Migration Period Research Articles

Cave funeral practices during the Roman and Migration Periods in the Cracow Upland, southern Poland

Although caves have been used for funerary purposes almost since the dawn of time, there is very little evidence of such use in Central European Barbaricum. This paper presents newly obtained results from the Cracow Upland (southern Poland) concerning multiple skeletal remains that apparently share a similar third–fifth centuries AD chronology, corresponding to the Late Roman and Early Migration Periods. Multiple analyses have been performed to supplement archaeological data, including radiocarbon dating, osteoarchaeological analysis, ancient DNA research and isotopic analysis. The complex picture points towards unusual burial practices, which generally spanned from the third to the fifth centuries AD and involved a broad demographic, with no indication of selection based on an individual's biological profile. Isotopic analysis has also indicated the individuals’ heterogeneity with regard to diet and local versus nonlocal origin. The results point towards the previously unrecognized unique role of caves in the Przeworsk culture, then present in southern Poland.

30,000 years of fishing in the Philippines: New ichthyoarchaeological investigations in Occidental Mindoro

Marine adaptations are considered to have been significant factors in the evolution of our species (Homo sapiens). As humans dispersed from Africa around 100 kya, marine resources provided essential nutrients in island environments of the tropical Southeast Asian seas. The Philippine archipelago has revealed significant evidence of early human settlement during this period of coastal migration. Yet, despite being a global marine biodiversity hotspot, few studies have investigated prehistoric marine adaptations there. In this study, we focus on the analysis of fish bones from three sites in Occidental Mindoro, Philippines: Bubog I, Bubog II, and Bilat Cave with the aim of enhancing the understanding of H. sapiens' coastal adaptations and maritime interactions since at least 32,000 BP. We utilized expanded skeletal element identification protocols to determine the lowest taxonomic level possible, combined with diversity indices. The analyses indicate that H. sapiens on Mindoro mostly exploited near-shore environments, with temporal variations in fishing practices reflecting differences in site occupation intensity and periods of climate-mediated habitat change. Inter-site variations in fishing practices are likely related to disparities in local marine habitats. Spatiotemporal differences in marine environments influenced the development of diverse fishing methods and technologies, demonstrating a detailed knowledge of local aquatic environments and the adaptability of modern humans in Island Southeast Asia since the Pleistocene.

Planet migration in massive circumbinary discs

ABSTRACT Most stars are in multiple systems, with the majority of those being binaries. A large number of planets have been confirmed in binary stars and, therefore, it is important to understand their formation and dynamical evolution. We perform simulations to investigate the migration of wide-orbit giant planets (semimajor axis 100 au) in massive circumbinary discs (mass $0.1\, {\rm M}_{\odot }$) that are marginally gravitationally unstable, using the three-dimensional Smoothed Particle Hydrodynamic code seren. We vary the binary parameters to explore their effect on planet migration. We find that a planet in a massive circumbinary disc initially undergoes a period of rapid inward migration before switching to a slow outward migration, as it does in a circumstellar disc. However, the presence of the binary enhances planet migration and mass growth. We find that a high binary mass ratio (binary with equal mass stars) results in more enhanced outward planet migration. Additionally, larger binary separation and/or higher binary eccentricity results to a faster outward planet migration and stronger planet growth. We conclude that wide-orbit giant planets attain wider final orbits due to migration around binary stars than around single stars.

The permanent regime of temporary solutions: Housing of forced migrants in Europe as a policy challenge

Periods of forced migration to and in Europe have been common in the past decade and show no expectation of stalling due to ongoing armed conflicts, global inequalities and the adverse effects of climate change. Nevertheless, the provision of accommodation for asylum seekers and refugees continues to depend on temporary, ad hoc solutions. In the context of housing financialisation and shortage of affordable housing across European cities, this decreases opportunities for integration and securing other needs, such as jobs, language acquisition and childcare, but increases the risk of refugee homelessness and social exclusion. Based on cross-national Urban Living Labs exchanges in Leipzig, Riga, Lund, Helsingborg and Vienna, this commentary argues for a European agenda for long-term housing solutions for forced migrants in the arrival and settling phases that tackle issues from discrimination to access, to belonging. Importantly, creating long-term housing solutions for refugees would benefit whole housing systems as instruments of social inclusion.

An integrated archaeo-palaeoenvironmental approach to the study of human-environment relationships in the Wierzchowo Lake microregion (Northern Poland) during the Mid- to Late Holocene

The area surrounding Wierzchowo Lake, located in the central part of Pomerania (Northern Poland), is of particular interest from the point of view of the development of past settlements. Archaeological data have revealed human activity during various periods, ranging from the Palaeolithic through the Modern Period. This may suggest the relative and long-term attractiveness of this area. Among archaeological sites from this microregion, a monumental, well-preserved hillfort located in the Wierzchowo Lake peninsula stands out. Although limited excavations were carried out and numerous archaeological materials were collected, its origin remains unclear. Unfortunately, this hillfort could not be properly investigated during the excavations, due to the conservation conditions resulting in a high level of administrative protection. Having these limitations in mind, it was decided to conduct a palaeoenvironmental investigation in the vicinity of this hillfort and correlate its results with the extensive archaeological information available for this area. An investigation based on pollen, charcoal, and geochemical analysis of the lake sediments and their juxtaposition with the available archaeological record, a broad insight into the past of this region, and the nature of the relationship between people and the natural environment were revealed. The first traces of permanent settlement have been linked to the Funnel Beaker culture. A strong increase in human impact within the microregion and important changes in local vegetation (e.g., deforestation, the spread of ruderal habitats) have been associated with the activities of Lusatian culture groups at the end of the Late Bronze Age. A significant transformation of the natural environment and modification of farming practices has been recorded during the Roman Period (Wielbark culture communities) and Medieval Times (Slavic culture). Changes in vegetation composition have also been related to climatic fluctuations around 850 BCE, during the Migration Period and Little Ice Age, when temporary settlement regressions were observed.

Post‐colony swimming migration in the genus Uria

Seabirds within the Alcini subfamily have a unique breeding strategy, with their offspring leaving the colony flightless, at only a quarter of adult body size, accompanied by the father and fledge (become independent) out at sea. In this study we test several hypotheses about this elusive second part of the breeding season, termed swimming migration, for common guillemots Uria aalge and Brünnich's guillemots Uria lomvia by tracking 34 chicks (of which 17 transmitted data) equipped with satellite linked Argos PTTs (Platform Transmitter Terminals) at Bjørnøya, a major colony in the European Arctic. All chicks, presumably accompanied by their fathers, swam actively towards species‐specific autumn staging areas, rather than passively drifted away from the colony with a swim speed generally twice that observed of surrounding surface currents. They swam fastest during the first two days after departure. This coincides with the only time they actively crossed a current and the time needed to leave the area of prey depletion around the colony. They otherwise took advantage of available currents, while still swimming actively during the remainder of their migration towards species‐specific autumn staging areas. These staging areas corresponded to areas used by breeding adults during their moulting period (as confirmed by complementary light‐level logger tracking of adults), rather than being specific nursery areas. Migration duration correlated with distance resulting in species‐specific migration periods that were only a fraction of previously reported fledging periods out at sea, indicating that not only the swimming migration, but also known adult autumn staging regions constitute in effect breeding areas. This work has important implications for our understanding of population dynamics within the Alcini subfamily and the management of these species under multiple threats, while providing the foundation to investigate swimming migrations across their distributional range.

Hot stops: timing, pathways, and habitat selection of migrating eastern whip‐poor‐wills

Although miniaturized data loggers allow new insights into avian migration, incomplete knowledge of basic patterns persists, especially for nightjars. Using GPS data loggers, this study examined migration ecology of the eastern whip‐poor‐will Antrostomus vociferus, across three migration strategies: flyover, short‐stay, and long‐stay. We documented migration movements, conducted hotspot analyses, quantified land cover within 1 and 5 km buffers at used and available locations, and modeled habitat selection during migration. From 2018–2020 we captured breeding whip‐poor‐wills from three study sites in Massachusetts and programmed GPS tags to collect data during fall and spring migration periods. Across 19 individual males (nine of them with repeated years of data), GPS tags collected 479 locations, where 30% were classified as flyover points, 33% as short‐stays, and 37% as long‐stay locations. We documented seasonal flexibility in migration duration, routes, and stopover locations among individuals and between years. Analyses identified hotspot clusters in fall and spring migration in the Sierra de Tamaulipas in Mexico. Land cover at used locations differed across location types at the 5 km scale, where closed forest cover increased and crop cover decreased for flyover, short‐stay, and long‐stay locations, and urban cover was lowest at long‐stay locations. Discrete choice modeling indicated that habitat selection by migrating whip‐poor‐wills differs depending on the scale and migration strategy. For example, at the 5 km scale birds avoided urban cover at long‐stay locations and selected closed forest cover at short‐stay locations. We suggest that whip‐poor‐wills may use land cover cues at large spatial scales, like 5 km, to influence rush or stay tactics during migration.

Regenerative economy: A pathway to a future-ready, sustainable Africa

ABSTRACT Africa is experiencing a period of rapid economic growth, booming population, and migration as biodiversity is deteriorating and the climate is warming. Together, these represent grand societal and environmental challenges. The African Union and the United Nations both promote sustainable development, in which society and nature flourish as the economy progresses. However, achieving this goal is not self-evident. We discuss the concept of regenerative economy and propose it as a path forward for the African context. We identify three levers of action evident in Africa that promote the idea of regenerative economy: clean innovation in technology and business models, leapfrogging through decentralized communication and energy systems, and leveraging African values of horizontal collectivism. We present some case examples of how this can and does work but highlight that achieving regenerative economy en masse depends on scaling up business models, effective governance structures, and capacity building in Africa. If implemented correctly, regenerative economy can offer pathways to a future-ready, sustainable Africa.

MIGRATION PROCESSES IN THE CHUVASH REPUBLIC: TRENDS, PROBLEMS

Migration processes in Russia and its regions at the present stage are an urgent object of study by specialists in the humanities due to their scale and consequences associated with the demographic development of the country. Regional historiography also focused on the aspects of migration situation related to population decline. The scientific novelty of the study consists in a comprehensive historical analysis of the migration situation in the Chuvash Republic in 2001–2020, which makes it possible to identify the features and conditional periods of migration in the region.
 
 The purpose of the research is to study the processes, scales and models of migration behavior of Chuvashia’s population, taking into account socio–demographic parameters, to identify trends and problems. Migration of the population is considered in connection with the processes of ethno-cultural development and the state of interethnic relations. Attention is paid to the study of the population’s attitude to migration and migrants.
 
 Materials and methods. The main sources of the study were statistical and archival data, official documents, the results of sociological surveys, media materials. The dynamics of the population’s attitude to migration processes is based on the results of sociological surveys of the Republic’s population, which have a monitoring nature. Migration of the population was assessed using statistical data analysis, the method of mass questioning was used in sociological surveys. Migration processes are characterized taking into account historical-comparative and problem methods.
 
 Study results. A number of factors affecting migration processes and changing migration behavior of the population have been identified in the region. The main ones remain socio-economic factors, changes in the ethno-cultural image of society. Social aspects are relevant and come to the forefront in the issues of integration of migrants and their interaction in the host community. The migration situation in the republic is quite complicated: a migration decline in the population is observed. Intensive temporary migrations of the Republic’s population result in pronounced social consequences in the context of the socio-demographic development of the Republic and its society. Young people show the most active readiness for migration. Among the trends in interethnic relations that cause certain wariness, a restrained attitude towards migrants should be noted, which manifests itself over a long period of time.
 
 Conclusions. Migration processes of the Republic’s population have both positive and negative consequences. Most residents of Chuvashia perceive migrants as potentially dangerous, firstly, from the point of view of increased competition in the labor market, and secondly, as people with their own traditions and customs who do not really respect local ethno-cultural characteristics. The issues of migration loss of the population, the tendency of a significant outflow of the working population from the Republic remain relevant. But in general, the population of Chuvashia is quite friendly to various contacts with representatives of other ethnic groups, Chuvashia is a region with stable and favorable interethnic relations.

Opening graves and turtles. The pond turtle (Emys orbicularis L.) from the cemetery of the Wielbark Culture in Czarnówko and the question of post-funeral interferences in the past

Abstract In 2010, the remains of a pond turtle were discovered at the bottom of a secondary pit (“robbery” trench) in one of the graves (feature 963) in the Wielbark Culture cemetery at Czarnówko (PL). This paper attempts to characterise the find from Czarnówko in the context of two important questions: the opening of graves and the presence of turtle remains in the grave against the background of similar finds from the Central and East European Barbaricum. The problem of post-burial manipulation affects about 90 % of the graves in the cemetery at Czarnówko. The situation from grave 963 finds analogies in the burial grounds of the Masłomęcz Group, the Chernyakhiv culture and the Sarmatian and Longobard sites. The problem of the presence of these reptiles in the graves is related as it turns out to the phenomenon of grave opening, a phenomenon of great territorial and chronological extent observed in the areas where inhumation was practised during the Roman Period and the Migration Period.

Assessing migratory bottlenecks and escapement of silver eel (Anguilla anguilla) in the highly urbanized North Sea Canal basin, the Netherlands

AbstractHabitat fragmentation and migration barriers have attributed to the decline of European eel (Anguilla anguilla). The migration of silver eels through pumping stations, ship locks, and migration facilities within the North Sea Canal basin using acoustic telemetry and overall escapement by mark–recapture was studied. A network of 61 acoustic receivers and three PIT‐tag stations was built, and 305 silver eels were tagged with acoustic transmitters and 3923 with PIT‐tags. Of all the silver eels that were detected, 55% passed barriers between the polders and the canal and 46% also passed the barrier complex at IJmuiden to sea, mainly via the ship locks. Overall, silver eel escapement to the North Sea per year averaged 81,629 silver eels and 14.3% suffered mortality in the pumping station at IJmuiden. Migration speed was lower for silver eels that initiated their migration upstream compared with silver eels further downstream, higher for silver eels passing barriers later in the migration period, and highest at sea. This study of silver eel movement and escapement in the North Sea canal basin indicated several bottlenecks. Passage success along barriers varied strongly between sites and types of barriers. While at two smaller locations, silver eels migrated through the pedal valves in the ship lock gates, a small passage facility and the pedal valves in a ship lock at complex IJmuiden did not enhance silver eel migration. The barriers and unnatural canal system caused additional delay during silver eel migrations. Mitigation measures for management could include installing fish‐friendly pumps, using pumping stations only during the day, and in addition opening ship locks and pedal valves at the beginning of the night.

Discharge‐Mediated Temperature Management in a Large, Regulated River, With Implications for Management of Endangered Fish

AbstractFor large, regulated rivers, operators can impact abiotic conditions for the benefit of the ecosystem, primarily by controlling the volume of discharge from upstream reservoirs. Understanding the decision space around discharge is necessary for evaluating tradeoffs between environmental and other objectives. As a result of climate change, warming water temperatures are increasingly becoming a concern for thermally‐sensitive fauna. In California's largest river, the Sacramento, extinction risk of salmon populations is linked to high water temperatures. Yet, little is known about how much water temperature in lower reaches can be affected by reservoir discharge operations, and the potential benefits to salmon. We used a process‐based water temperature model to estimate the ability of reservoir discharge to mediate river temperature heating processes impacting downstream locations (discharge‐mediated temperature management). To bound this analysis, we used historical forcings over a recent 29‐year span. Results indicate reservoir discharge increases of up to 340 cms over the historical record could have decreased water temperature in the lower reaches by up to 3.6°C. Salmon require water below 20°C during most stages of their lifecycle, and we found that normative water operations could ensure 20°C was rarely exceeded for two potential management seasons, in late‐spring and early‐fall. These periods coincide with important rearing and migratory periods for salmon, during which they frequently experience excessive temperatures under the management status‐quo. This analysis provides stakeholders tools to manage conditions for native fauna in the face of a warming climate, and a framework for developing similar tools in other large, regulated rivers.

Eulachon migration patterns in the lower Fraser River revealed through acoustic telemetry

AbstractObjectiveThe Fraser River in British Columbia, Canada, historically supported productive Indigenous, recreational, and commercial fisheries for Eulachon Thaleichthys pacificus. Although Eulachon spend most of their lives in the marine environment, they spawn in freshwater and it is hypothesized that habitat degradation in the Fraser River has contributed to population decline. A greater understanding of Eulachon life history strategies is necessary to develop species recovery strategies. The purpose of this study was to provide insight into population demographics, migration timing, residence time, travel speed and distance, and movement patterns of Eulachon traveling in the Fraser River by conducting index netting and acoustic telemetry.MethodsIn total, 244 Eulachon were acoustically tagged at the mouth of the Fraser River, and their movements were monitored using acoustic receivers in the lowermost 70 km of the Fraser River and in the Pitt River (a tributary to the Fraser River) over a 2‐year period.ResultTagged Eulachon displayed heterogeneous movement behaviors and a protracted migration period between February and May. Eulachon index gill netting revealed three discrete migration groups matching traditional ecological knowledge from Indigenous knowledge holders. There were shifts in population demographics, with sex ratios changing from predominately males to females throughout the migration. Residence time within the estuarine salt wedge and river was short. Upstream travel speeds varied significantly between sexes and slowed as fish traveled upstream.ConclusionOverall, Eulachon travel speeds, travel distances, and residence times, along with size and sex effects, provided insights into movement patterns. These results will increase our understanding of sex‐specific risks related to instream disturbance, harvest, and predation and will inform management decisions regarding protection of critical habitats. The observed patterns highlight the need for stock assessment methods to consider all discrete migration groups and will assist in prioritizing species recovery efforts.

Княжеская фибула из села Рэзень

The fibula is a stray find discovered by locals near the Răzeni village in the Ialoveni district of the Republic of Moldova and in 2022 was transferred to the National Museum of the History of Moldova. This is a two-plate fibula with a rhombic foot and a semicircular head. Its body was made of white metal (silver?) enclosed in a gold overlay. The shields and the arched bow were decorated with carnelian and overlaid metal elements (grain, double spirals, ribbed and openwork). This type of brooches is part of the “ethnographic” female costume of the Chernyakhov culture of the late Roman period. At the beginning of the Great Migration Period, this dress served as the basis for the formation of the “princely” costume of the East German tradition with large two-plate brooches, which became widespread in the 5 th century AD from the Atlantic to the North Caucasus. The fibula has a prestigious character and belongs to the “princely” culture of the initial phase of the Migration Period. According to the general morphology, it belongs rather to the D1 period i. e., 360/370—400/410, and according to the design analogues on large brooches, it belongs to the D2 period or 380/400—440/450. In Eastern Europe, both of these periods are usually combined in the framework of the so-called Hunnic time. Two versions of the identification of this fibula are possible. Perhaps this is a children’s copy of a large fibula. Another scenario is that the size of the fibula reflects the status level of their owners. It is possible that this item was intended for ladies who occupy a high position in society, but who, according to the hierarchy, were “below” the bearers of large polychrome brooches.

Воинские традиции в детском костюме элиты позднеантичной Фанагории

Warrior burials are not often found in late ancient necropolises of the Cimmerian Bosporus. Such burials rarely survive untouched by robbers. In this context, a recently discovered well-preserved large tomb in Phanagoria is a really unique find. After examining this grand two-chamber vault, archaeologists obtained a set of interesting data, but special attention should be paid to warrior traditions adopted by people who lived in the late ancient capital of the Asian Bosporus. The importance of warrior subculture of the Migration period for the urban elite is manifested in the use of warrior fittings in children clothes. It is a known fact that a buried man who belonged to the warrior class is marked not only by the weapons found with him, but also by shoulder belts, elements of warrior accessories fastened on his body in a certain way. The passing of such subculture through generations of Phanagorian noble men is greatly illustrated by finds from the vault where archaeologists found in situ remains of noble warriors and their descendants, children of various age. The children clothes were largely imitating the clothes of equestrian warriors. This outstanding archaeological situation expressly testifies to cultivation of warrior traditions among boys since their early childhood and pronounced external manifestations, including in elements of their costume, of male children’s inclusion in the warrior subculture.

Autumn migration of the migrant hawker (Aeshna mixta) at the Baltic coast

BackgroundMigratory insects are important for the provision of ecosystem services both at the origin and destination sites but – apart from some iconic species – the migration routes of many insect species have not been assessed. Coastlines serve as a funnel where migrating animals including insects accumulate. Migratory behaviour and captures of dragonflies in bird traps suggest autumn migration of dragonflies along coastlines while the origin and regularity of this migration remain unclear.MethodsDragonfly species were caught at the bird observatory Kabli at the Baltic coast in Estonia in 2009, 2010 and 2015. For the 2015 data set, we used a stable hydrogen (H) approach to trace the potential natal origin of the migrant hawker (Aeshna mixta).Results1079 (2009), 701 (2010) and 88 (2015) A. mixta individuals were caught during the study periods (35, 37 and 11 days in 2009, 2010 and 2015, respectively). The migration period lasted from end of August to end of September. Based on the results from our stable isotope analysis, we identified two populations of A. mixta: One (range of isotope signatures of non-exchangeable H [δ2Hn wing]: −78‰ to −112‰) had a local likely origin while the other (δ2Hn wing: −113‰ to −147‰) migrated from northerly directions even in headwind from the South. The former showed an even sex ratio whereas the actively migrating population was dominated by males.ConclusionsOur results suggest a regular southbound autumn migration of A. mixta along the Baltic coast. However, nearly half of the sampled individuals originated from the surroundings suggesting either no, partial or “leap-frog” migration. Contrary to our expectation, A. mixta did not select favourable wind conditions but continued the southbound autumn migration in the flight boundary layer even in case of headwinds. The dominance of males might indicate migration as a result of competition for resources. Further repeated, large-scale studies along the Baltic coast are necessary to pinpoint the migratory pattern and the reason for migration of A. mixta. Such studies should also comprise locations north of the known species range of A. mixta because of the rapid climate-change induced range expansion.

High-resolution GPS Tracking of American Kestrels Reveals Breeding and Post-Breeding Ranging Behavior in Northern Virginia, USA

ABSTRACT Long-term monitoring data indicate a persistent decline in American Kestrel populations across North America. Loss or alteration of habitat have been listed as potential causal factors, but basic information on kestrel space use, including breeding home range size, is lacking. No study has provided robust estimates of the ranging behavior of breeding kestrels based on tracking data of any resolution. We fitted 19 adult female kestrels with solar-powered GPS transmitters during the incubation period in northern Virginia. High-resolution tracking began during the early nestling stage for 17 birds. We collected an average of 1710 locations per bird through the end of the breeding season (31 August), with 13 birds tracked through the fledging of their young. Autocorrelated kernel density home range estimation showed that female kestrels used breeding home ranges that were smaller (average: 0.32 km2) than most previously published range sizes. Home ranges did not vary significantly in size across breeding stages and demonstrated little overlap with the ranges of neighboring kestrels. Five females shifted their territories in the post-breeding stage (i.e., after disappearance or dispersal of fledglings) between 1.5 and 12.3 km from their nest box; they maintained these new ranges at least to the migration period. We also documented home range excursion forays (n = 128) by all 12 consistently tracked females. Mean (4.0 km) and maximum (127.7 km) foray distances were some of the largest reported among birds and mammals relative to home range size. Weekly foray rates were highest during the nestling stage, and for birds that ultimately shifted from their breeding home range. The existence of long-distance foray behavior and the use of multiple summer home ranges, both shown here for the first time for this species, has a direct impact on interpretation of kestrel nest-site and habitat selection data, and on the assessment of potential threats to this species in the breeding season.

Mars and Mercury. A golden wolf from Western Poland – a mysterious find

Abstract The paper discusses a mysterious zoomorphic wolf-shaped copper alloy artefact that was discovered as a stray find in Międzyrzecz (Poland). The find is bar-like with a profiled engraved image of a lying animal, possibly a wolf. It is locally gilded on the visible side of “wolf” details. The gilding was made using an amalgam technique known since Antiquity, with the base metal composed of arsenical copper alloy with lead addition. A fixing element made of iron has only survived fragmentarily, which renders the reconstruction of the entire artefact’s shape impossible. Its function has not been identified, but a broad spectrum of possible interpretations has been proposed. Stylistic traits allow to date the artefact to the Migration Period, or more specifically to the 6th century. The wolf image implies that the artefact can be related to the Germanic warriors’ world. At present, it cannot be determined whether there was a 6th century settlement cluster in the vicinity of Międzyrzecz to which the find can be related, or we are dealing with an isolated testimony of population translocations.

Review of Conservation Challenges and Possible Solutions for Grassland Birds of the North American Great Plains

North America's grassland birds remain in crisis despite decades of conservation efforts. This review provides an overview of factors contributing to these declines, as well as strategies and resources available to a diversity of stakeholders to help conserve grassland bird communities with an emphasis on the Great Plains—a grassland region of global ecological significance and a habitat stronghold for grassland birds. Grassland bird declines are driven by historical and continuing threats across the full annual cycle including grassland habitat loss, agriculture intensification, woody encroachment, and disruption of fire and grazing regimes. More recently, energy development activities, the use of neonicotinoid pesticides, and anthropogenic climate change have emerged as additional threats. While threats to grassland birds are numerous and often synergistic, possibilities for conservation are also diverse and multifaceted. Land set-aside programs, incentives and voluntary practices for producers, improved environmental management by energy and utility companies, and policy and regulation can all contribute to the conservation of these unique species. We suggest that future grassland bird research should focus on poorly studied aspects of the annual cycle, such as overwinter survival and habitat use, and the migratory period, which remains completely unexplored for many species. Filling these knowledge gaps may facilitate more sophisticated population modeling that can identify limiting factors and more effectively guide investment in conservation.

Highlighting relationships between sand thicknesses, reservoir-seal pairs and paleobathymetry from a sequence stratigraphic perspective: An example from Tortonian Serravallian deposits, onshore Niger Delta Basin

The utilization of sequence stratigraphic concepts in identifying sands and their spatial continuity in distinct gross depositional settings is key, especially in frontier settings where data paucity is a common challenge. In the Baka field, onshore Niger Delta, detailed reservoir correlation guided by sequence stratigraphic framework analysis showed the distribution of sand and shale units constituting reservoir-seal pairs (RSP) correlatable across the field. Within the 3rd-order packages, it is observed that the lowstand systems tract (LST) and highstand systems tract (HST) contain more RSPs and thicker 4th- and 5th-order sands than the transgressive systems tract (TST). In terms of bathymetry, it is noted that irrespective of systems tracts, the RSP Index (RI) decreases from the proximal shallow/inner shelf settings to the more distal outer shelf areas. Amongst all three systems tracts, intervals interpreted as lowstand prograding complexes contain the best developed sands and highest RSP. Sand development within the LSTs has been controlled by a pronounced growth fault regime accompanied by high subsidence and sedimentation rates. This is linked to the basinward migration of the sands during prolonged sea-level fall, creating significant accommodation space for sand deposition. On the other hand, the TSTs known to mark periods of progressive sea-level rise and landward migration of sandy facies, show thinner sands enclosed in much thicker, laterally extensive, and better-preserved deeper marine shales. Interpreted seismic sections indicate intense growth faulting and channelization that influenced the syn- and post-depositional development of the sand packages across the field. The initial timing of deformation of sub-regional faults in this area coincides with periods of abrupt falls in sea level. This approach could be useful for predicting sand-prone areas in frontier fields as well as possible reservoir-seal parameters required for some aspects of petroleum system analysis and quick-look volume estimation.