varies with reforestation strategy, management decisions, and landscape context would guide restoration practice. We measured predation pressure by birds and arthropods on dummy caterpillars in five forest types in Panama. These land covers represent natural and managed forest conditions: non‐native monoculture plantation, native multispecies plantation, young natural forest succession, secondary gallery forest, and old‐growth forest. We also placed dummy caterpillars in residential countryside, a heavily disturbed nonforest land cover. In three land covers, we surveyed bird communities to examine the relationship between predator abundance and predation pressure. Predation pressure from birds was lowest in the intensively managed plantations and highest in land covers with structurally complex vegetation: successional forest, gallery forest, and residential countryside. In the non‐native plantation, bird predation increased with proximity to gallery forest. We found strong correspondence between bird abundance and bird attacks on dummy caterpillars. Arthropod predation pressure was highest in the native plantation but, unlike bird predation pressure, did not vary strongly by land cover. Our results suggest that ecosystem functions by insectivorous birds can be enhanced on reforestation lands by incorporating unmanaged areas and tolerating nonplanted understory vegetation. We recommend that, regardless of management objectives, forest managers adopt a holistic approach to reforestation to facilitate recovery of animal‐dependent ecosystem functions.

Escape distance and escape latency following simulated rapid bird attacks in an Andean lizard, Phymaturus williamsi

AbstractPredatory birds represent the greatest risk for many lizard species. However, little is known about the functional relationship between the escape distance and escape latency of lizards during a rapid bird attack. We hypothesised that escape latency and distance in the Andean lizard speciesPhymaturus williamsiwould increase proportionally, but vary according to the means of escape. Over a three-year period we observed seven types of antipredatory behaviour in 98%P. williamsilizards on simulated predatory bird attacks. Escape distance and latency were positively correlated. 65% of lizards emerged from their refuge within 2 min of an attack. All of these behaviours were positively correlated with escape latency and distance, although we found the former to be more precise. This study contributes to a better understanding of the general antipredatory behaviour in this species of Andean lizard, and will assist in future decisions concerning its conservation.

PERTUMBUHAN PADI HITAM VARIETAS WOJALAKA YANG DIBUDIDAYAKAN DENGAN SISTEM TANAM BANJAR

This research is aimed to study growth adaptation of Wojalaka black rice variety which is cultivated with The Banjarese system cultivation and its problem during planting period. A descriptive exploratory research was conducted in rainfed rice field in Binuang Village, Binuang District, Tapin Regency, South Kalimantan Province on November 2016 to May 2017. Land preparation was done with Tepulikampar technology and the seedbed was done in two stages, i.e. dry seedbed and continued with wet nursery. Observations were made on plant height, plant age, number of productive tillers, panicle length, number of seeds per panicle, weight per panicle, weight of 1000 seeds, total weight and problems during plant growth including pests, diseases and environmental conditions. The results showed that Wojalaka black rice variety were 125 cm high and the plant age was 176 days or longer than the normal age of 127 days. Number of productive tillers is relatively small as many as 12 tillers. The yield potential is almost equal to the potential yield in the area of origin. The Banjarese planting system is less suitable to be applied to the Wojalaka black rice variety because it causes the longer period of harvest and the decrease of the harvest. The attacks of rice ear bugs and birds and diseases caused by fungus Ustilaginoidea virens also cause the decline of crop yields. Keywords: Black rice, Growth, Wojalaka, Banjarese system cultivation

Fishery-specific solutions to seabird bycatch in the U.S. West Coast sablefish fishery

Abstract Bird scaring lines (BSLs) protect longline fishing gear from seabird attacks, save bait, reduce incidental seabird mortality and are the most commonly prescribed seabird bycatch mitigation measure worldwide. We collaborated with fishermen to assess the efficacy of applying BSL regulations from the demersal longline sablefish fishery in Alaska to a similar fishery along the U.S West Coast. In contrast to Alaska, some U.S. West Coast vessels use floats along the line to keep hooks off the seafloor, where scavengers degrade the bait and the target catch. Our results confirmed that BSL regulations from Alaska were sufficient to protect baits from bird attacks on longlines without floats, but not baits on longlines with floats. Longlines with floats sank below the reach of albatrosses (2 m depth) at a distance astern (157.7 m ± 44.8 95% CI) that was 2.3 times farther than longlines without floats (68.8 m ± 37.8 95% CI). The floated longline distance was well beyond the protection afforded by BSLs, which is approximately 40 m of aerial extent. Black-footed albatross attacked floated longlines at rates ten times more (2.7 attacks/1000 hooks, 0.48–4.45 95%CI) than longlines without floats (0.20 attacks/1000 hooks, 0.01–0.36 95% CI). Retrospective analysis of NOAA Fisheries Groundfish Observer Program data suggested that seabird bycatch occurs in a few sablefish longline fishing sectors and a minority of vessels, but is not confined to larger vessels. Analysis also confirmed fishermen testimonials that night setting reduced albatross bycatch by an order of magnitude compared to daytime setting, without reducing target catch. Night setting could be an effective albatross bycatch prevention practice if applied to the U.S. West Coast sablefish longline fishery and provide a practical alternative for vessels that elect to use floated longlines. These results highlight the importance of understanding region-specific longline gear modifications to identify effective bycatch reduction tools and the value of working collaboratively with fishermen to craft solutions.

Decreased losses of woody plant foliage to insects in large urban areas are explained by bird predation.

Despite the increasing rate of urbanization, the consequences of this process on biotic interactions remain insufficiently studied. Our aims were to identify the general pattern of urbanization impact on background insect herbivory, to explore variations in this impact related to characteristics of both urban areas and insect-plant systems, and to uncover the factors governing urbanization impacts on insect herbivory. We compared the foliar damage inflicted on the most common trees by defoliating, leafmining and gall-forming insects in rural and urban habitats associated with 16 European cities. In two of these cities, we explored quality of birch foliage for herbivorous insects, mortality of leafmining insects due to predators and parasitoids and bird predation on artificial plasticine larvae. On average, the foliage losses to insects were 16.5% lower in urban than in rural habitats. The magnitude of the overall adverse effect of urbanization on herbivory was independent of the latitude of the locality and was similar in all 11 studied tree species, but increased with an increase in the size of the urban area: it was significant in large cities (city population 1-5million) but not significant in medium-sized and small towns. Quality of birch foliage for herbivorous insects was slightly higher in urban habitats than in rural habitats. At the same time, leafminer mortality due to ants and birds and the bird attack intensity on dummy larvae were higher in large cities than in rural habitats, which at least partially explained the decline in insect herbivory observed in response to urbanization. Our findings underscore the importance of top-down forces in mediating impacts of urbanization on plant-feeding insects: factors favouring predators may override the positive effects of temperature elevation on insects and thus reduce plant damage.

Specific manipulation or systemic impairment? Behavioural changes of three-spined sticklebacks (Gasterosteus aculeatus) infected with the tapeworm Schistocephalus solidus

Manipulation of host behaviour by parasites to enhance transmission to the next host is a fascinating yet controversial phenomenon. This is because it is often hard to discriminate specific manipulation from unspecific side effects of the infection, i.e. a systemic impairment that could be due to a weakened general body condition. When infected with the tapeworm Schistocephalus solidus, stickleback fish swim closer to the water surface and exhibit reduced predation avoidance behaviour, which facilitates transmission of the tapeworm to the final host, most often a fish-eating bird. We here tested whether the behavioural changes of infected sticklebacks are specific to contexts where they would indeed enhance transmission, or rather more general. Therefore, we compared the behaviour of sticklebacks that were experimentally infected with S. solidus or left uninfected, in settings where the behaviour would influence parasite transmission to a high degree (response to a bird predator stimulus) or to a lesser extent (exploration of a new environment, activity while foraging). As expected, infected sticklebacks returned much faster to foraging after the bird predator stimulus and spent more time close to the water surface, compared to non-infected sticklebacks. By contrast, exploration of a new environment and activity while foraging did not differ between infected and non-infected sticklebacks. This suggests that alteration of the sticklebacks’ behaviour when infected with S. solidus is indeed due to specific manipulation of the predator avoidance behaviour and not a general, systemic impairment of infected sticklebacks. Manipulation of host behaviour by parasites is a fascinating but controversial phenomenon, since it is often difficult to disentangle if they are specifically induced or just a side effect of the infection. Stickleback fish, when infected with a tapeworm, change their behaviour dramatically; they swim closer to the water surface and reduce their escape behaviour, which exposes them to predation by birds, the final hosts of the parasite. We observed that sticklebacks infected with the tapeworm perform equally well as non-infected conspecifics in contexts with low relevance for parasite transmission, such as exploration of a new environment and foraging activity. However, the same infected sticklebacks exhibited the expected reduced escape behaviour when tested with a simulated bird attack. Our study suggests that the parasite specifically induces the sticklebacks’ behavioural changes and does not simply cause a systemic impairment.

The role of avian scavengers in the breakdown of carcasses in pastoral landscapes

ABSTRACTScavenging birds can provide ecosystem services to pastoralists by contributing to the breakdown of animal carcasses that can harbour and spread disease. However, these benefits have yet to be quantified in Australia. We monitored rabbit carcasses using motion-sensor cameras to identify beneficial avian scavengers across four landscape types (forest, riparian, fields with large isolated trees, and open fields) on a pastoral property in north-central Victoria. We quantified the ecosystem service of carcass breakdown by measuring the per cent weight loss of carcasses exposed to scavenging birds compared to carcasses excluded from birds. Seven of the twenty-four bird-accessible carcasses were attacked by raptors in 2014, and three in 2015. When a raptor attacked a carcass, there was a significantly higher median per cent weight loss of the carcass (16.67%, interquartile range (IQR) = 8.33–100.0) compared with sites where no bird attacks occurred (6.65%, IQR = 3.03–12.06). Our results indicate that raptors are major contributors to carcass breakdown in grazing landscapes and may potentially contribute to reducing the spread of diseases such as blowfly strike and leptospirosis. Maintaining key habitat features for these species (e.g. large isolated trees) is essential for raptor conservation and maximising the ecosystem services they provide.