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Migratory bottlenecks concentrate individuals and populations of Nearctic–Neotropical migrants from across vast breeding areas. The extent to which such concentrations occur has important ramifications for interpreting migratory connectivity and for the vulnerability of populations throughout the annual cycle but investigations of such phenomena are rare. We inferred breeding origins of 11 species of Nearctic–Neotropical migrants captured during fall migration in the Darién region, northwestern Colombia, using feather stable-hydrogen isotope values (δ2Hf). Our objectives were to determine (1) the extent to which this region acts as a catchment for individuals from across a species′ breeding range, (2) if temporal patterns of arrival arise as a function of migration distance inferred from δ2Hf, and (3) if phenological differences among species segregate populations. The Darién concentrated populations of 6 species, with individuals potentially derived from 78% to 94% of their respective North American breeding ranges. The catchment area for the remaining 5 species covered 40–72% of breeding ranges, with a bias in origin from the west (e.g., Northern Waterthrush [Parkesia noveboracensis], Swainson′s Thrush [Catharus ustulatus]), north or center (Yellow Warbler [Setophaga petechia]) of their range. Differential timing in the migration of populations occurred in 6 species, generating a degree of temporal segregation. In contrast, peak migration for all species occurred in October, resulting in high overlap among species in their use of the Darién. Overall, our results describe high mixing of populations in the Darién for several species, which, given the region′s highly restricted geographic extent, suggests that a bottleneck effect occurs; however, comparisons with other regions in Central America and northern South America are required. The combination of extensive population mixing and limited temporal segregation over a narrow geographical area suggests that long-distance migrants may be especially vulnerable to events occurring in such regions, including adverse weather conditions and anthropogenic land cover change. [ABSTRACT FROM AUTHOR]

Research into the phenomenon of stopovers during long haul air travel emerged only recently in the tourism literature. In this article a contribution to this new field is made by reporting perceptions of Dubai, in the context of an international stopover destination, during long haul air travel between UK/Europe and Australasia/South Pacific, relative to three competing places (Singapore, Hong Kong, Abu Dhabi). A mixed methods research approach was used. The first stage involved personal interviews with 66 consumers in the UK, France, Australia, and New Zealand to identify salient attributes of stopover destinations, and a pilot survey involving 777 consumers in Australia and France. A refined online survey was then used with a combined sample of 2,000 consumers in the same four markets, to identify determinant attributes of stopover destination attractiveness, as well as Dubai's perceived strengths and weaknesses. The study identified determinant attributes of stop-over destination attractiveness that have not featured in destination image research. The results support the propositions that 1) destination image might vary across travel contexts, and 2) there is a positive effect of previous visitation on destination image and attitudinal loyalty. Methodologically the study demonstrates the efficacy of combining the repertory test with importance–performance analysis, in destination image research. [ABSTRACT FROM AUTHOR]

Recent conservation plans for long-distance Neotropical migrant birds have emphasized the importance of understanding the ecology and threats facing a species throughout its life cycle, including migration and overwintering periods. To better understand the ecology of Broad-winged Hawks (Buteo platypterus) during the nonbreeding period, we followed the movements of 14 hawks from 2 breeding populations during July 2014–April 2019 to their overwintering sites. Three juvenile and 8 adult female Broad-winged Hawks were satellite-tracked from Pennsylvania, USA, and 3 adults (2 females and 1 male) were tracked from Alberta, Canada. We documented pre-migratory movements (post-breeding) of 4 of the 14 individuals. Adults initiated fall migration on ¯x¼25 August 6 16.38 d and 2 of the 3 juveniles began fall migration on ¯x¼20 August 6 2 d. Adults had 1–12 (¯x¼5.0 6 3.5) stopovers in autumn that lasted for 1–24 d and juveniles had 2–5 (¯x¼ 3.0 6 1.7) stopovers that lasted 2–51 d. Adults from Pennsylvania spent the overwintering period in Nicaragua, Brazil, Peru, and Colombia (n ¼ 8) whereas those from Alberta wintered in Suriname, Venezuela, and Bolivia (n ¼ 3). The distance traveled on autumn migration was greater for Alberta birds (¯x ¼ 10,021 6 866 km, n ¼ 3) than for Pennsylvania birds (¯x ¼ 7,925 6 1,631 km, n¼8). Migration distance and overwintering region varied by geographic origin with age but with some overlap between the 2 distinct geographic breeding populations. Broad-winged Hawks appear to follow a hybrid time–energy minimization strategy during fall and spring migrations with (1) energy minimization in North America, and (2) time minimization in Mexico and Central America. Stopover frequency, duration, and migration rate support this hypothesis. [ABSTRACT FROM AUTHOR]

Copyright of Ardeola is the property of Sociedad Espanola de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ardeola is the property of Sociedad Espanola de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Migrating birds make stopovers to rest and fuel to prepare for their next flight. The decision when to continue migration significantly affects total duration of migration and thus arrival timing at the migratory destination. Departure decisions of migrants are therefore important to understand variation in arrival timing. Since the amount of energy can limit flight duration, feeding conditions and energy stores have a significant effect on the departure decisions. Unexpectedly though, various fasting-refuelling experiments controlling for these two parameters and using migratory restlessness as a proxy for departure probability did not find consistent patterns within and across different songbird species of departure decisions. Here we performed a fasting-refuelling experiment on four actively migrating songbird species during autumn, to assess the significance and consistency of the feeding conditions and energy stores on the bird's departure decision. We found no differences in the departure probability between low and favourable feeding conditions in all species. During the low food phase, however, birds with higher energy stores were more likely to depart than leaner birds. When fasted individuals encountered improved feeding conditions, they significantly increased their energy stores and showed a significant drop in migratory restlessness. This is tantamount to the decision of staying at stopover. The consistency of the patterns seems to be generalizable across species. Additionally, the results highlight the importance of the interplay of feeding conditions, changes in these and the bird's current energy stores for the stopover decision-making process. Significance statement: Many migratory songbirds travelling thousands of kilometres do so by making several single nocturnal flights interrupted by resting periods on the ground. To decide when to continue migration, birds seem to follow general departure rules. Fat birds continue migration when they do not find food during their rest, while lean birds stay until the feeding conditions have improved. In this study, we show for the first time a generalizable consistent pattern that feeding conditions, changes in food availability and the current energy stores jointly influence the departure decisions of migratory songbirds at stopovers. This is in contrast to former studies showing inconsistent patterns on the reaction of a low food phase regarding the departure probability. Our experiment, therefore, advances our knowledge about the decision-making process of bird migrants and demonstrates the importance of favourable feeding conditions for migratory birds resting at a stopover site. [ABSTRACT FROM AUTHOR]

Cities are significant barriers for migrating birds, but providing suitable greenspaces for stopovers can mitigate urban impacts. City planning for greenspaces often focusses on forests as parks, yet brushy edges and other successional habitats may be equally important especially for songbirds who spend weeks at stopovers in cities to moult their feathers ('moult migrants'). To investigate the role of peri -urban landscapes on moult migrants, we captured 48 moulting and 41 post-moult migrating Swainson's thrushes (Catharus ustulatus) within a large (3000 ha) urban park in Montreal, Canada. Each bird was randomly translocated to one of eight sites of varying habitat type and tracked using radiotelemetry. We compared the time spent at each translocation site with habitat characteristics, expecting birds to spend more time in areas with high food availability and concealment from predators. Migrating thrushes spent ∼4 times as much time in dense forest margins than in fields and mature forests. Berry-producing shrubs that we identified as food for thrushes (by DNA-barcoding of their feces) best characterized those margins. Stopover home ranges were much smaller than the size of the park (50% core range: 10.6 ± 17.2 ha). This highlights the importance of urban greenspaces with dense forest margins during a vulnerable time for Swainson's Thrushes, and the conservation implications of maintaining these lower-valued greenspaces. Given that city parks are often lacking understory growth, we recommend keeping shrubby patches for migrating birds. [ABSTRACT FROM AUTHOR]

Abstract Background The motivation of birds to proceed with migration is associated with both endogenous and exogenous factors. According to their migratory situation and to the characteristics of stopover sites, birds might exhibit migratory motivation differently among sites. Although migratory motivation of migrating birds has been well studied in many species, the investigation of the same species in different migratory situations and at different stopover sites is still limited. We predicted that birds at different stopover sites could differ in migratory disposition, including expression of migratory restlessness and responses to environmental cues. Methods Here we compared migration motivation and orientation of Great Knots (Calidris tenuirostris) at two stopover sites, Chongming Dongtan in the south Yellow Sea, which is a temporary rest site, and Yalujiang Estuary Wetland in the north Yellow Sea, which is a critical refuelling site, during northward migration. Modified Emlen funnels, with thermal paper inside to record scratches of the birds, were used to detect activity (intensity and direction) of birds. Environmental conditions, including wind direction and speed, cloud cover, tide condition, times of the day (before and after sunset) were recorded during experiments. Generalized linear models were used to detect the effects of endogenous and exogenous factors on the migratory motivation of the birds. Results In the south Yellow Sea, the migratory activity intensity of Great Knots was positively related to wind assistance. In the north Yellow Sea, where birds exhibited higher intensity of migratory activity than in the south, the intensity increased and the motivation to initiate migration grew stronger as the season advanced. The Great Knots exhibited wind-related orientation behaviour in the funnels at both sites. Conclusions The results suggest that the intensity of migratory motivation differed between the two sites. Departure decisions of Great Knots appear to be affected mainly by external factors at the temporary rest site in the south Yellow Sea but possibly by endogenous factors at the final pre-breeding refuelling site in the north Yellow Sea.

Abstract Background Regional scale movement patterns of songbirds are poorly known largely due to difficulties tracking small organisms at broad scales. Using an array of over 100 automated radio telemetry towers, we followed Blackpoll Warblers (Setophaga striata) during fall migration in the Gulf of Maine region, and assessed how their regional scale movement pathways varied with age, distance to natal origin, and capture date. Results Many individuals had movement paths that were not oriented towards their migratory goal (‘indirect movement patterns’), regardless of age, distance to natal origin, or time of season. The probability of moving in indirect patterns, and the total tracking duration, decreased with capture date. The extent of indirect movement patterns varied considerably between individuals. Excluding direct flight patterns consistent with traditional migratory movements, adults tended to make more flights and moved in more tortuous patterns than hatch-years. Adults and individuals from more westerly natal origins were more likely to move south-west through time. Conclusions A greater proportion of individuals made movements that were not oriented towards the migratory than expected. A decrease in tracking duration with capture date indicates that individuals prioritize time as the season progresses. The shorter, indirect movement patterns may be a more complete representation of ‘reverse migration’ at a barrier or ‘landscape-scale stopovers movements’. The longer distances travelled are inconsistent with expected behaviour, even in front of a barrier. The extent of movement we observed indirectly suggests that flight is not as costly to individuals in a migratory state as is commonly assumed. Since adults were observed to move more than hatch-years, we suggest that the indirect movement patterns we observed are not accidental, and may provide some advantage to the individuals that undertake them.

Abstract Background Populations of Eastern Whip-poor-will (Antrostomus vociferous) appear to be declining range-wide. While this could be associated with habitat loss, declines in populations of many other species of migratory aerial insectivores suggest that changes in insect availability and/or an increase in the costs of migration could also be important factors. Due to their quiet, nocturnal habits during the non-breeding season, little is known about whip-poor-will migration and wintering locations, or the extent to which different breeding populations share risks related to non-breeding conditions. Results We tracked 20 males and 2 females breeding in four regions of Canada using geolocators. Wintering locations ranged from the gulf coast of central Mexico to Costa Rica. Individuals from the northern-most breeding site and females tended to winter furthest south, although east-west connectivity was low. Four individuals appeared to cross the Gulf of Mexico either in spring or autumn. On southward migration, most individuals interrupted migration for periods of up to 15 days north of the Gulf, regardless of their subsequent route. Fewer individuals showed signs of a stopover in spring. Conclusions Use of the southeastern United States for migratory stopover and a concentration of wintering locations in Guatemala and neighbouring Mexican provinces suggest that both of these regions should be considered potentially important for Canadian whip-poor-wills. This species shows some evidence of both “leapfrog” and sex-differential migration, suggesting that individuals in more northern parts of their breeding range could have higher migratory costs.

Many birds undertake long migrations when they are only a few months of age. Although they are typically of adult body size, their performance, and survival are often poor compared to adults. This differential performance could be due to lack of experience, selection against poor-performing cohort members, or inherent constraints of continuing physiological and morphological maturation of juveniles. Limited evidence suggests that digestive and muscle physiology of juveniles during their first migration may differ from that of adults. We compared body composition, metabolic rate, and digestive physiology between juvenile and adult passerines during fall migration. First, we measured fat and lean masses by quantitative magnetic resonance, and organ and muscle masses of salvaged carcasses of fall migrants from four passerine species. In general, juveniles had more lean mass and heavier digestive organs (especially liver) than adults in hermit thrushes (Catharus guttatus), Swainson's thrushes (Catharus ustulatus), ovenbirds (Seiurus aurocapilla), and white-throated sparrows (Zonotrichia albicollis). Principal components analysis of all organs and muscles revealed that juveniles for three of four species had overall larger digestive components and smaller flight muscles than adults. We then used open-flow respirometry to measure basal metabolic rates (BMRs) of juvenile and adult Swainson's thrushes and white-throated sparrows captured in fall at a migratory stopover site. Controlling for a significant effect of body mass, juveniles had 6% higher BMRs than adults in both species. We then conducted total collection mass balance feeding trials with fall migratory Swainson's thrushes and white-throated sparrows. Juvenile thrushes had greater metabolizable energy intake than adults, which was achieved through higher food intake rather than greater utilization efficiency. Age classes of white-throated sparrows did not differ in these measures of digestive performance, although juveniles had greater food intake capacity at low lean body masses. We propose that age-related differences in foraging ecology, diet composition, and energy requirements may be responsible for larger digestive organs of juvenile migrants. Larger guts may allow juveniles to consume more food or a more dilute diet, but may contribute to higher BMRs.

The Gulf of Maine has long been recognized as a major stopover area for shorebirds in fall. Knowing how birds move within and beyond the region will be paramount to protecting threatened shorebird habitat. To determine stopover behavior during fall migration (2013–2017) in Maine, 180 (104 AHY, 76 HY) Semipalmated Sandpipers, Calidris pusilla, were tracked using VHF radiotelemetry and an extensive array of automated receivers (Motus Wildlife Tracking System). Birds tagged at three locations along the Maine coastline showed no effect of age class or stopover site on body condition (body mass, estimated fat mass) or stopover length (post-capture detection period). However, movement after departure varied greatly among sites. Few birds captured at the northern-most site (“Downeast,” n = 71), which had the greatest amount of mudflats and offshore roost sites and the least amount of human disturbance, were detected beyond the initial tagging location, suggesting that they, like birds in the Bay of Fundy just to the north, initiated trans-oceanic flights from that location. At the Downeast site, leaner birds remained significantly longer than fatter birds, suggesting that time of departure there depended on energy reserves, which would be critical for making extensive flights. In contrast, over half of the birds tagged further south (Popham Beach, n = 59; Rachel Carson NWR, n = 50) were later detected at coastal locations to the north (few) or to the south (most). Stopover period at these sites was independent of fat, suggesting that other factors (e.g., feeding/roosting site availability, human activity) influenced departure decisions. In Maine, Semipalmated Sandpipers, regardless of age, may move north (Downeast) or south (e.g., Cape Cod, Rhode Island, Long Island Sound) where the local topography, habitat characteristics (feeding/roosting sites), and/or lower human activity, may best enable them to initiate trans-oceanic flights to the wintering grounds. Future study should determine if variation in stopover behavior is population-specific and if population-segregation occurs in Maine. Use of automated VHF radiotelemetry has led to a greater understanding of stopover behavior and the degree of connectivity among stopover sites, which should be taken into account for conserving migratory bird habitat across broad spatial scales.

Avian influenza has advanced from a regional concern to a global health issue with significant economic, trade, and public health implications. Wild birds, particularly waterfowl (Anseriformes), are known reservoirs for low-pathogenic avian influenza viruses (AIV) and recent studies have shown their potential in the spread of highly pathogenic forms of virus. East Asia remains an epicenter for the emergence of novel strains of AIV, however, information on movement ecology of waterfowl, and subsequently a clearer understanding of disease transmission risks in this region has been greatly lacking. To address this, we marked two species of wild waterfowl, northern pintail (Anas acuta) and Eurasian wigeon (Anas penelope), with satellite transmitters on their wintering grounds in Hong Kong, China to study the northward spring migration in the East Asian-Australasian Flyway in relation to disease transmission factors. Northern pintail were found to initiate migration 42 days earlier, travel 2,150 km farther, and perform 4.4 more stopovers than Eurasian wigeon. We found both species used similar stopover locations including areas along the Yangtze River near Shanghai, Bohai Bay and Korea Bay in rapidly developing regions of the Yellow Sea, and the Sea of Okhotsk where the species appeared to funnel through a migratory bottleneck. Both species appeared to exhibit strong habitat selection for rice paddies during migration stopovers, a habitat preference which has the potential to influence risks of AIV outbreaks as rapid land use and land cover changes occur throughout China. Both species had greatest association with H5N1 outbreaks during the early stages of migration when they were at lower latitudes. While Eurasian wigeon were not associated with outbreaks after the mean date of wintering ground departures, northern pintail were associated with outbreaks until the majority of individuals departed from the Yellow Sea, a migratory stopover location. Our results show species-level differences in migration timing and behavior for these common and widespread species, demonstrating the need to consider their unique temporal and spatial movement ecology when incorporating wild birds into AIV risk modeling and management.

• For birds, migration is likely more challenging in spring than in autumn. • Corticosterone profiles may mirror these migratory seasonal differences. • We found male junco migrants had weaker negative feedback during spring vs. autumn. • Weak negative feedback in spring may be adaptive as conditions are more unpredictable. • Baseline and stress-induced corticosterone did not differ between spring and autumn. Birds face many challenges during seasonal migrations and must make important decisions about whether to accelerate, maintain, or delay travel to their final destinations. Spring migration is likely more challenging than autumn migration as spring journeys are completed more quickly and weather conditions are harsher during this time. These differential challenges may be reflected in the endocrine stress response, as the hypothalamic–pituitary-adrenal (HPA) axis is important for both daily energetic needs and coping with stressors. Indeed, most avian studies have found that both baseline and stress-induced corticosterone (CORT) levels tend to be higher in spring migrants than in autumn migrants. We hypothesized that CORT negative feedback efficacy also differs across the season, and is likely weaker during times of year when birds must be most sensitive to stressors. We therefore predicted that CORT negative feedback efficacy would be weaker during spring vs. autumn migration as spring migrants are more likely to encounter situations where they must decide whether to turn back or delay their travel. We examined male dark-eyed juncos (Junco hyemalis) during their spring and autumn stopovers in Fargo, ND, USA. Our prediction was met as we did find that negative feedback efficacy was weaker during spring vs. autumn, although we notably did not find any seasonal differences in baseline and stress-induced CORT. We also found that spring migrants were heavier, had greater subcutaneous fat stores, and had slightly higher hematocrit compared to autumn migrants. These findings suggest that CORT negative feedback sensitivity may help migrating birds effectively cope with the differential challenges of autumn and spring migration. [ABSTRACT FROM AUTHOR]

The hooded crane (Grus monacha) is a vulnerable species. However, its stopover habitat receives little attention and is not well known or protected even. Here, we present the spatial distribution of the stopover habitats for hooded cranes in the East Asia. A machine learning modeling algorithm of maximum entropy (MaxEnt) weas applied and evaluated with Stochastic Gradient Boosting and Random Forests based on 115 every year used occurrence points (1990-2013) and 14 environmental layers as predictors. Results show that the Songnen Plain and Korea Peninsula are the most important stopover habitats. Four other major areas are also suitable for stopover: (i) the coastal area of the Bohai Sea, (ii) the Three Rivers Plain-Amur River Basin, (iii) the Torey Lake Basin and the (iv) Zeya River-Heilongjiang River. The gap analysis revealed that existing nature reserves conserve merely 16.7% of the suitable habitat and 26.7% of the core habitat. However, much more suitable habitat is still located widely outside nature reserves. Based on our predictions, a total of 22 priority areas should be considered when developing new nature reserves or expanding the existing nature reserves. In addition, we suggest that seven regions located at the Korean Peninsula are also suitable for dispersing hooded cranes from Izumi, Japan. Artificial feeding, including setting up feeding stations with grain, artificial cranes (decoys) and artificial flowing water impoundments can be used to attract wintering hooded cranes at these seven sites. Theoretically, our models show that these habitats can accommodate approximately 3,713 wintering individuals (ca. 35% of the wintering population in Izumi). [ABSTRACT FROM AUTHOR]

Stopover periods in between migratory flights determine the speed of migration and as such may affect birds' fitness. The decision to leave a stopover site is affected by, for example, energy stores and weather conditions. We investigated whether immunological state influences autumn stopover departure decisions in Northern Wheatear (Oenanthe oenanthe), a nocturnal long-distance migrant. We measured three parameters of constitutive immune function: microbial killing capacity, haptoglobin, and total immunoglobulins. None of them explained variation in departure probability, minimum stopover duration, or departure time within the night. Thus, we did not find an effect of the birds' immunological state on stopover departure decisions. [ABSTRACT FROM AUTHOR]

Copyright of Acta Ornithologica is the property of Polska Akademia Nauk, Muzeum i Instytut Zoologii and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Ornithologica is the property of Polska Akademia Nauk, Muzeum i Instytut Zoologii and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Many animal species migrate over long distances, but the physiological challenges of migration are poorly understood. It has recently been suggested that increased molecular oxidative damage might be one important challenge for migratory animals. We tested the hypothesis that autumn migration imposes an oxidative challenge to bats by comparing values of 4 blood-based markers of oxidative status (oxidative damage and both enzymatic and nonenzymatic antioxidants) between Nathusius' bats Pipistrellus nathusii that were caught during migration flights with those measured in conspecifics after resting for 18 or 24 h. Experiments were carried out at Pape Ornithological Station in Pape (Latvia) in 2016 and 2017. Our results show that flying bats have a blood oxidative status different from that of resting bats due to higher oxidative damage and different expression of both nonenzymatic and enzymatic antioxidants (glutathione peroxidase). The differences in oxidative status markers varied between sampling years and were independent from individual body condition or sex. Our work provides evidence that migratory flight might impose acute oxidative stress to bats and that resting helps animals to recover from oxidative damage accrued en route. Our data suggest that migrating bats and birds might share similar strategies of mitigating and recovering from oxidative stress. [ABSTRACT FROM AUTHOR]

Aim: The role of migratory birds in the spread of parasites is poorly known, in part because migratory strategies and behaviours potentially affecting transmission are not easy to study. We investigated the dynamics of infection by blood parasites through the annual cycle of a long‐distance Nearctic–Neotropical migratory songbird to examine the role of this species in dispersing parasites between continents. Location: The Americas. Taxon: Grey‐cheeked Thrush (Catharus minimus, Aves, Passeriformes, Turdidae), Birds. Methods: We used molecular and microscopy screening of haemosporidian parasites (Plasmodium, Haemoproteus, and Leucocytozoon) to examine the prevalence, distribution, and diversity of lineages through the annual cycle (breeding, migration, and wintering) of the grey‐cheeked thrush in North and Central America, Santa Marta mountains, the Andes, and the Amazon. We aimed to identify transmission areas, to examine the degree of sharing of haemosporidian lineages with resident birds in various areas and to assess the potential role of immunologically naïve juvenile individuals in parasite transmission. Results: Prevalence and lineage diversity of haemosporidians varied significantly over time, being higher during breeding and fall and spring migration, and declining during wintering. Grey‐cheeked thrush shared few parasite lineages with tropical resident birds and slightly more lineages with other migratory and resident boreal species. We detected gametocytes in blood during spring migration stopover, but these were of lineages not found in resident tropical birds, indicating relapses of parasites transmitted elsewhere. Transmission likely occurs mostly on the breeding grounds, where juveniles and adults carried lineages restricted to closely related species of thrushes and other species of boreal birds. Main conclusions: Long‐distance migratory songbirds are likely not important dispersers of blood parasites because there are ecological and evolutionary barriers to the interchange of parasites across vastly separated areas. Further work with thorough spatial and temporal sampling across other species, and considering the role of vectors, is necessary to understand the ecological and evolutionary factors explaining the distribution of parasites over broad scales. [ABSTRACT FROM AUTHOR]

This study reports a rare investigation into the phenomenon of stopovers during long-haul international travel. Although destination image has been one of the most popular topics in the tourism literature, there has been a lack of attention by researchers regarding the context of stopover destination image for long-haul international air travellers. Indeed most studies have measured destination image without explicitly stating any travel context. A mixed methods approach in two geographically distant markets yielded externally valid findings. This study commenced with a qualitative stage in two countries to elicit attributes deemed salient to individuals when considering an international stopover. Attributes elicited from the two samples were triangulated with the most common themes reported in the destination image literature. A set of 29 attributes was then tested in two online surveys involving 777 consumers in Australia and France. The study highlights the value of engaging with consumers in a qualitative stage, to design a context-specific destination image questionnaire. By using this approach, 12 potentially determinant attributes of stopover destination attractiveness were identified, eight of which have not been commonly used in destination image studies, and one of which represents a new destination image attribute in the literature. [ABSTRACT FROM AUTHOR]

Stopover niche utilization of birds during migration has not gained much attention so far, since the majority of the studies focuses on breeding or wintering areas. However, stopover sites are crucial for migratory birds. They are often used by a multitude of species, which could lead to increased competition. In this work, we investigated niche use of 8 migratory and closely related Emberiza bunting species at a stopover site in Far East Russia, situated on the poorly studied East Asian flyway. We used bird ringing data to evaluate morphological similarity as well as niche overlap on the trophic, spatial, and temporal dimension. Bill morphology was used as a proxy for their trophic niche. We were able to prove that a majority of the species occupies well-defined stopover niches on at least one of the dimensions. Niche breadth and niche overlap differ between spring and autumn season with higher overlap found during spring. Morphological differences are mostly related to overall size and wing pointedness. The temporal dimension is most important for segregation among the studied species. Furthermore, all species seem to exhibit a rather strict and consistent phenological pattern. Their occurrence at the study site is highly correlated with their geographic origin and the length of their migration route. We assume that buntings are able to use available resources opportunistically during stopover, while trying to follow a precise schedule in order to avoid competition and to ensure individual fitness. [ABSTRACT FROM AUTHOR]

Stopover sites are essential to bird migration between wintering and breeding grounds, but annual variation in use and habitat conditions make it difficult to determine which sites are most critical for conservation. By studying physiological factors that may influence a bird’s behavior when choosing and using a stopover site, researchers can target certain species or locations and more efficiently invest in conservation efforts. In spring 2013 and 2014, we studied stopover refueling performance in a common northeastern spring migrant, the White-throated Sparrow (Zonotrichia albicollis), at 2 locations near the south shore of Lake Ontario. We used morphological measurements and physiological techniques that assessed the concentration of the blood metabolite plasma triglyceride as a measure of fat deposition and feeding efficiency. We found that birds captured at an inland location had a significantly higher body condition score than birds captured at a coastal stopover site within 0.5 km of the shore; a trend toward higher triglyceride concentrations was also noted at the inland location. We found no significant differences in triglyceride concentrations between White-throated Sparrow color morphs, in contrast to previous studies performed during fall migration. Our results suggest that spring migrants arriving in the area in good energetic condition may begin their cross-lake journey directly from the inland site, while birds in poorer condition may ‘‘pile up’’ at the lakeshore and then compete with other migrants for available resources, slowing their fat deposition rate. Our results also reinforce the importance of protecting high-quality stopover habitat where birds congregate near geographic barriers but suggest that inland habitat patches are important stopover sites that may allow some migrants to bypass nearshore areas of intense competition. [ABSTRACT FROM AUTHOR]

Long‐distance migration by terrestrial mammals is a phenomenon critical to the persistence of populations, but such migrations are declining globally because of over‐harvest, habitat loss, and movement barriers. Increasingly, there is a need to improve existing routes, mitigate route segments affected by anthropogenic disturbance, and in some instances, determine whether alternative routes are available. Using a hypothesis‐driven approach, we identified landscape features associated with the primary functional attributes, stopovers and movement corridors, of spring migratory routes for mule deer in two study areas using resource selection functions. Patterns of selection for landscape attributes of movement corridors and stopovers mostly were similar; however, landscape features associated with movement corridors aligned better with areas that facilitated movement, whereas selection of stopovers was consistent with sites offering early access to spring forage. For movement corridors, deer selected for dry sites, low elevation, and low anthropogenic disturbance. For stopovers, deer selected for dry sites, with consistently early green‐up across years, south‐southwesterly aspects, low elevation, and low anthropogenic disturbance. Stopovers and movement corridors of a migratory route presumably promote different functions, but for a terrestrial migrant, patterns of habitat selection indicate that the same general habitat attributes may facilitate both movement and foraging in spring. Our findings emphasize the roles of topographical wetness, vegetation phenology, and anthropogenic disturbance in shaping use of the landscape during migration for this large herbivore. Avoiding human disturbance and tracking ephemeral forage resources appear to be a consistent pattern during migration, which reinforces the notion that movement during migration has a nutritional underpinning and disturbance potentially alters the net benefits of migration. [ABSTRACT FROM AUTHOR]

There has been limited published research examining travellers’ perceptions of international stopover destinations. This manuscript reports the modelling of consumer-based brand equity (CBBE) for Dubai, the first CBBE study to do so in the context of a stopover destination. Dubai has emerged relatively recently as a stopover destination option during long haul travel between UK/Europe and Australia/South Pacific, to rival traditional destinations such as Hong Kong and Singapore. The CBBE model was tested using survey data from samples of consumers in two geographically distant markets; France (n = 365) and Australia (n = 403). The findings suggest destination brand awareness, destination brand image and destination brand value are positively related to attitudinal destination loyalty. However, destination brand quality was not positively associated with loyalty. As a relatively new stopover destination for long haul travellers, Dubai is perceived more positively by previous visitors than those who have never visited the destination. [ABSTRACT FROM AUTHOR]

The dynamic weather conditions that migrating birds experience during flight likely influence where they stop to rest and refuel, particularly after navigating inhospitable terrain or large water bodies, but effects of weather on stopover patterns remain poorly studied. We examined the influence of broad-scale weather conditions encountered by nocturnally migrating Nearctic-Neotropical birds during northward flight over the Gulf of Mexico (GOM) on subsequent coastal stopover distributions. We categorized nightly weather patterns using historic maps and quantified region-wide densities of birds in stopover habitat with data collected by 10 weather surveillance radars from 2008 to 2015. We found spring weather patterns over the GOM were most often favorable for migrating birds, with winds assisting northward flight, and document regional stopover patterns in response to specific unfavorable weather conditions. For example, Midwest Continental High is characterized by strong northerly winds over the western GOM, resulting in high-density concentrations of migrants along the immediate coastlines of Texas and Louisiana. We show, for the first time, that broad-scale weather experienced during flight influences when and where birds stop to rest and refuel. Linking synoptic weather patterns encountered during flight with stopover distributions contributes to the emerging macro-ecological understanding of bird migration, which is critical to consider in systems undergoing rapid human-induced changes.

Migration patterns are fundamentally linked to the spatio-temporal distributions of prey. How migrating animals can respond to changes in their prey's distribution and abundance remains largely unclear. During the last decade, humpback whales ( Megaptera novaeangliae ) used specific winter foraging sites in fjords of northern Norway, outside of their main summer foraging season, to feed on herring that started overwintering in the area. We used photographic matching to show that whales sighted during summer in the Barents Sea foraged in northern Norway from late October to February, staying up to three months and showing high inter-annual return rates (up to 82%). The number of identified whales in northern Norway totalled 866 individuals by 2019. Genetic sexing and hormone profiling in both areas demonstrate a female bias in northern Norway and suggest higher proportions of pregnancy in northern Norway. This may indicate that the fjord-based winter feeding is important for pregnant females before migration. Our results suggest that humpback whales can respond to foraging opportunities along their migration pathways, in some cases by continuing their feeding season well into winter. This provides an important reminder to implement dynamic ecosystem management that can account for changes in the spatio-temporal distribution of migrating marine mammals., Competing Interests: We declare we have no competing interests., (© 2023 The Authors.)

The occurrence of molt during migration, known as "molt-migration," has increasingly received attention across many avian taxa since first being described in waterfowl in the 1960s. However, despite the many different types of molt stages and strategies, most, if not all, uses of the term "molt-migration" apply to the definitive prebasic molt of flight feathers in post-breeding adults, whereas fewer studies address migration for body-feather molts. Here, we argue that the current definition of molt-migration, as applied, is limited in focus relative to the diverse ways in which it can manifest in avian populations. We suggest a new, broader definition of molt-migration and highlight examples of molt-migration as traditionally defined, and the many examples that have not been defined as such. We propose a new, 2-tiered typology for defining different forms of molt-migration, based on (1) its progression relative to stationary portions of the annual cycle, and (2) the stage of molt involved. In order to advance our understanding of the ecology and evolution of this increasingly documented phenomenon and apply this knowledge to conservation and management, avian researchers must begin to utilize a common framework for describing molt-migration in its various form. [ABSTRACT FROM AUTHOR]

During migration, birds require stopover habitat to rest and refuel before resuming flight. While long-distance migratory flights represent a large energy investment, stopover accounts for roughly two-thirds of a bird's total energy expenditure during migration. Therefore, birds should minimize energy expenditure while also minimizing time and predation risk during stopover. To understand activity during migration, we recorded activity patterns (i.e. fine-scale movements associated with a range of behaviors) of 3 species, Red-eyed Vireo (Vireo olivaceus), Swainson's Thrush (Catharus ustulatus), and Wood Thrush (Hylocichla mustelina), at a stopover site along the northern coast of the Gulf of Mexico during autumn migration using automated radio telemetry. We found Red-eyed Vireos to be the most active and Swainson's Thrushes the least active. For each species, we used boosted regression trees to investigate associations between activity and factors known to influence bird behavior during stopover. While species differed, day of year and temperature were important predictors of activity for all species. Vireos were active early in the season, under light winds and warmer temperatures, and on evenings when winds were more favorable. Thrushes were more active as the season progressed and when temperatures were cooler. Thrush activity also differed between years, although thrushes increased activity later in the season during all years. Our results illustrate automated radio telemetry as a unique and valuable tool for understanding fine-scale behaviors of birds during stopover. [ABSTRACT FROM AUTHOR]

Abstract: Whether long‐distance animal migration facilitates or hampers pathogen transmission depends on how infections affect the routes and timing of migrating hosts. If an infection directly or indirectly impedes migratory flight capacity, infected individuals lag behind their uninfected conspecifics. Although such temporal segregation can limit parasite transmission and thus play an important role for host–parasite interactions, empirical evidence remains scarce. Here, we investigated haemosporidians – blood parasites commonly infecting birds – in four passerine species on spring passage and linked infection status to passage date. As a step towards identifying the mechanisms behind infection‐related delays, we incorporated sets of individual, energetic, haematological and biometric variables into the analysis. Haemosporidian prevalence virtually doubled between birds sampled at the beginning of the passage period with those sampled 1 month later. This indicates that infected individuals arrived later than uninfected individuals. Both the average prevalence and its increase over time varied among host species. In addition, the leucocyte counts of infected birds were elevated, suggesting that immune response may require resources which could otherwise be allocated to migratory flights. However, infection status was not related to any other variable such as body mass, energy stores, sex, age and feather length. Yet regardless of the underlying mechanisms, infection‐related differential timing might influence transmission and affect pathogen prevalence in wildlife populations year‐round. [ABSTRACT FROM AUTHOR]

To achieve greater understanding of the full annual cycles of birds, It Is critical to describe the spatial nature of little- understood phases. One of the least understood aspects of avian annual cycles Is the ecology of molt: the periodic replacement of feathers. While work on the spatial nature of molt In migratory passerines has Increasingly found Incidences of species and populations completing molt during migration, this work has been limited entirely to prebaslc flight feather molt. We examined the prevalence and progression of contour feather molt In a migratory songbird, the Rusty Blackbird (Euphagus carolinus), during spring stopover. We found that 98% of birds exhibited a partial prealternate molt during stopover, primarily In the head region. Furthermore, molt Intensity peaked In the middle of the migration period and was negatively associated with fat score. This Is the first evidence In the passerine literature of an obligate prealternate molt completed during migration, which Is In many ways similar to the molt strategy of a variety of shorebirds (Families Charadrlldae and Scolopacldae). These findings could prove crucial to understanding the constraints on spring migration In this declining species. Furthermore, we argue that molt schedules such as those of the Rusty Blackbird and shorebirds should be referred to as "prealternate molt-migratlon," broadening the traditional definition of molt-migratlon beyond prebaslc flight feather molt. [ABSTRACT FROM AUTHOR]

Migratory birds spend most of their journeys at stopover sites where they rest and refuel. Many migrants are in steep decline, and understanding their behavior within and among migrations is crucial for developing effective conservation strategies across the full annual cycle. One of the most rapidly declining songbirds in North America is the Rusty Blackbird (Euphagus carolinus; 85-95% decline over the past 50 yr), and stopover ecology is a major gap in our knowledge of its annual cycle. We utilized an automated telemetry array in western Lake Erie and the Motus Wildlife Tracking System to track landscape-scale movements, stopover duration, departure behavior, and between-season site fidelity in this species. W e found that stopover duration during both fall and spring was nearly 1 mo (mean = 25.5 days)--exceptionally long fora passerine. During spring, birds in both poor condition and high degree of molt had longer stopovers, post-departure flights were relatively long fora songbird, and tailwinds predicted departure in both seasons. Many individuals made landscape-scale (10-35 km) relocations during stopover. Site fidelity was high for a passerine, in terms of both route and stopover site. Taken together, these behaviors describe a migration strategy that largely matches the staging behavior of shorebirds. Lastly, we found that Rusty Blackbirds migrate directly across Lake Erie and migrate primarily at night, which might expose them to mortality from offshore wind development. Collectively, our results indicate that high-quality stopover habitat may be critically important to Rusty Blackbird populations. More broadly, our results highlight the need to expand the scale of stopover studies, and to further explore all aspects of species' annual cycles to understand potential limiting factors on populations. [ABSTRACT FROM AUTHOR]

Most migrating birds make multiple stopovers to fuel and/or rest. The decision to resume migration from stopover is based on various cues, such as time within the season and wind conditions. There are hints that the strength of these departure cues shapes corticosterone level, which in its turn appears to regulate the timing of departure. We here provide results that very strongly indicate that indeed departure cues jointly shape corticosterone level of migrants at stopover. We compared corticosterone level between migrating and sedentary common blackbirds ( Turdus merula ) sampled simultaneously at the same location during autumn migration. As expected, in migrating individuals corticosterone level was positively associated with time within the season and with current wind conditions. The latter was only apparent in adult birds and not in 1st year migrants, thus matching the observation that 1st year autumnal migrants are less wind selective than adults. In contrast to the migrants, in sedentary blackbirds these “cues” did not explain variation in corticosterone level. Furthermore, stopover departure seemed more likely and to occur earlier in the night in migrants with high corticosterone level. Our unique comparative study thus supports the newly developed concept that corticosterone mediates between departure cues and stopover departure timing in avian migrants. [ABSTRACT FROM AUTHOR]

During late summer and early autumn, the Bay of Fundy, Canada, is an important foraging area for many species of post-breeding and migratory seabirds, yet there has been limited effort to quantify the number of birds using these waters. Furthermore, the numbers of phalaropes Phalaropus spp. using this region as a stopover during autumn migration is much lower than in previous decades, but an explanation of their disappearance remains elusive. We examined the species composition, abundance and distribution of seabirds using the lower Bay of Fundy during September, 2015. Aerial surveys were conducted in three regions known to encompass good habitat for seabirds: Brier Island Ledges (hereafter Brier: 622 km2), shoals southeast of Grand Manan Island (hereafter Grand Manan: 531 km2), and Lurcher Shoals/German Bank (hereafter Lurcher: 7 433 km2). Using distance sampling, detection probabilities, densities and abundance estimates were calculated for phalaropes, shearwaters (Procellariidae), Northern Gannets Morus bassanus, gulls (Laridae), storm-petrels (Hydrobatidae), and alcids (Alcidae). All species were found in higher densities in Brier and Grand Manan than in the larger area of Lurcher, with phalaropes, shearwaters, and Northern Gannets being the most numerous. Among the three regions, we estimated >100 000 phalaropes during each of two survey periods, and upwards of 30 000 shearwaters, 3 500 Northern Gannets, 2 800 gulls, 2 000 alcids, and 2 000 stormpetrels during one of the two periods. Our abundance estimates for phalaropes were similar to recent surveys, and the low numbers seen in Lurcher suggests this area is not an alternative stopover. Areas of tidal upwelling around Brier and Grand Manan islands provide important foraging habitat for a diverse community of resident and migratory seabirds, but these areas do not account for the disappearance of very large numbers of Red-necked Phalaropes P. lobatus from the nearby Passamaquoddy Bay since the 1980s. [ABSTRACT FROM AUTHOR]

Most migrating birds make stopovers to replenish fuel stores. The decision to resume migration from stopover to a large extent shapes the temporal organization of migration. This decision is known to be shaped by a suite of intrinsic and extrinsic factors such as the bird's fuel stores and current weather conditions. However, how departures from stopover are physiologically regulated is largely unknown. We here present data that strongly indicate that corticosterone, a hormone with a stimulatory effect on locomotion, acts as a mediator between fuel stores and departure from stopover. In migrating northern wheatears ( Oenanthe oenanthe ) temporarily caged at stopover, we observed a positive relationship between the change in fuel stores and the concurrent change in glucocorticoid metabolite (GCM) levels measured in the birds' droppings. We also found a positive relationship between the change in GCM levels and the change in the intensity of nocturnal migratory restlessness. As in northern wheatears nocturnal migratory restlessness is an accurate proxy for stopover departure likelihood, our results indicate that corticosterone mediates between fuel stores and the decision to resume migration. Our unique longitudinal study represents a considerable advance in our understanding of the endocrine regulation of avian migration. [ABSTRACT FROM AUTHOR]

This perspective on the stopover biology of migratory landbirds is organized around the response of migrants to challenges that can arise during stopover and how events during stopover are interconnected with other phases of the annual cycle. Landbird migrants seldom move nonstop from origin to destination, rather they stopover periodically, sometimes for a few hours, sometimes days. How well migrants meet challenges that arise during passage in a timely manner influences the success of their migration; a successful migration is measured in terms of survival and reproductive performance over the annual cycle. What transpires during migration is not isolated from other phases of the migrant's annual cycle. Events taking place in one phase carry over to affect an individual's biology in other phases, including linkage between breeding and wintering phases and the intervening migratory phase. [ABSTRACT FROM AUTHOR]

Much of our understanding of en route landbird habitat use comes from research performed at local scales, ignoring effects at larger spatial scales. We used a multiscale approach to investigate stopover habitat use by landbirds using transect surveys in 68 forested sites in southwestern Michigan, USA, during the springs of 2002 and 2003. We modeled relationships of bird density and arthropod abundance with broad-scale spatiotemporal factors (year, day of year, geographic location) and local landscape (forest composition and structure, presence of open water) as well as site-scale factors (bird density and arthropod abundance, which exchanged roles as predictor and response variables). We found migrant densities to be most influenced by fine-scale factors, such as the abundance of other avian taxa and substrate arthropods, followed by broader-scale factors, such as forest structure and location, within the local and broader surrounding landscape. We found that migrant habitat associations either did not directly match or were weakly associated with the availability of riparian or lacustrine water habitats at a local scale, even though our results suggested that birds using these habitat cues would have encountered more arthropods. Rather than finding indirect measures of food abundance--such as distance to a water source or forest cover at the landscape scale--important, our models best explained bird density by a direct relationship with site-scale food resources. Thus, the scale at which migrants demonstrate habitat selection appears to be influenced by proximate mechanisms such as high-quality habitat availability and the presence of large ecological features within the landscape. Not only do factors operating at multiple scales influence how birds use habitats, but scale also influences how we interpret research findings, in turn influencing conservation decisions. [ABSTRACT FROM AUTHOR]

The ability to locate high-quality stopover habitat has fitness implications for migrating landbirds, and alteration of stopover habitats due to human land-use change, including the introduction of nonnative plants, has been identified as a conservation concern. We tested whether the use and selection of shrublands dominated by exotic plants differed from that of native-dominated shrublands. Specifically, we compared capture rates, transfer rates between habitats, within-foraging-range habitat selection, and food items of Swainson's Thrushes {Catharus ustulatus) and Gray Catbirds [Dumetella carolinensis) between exotic- and native-dominated shrublands in Michigan, USA, during fall migration of 2012 and 2013. Capture rates were >20% higher for thrushes and >250% higher for catbirds in native shrubland. Capture-recapture data showed that birds moved from exotic to native shrubland at higher rates than vice versa. For radio-tagged thrushes and catbirds, native shrubland was --30% more likely to be used than expected by land cover at the within-foraging-range scale. Thrushes, but not catbirds, avoided exotic shrubs within their foraging ranges. Native Lindera benzoin fruit was >50% more likely to be found in fecal samples from both bird species in native-dominated shrubland than in exotic-dominated shrubland, and was the predominant food item in the former habitat type. Collectively, our results suggest that fall migrating Swainson's Thrushes and Gray Catbirds select, and hence occur at higher densities in, predominantly native shrublands rather than exotic-dominated shrublands. One mechanism for this pattern may be their preference for certain native fruits, such as L. benzoin. Our results suggest that native shrubland may be an especially important stopover habitat for frugivorous birds during fall migration. [ABSTRACT FROM AUTHOR]

Cover crops, established between the growing seasons of primary crops to improve soil and water quality, have become increasingly popular in the Midwest region of the United States; however, the impact on migratory and resident birds is largely unknown. We conducted avian surveys on four field types in east central Illinois in the spring of 2015 and 2016: maize ( Zea mays L.) stubble with cover crop, maize stubble only, soybean [ Glycine max (L.) Merr.] stubble with cover crop, and soybean stubble only. For each field type, we calculated relative bird abundance and the Avian Conservation Significance value (ACS). Relative bird abundance was greater in cover crop fields than non-cover crop fields, with the maize fields planted with cover crops providing the greatest value (nearly twice the number of individuals and twice the species compared with non-cover crop soybean fields). The most common species were Red-winged Blackbird ( Agelaius phoeniceus ), Common Grackle ( Quiscalus quiscula ), and American Robin ( Turdus migratorius ). ACS values were most influenced by the Eastern Meadowlark ( Sturnella magna ), a species of high conservation concern. Many agricultural landscapes lack habitat in the spring and cover crop fields may be important areas to provide shelter and forage for birds. While we documented greater use of these fields more research is needed to understand why birds use these fields; more explicitly are birds finding cover, foraging, or attempting to breed in cover crop fields? As the amount of cover crop area increases, the value of these fields for migratory and resident bird use may increase. While habitat for wildlife is a secondary consideration when planting cover crops, my research suggests the use of cereal rye and later termination of cover crops benefits birds. Cover crops will not replace natural habitats for birds, but the widespread use of cover crops may benefit some bird populations. [ABSTRACT FROM AUTHOR]

River deltas along Alaska's Beaufort Sea coast are used by hatch-year semipalmated sandpipers ( Calidris pusilla) after leaving their terrestrial natal sites, but the drivers of their use of these stopover sites on the first 'hop' of fall migration are unknown. We quantified sandpiper temporal distribution and abundance as related to food resources at three river deltas during the beginning of their fall migration (post-breeding period) to compare the habitat quality among these deltas. We conducted population counts, sampled invertebrates, and captured birds to collect blood samples from individuals for triglyceride and stable isotope analyses to determine fattening rates and diet. Patterns of sandpiper and invertebrate abundance were complex and varied among deltas and within seasons. River deltas were used by sandpipers from late July to late August, and peak sandpiper counts ranged from 1000 to 4000 individuals, of which 98% were hatch-year semipalmated sandpipers. Isotopic signatures from blood plasma samples indicated that birds switched from a diet of upland tundra to delta invertebrate taxa as the migration season progressed, suggesting a dependence on delta invertebrates. Despite differences in diet among deltas, we found no differences in fattening rates of juvenile sandpipers as indicated by triglyceride levels. The number of sandpipers was positively associated with abundance of Amphipoda and Oligochaeta at the Jago and Okpilak-Hulahula deltas; an isotopic mixing model indicated that sandpipers consumed Amphipoda and Oligochaeta at Jago, mostly Chironomidae at Okpilak-Hulahula and Spionidae at Canning. Regardless of the difference in sandpiper diets at the Beaufort Sea deltas, their similar fattening rates throughout the season indicate that all of these stopover sites provide a critical food resource for hatch-year sandpipers beginning their first migration. [ABSTRACT FROM AUTHOR]

Much of our understanding of en route landbird habitat use comes from research performed at local scales, ignoring effects at larger spatial scales. We used a multiscale approach to investigate stopover habitat use by landbirds using transect surveys in 68 forested sites in southwestern Michigan, USA, during the springs of 2002 and 2003. We modeled relationships of bird density and arthropod abundance with broad-scale spatiotemporal factors (year, day of year, geographic location) and local landscape (forest composition and structure, presence of open water) as well as sitescale factors (bird density and arthropod abundance, which exchanged roles as predictor and response variables). We found migrant densities to be most influenced by fine-scale factors, such as the abundance of other avian taxa and substrate arthropods, followed by broader-scale factors, such as forest structure and location, within the local and broader surrounding landscape. We found that migrant habitat associations either did not directly match or were weakly associated with the availability of riparian or lacustrine water habitats at a local scale, even though our results suggested that birds using these habitat cues would have encountered more arthropods. Rather than finding indirect measures of food abundance--such as distance to a water source or forest cover at the landscape scale--important, our models best explained bird density by a direct relationship with site-scale food resources. Thus, the scale at which migrants demonstrate habitat selection appears to be influenced by proximate mechanisms such as high-quality habitat availability and the presence of large ecological features within the landscape. Not only do factors operating at multiple scales influence how birds use habitats, but scale also influences how we interpret research findings, in turn influencing conservation decisions. [ABSTRACT FROM AUTHOR]