Acridotheres Tristis Research Articles

Ventriculotomy for the removal of a foreign body in a common myna (Acridotheres tristis): a case report

A seven-month old common myna with a history of ingesting a wire was transferred to the Iranmehr companion animal clinic in Mashhad, Iran. The bird’s symptoms included anorexia, retching, intermittent vomiting, a lack of vocalisation, fluffing, and nervousness lasting for two days. X-rays confirmed a radiopaque foreign body in the proventriculus. Initial attempts to remove the wire thorough the oral route were futile; however, surgical removal using ventriculotomy (ventral midline celiotomy) under general anaesthesia proved successful. Slight haemorrhaging occurred when the incision was made in the caudal aspect of the ventriculus, but overall, the procedure was performed with no serious complications. A follow-up after three month revealed no complications. Despite the negative views associated with this technique, our study shows that ventriculotomy can be recommended for the removal of ventricular and proventricular foreign bodies, at least in this species.  

Correlation Between the Type of Vegetation and Occurrence of Birds in Agrifields

Avian diversity in four areas of agrifields of Punjab Agricultural University (PAU), Ludhiana was studied in order to find a correlation between agricultural land use, woody vegetation and the occurrence of bird species. The areas included College Orchard (Transect I), Agrifields of Oil seed section of Department of Plant Breeding and Genetics adjacent to orchards of PAU (Transect II), Crop field area of Department of Plant Breeding and Genetics on the back of Thapar Hall, PAU (Transect III) and Experimental area of Department of Plant Breeding and Genetics of PAU (Transect IV) which was without any trees around it. A total of 12,642 birds including 30 different species were recorded in all the four transects. The total no. of birds (5,074) and species (22) was highest in transect IV. House crow, red wattled lapwing, rose ringed parakeet and common myna were found to be the dominant birds in Transect I, II, III and IV respectively. Species richness and species diversity varied throughout the year. All the four areas had one or the other crop which attracted a number of bird species for food and the adjacent woody vegetation in Transect I, II and III providing nesting, perching and roosting sites to birds. It reveals that both the trees and food availability in the agrifields attract different bird species for different purposes like food, nesting and roosting.

Innovative problem solving in birds: a key role of motor diversity

Foraging innovations are increasingly viewed as a key source of phenotypic plasticity and evolutionary change. Often thought to be associated with increased cognitive abilities, innovative foraging behaviour could potentially emerge as a simple consequence of being able to use a greater variety of motor actions in the foraging context. Here, we explored the role of motor diversity in the innovative problem-solving abilities of a highly successful ecological invader, the Indian myna, Sturnus tristis, using an extractive foraging task with multiple compartments. Consistent with findings from several other species, persistence predicted the latency to solve the first compartment. However, motor diversity was the strongest predictor of both solving latency of all further compartments and number of compartments solved. We suggest that motor diversity may facilitate innovation by increasing the ways in which objects can be handled, which in turn would allow for associative learning processes to enhance the expression of successful foraging behaviours.

Visceral coccisdiosis in a common mynah (Acridotheres tristis) due to Isospora sp. infection

A captive adult common mynah (Acridotheres tristis) died shortly after a course of seizure and opisthotonous with an illness characterized by severe lethargy, depression, loss of appetite, polyurate, and urate discoloration. Abdominal distention and hepatomegly, visible over the abdominal skin, were noticed clinically. At necropsy, severe enlargement of liver with general discoloration was obvious. Histopathological findings included schizonts and gametes in the intestine, especially in the duodenum. Cytology from impression smears revealed intracyto-plasmic Atoxoplasma-like zoites in the inflammatory cells especially macrophages within the liver and in the contact smears prepared from the liver, lung, and spleen. Based on postmortem findings of the organisms in blood mononuclear cells and in impression smears of liver and Giemsa stained impression smears of liver, the spleen and lung atoxoplasmosis caused by Isoapora sp. was specified as the cause of death. According to the literature, visceral coccidiosis (atoxo-plasmosis), described here, could be considered as one of the severe causes of mortality among captive birds.

Invasive Myna Control in American Samoa

The common myna is an invasive species in Florida, Hawaii, and in numerous other locations around the world. It is native to southern and south-east Asia. Common mynas are considered pests to fruit crops in many locales, and they are predators on eggs of other birds. Since their introduction to American Samoa in the 1980s, mynas have become the most frequently observed avifauna in developed areas in the country. The American Samoa Department of Marine and Wildlife Resources (DMWR) is concerned that expanding myna populations will exert competitive pressures on native species such as the Samoan starling and white-collared kingfisher. Additionally, the mynas are increasingly becoming social nuisances through nesting, foraging, and vocalization behaviors. The government and general population of American Samoa would like to eradicate these birds before populations are too large to control. In partnership with DMWR, we conducted trials with captive mynas to determine sensitivity to the avian toxicant DRC-1339, and to evaluate a potential baiting strategy for applying this toxicant on American Samoa to reduce myna populations.

A Case Report of Hepatic Lipidosis (HL) in Common Myna (<i>Acridotheres tristis</i>) Fed by High Caloric Broiler Diet in Iran

Hepatic lipidosis (HL) is common in birds fed all seed, high caloric or high-fat diets, especially psittacine birds. The most common cause of avian HL is obesity related to over feeding. This case report describes the clinical and pathological features of 10 Common Myna (Acridotheres tristis) fed by commercial broiler diet and were presented for depression and anorexia, with severe he- patopathy associated hepatic lipidosis (HL). The patients died 4 days after presentation, and se- vere hepatomegaly was observed at necropsy. Based on histopathological findings, the acute he- patic lipidosis (HL) was found.

Tracking Changing Environments: Innovators Are Fast, but Not Flexible Learners

Behavioural innovations are increasingly thought to provide a rich source of phenotypic plasticity and evolutionary change. Innovation propensity shows substantial variation across avian taxa and provides an adaptive mechanism by which behaviour is flexibly adjusted to changing environmental conditions. Here, we tested for the first time the prediction that inter-individual variation in innovation propensity is equally a measure of behavioural flexibility. We used Indian mynas, Sturnus tristis, a highly successful worldwide invader. Results revealed that mynas that solved an extractive foraging task more quickly learnt to discriminate between a cue that predicted food, and one that did not more quickly. However, fast innovators were slower to change their behaviour when the significance of the food cues changed. This unexpected finding appears at odds with the well-established view that avian taxa with larger brains relative to their body size, and therefore greater neural processing power, are both faster, and more flexible learners. We speculate that the existence of this relationship across taxa can be reconciled with its absence within species by assuming that fast, innovative learners and non innovative, slow, flexible learners constitute two separate individual strategies, which are both underpinned by enhanced neural processing power. This idea is consistent with the recent proposal that individuals may differ consistently in ‘cognitive style’, differentially trading off speed against accuracy in cognitive tasks.

Characteristics of aeolian dust across northwest Australia

South easterly trade winds have long been thought to transport aeolian dust across northwest Australia, but very little is known about the chemical and particle size characteristics of this material. From July 2008 to May 2009, 36 aeolian dust samples were collected monthly at four sites across Australia’s northwest. The results of ion beam analysis indicate that the samples consisted of four major elemental groups, one of which appeared to be transported across the sites during months in winter and summer. This group (characterised by higher ratios of Fe, Ti and Mn/Si than the Earth’s Crustal Average) also showed a decrease in particle sizes towards the west. This suggests that the dust may have had a central Australian source, while other groups richer in Si appear to have been locally derived. These results support previous models of seasonal dust transport, and may have relevance in regional climate modelling, the transport of nutrients into the Indian Ocean, mineral exploration and studies of respiratory health.

Hydraulic Fracturing on Federal and Indian Lands: An Analysis of the Bureau of Land Management's Revised Proposed Rule

The federal government controls 700 million acres of subsurface rights (plus 56 million subsurface acres of Indian mineral estate) across 24 states, making it the largest landowner in the nation, and therefore in a position to negotiate lease terms and shape regulations of oil and gas development. The federal Bureau of Land Management’s (BLM) rules on how drilling activity can take place on federal lands essentially dictate terms, making BLM the largest “regulator” of drilling activity in the country. BLM last revised its oil and gas regulations (the Onshore Orders) in the 1980s and early 1990s, well before the recent rapid expansion of shale gas development. To date there are two rounds of proposed revisions, the first issued in 2012 and the most recent issued in May 2013, after BLM received 177,000 comments on the first round. This paper examines the 2013 proposal in several key respects, including the scope and requirements of the new proposal, the substantial changes from the 2012 proposal, and a comparison of BLM’s proposed rules with rules in states with shale gas development and significant federal land holdings, based on earlier work. We find that BLM’s proposal addresses some apparent gaps in state-level regulation and that, generally, BLM rules do not appear to impose significant requirements beyond existing state regulations, at least across the regulatory elements we analyzed and in those states with large federal land holdings.

The native versus alien dichotomy: relative impact of native noisy miners and introduced common mynas

Human activity can dramatically affect biodiversity, often by introducing non-native species, or by increasing the abundance of a small number of native species. Management strategies aimed at conserving biodiversity need to be informed by the actual impacts of highly abundant species, whether native or introduced. In this study we examined characteristics of two bird species, introduced common mynas and native noisy miners, both of which are highly abundant in urbanised areas along the East coast of Australia. Current managerial practices have a strong focus on eradication of common mynas, while noisy miners are largely ignored. However, in this study noisy miners were found in a broader range of habitats, and in greater abundance, than common mynas; displayed more aggressive behaviour; and were linked to a decline in the diversity and abundance of other species where common mynas were not. We suggest that the adaptability of a species and the variety of habitats it can colonise may be a better predictor of its potential impact, than whether it is native or introduced.

Understanding basic species population dynamics for effective control: a case study on community-led culling of the common myna (Acridotheres tristis)

Population manipulation of introduced species can be difficult and many widespread eradication or reduction attempts have failed. Understanding the population dynamics of a species is essential for undertaking a successful control program. Despite this, control attempts are frequently undertaken with limited knowledge of the species population dynamics. For example, in Australia, concern over the impact of the introduced common myna (Acridotheres tristis) has led to community members culling the species. In this paper, we assessed the impact of community-led common myna culling program over broad and fine-scales in Canberra, Australia. We utilized a basic population model to enhance understanding of common myna population dynamics and the potential influence of various culling regimes. We found a significant negative relationship between common myna abundance and culling at fine-scales (1 km2). However, over broad-scales the relationship between common myna abundance and culling was not significant. Our population model indicated culling at a rate of 25 birds per km2 per year would reduce common myna abundance, regardless of initial density. Our results suggest that currently too few individuals are being removed from the Canberra population, and natural reproduction, survival and/or immigration is able to replace the culled individuals. This highlights the value of undertaking basic population modeling to assess if potential control measures are capable of achieving desired outcomes. Our work provides information for researchers, government and community groups interested in controlling not only the common myna, but also other introduced species.

To innovate or not: contrasting effects of social groupings on safe and risky foraging in Indian mynahs

Foraging innovations are increasingly recognized as an important source of phenotypic plasticity, evolutionary change and adaptation to environmental challenges. One line of research has successfully demonstrated that innovation can represent a stable individual trait, but by the same token has shown strong contextual effects on innovation. We examined the effects of social context on innovative foraging behaviour. Across two separate experiments, we measured the individual propensity of Indian mynahs, Acridotheres tristis, to innovate when alone, in pairs, or in groups of five birds. Although innovators remained consistent in their relative innovation performance ranking (high, medium, low), the presence of one or more conspecifics reduced the likelihood of innovating, and increased innovation latencies, significantly relative to when individuals were tested alone. A neophobia test in which latency to forage was compared in both the absence and the presence of a novel object, in each of two social contexts (solitary versus social), showed that the presence of conspecifics caused mynahs to forage significantly faster in a safe situation (object absent) relative to when alone, but to delay foraging in a risky situation (object present). Together, these findings suggest that sociality can have contrasting effects on foraging in safe and risky situations, and, in some species at least, effects of sociality on innovative foraging may hence be more akin to those observed in the presence of risk. Negotiation over engaging with risks inherent to innovative foraging offered the most likely explanation for socially inhibited innovation behaviour, and may act to constrain the diffusion of innovations under some conditions.

Using invasion process theory to enhance the understanding and management of introduced species: A case study reconstructing the invasion sequence of the common myna (Acridotheres tristis)

Research indicates that invasion is a multi-step process, where each stage is contingent on the stage that precedes it. Numerous hypotheses addressing the factors that influence each stage of the invasion process have been formulated, but how well does this theory match what occurs in the natural world? We created a general conceptual model for the invasion process based on invasion theory. Using a composite 41-year data set, we then reconstructed the invasion sequence of the common myna (Acridotheres tristis) to investigate the similarities between invasion theory and this observed invasion. We observed a lag period before population growth of 2.7 (±0.3) years, a maximum rate of population growth of 24.1 (±6.4) birds per km2 per year, a lag period before spreading of six years and an average spreading rate of 0.4 km per year. The length and duration of these stages correspond closely with what invasion process theory would anticipate. We suggest that a conceptual model, coupled with basic species, environment and event information, could be a useful tool to enhance the understanding and management of invasions.

RETRACTED ARTICLE: Cervical type AB thymoma (Mixed) tumour diagnosis in a mynah as a model to study human: clinicohistological, immunohistochemical and cytohistopathological study

Thymoma is a primary mediastinal neoplasm arising from or exhibiting differentiation towards thymic epithelial cells, typically with the presence of non-neoplastic lymphocytes. A 13-year-old male Mynah bird (acridotheres tristis) was presented for evaluation of a 2.3 × 1.5 × 1.0 cm mass in the left ventrolateral cervical region. The clinical signs, radiology, cytohistopathology and immunohistochimy findings related to the thymoma are presented. These findings indicated that the tumor was a type AB thymoma according to the World Health Organization (WHO) and veterinary classification. Thymomas are rarely reported in avian species and this is the first report in a Mynah bird.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1159525819982779.

Tolerance of human approaches by Common Mynas along an urban-rural gradient

Successful urban colonisation by birds requires tolerance of many disturbances and avoidance of chronic stress and major disruption to critical activities. Habituation may be involved in acquiring tolerance of human proximity, in which case tolerance should vary with the degree of opportunity to learn that most humans do not present a threat and should therefore vary with human population density. We studied Common Mynas (Acridotheres tristis) in the urban, suburban, peri-urban and surrounding rural zones of Melbourne, Australia, to determine whether flight-initiation distance (FID) and time allocated to anti-predator vigilance increased along this gradient from the urban to the rural zone. This gradient encompassed a 143-fold variation in average human population density during daylight hours. Urban and suburban Mynas had a 2.3-5.7 times shorter FID, were 1.6-2.5 times less likely to retreat by flying and were 1.9-3.1 times more likely to flee >5 m than their peri-urban and rural conspecifics. Fleeing behaviour was not strongly correlated with estimated human population density, but exhibited an apparent ‘step’ in response at the suburban-peri-urban divide. Vigilance effort did not vary significantly between zones. This suggested that habituation did not occur with respect to surveillance for people, although surveillance presumably encompassed other predators too. Similar foraging effort and rates of food acquisition among zones could suggest that food abundance per individual was similar in urban and rural environments for Common Mynas, although this requires direct measurement.

Does Human-Induced Habitat Modification Influence the Impact of Introduced Species? A Case Study on Cavity-Nesting by the Introduced Common Myna (Acridotheres tristis) and Two Australian Native Parrots

Introduced species pose a major threat to biodiversity across the globe. Understanding the impact of introduced species is critical for effective management. Many species around the world are reliant on tree cavities, and competition for these resources can be intense: threatening the survival of native species. Through the establishment of 225 nest boxes, we examined the relationship between tree density and the abundance and nesting success of three bird species in Canberra, Australia. The common myna (Acridotheres tristis) is an introduced species in Australia, and the crimson rosella (Platycercus elegans) and eastern rosella (Platycercus eximius) are native species. We then investigated the impact of common myna nest box occupation on crimson rosella and eastern rosella abundance. Tree density significantly influenced the abundance and cavity-nesting of all three species. Common myna abundance (birds per square kilometer) was greatest at low tree density sites (101.9 ± 22.4) and declined at medium (45.4 ± 10.1) and high (9.7 ± 3.6) tree density sites. The opposite pattern was observed for the crimson rosella, with greater abundance (birds per square kilometer) at high tree density sites (83.9 ± 9.3), declining over medium (61.6 ± 6.4) and low (31.4 ± 3.9) tree density sites. The eastern rosella was more abundant at medium tree density sites (48.6 ± 8.0 birds per square kilometer). Despite the strong influence of tree density, we found a significant negative relationship between common myna nest box occupancy and the abundance of the crimson rosella (F 1,13 = 7.548, P = 0.017) and eastern rosella (F 1,13 = 9.672, P < 0.001) at some sites. We also observed a slight increase in rosella nesting interruptions by the common myna at lower tree densities (high: 1.3% ± 1.3, medium: 6.6% ± 2.2, low: 12.7% ± 6.2), although this increase was not statistically significant (F 2,40 = 2.435, P = 0.100). Our study provides the strongest evidence to date for the negative impact of the common myna on native bird abundance through cavity-nesting competition. However, due to the strong influence of habitat on species abundance and nesting, it is essential to investigate the impacts of introduced species in conjunction with habitat variation. We also suggest one component of introduced species management could include habitat restoration to reduce habitat suitability for introduced species.

The impact of introduced predators on an island endemic, the St Helena Plover, Charadrius sanctaehelenae

SummaryWe investigated the impact of introduced predators on the productivity of the St Helena Plover Charadrius sanctaehelenae, a shorebird endemic to the South Atlantic island of St Helena. The nest predator species identified have all been introduced to St Helena in the last 510 years, and all are species that are known to be invasive on other islands. The species responsible for taking the largest proportion of eggs was the domestic cat Felis catus, with rats (Rattus rattus or R. norvegicus) and Common Myna Acridotheres tristis taking smaller proportions. Nest survival varied spatially and was correlated with an index of cat density. No relationship was observed between the number of nesting attempts per pair in a year and predator density. The resulting estimates of productivity were insufficient in some areas to allow stable populations to persist locally. Future work should focus on assessing the population level impacts of current and reduced predator densities to St Helena Plovers, and understanding the influence of resource availability and habitat structure on the densities and impacts of predators.

Are invasive species drivers of native species decline or passengers of habitat modification? A case study of the impact of the common myna (Acridotheres tristis) on Australian bird species

AbstractHabitat modification and invasive species are significant drivers of biodiversity decline. However, distinguishing between the impacts of these two drivers on native species can be difficult. For example, habitat modification may reduce native species abundance, while an invasive species may take advantage of the new environment. This scenario has been described as the driver‐passenger model, with ‘passengers’ taking advantage of habitat modification and ‘drivers’ causing native species decline. Therefore, research must incorporate both habitat modification and invasive species impact to successfully investigate native species decline. In this paper, we used the common myna (Acridotheres tristis) as a case study to investigate the driver‐passenger model. We investigated changes in bird abundance, over 2 years, in relation to different habitat types and common myna abundance. We hypothesized that the common myna is both a passenger of habitat change and a driver of some bird species decline. Our results indicated that the abundance of many native species is greater in high tree density nature reserves, while the common myna was uncommon in these areas. Common myna abundance was almost three times higher in urban areas than nature reserves and declined rapidly as tree density in nature reserves increased. Our findings indicated that the common myna is primarily a passenger of habitat change. However, we also observed negative associations between common myna abundance and some bird species. We stress the importance of simultaneously investigating both invasive species impact and habitat modification. We suggest habitat restoration could be a useful tool for both native species recovery and invasive species control. Understanding the drivers of native species decline will help inform impact mitigation and direct further research.

English

Intercity roads potentially offer a high availability of easily accessible food and could therefore be expected to represent a preferential area for synanthropic bird foraging. As a consequence, a road-network could act as an invasion corridor for non-native urban birds. This study is a first approximation to verify such pattern of spread, by determining if foraging is actually the main activity carried out along intercity roads. With this aim, during the spring of 2011 we surveyed 200 points along the New Zealand intercity road-network, carrying out observations on four invasive synanthropic bird species (Eurasian house sparrow Passer domesticus, Eurasian blackbird Turdus merula, Eurasian starling Sturnus vulgarisand Indian myna Acridotheres tristis). For every species we also investigated: food preferences, the possibility that certain road features could affect the occurrence of feeding activity along roads, and foraging micro-habitat selection along roads. Predominant observed behaviors related to feeding activity, with differences concerning species-specific foraging strategies. Sparrows were mainly observed feeding on small-sized items (such as seeds and invertebrates), while both starlings and mynas showed more generalist feeding habits. These three species were mostly observed along the side of the lane, in contrast with blackbirds, mainly detected preying on invertebrates along the mown grassy verges of the road. Similarly to urban areas, intercity roads provide easily accessible food, available for all the study species. We propose a road-mediated invasion pattern for synanthropic birds, and encourage future studies to optimize management strategies, and targeting intercity roads as the most suitable control areas to prevent spread.

Histomorphological and Histochemical Observations of the Common Myna (Acridotheres tristis) Tongue

Common myna tongue was studied histomorphologically and histochemically. Four tongues of adult birds were carried out macroscopically and microscopically. The tongue was triangular; the dorsum of the body had median groove. Two to three backward directed papillae were located on each side of the body-base junction. A single transverse row of pharyngeal papillae was located behind the laryngeal cleft. The parakeratinized mucosa covered the entire surface of the tongue except clearly keratinized band on the ventrolateral surface and the conical papillae. Compared with the lateral group (LG), the secretory cells of the medial group (MG) of the anterior lingual glands (ALG) and the posterior lingual glands (PLG) contained large amount of mucin. It was neutral mucin. However, the LG had weak acid mucin with carboxylated group. Meanwhile, the MG of the ALG and the PLG had strong acid mucin with both carboxylated and sulphated groups. In conclusion, the morphological observation of the common myna tongue showed some variation from the other birds. Histochemical results indicated the differences between the LG and MG of the anterior lingual glands. However, no difference was observed between the latter and the PLG.