stopover sites
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2022 ◽  
Vol 43 (1) ◽  
pp. 1-10
Author(s):  
A.S. Dixit ◽  
◽  
R. Chetri ◽  
N.S. Singh ◽  
◽  
...  

Migratory birds undergo physiological and behavioral changes to fuel their high energy demanding migratory flights. They increase their food intake as a part of the preparation for migration which results in increase in their body mass. Fat, carbohydrate and protein acquired from food are stored mainly in the adipose tissue (triglycerides), muscle and liver (glycogen) and body organs (protein) in migratory birds. These stored foods act as fuels to support birds’ migratory flights. Dietary carbohydrates and lipids not only provide energy for migration but also help in fattening as carbohydrates can be converted into fat and lipids which can be stored. Lipolysis of adipose-stored fats leads to the production of triglycerides, fatty acids and glycerol, which provide energy for migration. Fats are depleted after long migratory flights and replenished during refueling at the stopover sites. Being chemically reduced and hydrophobic in nature, fat releases more energy on oxidation as compared to carbohydrate and protein. Due to its high energy-yielding nature, the fat is the preferred fuel to support migration in birds. Migratory birds deposit fat and deplete it during the course of migration. Though, the stored fat acts as the primary source of energy, metabolism of body protein also provides energy for migratory flights. Uric acid in plasma is elevated when protein is catabolized. The metabolism of carbohydrate, stored as glycogen in liver and muscle in migratory birds, produces glucose which also fuels migration. Glucose in migratory birds is maintained at stable levels in plasma and it provides energy only for a flight of short period. Further, catabolism of carbohydrate and protein results in release of metabolic water which helps the migratory birds to maintain their water balance during long dehydrating flight conditions. Different levels of plasma metabolites in migratory birds act as significant indicators of their physiological and metabolic state. Plasma metabolites also give an idea of feeding, fasting and refueling during migration in birds. The available information is scanty and fragmented about how birds meet their migratory requirements and overcome the physiological challenges encountered during migration. The present review article, therefore, focuses on the biomolecules and their plasma biochemistry during migration in birds.


Polar Biology ◽  
2021 ◽  
Author(s):  
Petra Quillfeldt ◽  
Julius Morkūnas ◽  
Helmut Kruckenberg ◽  
Alexander Kondratyev ◽  
Julia Loshchagina ◽  
...  

AbstractArctic birds migrating southwards face a multitude of challenges such as habitat loss, pollution, overexploitation of food resources and climate change impacts. Long-tailed Duck winter populations in the Baltic Sea have declined in recent decades. However, precise spatial data are lacking, especially from males. Thus, we aimed to identify the wintering grounds, timing of migration and stopover sites of males and females. We studied spatiotemporal distribution patterns of eight male and five female Long-tailed Ducks using implanted ARGOS satellite transmitters. Birds were tagged in the breeding season on Kolguev Island, Russia. After the breeding period, Long-tailed Ducks from Kolguev used three main post-breeding areas: most males undertook long distance eastward post-breeding migration to areas around the Yamal and Gydan peninsulas, while one male and four females moved short to the southeast coast of Kolguev, and one female moved to Mezhdusharsky Island in the Novaya Zemlya Archipelago. Autumn migration included stopover sites in the White Sea, Lake Ladoga, the Gulf of Finland and the Gulf of Riga, and all birds except one spent the winter in the southern part of the Baltic Sea, from the Pomeranian coast and Hoburgs bank to the Gulf of Finland. Only one female stayed in the White Sea for the winter. All but one bird used the White Sea as a stopover site in May, suggesting that this area is of special importance.


2021 ◽  
Vol 13 (20) ◽  
pp. 4049
Author(s):  
Nyambayar Batbayar ◽  
Kunpeng Yi ◽  
Junjian Zhang ◽  
Tseveenmyadag Natsagdorj ◽  
Iderbat Damba ◽  
...  

We tracked 39 western flyway white-naped cranes (Antigone vipio) throughout multiple annual cycles from June 2017 to July 2020, using GSM-GPS loggers providing positions every 10-min to describe migration routes and key staging areas used between their Mongolian breeding and wintering areas in China’s Yangtze River Basin. The results demonstrated that white-naped cranes migrated an average of 2556 km (±187.9 SD) in autumn and 2673 km (±342.3) in spring. We identified 86 critical stopover sites that supported individuals for more than 14 days, within a 100–800 km wide migratory corridor. This study also confirmed that Luan River catchment is the most important staging region, where white-naped cranes spent 18% of the annual cycle (in both spring and autumn) each year. Throughout the annual cycle, 69% of the tracking locations were from outside of the currently protected areas, while none of the critical staging areas enjoyed any form of site protection. We see further future potential to combine avian tracking data and remote-sensing information throughout the annual range of the white-naped crane to restore it and other such species to a more favourable conservation status.


2021 ◽  
Vol 8 ◽  
Author(s):  
Carl S. Cloyed ◽  
Elizabeth E. Hieb ◽  
Kayla DaCosta ◽  
Monica Ross ◽  
Ruth H. Carmichael

Partial migration provides a mechanism for species to shift their geographic ranges into new, environmentally favorable regions but has been poorly studied as a means to alleviate effects of climate change. Populations at the edge of their geographic range are ideal to investigate how migratory behaviors may enable range expansion as adjacent areas become more climatically favorable. We determined the contribution of partial migration to the range expansion of West Indian manatees (Trichechus manatus) using GPS data from tagged individuals that migrated between the northern Gulf of Mexico (nGoM) and primary habitat in peninsular Florida. Most of these manatees migrated to the nGoM annually and exhibited high site fidelity among years. Many individuals spent cumulatively more time in the nGoM than in peninsular Florida, indicating the nGoM is a regular part of their geographic range, and they returned to peninsular Florida to meet temperature-related physiological needs for survival. Autumn migrations most frequently terminated at Crystal River, Florida, and manatees that commenced migration late in the season stopped less frequently and had more directed movements. Spring migrations most frequently terminated at Mobile Bay, Alabama, and several manatees quickly and directly migrated from Florida to nGoM stopover sites. Migrations ranged from 10 to 133 days in length, and variation in duration was primarily driven by use of stopover sites and directedness of travel. These data confirm partial migration as an important component of manatee migratory behavior that has already enabled range shifts for manatees on the U.S.A. Gulf of Mexico coast and has potential to facilitate future responses to climate change. As the most common type of migration across the animal kingdom, partial migration may provide a global mechanism for a diverse variety of species to resist the range limiting effects of climate change.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kevin A. Wood ◽  
Julia L. Newth ◽  
Geoff M. Hilton ◽  
Eileen C. Rees

Abstract Background Winter numbers of the northwest European population of Bewick’s Swans (Cygnus columbianus bewickii) declined recently by c. 40%. During the same period, numbers of two sympatric and ecologically-similar congeners, the Mute Swan (Cygnus olor) and Whooper Swan (Cygnus cygnus) showed increases or stability. It has been suggested that these opposing population trends could have a causal relationship, as Mute and Whooper Swans are larger and competitively dominant to Bewick’s Swans in foraging situations. If so, effects of competition of Mute and Whooper Swans on Bewick’s Swans should be detectable as measurable impacts on behaviour and energetics. Methods Here, we studied the diurnal behaviour and energetics of 1083 focal adults and first-winter juveniles (“cygnets”) of the three swan species on their winter grounds in eastern England. We analysed video recordings to derive time-activity budgets and these, together with estimates of energy gain and expenditure, were analysed to determine whether individual Bewick’s Swans altered the time spent on key behaviours when sharing feeding habitat with other swan species, and any consequences for their energy expenditure and net energy gain. Results All three swan species spent a small proportion of their total time (0.011) on aggressive interactions, and these were predominantly intraspecific (≥ 0.714). Mixed-effects models indicated that sharing feeding habitat with higher densities of Mute and Whooper Swans increased the likelihood of engaging in aggression for cygnet Bewick’s Swans, but not for adults. Higher levels of interspecific competition decreased the time spent by Bewick’s Swan cygnets on foraging, whilst adults showed the opposite pattern. When among low densities of conspecifics (< c. 200 individuals/km2), individual Bewick’s Swans spent more time on vigilance in the presence of higher densities of Mute and Whooper Swans, whilst individuals within higher density Bewick’s Swan flocks showed the opposite pattern. Crucially, we found no evidence that greater numbers of interspecific competitors affected the net energy gain of either adult or cygnet Bewick’s Swans. Conclusions We found no evidence that Bewick’s Swan net energy gain was affected by sharing agricultural feeding habitat with larger congeners during winter. This was despite some impacts on the aggression, foraging and vigilance behaviours of Bewick’s Swans, especially among cygnets. It is unlikely therefore that competition between Bewick’s Swans and either Mute or Whooper Swans at arable sites in winter has contributed to the observed decline in Bewick’s Swan numbers. Further research is needed, however, to test for competition in other parts of the flyway, including migratory stopover sites and breeding areas.


Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 240
Author(s):  
Alessandro Ferrarini ◽  
Marco Gustin ◽  
Claudio Celada

Biodiversity loss has multiple causes, but habitat degradation through land-use change is the predominant driver. We investigated the effectiveness of the Natura 2000 network in preserving the main wetlands of the two largest islands of the Mediterranean region, whose conservation is critical for many avian species at European and global level, in a 23-year period (1990–2012). In Sardinia, the surroundings of 22 wetlands were affected by an increase in artificial areas (+64 ha/year) and decrease in agricultural (−54 ha/year) and natural (−17 ha/year) ones. In Sicily, the surroundings of 16 wetlands were impacted by an increase in agricultural areas (+50 ha/year) and decrease in natural and semi-natural ones (−62 ha/year). Results show that the Natura 2000 policies were effective in preserving wetlands (no shrinkages detected in both regions), but their surroundings experienced intense processes of degradation and artificialization in all the sub-periods considered (1990–2000, 2000–2006, 2006–2012), whose effects are now threatening waterbirds and wetland integrity. The enlargement of the existing Natura 2000 sites, the creation of new ones and the speedup of the application of the rules of the Habitats and Birds Directives seem necessary to counteract the rapid land-use changes around these important stopover sites.


2021 ◽  
Vol 9 ◽  
Author(s):  
J. David Blount ◽  
Joshua J. Horns ◽  
Kyle D. Kittelberger ◽  
Montague H. C. Neate-Clegg ◽  
Çağan Hakkı Şekercioğlu

An estimated 17% of migratory bird species are threatened or near threatened with extinction. This represents an enormous potential loss of biodiversity and cost to human societies due to the economic benefits that birds provide through ecosystem services and ecotourism. Conservation of migratory bird species presents many unique challenges, as these birds rely on multiple geographically distinct habitats, including breeding grounds, non-breeding grounds, and stopover sites during migration. In particular, stopover habitats are seldom studied relative to breeding and non-breeding habitats, despite their importance as refueling stations for migratory birds. In this study, we summarize the current research on the use of temporary primary crops by birds during migration and we assess the species characteristics and agricultural practices most often associated with the use of cropland as stopover habitat. First, we conducted a systematic review of the literature to document the effects various farming practices and crop types have on the abundance and diversity of migratory birds using agricultural areas for stopovers. Second, we analyzed the ecological correlates of bird species in the Northern Hemisphere that predict which species may use these areas while migrating. We ran a GLMM to test whether primary diet, diet breadth, primary habitat, habitat breadth, or realm predicted stopover use of agricultural areas. Our review suggests that particular crop types (principally rice, corn, and sunflower), as well as farming practices that result in higher non-cultivated plant diversity, encourage the use of agricultural areas by migrating birds. We found that cropland is used as stopover habitat by bird species that can utilize a large breadth of habitats, as well as species with preferences for habitat similar in structure to agricultural areas.


Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 941
Author(s):  
Nazia Mahtab ◽  
Lizhi Zhou ◽  
Fengling Zhang ◽  
Wei Wang

The “gut fungal microbiome” maintains the immune system, homeostasis, and various physiological functions of an organism. Different factors shape and affect gut fungal diversity and community composition, such as environment, habitat type, food resources, and seasons during migration. Wild birds amid migration are exposed to different habitats with different environments, available food resources, and seasons, which may substantially impact their gut fungal community composition and diversity. The hooded crane (Grus monacha) is a known migratory bird that migrates over long distances and is exposed to varied habitats with different environments and food types. We investigated the differences in gut fungal diversity and community composition between wintering and stopover sites amid three migratory seasons. We deduced the gut fungal pathogenic diversity and community composition during winter, fall, and spring by using high throughput sequencing (Illumina Mi-seq), and the internal transcribed region 2 (ITS2) was examined. Samples were collected from Shengjin Lake in the winter and Lindian during the fall and spring. The dominant fungal phyla found across the three seasons were Ascomycota, Basidiomycota, Zygomycota, and Rozellomycota. The gut fungal alpha diversity showed significant shifts during winter at the wintering site compared with the fall and spring seasons at the stopover site. The fungal community composition exhibited a significant change across the three seasons (ANOSIM p = 0.001). The results also demonstrated that the diversity and relative abundance of potential pathogens also showed divergence in winter compared to fall and spring. This study provides the basis for understanding the discrepancy in gut fungal diversity and community composition during migratory seasons at both wintering and stopover grounds. It also suggests that conservation measures should be applied to the conservation of hooded cranes and other wild birds, as the risk of cross-infection increases during seasonal migration.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Kristen A. Mancuso ◽  
Megan A. Fylling ◽  
Christine A. Bishop ◽  
Karen E. Hodges ◽  
Michael B. Lancaster ◽  
...  

Abstract Background For many songbirds in North America, we lack movement details about the full annual cycle, notably outside the breeding season. Understanding how populations are linked spatially between breeding and overwintering periods (migratory connectivity) is crucial to songbird conservation and management. We assessed migratory connectivity for 2 breeding populations of Gray Catbirds (Dumetella carolinensis) west of and within the Rocky Mountains by determining migration routes, stopover sites, and overwintering locations. Additionally, we compared apparent annual survivorship for both populations. Methods We deployed 39 archival light-level geolocators and 21 Global Positioning System (GPS) tags on catbirds in the South Okanagan Valley, British Columbia, Canada, and 32 geolocators and 52 GPS tags in the Bitterroot River Valley, Montana, USA. These devices allowed us to determine migration routes, stopover sites, overwintering locations, and migratory connectivity. Migratory connectivity was quantified using Mantel’s correlation. We used mark-recapture of colour banded catbirds in both sites to estimate apparent annual survivorship. Results We retrieved 6 geolocators and 19 GPS tags with usable data. Gray Catbirds from both populations passed through the Rocky Mountains eastward before heading south towards their overwintering locations in northeastern Mexico and Texas. Stopover sites during fall migration occurred primarily in Montana, Kansas, Oklahoma, and Arkansas. Overwintering locations spanned Texas and 5 states in northeastern Mexico. Individual catbirds used up to 4 distinct sites during the overwintering period. Catbirds separated by almost 500 km during the breeding season overlapped during the non-breeding season, suggesting weak migratory connectivity among western populations (Mantel’s correlation = 0.013, P-value = 0.41). Catbird apparent annual survivorship estimates were higher in British Columbia (0.61 ± 0.06 females; 0.64 ± 0.05 males) than in Montana (0.34 ± 0.05 females; 0.43 ± 0.04 males), though the main driver of these differences remain unclear. Conclusions Our results provide high precision geographic details during the breeding, migration, and overwintering phases of the annual cycle for western Gray Catbirds. Notably, we found that western catbirds followed the Central Flyway as opposed to the Pacific Flyway. We document that catbirds used multiple sites over winter, contrary to the popular belief that this phase of the annual cycle is stationary for most songbirds.


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