Community structure, threats and conservation issues of migratory birds in the south-central coastal area of Bangladesh

The Pliocene-Pleistocene transition had dual effects on North American migratory bird speciation

Mangrove forests throughout the world are recognized as stopover sites by many migratory birds – including waders – as they contain ample food resources such as invertebrates, fruits, and flowers that are beneficial to most birds. In connection, the Talabong Mangrove Forest located in Bais, Negros Oriental, Philippines is recognized as a wildlife sanctuary, but no recent data on birds could supplement this. Thus, this study aims to assess the distribution patterns of migratory and resident birds in the said site during the southward migration which encompasses both wet and dry seasons. Also, the investigation determines whether Talabong mangrove could function as a stopover site for migratory birds. To examine the community structure, the populations of resident and migratory bird species were assessed for species composition, diversity, density, and abundance in three sampling periods: pre-migration, migration, and post-migration. The line transects and point-count methods were employed with four transect lines laid out on the study site. Each line stretched a kilometer long with a 250-m interval with five points for point-counting and was visited on each sampling period. Points were marked for a consistent sampling. For each sampling period, results showed that the birds’ abundance, diversity, and density remained consistently high throughout each sampling. Specifically, the species composition and the number of resident birds did not seem to alter and remained high as well. On the other hand, migrants had an abrupt increase during migration sampling and decreased towards the end. But similarity analyses suggest species composition remained approximately similar for the migrants. The results showed that Talabong mangrove forest contained some migratory species – making it a decent stopover site, although not as many migrants as in other protected mangroves and wetlands in the Philippines. The resident birds occupying the site may also have served as cues for the migrants.

Consequences of seasonal migration : How goose relocation strategies influence infection prevalence and pathogen dispersal

Off peak

BackgroundThe range of vertebrate hosts on which species of mosquito blood-feed is an important parameter for identifying potential vectors and in assessing the risk of incursion and establishment of vector-borne pathogens. In the United Kingdom, studies of mosquito host range have collected relatively few specimens and used techniques that could only broadly identify host species. This study conducted intensive collection and analysis of mosquitoes from a grazing marsh environment in southeast England. This site provides extensive wetland habitat for resident and migratory birds and has abundant human nuisance biting mosquitoes. The aim was to identify the blood-feeding patterns of mosquito species present at the site which could contribute to the transmission of pathogens.MethodsTwice-weekly collections of mosquitoes were made from Elmley Nature Reserve, Kent, between June and October 2014. Mosquitoes were collected using resting boxes, by aspiration from man-made structures and using a Mosquito Magnet Pro baited with 1-octen-3-ol. Blood-fed specimens were classified according to the degree of blood meal digestion using the Sella scale and vertebrate origin determined using sequencing of a fragment of the mitochondrial cytochrome C oxidase subunit I gene. Mosquitoes that were morphologically cryptic were identified to species level using multiplex PCR and sequencing methods.ResultsA total of 20,666 mosquitoes of 11 species were collected, and 2,159 (10.4%) were blood-fed (Sella scale II-VI); of these 1,341 blood-fed specimens were selected for blood meal analysis. Vertebrate origin was successfully identified in 964 specimens (72%). Collections of blood-fed individuals were dominated by Anopheles maculipennis complex (73.5%), Culiseta annulata (21.2%) and Culex pipiens form pipiens (10.4%). Nineteen vertebrate hosts comprising five mammals and 14 birds were identified as hosts for mosquitoes, including two migratory bird species. Feeding on birds by Culex modestus and Anopheles atroparvus populations in England was demonstrated.ConclusionsThis study expands the vertebrate host range of mosquitoes in the Thames estuary region of the UK. Feeding on both resident and migratory bird species by potential arbovirus vectors including Cx. pipiens f. pipiens and Cx. modestus indicates the potential for enzootic transmission of an introduced arbovirus between migratory and local bird species by native mosquito species.

This study was carried out to assess the status and conservation issues of migratory water birds in Komaranahalli Kere, a lake in Malebennur, Harihar Taluk, Davanagere District from November 2012 to October 2013. The dominant family was Ardeidae represented by 10 species, followed by the Scolopacidae with seven species. The families with lowest representations of one species were Podicipididae, Anhingidae, Rostratulidae and Recurvirostridae. The study revealed that the lake harbors many resident and a few migratory bird species. Among the species recorded five species namely the Black-headed Ibis Threskiornis melanocephalus, Oriental Darter Anhinga melanogaster, Black-tailed Godwit Limosa limosa, Painted Stork Mycteria leucocephala and River Tern Sterna aurantia are Near Threatened. The present study location is also facing tremendous conservation challenges by the impact of anthropogenic alteration of the habitats in and around the lake. Though the lake is highly disturbed, it still provides some potential habitats for a few migratory and several resident water bird species.

This study was carried out to assess the status and conservation issues of migratory water birds in Komaranahalli Kere, a lake in Malebennur, Harihar Taluk, Davanagere District from November 2012 to October 2013. The dominant family was Ardeidae represented by 10 species, followed by the Scolopacidae with seven species. The families with lowest representations of one species were Podicipididae, Anhingidae, Rostratulidae and Recurvirostridae. The study revealed that the lake harbors many resident and a few migratory bird species. Among the species recorded five species namely the Black-headed Ibis Threskiornis melanocephalus, Oriental Darter Anhinga melanogaster, Black-tailed Godwit Limosa limosa, Painted Stork Mycteria leucocephala and River Tern Sterna aurantia are Near Threatened. The present study location is also facing tremendous conservation challenges by the impact of anthropogenic alteration of the habitats in and around the lake. Though the lake is highly disturbed, it still provides some potential habitats for a few migratory and several resident water bird species.

The importance of native valley oaks (Quercus lobata) as stopover habitat for migratory songbirds in urban Sacramento, California, USA

The Dongargarh-Dhaara Forest, situated in north-west region of Rajnandgaon District of Chhattisgarh, India, represents a crucial habitat for avian biodiversity. This study presents a comprehensive checklist of the avian fauna within this reserve forest, aiming to document the diversity and provide a baseline for future conservation efforts. Systematic surveys were conducted over a period of one year, from January 2022 to December 2022, covering various seasons to account for migratory, local migratory and resident bird species. Standard ornithological methods, including point counts and transect walks, were employed to ensure robust data collection. A total of 289 bird species were recorded, belonging to 56 families, 289 genera and 19 orders. Among these, several species of conservation concern were identified, including the Grey-headed Fish Eagle (Haliaeetus ichthyaetus) laggar falcon (Falco jugger) Ferruginous duck (Aythya nyroca), painted stork (Mycteria leucocephala), black-headed ibis or Oriental white ibis (Threskiornis melanocephalus), are listed on the IUCN Red List. The avian community structure showed a dominance of Passeriformies species, reflecting the diverse habitats ranging from dense forest canopies to open grasslands and water bodies within the reserve forest. The findings highlight the Dongargarh-Dhaara Forest as a significant avian biodiversity hotspot in the region. The presence of a variety of species, including endemic and migratory birds, underscores the ecological importance of this forest and the need for its conservation. -This checklist serves as a vital resource for ornithologists, conservationists, and policy-makers, providing a foundation for monitoring avian population trends and implementing effective management strategies to preserve this rich avian heritage.

AimDuring the Plio‐Pleistocene, glacial cycles shaped Northern Hemisphere species' distributions causing range contractions followed by interglacial expansions. In migratory bird species, climatic changes could result in a rapid reshaping of their ranges and/or migratory behaviour, given their dispersal capacity. In this context, it has been suggested that long‐distance North American migratory species could have lost their migratory condition during cold glacial periods, regaining it later in warmer periods. Here, we explored this hypothesis for extant Eurasian‐African migratory bird species.LocationEurasia and Africa.TaxonMigratory birds.MethodsWe used Species Distribution Models (SDMs) to infer the present and Last Glacial Maximum (LGM) potential distribution of 81 Trans‐Saharan migratory bird species, and reviewed the available bird fossil record for the Plio‐Pleistocene covering Eurasia and Africa.ResultsSDMs predicted a reduction of the northern edges of the breeding ranges during the LGM compared to the present. However, the current wintering ranges were somewhat similar in the Pleistocene, with the Saharan desert belt gap being always present through time, not overlapping with their breeding ranges. The fossil record also supports the persistence of migration during the Pleistocene.Main conclusionsThe palaeo‐distributions and absence of medullary bone in Pleistocene fossils from wintering Euro‐African migratory species confirm that they were migratory, providing independent support for our models. The hypothesis of the loss of migratory behaviour in these species during the Pleistocene is not supported. Furthermore, the differences in migratory species from Eurasia‐Africa and the Americas can be influenced by geographical differences, the persistence of the Mediterranean basin as climatically suitable area during glaciations and the existence of the Saharan belt.

AimRecent, rapid population declines in many Afro‐Palaearctic migratory bird species have focussed attention on changing conditions within Africa. However, processes influencing population change can operate throughout the annual cycle and throughout migratory ranges. Here, we explore the evidence for impacts of breeding and non‐breeding conditions on population trends of British breeding birds of varying migratory status and wintering ecology.LocationGreat Britain (England & Scotland).MethodsWithin‐ and between‐species variation in population trends is quantified for 46 bird species with differing migration strategies.ResultsBetween 1994 and 2007, rates of population change in Scotland and England differed significantly for 19 resident and 15 long‐distance migrant species, but were similar for 12 short‐distance migrant species. Of the six long‐distance migrant species that winter in the arid zone of Africa, five are increasing in abundance throughout Britain. In contrast, the seven species wintering in the humid zone of Africa are all declining in England, but five of these are increasing in Scotland. Consequently, populations of both arid and humid zone species are increasing significantly faster in Scotland than England, and only the English breeding populations of species wintering in the humid zone are declining.Main conclusionsPopulation declines in long‐distance migrants, especially those wintering in the humid zone, but not residents or short‐distance migrants suggest an influence of non‐breeding season conditions on population trends. However, the consistently less favourable population trends in England than Scotland of long‐distance migrant and resident species strongly suggest that variation in the quality of breeding grounds is influencing recent population changes. The declines in humid zone species in England, but not Scotland, may result from poorer breeding conditions in England exacerbating the impacts of non‐breeding conditions or the costs associated with a longer migration, while better conditions in Scotland may be buffering these impacts.

Migratory birds may be unable to respond to climate change at their breeding grounds in the same way as residents because they do not experience local environmental conditions until migration has been completed, or because of limited plasticity in response to environmental variation. Indeed, several studies have shown that long-distance migrants have advanced their phenology less than short-distance migrants in recent decades, suggesting a slower phenological response to ongoing climate warming. However, few studies compared the phenological response of species that live year-round within the same climatic region (including residents) with that of species migrating over longer distances. We used an extensive data set on temporal change in spring first singing date (FSD) during 1977-2006 of 56 resident and migratory bird species in Northern Germany to test whether migratory status affected 2 aspects of the phenological response: the temporal trend in FSD and the response of FSD to local temperatures. Species migrating <4° latitude (ca. 450 km) (less migratory species) showed greater temporal advancement in FSD compared to more migratory species. In addition, the variance in temporal trends was larger among less migratory species. Higher local temperatures were associated with earlier FSD, and multi-brooded species showed a stronger advancement in FSD with higher temperatures than single-brooded species. However, the tempera- ture response was unaffected by migratory status, suggesting that the difference in the temporal trend in FSD between less migratory and more migratory species was mainly due to climatic and/or environmental cues regulating departure of the latter from the wintering areas and/or temporal scheduling of migratory flights, rather than to differential responses of FSD to local temperatures. Therefore, migratory behaviour should be regarded as a life-history trait possibly constraining the phenological response to rapid climatic changes in avian species.

BackgroundWest Nile virus (WNV) and Usutu virus (USUV), both belonging to the genus Flavivirus, are emerging in Italy as important human and animal pathogens. Migratory birds are involved in the spread of Flaviviruses over long distances, particularly from Africa to Europe. Once introduced, these viruses can be further be dispersed by short-distance migratory and resident bird species. Thus far, there is still a considerable knowledge gap on the role played by different bird species in the ecology and transmission mechanisms of these viruses. The Region of Trentino-Alto Adige (north-eastern Italy) is located on the migratory route of many of the short- and long-distance migratory birds that cross the Alps, connecting northern Europe and western Asia with southern Europe and Africa. Until now, only a silent circulation of WNV and USUV within the territory of the Province of Trento has been confirmed by serological screening, whilst no cases of infected humans or animals have so far been reported. However, continuous spillover events of both viruses have been reported in neighbouring Regions. The aim of this study was to monitor the circulation of WNV and USUV in Trentino-Alto Adige, in order to detect if active virus shedding occurs in migratory birds captured during their seasonal movements and to evaluate the role that different bird species could play in the spreading of these viruses.MethodsWe carried out a biomolecular survey on oral and cloacal swabs collected from migratory birds during seasonal migrations. Birds belonging to 18 transaharian and 21 intrapaleartic species were examined during spring (n = 176) and autumn (n = 146), and were tested using a generic nested-PCR.ResultsAll samples tested negative for Flaviviruses. The possible causes of unapparent shedding, along with ecological and epidemiological implications are discussed.ConclusionsThe lack of detection of active virus shedding in these bird species does not exclude the circulation of these viruses within the Trentino-Alto Adige region, as reported in previous studies. The possible ecological implications are discussed.

The gut microbiota, considered the “invisible organ” in the host animal, has been extensively studied recently. However, knowledge about the gut microbiota characteristics of passerine migratory birds during migration is limited. This study investigated the gut microbiota characteristics of three dominant migratory bird species (namely orange-flanked bluetail Tarsiger cyanurus, yellow-throated bunting Emberiza elegans, and black-faced bunting Emberiza spodocephala) in the same niche during spring migration and whether they were bird sex-specific. The compositions of gut microbiota species in these three migratory bird species and their male and female individuals were found to be similar. The main bacterial phyla were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes, and the main genera were Lactobacillus, Acinetobacter, Rickettsiella, and Mycobacterium; however, their relative abundance was different. Moreover, some potential pathogens and beneficial bacteria were found in all the three bird species. Alpha diversity analysis showed that in T. cyanurus, the richness and diversity of the gut microbiota were higher in male individuals than in female individuals, while the opposite was true for E. elegans and E. spodocephala. The alpha diversity analysis showed significant differences between male and female individuals of E. elegans (p < 0.05). The beta diversity analysis also revealed that the gut microbial community structure differed significantly between the male and female individuals of the three migratory bird species.

Ireland's geographic location on the western fringe of the European continent, together with its island status and impoverished avifauna, provides a unique opportunity to observe changes in bird migration and distribution patterns in response to changing climatic conditions. Spring temperatures have increased in western Europe over the past 30 years in line with reported global warming. These have been shown, at least in part, to be responsible for changes in the timing of life cycle events (phenology) of plants and animals. In order to investigate the response of bird species in Ireland to changes in temperature, we examined ornithological records of trans-Saharan migrants over the 31-year period 1969-1999. Analysis of the data revealed that two discrete climatic phenomena produced different responses in summer migrant bird species. Firstly, a number of long-distance migrants showed a significant trend towards earlier arrival. This trend was evident in some species and was found to be a response to increasing spring air temperature particularly in the month of March. Secondly, (1) a step change in the pattern of occurrences of non-breeding migrant bird species, and (2) an increase in the ringing data of migrant species were found to correlate with a step change in temperature in 1987-1988. These results indicate that, for migrant bird species, the impact of a sudden change in temperature can be as important as any long-term monotonic trend, and we suggest that the impact of step change events merits further investigation on a wider range of species and across a greater geographical range.