Acridotheres Tristis Research Articles

검은머리갈색찌르레기 (가칭) Acridotheres tristis의 국내 관찰 기록

2020년 5월 21일과 11월 12일 전라북도 군산시 고군산군도의 방축도(35°51΄1.20˝N, 126°22΄30.30˝E)에서 검은머리갈색찌르레기(가칭, Acridotheres tristis)를 관찰하였다. 2019년 7월 11일 검은머리갈색찌르레기의 관찰기록이 있으며, 이번 관찰은 촬영한 사진을 근거로 검은머리갈색찌르레기의 공식 기록으로 보고하고자 한다.

Restricted human activities shift the foraging strategies of feral pigeons (Columba livia) and three other commensal bird species

Invasive species are a growing concern with increasing global connectivity. Feral pigeons (Columba livia) are widespread and invasive, thus their effective control is of keen international interest. The COVID-19 pandemic has offered an unprecedented opportunity to investigate the impact of a nation-wide Circuit Breaker (restricted human activities) in Singapore on first, the abundance of the feral pigeons and three urban commensals—the Javan myna (Acridotheres javanicus), common myna (A. tristis), and house crow (Corvus splendens) in different food source types; and second, the activity budgets of feral pigeons. A significant and progressive decline in feral pigeon abundance was observed in open food centres and feeding hotspots after the Circuit Breaker was implemented. While the house crow and common myna were less affected, the Javan myna abundance increased moderately at refuse collection centres during the Circuit Breaker and decreased significantly in green spaces after the Circuit Breaker. Changes in food abundance could also predict changes in feral pigeon abundance and its effect was greatest in feeding hotspots. A greater proportion of feral pigeons was observed foraging and moving with a smaller proportion seen resting with probable consequences on their reproductive capacity. Our study also cautions against drawing inferences on biological responses due to similar social restrictions without careful consideration of other ecological factors, like average flock size and time of the day, which also affected the proportion of pigeons foraging on natural versus anthropogenic food. In summary, our results advocate a food limitation approach to control the feral pigeon populations.

Intraocular Pressure Measurements Using Rebound Tonometry in Eight Different Species of Companion Birds.

The purpose of this study was to determine reference interval intraocular pressure (IOP) values in 8 different species of companion birds. One hundred and nineteen companion birds (238 eyes) from a captive colony were examined: 21 pigeons (Columba livia; 18%), 17 African grey parrots (Psittacus erithacus; 14%), 22 common mynahs (Acridotheres tristis; 18%), 24 cockatiels (Nymphicus hollandicus; 20%), 12 zebra finches (Taeniopygia guttata; 10%), 9 budgerigars (Melopsittacus undulatus; 8%), 6 domestic canaries (Serinus canaria domestica; 5%), and 8 ring-necked parakeets (Psittacula krameri; 7%). Intraocular pressure was measured by rebound tonometry (TonoVet) avoiding induced, undesired pressure on the head, neck, or eyes. Mean IOP values varied by species. Mean (± SD) IOP values determined for each species were pigeon (5.42 ± 2.06 mm Hg), African grey parrot (4.93 ± 1.91 mm Hg), common mynah (6.22 ± 2.04 mm Hg), cockatiel (5.08 ± 1.76 mm Hg), zebra finch (5.90 ± 2.11 mm Hg), budgerigar (5.88 ± 2.31mm Hg), canary (5.83 ± 1.60 mm Hg), and ring-necked parakeet (6.25 ± 1.75 mm Hg). No statistically significant differences were found in IOP values between right and left eyes for the species studied (P > .22), with the exception of the ring-necked parakeet (P = .001). The results of this study provide representative IOP values measured using rebound tonometry in 8 different species of companion birds.

Molecular characterization of the Fe‑hydrogenase gene marker in Trichomonas gallinae isolated from birds in Riyadh, Saudi Arabia

Trichomonas gallinae causes avian oropharyngeal trichomonosis. This pathogen affects a large number of bird species and may cause substantial economic losses to the poultry industry. Al-Azizia poultry market in Riyadh, Saudi Arabia is among the largest poultry markets in the Arabian Gulf. Birds traded in this market may be exposed to a variety of T. gallinae strains. Genetic diversity of T. gallinae among birds in the market was examined using Fe‑hydrogenase gene sequences. These sequences were amplified by PCR for twenty-nine isolates of T. gallinae from four different avian species, including 21 feral pigeons, one common mynah, three chickens, and four turkeys. Sequence analysis showed ten variant gene sequences. Nine sequences comprise a new subtype, including A(KSAF1), C(KSAF1) and C(KSAF3) with 34.48% (n=10), 6.90% (n=2), 6.90% (n=2) of the isolates, respectively. Analyses also showed an additional five new sequences (KSAF1.1., KSAF2, KSAF13, KSAF14, KSAF15), representing 17.24% of the isolates. Subtype II (KSAF) was found in four feral pigeons (13.80%). To our knowledge, this report is the first to describe genotypes of T. gallinae from pigeons in Saudi Arabia using Fe‑hydrogenase gene sequences for subtyping. Subtype analysis infers the presence of multiple genotypes of T. gallinae in Saudi avian populations.

Bird species assemblages in railway stations: variations along an urban-rural gradient

Abstract The transportation infrastructures like railway tracks and roads bear negative impacts on natural environment. However, the opposite effects are also true in some instances where the man-made constructions have positive effect on faunal assemblages. This proposition was justified through the assessment of bird species using railway stations as model man-made structures in an urban-rural gradient, in the suburbs of Kolkata, India. During the entire study period along nine different railway stations, a total of 43 bird species belonging to 12 orders and 26 families were observed. Among these, the order Passeriformes was predominant in its species composition having 18 different species from 11 different families. In urban railway stations, a total of 23 bird species under 22 genera and 14 families were observed. In suburban railway stations, a total of 35 bird species under 32 genera and 22 families were documented. The railway stations from rural region showed the maximum number of species and abundance of bird families, where a total of 36 bird species under 32 genera and 23 families were observed. The railway stations from the suburban and rural regions were more similar in species composition. Irrespective of the locations, during the entire study period, the House Crow (Corvus splendens) was the dominant species followed by the Common Myna (Acridotheres tristis). About 18 bird species exhibited a decreasing population trend observed through the global population trend analysis. In all the railway stations, the abundance of omnivores were dominant while, the number of granivores were higher in the rural regions and the nectarivores were absent in the urban regions. It was apparent that the railway stations bear a positive effect on the bird species assemblages, which can be sustained through proper environmental management planning inclusive of urban greening.

Parasitic enteritis in the free-ranging Common Myna Acridotheres tristis (Aves: Passeriformes: Sturnidae)

Two deceased adult Common Myna Acridotherestristispresented for post-mortem investigations revealed weak carcasses with pale mucus membranes. The small intestine was completely blocked by balled-up tapeworms, which wereconfirmed as Hymenolepiscantaniana. Grossly, the intestine showed severe, diffuse congestion and catarrhal enteritis. Histopathological examination of the intestine exhibited severe congestion, denuded epithelium with necrotic cells along with homogenous catarrhal exudates admixed with a few polymorphonuclear cells. This report puts into record a rare case ofHymenolepisspeciesincidence in Common Myna.

Aspects of the feeding ecology of introduced Rose-ringed Parakeets Psittacula krameri in the urban landscape mosaic of Durban, KwaZulu-Natal Province, South Africa

The Rose-ringed Parakeet Psittacula krameri is one of the world’s commonest invasive bird species and has established in the South African urban landscapes. However, relatively little is known about the feeding biology of parakeets here. We surveyed areas in eThekwini Municipality, Durban, South Africa, to determine their feeding sites and the related land-use types. Patterns of the association were explored using Correspondence Analysis to determine parakeets’ diet across seasons and interaction between different tree species fed on by parakeets and other bird species. Dietary items were determined visually using binoculars. We identified a total of 63 feeding sites with many in the urban built land-use cover type. The parakeets’ diet differed significantly across the seasons with spring accounting for 33% of annual food items. We identified 31 fruiting/flowering tree species fed on by the parakeets, with fleshy fruits and flowers accounting for 58% and 19%, respectively. Native tree species (63%) were mostly relied on when compared with non-native (27%). They also fed on carpenter ants Camponotus cinctellus which contributed 3% of their diet. The forest fever-berry Croton sylvaticus (fleshy fruits) and African star-chestnut Sterculia africana (flowers) were the most preferred tree species in autumn and summer. The observed number of bird species that communally fed with parakeets were significantly different across the sampled seasons. The diets for the Common Myna Acridotheres tristis and the Speckled Mousebird Colius striatus overlapped with parakeets for most tree species. Parakeets were observed actively feeding in the early mornings and late afternoons before roosting. Our study supports that parakeets are generalist-opportunistic feeders. The assessment of Rose-ringed Parakeets feeding ecology may help understand their potential impact on native tree and bird species within an urban landscape.

A myna problem: alien species no obstacle to recovery for the Mangaia kingfisher

AbstractEndemic island species are of conservation interest as unique taxa, often with restricted populations, but many are data poor. The Mangaia kingfisherTodiramphus ruficollaris, known locally as the tanga‘eo, is endemic to the island of Mangaia in the Cook Islands, and categorized as Vulnerable on the IUCN Red List. The population size has not been estimated since 1996, despite concerns over habitat loss and competition with an invasive species, the common mynaAcridotheres tristis. We provide new population estimates for both the tanga‘eo and the common myna, using the same methodology as previous estimates. During December 2018–February 2019 we surveyed with distance sampling along 73 line transects walked across the six habitat types on Mangaia. We estimate there are 4,106 tanga‘eo on Mangaia (95% CI 3,191–5,283), a dramatic 7–8 fold increase compared to the previous estimate of 393–764. We estimate there are 13,350 common myna (95% CI 10,998–16,206), a slight increase, although densities in the two most favoured habitats for myna have declined. There is no evidence that the common myna poses a threat to the viability of the tanga‘eo population, as the latter has increased despite a much larger population of common myna. Presumed declines in the tanga‘eo population in the past were probably a result of habitat loss as a result of the cultivation of pineapplesAnanas comosusfor export, an industry that collapsed in the 1980s. We recommend a review of the IUCN Red List status of the tanga‘eo.

Tissue structure contributes to the production of a coloured skin display in the Common Myna

Conspicuous coloured displays from ultraviolet to bright red have been documented in many species throughout the animal kingdom. These colours often occur as sexual signals and can be incorporated into different types of integuments (e.g. scales, feathers, skin). Two main mechanisms are known to produce coloured integuments: pigmentation and tissue structure. Although pigmental and structural coloration are separate mechanisms and can occur independently, some coloured displays might emerge from a combination of both. Here, we demonstrate, using biochemical, optical and morphological methodologies, that the yellow coloration of the skin located around the eye of Common (Indian) Mynas ( Acridotheres tristis) is produced by both light-reflecting nanostructures and light-absorbing carotenoid pigments. Our analysis confirms that nanostructured collagen in the avian dermis work in combination with carotenoid pigments to produce vivid integumentary colours. Identifying the mechanisms behind the production of a coloured signal provides a basis for predicting how a signal’s function might be influenced by environmental factors such as fledgling nutrition.

Population estimates of non-native rose-ringed parakeets Psittacula krameri (Scopoli, 1769) in the Durban Metropole, KwaZulu-Natal Province, South Africa

Rose-ringed parakeets Psittacula krameri are one of the most widely distributed urban avian invader species present in ~ 35 countries with population sizes increasing. These parakeets were introduced to South Africa as part of the pet trade, and feral populations have established in several urban areas since and are of concern. We, therefore, conducted monthly surveys between August 2018 – December 2019 in the greater Durban Metropole, KwaZulu-Natal Province, to determine their population size and roosting sites. In addition, we recorded bird species that communally roosted with rose-ringed parakeets, and tree species characteristics that they used for roosting. We identified five main roost site areas with an overall mean (± SD) monthly population size of 1 783.3 ± 505.2 rose-ringed parakeets. There was an increase in rose-ringed parakeet numbers, particularly in August and December after their breeding. Most rose-ringed parakeets were recorded in the north, with fewer in the south of the metropole; and many were located around shopping centres and parks. A total of seven bird species communally shared roost sites with rose-ringed parakeets, with the non-native common myna Acridotheres tristis being the species that frequently shared roosts with parakeets. Three tree species were used as roosts, with the Natal mahogany Trichilia emetica and the giant palm Raphia australis, so being the preferred roost tree species. The results showed variations in the measured tree traits and the number of individual parakeets roosting per tree species. The population size of non-native rose-ringed parakeets showed persistent growth, and it is, therefore, suggested that control measures for this species are introduced before its population expands further.

How does human disturbance affect brood parasitism and nest predation in hosts inhabiting a highly fragmented landscape?

Human disturbance represents a considerable challenge for the conservation of living organisms and has profound negative impacts globally. There is substantial variation in how species respond to human disturbance. The main aim of the present study is to examine how human activities influence the risk of brood parasitism and nest predation for three passerine species living in a highly fragmented landscape in Central Bangladesh. We use data collected from 518 nests over nine breeding seasons for three host species of the Asian koel (Eudynamys scolopaceus), a non-evicting brood parasite: i) long-tailed shrike (Lanius schach), ii) common myna (Acridotheres tristis) and iii) house crow (Corvus splendens). Two sources of disturbance were considered: i) houses and buildings inside the study area, the Jahangirnagar University campus and ii) the highly urbanized area outside the campus boundary. Additionally, we regarded iii) nest height, iv) number of days after egg laying until discovery (time unmonitored), v) distance to nearest fruit tree and vi) distance to nearest conspecific neighbor, as important habitat and nest characteristics. We found significantly lower predation risk with increasing time unmonitored in all three host species, thus more regular nest checks by fieldworkers lead to more predation. Moreover, we found that the distance to nearest fruit tree was the most important factor for the risk of parasitism. Although we could not find any significant impacts of distance to boundary or buildings on either predation or parasitism risk, we found a trend both in common myna and house crow that nesting success was higher closer to the boundary. Ultimately, increased monitoring time had the most consistent negative impact on nesting success among the host species. This study highlights the effect of disturbance caused by nest monitoring, exceeding the impact of permanent structures in an around the university campus i.e. boundary and buildings.

The effect of mobbing vocalizations on risk perception in common mynas (Acridotheres tristis)

Animals emit predator-elicited calls in response to potential predation threats. These vocalizations induce a variety of anti-predator behaviors in conspecific receivers ranging from moving away from predators (alarm calls) to rallying conspecifics to fend them off (mobbing calls). While much is known about the immediate response to alarm calls, less is known about how mobbing calls influence subsequent antipredator decisions. Mobbing calls stimulate harassment of a potential predator. Therefore we predicted that hearing a mobbing call would make animals less likely to immediately flee an approaching threat. To study the potential effect of mobbing vocalizations on risk assessment, we primed common mynas (Acridotheres tristis) with a series of different stimuli and studied the variation in their subsequent decisions to flee an approaching human by quantifying flight initiation distance (FID). We found that although mynas increased their rate of locomotion after hearing mobbing calls, their subsequent decision to flee was not influenced. We also found that an individual’s propensity to move and look explained some variation in FID. This suggests that while mobbing calls do not influence subsequent decisions to flee, they do affect subsequent behavior.

Impact of vehicular traffic on birds in Tiruchirappalli District, Tamil Nadu, India

Roads have numerous direct and indirect ecological impacts on wildlife. Roads constitute an extensive and integral part of our environment. Collisions with vehicles kill a large number of birds every year. The present study was carried out from January 2016 to December 2016. The data was collected from Nehru Memorial College to Pavithram Lake of Thuraiyur to Namakkal road of Musiri Taluk, Tiruchchirappalli District. During this study, we recorded a total of 64 birds belonging to 12 species killed due to vehicular traffic. A maximum of 11 birds were killed in the months of January and October, and a minimum of two bird kills were observed in the months of September and December. Of the 64 birds, the roadside mortality was observed to the tune of 25%, 20.3%, 14%, 12.5%, 10.9%, 4.6%, and 4.6% for Southern Coucal Centropus parroti, Common Myna Acridotheres tristis, House Crow Corvus splendens, Spotted Owlet Athene brama, Indian Jungle Crow Corvus culminatus, Yellow-billed Babbler Turdoides affinis, and Large Grey Babbler Turdoides malcolmi. Other birds such as Asian Koel Eudynamys scolopaceus, Indian Roller Coracias benghalensis, Shikra Accipiter badius, White-breasted Waterhen Amaurornis phoenicurus, and White-browed Bulbul Pycnonotus luteolus accounted for 1.5% mortality. Suggestive measures to prevent wildlife loss due to vehicular traffic are presented in this communication.

Noisy neighbours and myna problems: Interaction webs and aggression around tree hollows in urban habitats

Abstract Interaction networks among native and invasive species in a community can inform both invasion impacts and applied management of invasive species. The intensity of aggressive interactions may be related to the overlap in species’ ecological niche and functional traits, especially in cavity‐breeding species, that often compete for limited nesting sites. Australia is home to over 100 native and introduced cavity‐nesting species, including several invasive species that are widespread globally, such as the common myna Acridotheres tristis. Here, we aimed to test the extent to which shared functional traits inform the intensity of aggression between cavity‐nesting birds. We quantified the outcomes of aggressive interactions between birds in large hollow‐bearing trees in SE Queensland, Australia. We examined whether more similarly sized birds interacted more frequently, whether larger species won aggressive interactions more often, and whether cavity‐breeding species with similar preferences for nesting sites (breeding‐niche space) interacted more frequently. We recorded a total of 410 aggressive interactions and 48 interacting bird species around tree hollows, including 20 cavity‐nesting bird species. These interactions were dominated by the invasive common myna, the native noisy miner (a non‐cavity‐breeder) and the native rainbow lorikeet Trichoglossus moluccanus, but the common myna won the largest total number of interspecific interactions. On average, larger birds won aggressive interactions more frequently, yet there were some important exceptions to this finding; the common myna (113 ± 30 g) won 26 of the 29 interactions against the larger native rainbow lorikeet (126 ± 44 g). Importantly, species with more similar nest‐site preferences were observed aggressively interacting more frequently. Synthesis and applications. The impact of the invasive common myna was higher‐site preferences. Control efforts for the myna should focus on birds that nest in natural tree hollows. An analysis of shared traits by managers could be used to help identify how many local species would benefit from common myna control in a given area and test if further behavioural studies of common myna are warranted.

Radiotracking invasive spread: Are common mynas more active and exploratory on the invasion front?

Understanding the drivers of invasive species’ range expansion is key to effective management and successful control. Spatial sorting theory advances that invasive species can spread via a selection-neutral process predicated on differential movement. In addition to morphology and physiology, it has been predicted that variation in exploration and activity among individuals can be crucial to this model because these behaviors enhance movement. We aimed to address the question of whether exploration and activity are associated with invasive spread using the free-ranging invasive common myna (Acridotheres tristis) in Australia, one of the most broadly distributed invasive birds globally. We radio-tracked mynas from invasion-front sites versus long-established sites in New South Wales. We quantified activity using frequent movements in familiar areas and exploration using infrequent long-distance excursive movements, while also accounting for environmental variation. We discovered that mean daily distance travelled was larger in invasion-front than in invasion-source mynas, suggesting front mynas were more active. Invasion front mynas had significantly larger exploratory home ranges, moved greater maximum daily distances, and changed roost more frequently, suggesting front mynas were also more exploratory; the results were maintained when climate was included as a covariate. To our knowledge, this is the first study to show enhanced exploration and activity in free-ranging invasion-front birds. Inter-individual variation in movement-relevant behaviors might be facilitating the ongoing Australian myna range expansion, although habitat effects cannot be fully excluded. These findings point to the potential importance of considering changes in behavior when modelling alien animal invasions and applied conservation actions.

Rat and invasive birds control to save the Tahiti monarch (Pomarea nigra), a critically endangered island bird

The Tahiti monarch is a critically endangered bird species endemic to the island of Tahiti. In 1998, when a conservation program started, its range was restricted to four valleys, with 19 birds living in accessible lower valleys. In one of these valleys, a remote population located upstream of a series of waterfalls was present but, was first protected only in 2009. The first conservation actions focused on rat control alone and this probably save the species from imminent extinction. However, the accessible population, living in the lower sites, had only increased to 22 birds by 2012 (1 % per annum), part of a global population of just 40 birds. The introduced common myna and red-vented bulbul were identified as additional threats to monarch breeding success. With the help of a network of local inhabitants living near the valley entrance, 8475 mynas and 17859 bulbuls were eliminated in seven years. This study shows that the overall nest and fledging survival was increased by bird control, reduced by heavy rain but not substantially changed by increases in the level of rat control. During this period, the total Tahiti monarch population increased from 40 adults to 79 in 2018, (12 % per annum). Our results illustrate the necessity to control several threats together in order to recover island birds with low productivity. Conservationists need to consider that several other island birds, with low productivity, may need multi invasive control to recover.

Overlap in reproductive phenology increases the likelihood of cavity nest usurpation by invasive species in a tropical city

Abstract Multiple invasive cavity-nesting bird species can be present in a nest web, the network linking birds using cavities. We investigated the nest preferences and breeding phenologies of the cavity-nesting guild in the region surrounding Miami, Florida, USA, where invasive starlings, mynas, and parrots potentially usurp cavities from native woodpeckers and secondary cavity-nesters. We asked if the timing of reproduction determines which invasive species will usurp cavities from native birds with similar nest preferences. Nest usurpations between European Starlings (Sturnus vulgaris) and the woodpecker species present in Miami is well documented, but we predicted that a recently arrived sturnid species and introduced psittacids would also usurp nests. European Starlings had the largest breeding population of any species in our nest web, breeding during the peak of nesting season, and usurped the largest number of active nest cavities. We found that a small population of Common Mynas (Acridotheres tristis) usurped nests, sharing the peak-season nesting period with starlings and native woodpeckers. Parrots bred later than we expected, avoiding nest-site overlap with similarly large native birds that use cavities with similar characteristics. Parrots did not usurp any active nest cavities from native birds. Our results demonstrate how to use analysis of cavity characteristics and reproductive timing to evaluate threats to a cavity nest web posed by multiple invasive species. Common Myna currently usurp few nests; if they increase greatly in population, they could pose a problem for native cavity-nesters.

Predation on a Common Water Monitor (Varanus salvator) by a Common Myna (Acridotheres tristis) in Malda, West Bengal, India

Predation on a Common Water Monitor (Varanus salvator) by a Common Myna (Acridotheres tristis) in Malda, West Bengal, India

Innovation and decreased neophobia drive invasion success in a widespread avian invader

Certain behavioural traits, including innovation and reduced neophobia, may facilitate successful invasions by allowing first arrivals to overcome the challenges of a novel environment. However, the extent to which these traits occur in invasive populations in comparison with native populations, and whether these traits' prevalence remains consistent throughout a species’ introduced range, have been scarcely investigated. We tested whether object neophobia, food neophobia and two levels of motor innovation in the common myna, Acridotheres tristis, a widespread avian invader, in its native range (India) as well as across an invasive range (Israel), are more prevalent at the edge of the invasion front relative to its centre and to the native ranges. We found that individuals from the invasion front were more innovative and more tolerant of novel food than those from both nonfront invasive populations and the native range. Moreover, these traits showed a gradual loss within the invasive population with increasing time since population establishment. Our results provide crucial empirical evidence to support the adaptive flexibility hypothesis for invasion processes and emphasize the role of behaviour in biological invasions.

Impact assessment of seven alien invasive bird species already introduced to South Africa

Globally, various avian species have been introduced accidentally and deliberately by humans through different pathways. Some of these species were able to establish, multiply, and become invasive. In this study, we identified areas that are climatically suitable for seven introduced invasive bird species and assessed the environmental and socio-economic impacts associated with the selected bird species in South Africa. We used present distribution records to predict potential climatic suitability distributions and used the Generic Impact Scoring Scheme to assess the impacts associated with seven invasive bird species in South Africa. We found that all the seven species were climatically suitable to South Africa and Passer domesticus, Sturnus vulgaris, and Anas platyrhynchos each had relatively large climatic suitability distributions. The climatic suitability for all the species was within their occurrence ranges in and outside South Africa. For impact assessments, we found that all seven selected species had impacts, with A. platyrhynchos, Acridotheres tristis, Columba livia, and Psittacula krameri having the highest overall impacts respectively. The socio-economic impact ranked higher than environmental impact for all species. The socio-economic impacts were frequently through agricultural production and human infrastructure, while the environmental impact was mostly through impacts of birds on other animals and competition. These need to be incorporated in decision-making and eradication plans for these alien invasive birds in South Africa.