Winter Migration Research Articles

Delayed post-juvenile moult in malaria-infected Eurasian blackcaps.

Parasites have their strongest impact on fitness when host defences deplete resources needed for other critical life-history stages, such as development, breeding or migration. Among birds, one greatly neglected stage that could be altered by parasites is post-juvenile moult (PJM), through which yearling juvenile birds replace their fast-generated, low-quality juvenile feathers with adult-like feathers after leaving the nest. The earlier the birds complete PJM, the earlier they will be prepared to withstand forthcoming challenges, such as adverse winter conditions or migration. We used data from 435 juvenile Eurasian blackcaps (Sylvia atricapilla) sampled during three years in 26 localities spanning the wide range of environmental conditions across Iberian Spain to test whether haemosporidian infections (presence and abundance in blood of parasites of the genera Haemoproteus, Plasmodium and Leucocytozoon) were related to the progress of PJM. Controlling for body condition, sex, year and date of capture, infected blackcaps (single-infected or co-infected) had lower moult scores indicative of delayed moult, especially when birds had Plasmodium infections or high intensities of Haemoproteus parasites. Our results broaden the range of fitness costs that haemosporidian parasites may have on birds, as delayed post-juvenile plumage acquisition can impact subsequent key life-history stages.

Highly Pathogenic H5N1 Influenza A Virus (IAV) in Blue-Winged Teal in the Mississippi Flyway Is Following the Historic Seasonal Pattern of Low-Pathogenicity IAV in Ducks.

Highly pathogenic H5N1 (HP H5N1) influenza A virus (IAV) has been detected annually in North American ducks since its introduction during 2021, but it is unknown if this virus will follow the same seasonal and geographic patterns that have been observed with low-pathogenicity (LP) IAV in this reservoir. We monitored blue-winged teal in the Mississippi flyway prior to the detection of HP H5N1 and during two post-introduction migration cycles from spring 2022 to spring 2024, testing birds for infection and antibodies to IAV nucleoprotein (NP), hemagglutinin subtype H5, and neuraminidase subtype N1. Antigens representing clade 2.3.4.4b HP H5 and LP North American H5 were used for hemagglutination inhibition (HI) and virus neutralization (VN) tests for H5 antibodies. Virologic results were consistent with historic seasonal and geographic patterns reported for LP IAV with peak infections occurring in pre-migration staging areas in Minnesota during fall 2022. However, the high prevalence of the H5 subtype was exceptional compared to historic prevalence estimates at this same site and for the Mississippi flyway. HP H5N1 was detected on wintering areas in Louisiana and Texas during the fall of that same year and this was followed by an increase in estimated antibody prevalence to NP, H5, and N1 with no HP H5N1 detections during the wintering or spring migration periods of 2022/2023. HP H5N1 was not detected in Minnesota during fall 2023 but was detected from a single bird in Louisiana. However, a similar increase in antibody prevalence was observed during the winter and spring period of 2023 and 2024. Over the two migration cycles, there was a temporal shift in observed prevalence and relative titers against the H5 antigens with a higher proportion of ducks testing positive to the 2.3.4.4b H5 antigen and higher relative titer to that antigen compared to the representative LP North American H5 antigen. The seasonal and geographic patterns observed appear to be driven by population immunity during the migration cycle. Results support an initial high infection rate of HP H5N1 in blue-winged teal in the Mississippi flyway followed by a high prevalence of antibodies to NP, H5, and N1. Although prevalence was much reduced in the second migration cycle following introduction, it is not known if this pattern will persist in the longer term or affect historic patterns of subtype diversity in this reservoir.

Intraseasonal shift in the wintertime North Atlantic jet structure projected by CMIP6 models

The projected winter changes of the North Atlantic eddy-driven jet (EDJ) under climate change conditions have been extensively analysed. Previous studies have reported a squeezed and elongated EDJ. However, other changes present large uncertainties, specifically those related to the intensity and latitude. Here, the projections of the EDJ in a multimodel ensemble of CMIP6 are scrutinised by using a multiparametric description of the EDJ. The multimodel mean projects non-stationary responses of the EDJ latitude through the winter, characterised by a poleward shift in early winter and equator migration in late winter. These intraseasonal shifts (rather than a genuine narrowing) explain the previously established squeezing of the EDJ and are linked to the future changes in different drivers: the 200 hPa meridional temperature gradient and Atlantic warming hole in early winter, and the stratospheric vortex in late winter. Model biases also influence EDJ projections, contributing to the poleward shift in early winter.

Influence of migration range and foraging ecology on mercury accumulation in Southern Ocean penguins

In order to evaluate mercury (Hg) accumulation patterns in Southern Ocean penguins, we measured Hg concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in body feathers of adult Adélie (Pygoscelis adeliae), gentoo (Pygoscelis papua), and chinstrap (Pygoscelis antarctica) penguins living near Anvers Island, West Antarctic Peninsula (WAP) collected in the 2010/2011 austral summer. With these and data from Pygoscelis and other penguin genera (Eudyptes and Aptenodytes) throughout the Southern Ocean, we modelled Hg variation using δ13C and δ15N values. Mean concentrations of Hg in feathers of Adélie (0.09 ± 0.05 μg g−1) and gentoo (0.16 ± 0.08 μg g−1) penguins from Anvers Island were among the lowest ever reported for the Southern Ocean. However, Hg concentrations in chinstrap penguins (0.80 ± 0.20 μg g−1), which undertake relatively broad longitudinal winter migrations north of expanding sea ice, were significantly higher (P < 0.001) than those in gentoo or Adélie penguins. δ13C and δ15N values for feathers from all three Anvers Island populations were also the lowest among those previously reported for Southern Ocean penguins foraging within Antarctic and subantarctic waters. These observations, along with size distributions of WAP krill, suggest foraging during non-breeding seasons as a primary contributor to higher Hg accumulation in chinstraps relative to other sympatric Pygoscelis along the WAP. δ13C values for all Southern Ocean penguin populations, alone best explained feather Hg concentrations among possible generalized linear models (GLMs) for populations grouped by either breeding site (AICc = 36.9, wi = 0.0590) or Antarctic Frontal Zone (AICc = 36.9, wi = 0.0537). Although Hg feather concentrations can vary locally by species, there was an insignificant species-level effect (wi < 0.001) across the full latitudinal range examined. Therefore, feeding ecology at breeding locations, as tracked by δ13C, control Hg accumulation in penguin populations across the Southern Ocean.

Patterns of persistence: Genetic and behavioral population complexity of winter flounder amid population declines.

Winter flounder Pseudopleuronectes americanus (Walbaum 1792) are a coastal flatfish species of economic and cultural importance that have dwindled to <15, % of their historic abundance in the southern New England/Mid-Atlantic region of the United States, with evidence indicating near-extirpation of certain local populations. This species exhibits intricate behaviors in spawning and migration that contribute to population complexity and resilience. These behaviors encompass full or partial philopatry to natal estuaries, the generation of multiple pulses of larval delivery, and partial migration. The patterns of genetic diversity within and among estuaries and cohorts presented here carry important implications in understanding the susceptibility to demographic shocks, even if the full extent of genetic diversity within and among winter flounder stocks on the US East Coast remains unresolved. Our findings reveal connectivity between estuaries in Long Island, New York, suggesting the potential for genetic rescue of depleted subpopulations. Family reconstruction and relatedness analysis indicate that split cohorts and migration contingents are not the result of genetically distinct lineages. We found no evidence for genetic structure separating these groups, and in some instances, we were able to detect closely related individuals that belonged to different migratory contingents or cohorts. Characterizing the spatial and behavioral organization of this species at the population level is crucial for comprehending its potential for recovery, not only in terms of biomass but also in reinstating the complex population structure that supports resilience. The search for generality in winter flounder spawning and migration behavior remains elusive, but perhaps the lack of generalities within this species is what has allowed it to persist in the face of decades of environmental and anthropogenic stressors.

Long-term effects of climate change on juvenile bull shark migratory patterns.

Seasonal variability in environmental conditions is a strong determinant of animal migrations, but warming temperatures associated with climate change are anticipated to alter this phenomenon with unknown consequences. We used a 40-year fishery-independent survey to assess how a changing climate has altered the migration timing, duration and first-year survival of juvenile bull sharks (Carcharhinus leucas). From 1982 to 2021, estuaries in the western Gulf of Mexico (Texas) experienced a mean increase of 1.55°C in autumn water temperatures, and delays in autumn cold fronts by ca. 0.5 days per year. Bull shark migrations in more northern estuaries concomitantly changed, with departures 25-36 days later in 2021 than in 1982. Later, migrations resulted in reduced overwintering durations by up to 81 days, and the relative abundance of post-overwintering age 0-1 sharks increased by >50% during the 40-year study period. Yet, reductions in prey availability were the most influential factor delaying migrations. Juvenile sharks remained in natal estuaries longer when prey were less abundant. Long-term declines in prey reportedly occurred due to reduced spawning success associated with climate change based on published reports. Consequently, warming waters likely enabled and indirectly caused the observed changes in shark migratory behaviour. As water temperatures continue to rise, bull sharks in the north-western Gulf of Mexico could forgo their winter migrations in the next 50-100 years based on current trends and physiological limits, thereby altering their ecological roles in estuarine ecosystems and recruitment into the adult population. It is unclear if estuarine food webs will be able to support changing residency patterns as climate change affects the spawning success of forage species. We expect these trends are not unique to the western Gulf of Mexico or bull sharks, and migratory patterns of predators in subtropical latitudes are similarly changing at a global scale.

Specifics of &lt;i&gt;Anisakis simplex&lt;/i&gt; larvae infection in the Pacific herring &lt;i&gt;Clupea pallasii&lt;/i&gt; Valenciennes, 1847 from Lake Tunaicha

The purpose of the research is to analyze specifics of Anisakis simplex larvae infection in the body cavity of the lake Pacific herring in Lake Tunaicha (from materials of 1980 to 1995).Materials and methods. Conventional parasitological methods were used for collecting the material. The dissection recorded the number of nematodes in the fish. Parasitological studies of the herring from Lake Tunaicha (southern Sakhalin) were conducted from 1980 to 1995. A total of 4,438 fish caught in the Krasnoarmeyskaya channel and Lake Tunaicha were examined.Results and discussion. The parasite fauna in the herring from Lake Tunaicha included six parasite species of which two nematode species (Anisakis simplex l., Hystorethylacium aduncum l.), one acanthocephala species (Corynosoma strumosum juv.), one trematode species (Brachyphalus crenatus) and two parasitic copepod species (Ergasilus wilsoni and E. hypomesi). Among all the above species, A. simplex larvae were of greatest interest for study. The helminth is a typical species of the Pacific herring and poses a threat to human and animal health. The results of the studies found no difference in the infection of herring females or males in Lake Tunaicha. A change in the infection rate was demonstrated in the herring by age and linear dimensions depending on the fish life cycle (spawning and wintering migration periods). The first cases were recorded for herrings infected with Anisakis sp. larvae sized from 14 cm.

Diamond Gymnura natalensis and duckbill Aetomylaeus bovinus rays undertake nationwide coastal migrations.

Migration is a critical aspect of ocean ecosystems, and understanding this phenomenon answers ecological and management questions. Given the difficulty in tracking ocean animals across large distances, the extent to which different ray species perform long-distance movements, such as migrations, remains unknown. This study used passive acoustic telemetry to track the movements of endemic diamond Gymnura natalensis and critically endangered duckbill Aetomylaeus bovinus rays along the South African coastline using a collaborative nationwide network of coastal acoustic receivers for up to 7 years. Duckbill rays were detected significantly more frequently than diamond rays, but both species moved between the south and east coasts of South Africa (traveling up to 1167 km). Tagged individuals were detected significantly more often in their tagging locations during summer months but traveled significantly further distances during winter months. Furthermore, movement models fitted to individual duckbill rays' annual net-squared displacement identified most individual annual movements as migratory. This evidence suggests that both diamond and duckbill rays make eastward winter migrations and return to specific areas along the coastline during the summer months. The exceptions to this were diamond rays tagged on the east coast that were not found to migrate seasonally, which supports previous research that there is intraspecific variability in migrations for ray species. These findings have implications for understanding ray migration not only on a global scale but also locally for spatial management interventions and population delineation.

Spread of antibiotic resistance genes to Antarctica by migratory birds

Recent studies have highlighted the presence of antibiotic resistance genes (ARGs) in Antarctica, which are typically indicative of human activity. However, these studies have concentrated in the Antarctic Peninsula region, and relatively less is known about ARG prevalence in East Antarctica, where human activity levels are lower compared to the Antarctic Peninsula. In addition, the mechanisms of ARG transmission to Antarctica through natural or anthropogenic pathways remain unclear. In this study, we analyzed the fecal samples of Adélie penguins and South polar skuas by using high-throughput sequencing and microfluidic quantitative PCR to detect potential pathogens and ARGs at their breeding colonies near Syowa Station in East Antarctica. These results revealed the presence of several potential pathogens in the fecal matter of both bird species. However, the HF183 marker, which indicates human fecal contamination, was absent in all samples, as well as seawater sampled near the breeding colonies. This suggests that the human fecal contamination was negligible in our study area. In addition to pathogens, we found a significant number of ARGs and metal resistance genes in the feces of both Adélie penguins and South polar skuas, with higher detection rates in skuas than in penguins. To better understand how these birds acquire and transmit these genes, we analyzed the migratory patterns of Adélie penguins and South polar skuas by geolocator tracking. We found that the skuas migrate to the tropical and subtropical regions of the Indian Ocean during the austral winter. On the other hand, Adélie penguins exhibited a more localized migration pattern, mainly staying within Antarctic waters. Because the Indian Ocean is considered one of the major reservoirs of ARGs, South polar skuas might be exposed to ARGs during their winter migration and transfer these genes to Antarctica.

Barometric geolocators can reveal unprecedented details about the migratory ecology of small birds

Abstract Knowing the location of migratory birds throughout their annual cycle is fundamental for many questions in ornithology. Technological advances have provided several approaches, with increasing miniaturization allowing deployment on smaller and smaller birds. Here, we examine the strengths and limitations of barometric pressure geolocators (pressure tags), which have recently been shown to be extremely effective in tracking small birds (&amp;lt;25 g). The newly developed geolocation by pressure workflow (GeoPressureR) uses a global weather analysis dataset and hidden Markov movement model to reveal locations more accurately or continuously than can be achieved by other available light-weight devices (e.g., light-level geolocators, automated radio telemetry, and archival GPS tags). Additionally, pressure data can provide altitude information and document generally intractable flight behavior, as well as exact migratory phenologies. This new technology can be applied to important unresolved problems such as altitudinal migration, stopover site use, molt migration, vertical airspace use, and drivers of migratory flight initiation, duration, and direction. We provide an example of a pressure tag on a Swainson’s Warbler (Limnothlypis swainsonii) deployed on its breeding territory in Virginia, USA, revealing the complete story of its migration to and from Cuba, including its refined wintering site, stopover sites, and migration routes, all with precise timing. Studies relying on pressure tags are still subject to biases related to recovery of the devices for data extraction, and application to birds that exhibit extensive aerial movements (e.g., swallows and swifts) remains challenging. Widespread deployment of pressure tags could show unprecedented details of bird migration and other aspects of aerial behavior, which could benefit conservation and greatly enrich our understanding of avian movement ecology.

Intracolony variability in winter feeding and migration strategies of Atlantic puffins and black-legged kittiwakes

Polar ecosystems are subjected to many stressors, including climate change, that impact their overall functioning. Seabirds are good bioindicators of these systems as they readily respond to changes in environmental conditions. To quantify how environmental changes affect their life history, data on seabird diet, spatial distribution and body condition are needed to reveal the underlying mechanisms. We explored possible drivers of the winter distribution of single-colony populations of Atlantic puffins Fratercula arctica and black-legged kittiwakes Rissa tridactyla, two of the most numerous seabird species in the North Atlantic. Based on carbon and nitrogen stable isotopic data from feathers moulted during winter migration, we identified three groups of Atlantic puffins and two groups of black-legged kittiwakes occupying different isotopic niches. We then used geolocator tracking data for the same birds to determine if these groups reflected parallel differences in the location of moulting grounds rather than differences in their diet. We found that the isotopic niches of the three Atlantic puffin groups likely resulted from their use of different habitats during winter moult. In contrast, the isotopic niches of the two black-legged kittiwake groups were more likely a result of differences in their diet, as both groups were distributed in the same area. These findings suggest that different winter feeding and/or migration strategies may play a role in shaping the body condition of individuals for their following breeding season. We discuss the role of environmental conditions encountered by seabirds during winter migration to further elucidate such intracolony divergence in strategies. As polar ecosystems experience rapid changes in environmental conditions, the approach presented here may provide valuable information for the development of effective conservation measures (taking both intra- and intercolony variability into account), and to better predict future impacts of climate change.

Going with the floe: Sea-ice movement affects distance and destination during Adélie penguin winter movements.

Seasonal migration, driven by shifts in annual climate cycles and resources, is a key part of the life history and ecology of species across taxonomic groups. By influencing the amount of energy needed to move, external forces such as wind and ocean currents are often key drivers of migratory pathways exposing individuals to varying resources, environmental conditions, and competition pressures impacting individual fitness and population dynamics. Although wildlife movements in connection with wind and ocean currents are relatively well understood, movements within sea-ice fields have been much less studied, despite sea ice being an integral part of polar ecology. Adélie penguins (Pygoscelis adeliae) in the southern Ross Sea, Antarctica, currently exist at the southernmost edge of their range and undergo the longest (~12,000 km) winter migration known for the species. Within and north of the Ross Sea, the Ross Gyre drives ocean circulation and the large-scale movement of sea ice. We used remotely sensed sea-ice movement data together with geolocation-based penguin movement data to test the hypothesis that penguins use gyre-driven sea-ice movement to aid their migration. We found that penguins traveled greater distances when their movement vectors were aligned with those of sea ice (i.e., ice support) and the amount of ice support received depended on which route a penguin took. We also found that birds that took an eastern route traveled significantly further north in two of the 3 years we examined, coinciding with higher velocities of sea ice in those years. We compare our findings to patterns observed in migrating species that utilize air or water currents for their travel and with other studies showing the importance of ocean/sea-ice circulation patterns to wildlife movement and life history patterns within the Ross Sea. Changes in sea ice may have consequences not only for energy expenditure but, by altering migration and movement pathways, to the ecological interactions that exist in this region.

European plaice movements show evidence of high residency, site fidelity, and feeding around hard substrates within an offshore wind farm

Abstract Offshore wind farms (OWFs) are expanding rapidly in the North Sea, often creating spatial conflicts with fisheries. Managing such conflicts requires knowledge on the impact of OWFs on the spatial distribution and movement behaviour of fished species. However, such knowledge is still lacking, especially for soft sediment fish such as flatfish, which are vital fisheries resources in the region. Therefore, we used acoustic telemetry to examine the spatial behaviour of European plaice in relation to an OWF and its structures. In a small study area (1.37 km2), we observed high residency for plaice around the turbines and scour protection layer (SPL), which consists of large rocks around the turbine foundation. The fish primarily resided on sandy sediments near the hard substrates, but showed a diurnal pattern of proximity to the turbine, being closer during the day. Considering their trophic ecology, these findings suggest that plaice moves towards the SPL for feeding opportunities on the hard substrate, potentially leading to increased ecological fish production within OWFs. Although most plaice moved away from the OWF in winter, likely towards spawning grounds, many exhibited high site fidelity returning to the study area after the winter migration. OWFs thus offer protection from fishing mortality as “closed” feeding grounds in spring and summer, but not during winter spawning migrations, which may result in spillover effects. These insights should inform local fisheries management in relation to plaice movement within and around OWFs.

Untangling Humpback Whale-Watching Management Networks: Collaboration and Conflict in the Northeast Pacific

Humpback whales face emerging anthropogenic challenges such as entanglement in abandoned fishing gear and stranding during their winter migration. Such challenges require collective action solutions involving diverse stakeholders across jurisdictions, social sectors, and geographies. Collaborative governance systems involve conflictual and collaborative interactions. We used a quantitative approach (social network analysis) to map the structure of three social networks: Collaboration in disentanglement, collaboration in stranding, and conflict. We administered a face-to-face survey to 38 stakeholders from four social sectors across seven coastal localities from April to November 2021. We also obtained perspectives from the same stakeholders about pressing conflicts, rule compliance, and law enforcement regarding whale-watching management in the region using a semi-structured questionnaire. We found hints of different dimensions of collaboration occurring simultaneously: Coordination, cooperation, and conflict. Networks played distinct roles in promoting collaboration across sectors, and while the disentanglement network coordinated civil society and the public sector, the stranding network facilitated cooperation within the public sector. The most pressing social conflicts detected by stakeholders were pleasure boats, abandoned fishing gear, and poor rule compliance regarding the distance between boats and whales. Our results suggest that in the context of institutional weakness, collaborative social networks play a crucial role in the management and conservation of coastal and marine common-pool resources.

Wintering and migration strategies of Slavonian Grebes Podiceps auritus breeding in Iceland

ABSTRACT Capsule Slavonian Grebes Podiceps auritus breeding in Iceland moult on freshwater, before migrating to the seas around the British Isles for the winter. Aims The aims were to describe the migration strategies and identify wintering areas of Slavonian Grebes breeding in Iceland. Methods Geolocators were fitted to 37 Slavonian Grebes breeding on two lakes in north-east Iceland from 2009 to 2012. Of these, 19 were recovered and provided useful data on wintering areas and migration timing. Results The results indicated that the grebes moulted on freshwater lakes before gradually moving to the sea and later migrating to the wintering areas. Most of the birds wintered on the sea around the British Isles. However, there was surprisingly high variation in wintering strategies and little overlap of wintering areas. Grebes tracked for consecutive years showed high wintering philopatry. Conclusion Individual Slavonian Grebes may be vulnerable to local environmental conditions, but the high variability in wintering strategies and relatively large non-breeding distribution is expected to make the population generally less sensitive to local environmental conditions in the wintering areas over the long term.

Significantly Earlier Spring Migration in Most Bird Species at the Eastern Limit of Europe.

The first arrival dates of 31 species of migrant birds in the Tatarstan Republic of Russia were monitored for the 34-year period from 1989-2022. Trends in first arrival date were evaluated using regression against the year value. Patterns in arrival data with respect to species traits (habitat, migration distance, body weight, etc.) were evaluated using redundancy analysis. Relationships between first arrival dates and Tatarstan temperatures were also evaluated using regression methods of first-arrival date on monthly mean temperatures. Almost all (28 of 31) species revealed a significantly earlier migration arrival date; however, associations between arrival patterns and species traits were equivocal. Warmer temperatures were significantly associated with earlier arrival in 26 of the 31 species, but the relationship was insufficient to explain the average 11-day advance in species. For these species and in this location only the timing and location of arrival are well recorded; the exact wintering areas and migration routes, and the timing of these phases are less well understood. When these become better known, an investigation of the influence of environmental conditions (including temperature) on departure timing and passage timing and speed is recommended.

Estimating potential menhaden consumption by double-crested cormorants along the coast of North Carolina

The south Atlantic coast supports one of the highest assemblages of non-breeding double-crested cormorants (Nannopterum auritum) known and is a convergence area for Atlantic menhaden (Brevoortia tyrannus) during the winter months. We surveyed cormorants along the coast of North Carolina and used a bioenergetics approach to estimate potential menhaden consumption. We estimated cormorant numbers using a network of repeatable aerial transects along the outer coast (366 km) and within sounds (266 km) during fall migration, winter and spring migration (2019-2021). We estimated the number of bird days, metabolic demand and menhaden equivalents of demand. Cormorant numbers peaked around 122,000 to 131,000 during southward migration, reached a low of 30,000 to 39,000 in winter and then increased to 67,000 to 68,000 during northward migration. We did not capture the peak of spring migration during the study period (20 November through 24 March). We estimated the number of cormorant days within the study period to be 8.6 x 106 and 9.2 x 106 for the two field seasons respectively. We estimated that cormorants consumed approximately 5,334 and 5,660 mt of menhaden equivalents within the study area. Estimated consumption peaked between 76 and 81 mt-d during fall passage and reached a low of 19 and 24 mt-d during the winter. Annual menhaden take by humans and predatory fish is around 354,000 mt. Menhaden consumption by cormorants within the study area represents 4% of the commercial and recreational take and 7% of the estimated consumption by predatory fish or 2.5% of the known take.

FOOD CONTENTS ANALYSIS OF WATERFOWL PASSING THROUGH INDUS THE RIVER AT TAUNSA, SOUTH PUNJAB, PAKISTAN

A study was carried out to assess the food composition of migratory waterfowl in Bet Makwal Kalan, near the Head Taunsa Barrage, along the River Indus passage. Migratory water birds are thought to be important components in dispersal of total living entity especially seeds due to their proclivity for extensive relocations. They might be found in large numbers in the muddy sections. Migratory water birds are important components of total plant dispersal due to their proclivity for making extensive migrations. A sum of 459 gizzard samples was collected, during their Fall migration, relating to 10 Waterfowl species i.e. Northern Pintail (n=56), Eurasian Wigeon (n=17), Garganay (n=07), Mallard (n=02), Northern Shoveler (n=22), Common Teal (n=129), Gadwall (n=158), Tufted Duck (n=04), Common Pochard (n=29) and Ferruginous Duck (n=34). During their winter migration, the Waterfowl species picked plants over animals as their primary source of sustenance when travelling through Taunsa. Food research revealed that all 10 species of birds consumed large amounts of seeds. Out of ten duck species, two plant species (Naias marina and Potamogeton pusillus) consistently ranked among the top seeds ingested by six of the duck species (Eurasian Wigeon, Garganey, Mallard, Gadwall, Tufted Duck, and Common Pochard). Whereas the Northern Pintail, Northern Shoveler, Common Teal, and Ferruginous Duck have been found to consume large amounts of seeds from Potamogeton pectinatus and Poligonum spp. It was determined that molluscans and crustaceans residues were found to be well-represented in the gizzard samples of ducks. The recent study also highlighted that various vegetations play vital role in wetland ecosystems as a basic wild food provider. A larger population of migrating Waterfowl yield better findings for this study, which is currently being undertaken.

Survival and cause-specific mortality in adult females of a northern migratory ungulate

Survival of ungulates can vary seasonally due to changing environmental conditions, e.g. weather or predation pressure. The wild forest reindeer (Rangifer tarandus fennicus, “WFR”) migrate between calving and wintering grounds. The annual cycle of female WFR includes four main seasons (wintering, calving, rutting and autumn migration) during which they are subject to different conditions, but almost nothing is known about their survival or mortality patterns. We measured survival in 305 GPS-tagged female WFR in two subpopulations in Finland (2010–2022). Data were analysed for inter-annual and seasonal patterns in survival and cause-specific mortality (predation, traffic, accidents and unknown causes) with known-fate models. Inter-annual survival in Suomenselkä (mean 0.90) showed an increasing trend during the study and was higher than in Kainuu (mean 0.84) which showed a declining trend. Seasonal variation in survival was population dependent. Survival was lowest in Kainuu during the winter while in Suomenselkä, it was lowest during autumn migration. Concerning cause-specific mortality, seasonal variation mirrored variation in predation that was the primary cause of mortality (55% of cases). Wolves (Canis lupus) killed the majority of predated individuals (58%). Predation rates were two times higher in Kainuu where the wolf density was higher. We provide the first adult survival estimates for WFR and show that the seasonal variation in survival is clearly different between these two northern ungulate populations. This indicates that seasonal variation in survival is determined by site-dependent factors and cannot be generalised across populations.

Evaluation of nutritive condition and reproductive status of migrating gray whales (Eschrichtius robustus) based on analysis of photogrammetric data

Vertical aerial photographs were collected of gray whales migrating along the California Coast between 1994 and 1998 to readdress some published findings on the biology and life history of this population based on examination of specimens. For each whale, an attempt was made to measure standard total length, the width of the whale at its widest point, the distance from the tip of the rostrum to the widest point, and the width of the flukes. For southbound gray whales, early migrants were longer on average and more likely to be parturient than those migrating later. Near-term pregnant females were wider relative to their length than other southbound gray whales. This difference was easily detected by visual inspection of the images and through statistical evaluation of length and width data. There was 100% agreement between identification of parturient females based on linear regression analysis of length and width and discriminate analysis of all measurements. Based on the proportion of parturient females to those with calves during sampling of southbound whales, the median calving date was estimated to be 13 January. Southbound calves averaged 4.6m in length; those photographed northbound in late April, at an age of about three months, averaged 7.1m. Average length for yearlings, based on combined southbound and northbound data, was 8.5m. Residuals from a regression of width on length were compared, and significant changes in the relationship were detected which were consistent with changes in nutritive condition or fatness described from examination of whales taken along the California Coast between 1959 and 1969 (Rice and Wolman, 1971). Parturient females were the widest relative to their length and northbound cows with calves were the narrowest in the sample. The relationship between length and width for migrating gray whales that were not parturient or associated with a calf, showed that southbound gray whales were significantly wider than northbound whales photographed approximately 60 days later. These results indicate that the predictable but relatively small changes in condition or fatness of gray whales associated with fasting during their winter migration can be reliably detected in measurements from vertical aerial photographs.