Stopover Strategies Research Articles

Molecular changes and physiological responses involved in migratory bird fuel management and stopover decisions.

Migratory birds undertake long journeys across continents to reach breeding habitats with abundant resources. These migrations are essential for their survival and are shaped by a complex interplay of physiological adaptations, behavioral cues, and gene expression patterns. Central to migration are stopovers, critical resting points where birds replenish energy stores before continuing their journey. In this study, we integrate physiological measurements, behavioral observations, and molecular data from temporarily caged migrating Garden Warblers (Sylvia borin) to gain insights into their stopover strategies and physiological adaptations after crossing the extended ecological barrier formed by the Sahara Desert and the Mediterranean Sea. Depleted individuals, marked by low body mass and flight muscle mass, showcased remarkable plasticity in recovering and rapidly rebuilding energy stores within a short 5-day stopover. Flight muscle mass increased during this period, highlighting a dynamic trade-off between muscle rebuilding and refuelling. Notably, birds prioritizing muscle rebuilding exhibited a trade-off with the downregulation of genes related to lipid transport and metabolism and at the same time showing evidence of skeletal muscle angiogenesis. Early arrivals were more motivated to depart and exhibited higher levels of physiological stress. Our study highlights the importance of understanding the adaptive responses of birds to changing environmental conditions along their migration routes.

Evaporative Water Loss and Stopover Behavior in Three Passerine Bird Species During Autumn Migration

Migratory birds are often not specifically adapted to arid conditions, yet several species travel across deserts during their journeys, and often have more or less short stopovers there. We investigated whether differences in thermoregulatory mechanisms, specifically evaporative cooling, explain the different behavior of three passerine species while stopping over in the Negev desert, Israel. We measured cutaneous water loss (CWL) under ambient conditions and the temperature of panting onset in an experimental setup. In addition, we performed behavioral observations of birds at a stopover site where we manipulated water availability. Blackcaps had slightly higher CWL at relatively low temperatures than Willow Warblers and Lesser Whitethroats. When considered relative to total body mass, however, Willow Warblers had the highest CWL of the three species. Blackcaps started panting at lower ambient temperature than the other two species. Taken together, these results suggest that Willow Warblers are the most efficient in cooling their body, possibly with the cost of needing to regain water by actively foraging during their staging. Lesser Whitethroats had a similar pattern, which was reflected in their slightly higher levels of activity and drinking behavior when water was available. However, in general the behavior of migratory species was not affected by the availability of water, and they were observed drinking rather rarely. Our results indicate that differences in thermoregulatory mechanisms might be at the basis of the evolution of different stopover strategies of migratory birds while crossing arid areas such as deserts.

Differences in a Cage Escape Behaviour between Two Migrating Warblers of Different Stop-Over Strategy.

Simple SummaryCognitive abilities play an important role for migratory birds that are briefly visiting a variety of unfamiliar stop-over habitats. Here, we compared cognitive abilities-linked behaviour (escape from an experimental cage) between two long-distant migrants differing in refuelling strategy during autumn migration, Sedge Warbler (not territorial, searching for locally superabundant food) and Reed Warbler (territorial, foraging on a common prey). We performed a cage experiment on individuals captured in mist-nets. After two minutes of acclimatization in the cage, we remotely opened the cage door and recorded the bird’s reaction. We measured latency that individuals needed to escape from a cage. Sedge warblers were more likely to escape from the cage than Reed Warblers. Sedge warblers generally escaped earlier after the door was opened and were more likely to escape at any given time than Reed Warblers. We interpret the prevalence of non-escaped individuals as a general feature of migratory birds. In contrast to resident species, they are more likely to enter an unfamiliar environment, but they are less explorative. Differences in escape latency between the studied species may be linked to various refuelling strategies in the context of specialist-generalist foraging. Our study provides ecological insight into the cognitive abilities-linked behaviour of wild animals.Cognitive abilities play an important role for migratory birds that are briefly visiting a variety of unfamiliar stop-over habitats. Here, we compared cognitive abilities-linked behaviour (escape from an experimental cage) between two long-distant migrants differing in stop-over ecology, Sedge Warbler (Acrocephalus schoenobaenus; not territorial, searching for locally superabundant food) and Reed Warbler (A. scirpaceus; territorial, foraging on a common prey) during the autumn migration. After two minutes of acclimatization in the cage, we remotely opened the cage door and recorded the bird’s reaction. We measured latency that individuals needed to escape from a cage. Sedge warblers were 1.61 times more likely to escape from the cage than Reed Warblers. Sedge warblers generally escaped earlier after the door was opened and were 1.79 times more likely to escape at any given time than Reed Warblers. We interpret the prevalence of non-escaped individuals as a general feature of migratory birds. In contrast to resident species, they are more likely to enter an unfamiliar environment, but they are less explorative. We attributed inter-species differences in escape latency to species-specific autumn stop-over refuelling strategies in the context of specialist-generalist foraging. Our study provides ecological insight into the cognitive abilities-linked behaviour of wild animals.

Male post‐breeding movements and stopover habitat selection of an endangered short‐distance migrant, the Little Bustard Tetrax tetrax

Migratory decisions, such as the selection of stopover sites, are critical for the success of post‐breeding migratory movements and subsequent survival. Recent advances in bio‐logging have revealed the stopover strategies of many long‐distance migrants, but far less attention has been given to short‐distance migrants. We investigated the stopover ecology of an endangered grassland bird, the Little Bustard Tetrax tetrax, a short‐distance migrant in Iberia. Using high‐resolution spatial GPS/GSM data, 27 male Little Bustards breeding in southern Portugal were tracked between 2009 and 2011. We studied post‐breeding movements using Dynamic Brownian Bridge models to identify the main stopover sites, and generalized linear mixed models to examine habitat selection in stopovers. During their post‐breeding movements, males were essentially nocturnal migrants, making frequent stopovers while maintaining a relatively fast pace to reach more productive agricultural post‐breeding areas. Stopovers occurred in most post‐breeding movements (83%) regardless of the total distance covered (average 64.3 km), and most stopovers (84%) lasted less than 24 h. Birds used mostly agricultural non‐irrigated and irrigated croplands as stopover sites and avoided other land uses and rugged terrain. There was a negative relationship between stopovers and the proximity to roads, but not to power lines. The high frequency of stopovers during post‐breeding movements, despite the short distances travelled, together with the nocturnal migratory behaviour of bustards, may impose additional risks to a bird mainly threatened by collision with power lines in non‐breeding areas. We also conclude that even for short‐distance migrants, habitat connectivity between breeding and post‐breeding areas is likely to be a key conservation concern.

Range‐wide populations of a long‐distance migratory songbird converge during stopover in the tropics

AbstractGeographic convergence during migration influences the extent to which animal populations may experience carry‐over effects across periods of the annual cycle. When most individuals of a population share geographic areas during a given priod, carry‐over effects are likely stronger than when individuals occupy multiple areas. We used genetic data and stable isotope (δ2H) measurements from feathers and claws to describe the likely breeding and wintering geographic origins of a long‐distance migratory songbird (Gray‐cheeked Thrush, Catharus minimus) moving through northern Colombia in spring and fall migration. Furthermore, we used these data coupled with regional occupancy surveys to assess whether individuals from various breeding populations converge during migration and evaluated whether geographic origin, age, or sex affected stopover strategies. We found that range‐wide breeding populations of Gray‐cheeked Thrush converged in northern Colombia in an area spanning <1% of the breeding range, especially during a prolonged spring stopover in the Sierra Nevada de Santa Marta. Breeding (but not winter) origin, sex, and age influenced arrival date and body condition upon arrival at stopover sites where populations converged. Birds from more northerly breeding latitudes, males and adults generally arrived earlier and in lower body condition than those with more southerly breeding origins, females, and juveniles. Our work and other studies suggest that areas in northern Colombia may function as ecological bottlenecks for Gray‐cheeked Thrush because they concentrate individuals from across the breeding range, provide critical resources, and impose constraints during migration. Future studies quantifying the effects of high‐convergence areas on fitness and survival of individuals and their demographic consequences are required to assess their roles as ecological bottlenecks.

Stopover strategies of Eurasian Blackcaps (Sylvia atricapilla) during the post-fledging period in western Hungary

Stopover strategies of the Eurasian Blackcap (Sylvia atricapilla) during the post-fledging period were studied at Tömörd, western Hungary, between 1998 and 2015. Capture data of juveniles and adults were pooled for both sexes, and recapture rate, stopover length and fat deposition patterns were analyzed. During stopover, males and females did not differ significantly in stopover length, total change in body mass, proportion or rate of body mass change, or change in fat score. Among all recaptures, an overall significant positive correlation was recognized between mass deposition rate (g/day) and departure body mass. According to our results, both males and females use a time-minimization migration strategy in autumn. The benefit of this strategy might be that it favors early arrival in the overwintering areas, before competitors. The individuals arriving earlier at wintering sites might obtain higher-quality territories and achieve higher winter survival.

Connecting the dots: Stopover strategies of an intercontinental migratory songbird in the context of the annual cycle.

The phases of the annual cycle for migratory species are inextricably linked. Yet, less than five percent of ecological studies examine seasonal interactions. In this study, we utilized stable hydrogen isotopes to geographically link individual black‐and‐white warblers (Mniotilta varia) captured during spring migration with breeding destinations to understand a migrant's stopover strategy in the context of other phases of the annual cycle. We found that stopover strategy is not only a function of a bird's current energetic state, but also the distance remaining to breeding destination and a bird's time‐schedule, which has previously been linked to habitat conditions experienced in the preceding phase of the annual cycle. Birds in close proximity to their breeding destination accumulate additional energy reserves prior to arrival on the breeding grounds, as reflected by higher migratory condition upon arrival, higher refueling rates measured via blood plasma metabolites, and longer stopover durations compared to birds migrating to breeding destinations farther from the stopover site. However, late birds near their breeding destination were more likely to depart on the day of arrival (i.e., transients), and among birds that stopped over at the site, the average duration of stopover was almost half the time of early conspecifics, suggesting late birds are trying to catch‐up with the overall time‐schedule of migration for optimal arrival time on the breeding grounds. In contrast, birds with long distances remaining to breeding destinations were more likely to depart on the day of arrival and primarily used stopover to rest before quickly resuming migration, adopting similar strategies regardless of a bird's time‐schedule. Our study demonstrates that migrants adjust their en route strategies in relation to their time‐schedule and distance remaining to their breeding destination, highlighting that strategies of migration should be examined in the context of other phases of the annual cycle.

Light‐level geolocation reveals wintering distribution, migration routes, and primary stopover locations of an endangered long‐distance migratory songbird

The importance of understanding the geographic distribution of the full annual cycle of migratory birds has been increasingly highlighted over the past several decades. However, the difficulty of tracking small birds between breeding and wintering areas has hindered progress in this area. To learn more about Kirtland's warbler Setophaga kirtlandii movement patterns throughout the annual cycle, we deployed archival light‐level geolocators across their breeding range in Michigan. We recovered devices from 27 males and analyzed light‐level data within a Bayesian framework. We found that most males wintered in the central Bahamas and exhibited a loop migration pattern. In both fall and spring, departure date was the strongest predictor of arrival date, but in spring, stopover duration and migration distance were also important. Though stopover strategies varied, males spent the majority of their spring migration at stopover sites, several of which were located just before or after large ecological barriers. We argue that loop migration is likely a response to seasonal variation in prevailing winds. By documenting a tight link between spring departure and arrival dates, we provide a plausible mechanism for previously documented carry‐over effects of winter rainfall on reproductive success in this species. The migratory periods remain the least understood periods for all birds, but by describing Kirtland's warbler migration routes and timing, and identifying locations of stopover sites, we have begun the process of better understanding the dynamics of their full annual cycle. Moreover, we have provided managers with valuable information on which to base future conservation and research priorities.

Phenology of southward migration of shorebirds in the East Asian-Australasian Flyway and inferences about stop-over strategies

The southward migration strategies of shorebirds remain poorly understood in the East Asian-Australasian Flyway, yet understanding such strategies is critical to shorebird conservation. We estimate passage dates of 28 species of shorebird from count data at 15 sites to infer their migration strategies, using Thompson's modelling approach. Our estimates of passage dates were consistent with available tracking data, giving us confidence that the modelled estimates were accurate. For large-bodied shorebirds, modelled departure dates from the northern Yellow Sea were similar to arrival dates throughout Australia, and their arrival dates in different regions in Australia were also similar, suggesting they flew directly from Asian staging areas to Australian non-breeding areas, or stopped only very briefly on the way. In contrast, small-bodied species apparently made multiple stops, especially in northern Australia, during their migration to their final non-breeding destinations. These differing patterns suggest that larger species in this Flyway depend on a small number of staging sites, whereas smaller species migrate in shorter steps and require additional staging sites between the northern Yellow Sea and Australasia. It is likely that some of these sites have not as yet been discovered, and that conservation of small shorebird species requires a more complete accounting of unknown and understudied staging sites.

Physiological conditions influence stopover behaviour of short-distance migratory passerines

During migration, birds spend more than 80 % of the time at stopover sites to rest and refuel before and after crossing ecological barriers such as deserts or seas. Since stopover has intrinsic costs in terms of energy and time, birds should try to minimize its duration, which is dependent on the combined effects of environmental factors, endogenous programmes, and physiological conditions. Previous studies on long-distance migrants caught after crossing an ecological barrier have indicated that body condition strongly influences the decision whether to prolong stopover or resume migration, with lean birds staying longer than fat birds. In short-distance migrants, evidence is still scarce regarding a determinant role for physiological condition in stopover behaviour after crossing an ecological barrier. Here, we studied whether migratory restlessness (Zugunruhe) at a stopover site is dependent on physiological condition in three European short-distance migratory passerines: black redstarts, European robins, and European stonechats. In all species, an integrated measure of condition based on body mass, amount of subcutaneous fat, and thickness of pectoral muscles predicted the intensity of Zugunruhe. Overall, our results confirmed the importance of energy reserves in determining stopover duration, illustrating similar stopover strategies in short- and long-distance migrants.

Fall stopover strategies of three species of thrush (Catharus) in northern South America

ABSTRACT Northern South America is a geographic bottleneck that may be limiting the survival of Nearctic–Neotropic migrants. However, very little is known about the migration ecology of transcontinental migrants wintering in South America. We studied the fall migratory strategies of three species of thrush (Catharus ustulatus, C. fuscescens, and C. minimus) at 2 major migrant gateways into South America: the Darien and the Sierra Nevada de Santa Marta (SNSM) of northern Colombia. Assuming that migration route shapes the stopover strategy of birds and that our sites receive birds from 2 different routes, we predicted that (1) migrants traveling over land through Central America (Darien) would make short and frequent stopovers followed by short flights and (2) migrants crossing the Caribbean (SNSM) would make few and long stopovers to acquire fuel for longer flights. To test these predictions, we estimated condition on arrival, stopover duration, fuel deposition rates, and potential flight ranges after stop...

Wing Shape Influences Stopover Strategies in a Migratory Shorebird, the Common Snipe

The basic assumption in the morphology of avian migrants is that longer, more pointed and concave wings are well adapted for long-distance migratory flights. We investigated how wingtip morphology of the Common Snipe was associated with aspects of its migration, such as amount of accumulated fat, refueling rates, length of stay at the stopover site, and timing of post-juvenile molt. Our study took place at the Jeziorsko reservoir, central Poland, where over 400 first-year Common Snipe (Gallinago gallinago) were caught in 2008 and 2009. Wing shape was found to correlate with different components of the species' stopover strategies. After controlling for the date of capture we found that first-year birds with wings adapted for efficient migration (pointed/concave wingtips) refueled more quickly and stayed for shorter times at the stopover site. Pointed/concave wing shape was also associated with accumulation of smaller fat reserves and later initiation of post-juvenile molt during the period of migration. By contrast, snipe having a wing shape adapted for predator evasion (rounded/convex wingtips) refueled more slowly, remained longer, and accumulated greater amounts of fat, which in turn facilitated earlier molting.

The impact of an invasive exotic bush on the stopover ecology of migrant passerines

Migration is highly energy-demanding and birds often need to accumulate large fuel loads during this period. However, original habitat at stopover sites could be affected by invasive exotic plants outcompeting native vegetation. The impact of exotic plants on the stopover behavior of migrant bird species is poorly understood. As a general hypothesis, it can be supposed that habitat change due to the presence of exotic plants will affect migrants, having a negative impact on bird abundance, on avian community assemblage, and/or on fuel deposition rate. To test these predictions, we used data obtained in August 2011 at a ringing station in a coastal wetland in northern Iberia which contained both unaltered reedbeds (Phragmites spp.) and areas where the reedbeds had been largely replaced by the invasive saltbush (Baccharis halimifolia). Passerines associated with reedbeds during the migration period were used as model species, with a particular focus on sedge warblers (Acrocephalus schoenobaenus). The saltbush promoted a noticeable change on bird assemblage, which became enriched by species typical of woodland habitats. Sedge warblers departed with a higher fuel load, showed a higher fuel deposition rate, and stayed for longer in the control zone than in the invaded zone. Invasive plants, such as saltbush, can impose radical changes on habitat, having a direct effect on the stopover strategies of migrants. The substitution of reedbeds by saltbushes in several coastal marshes in Atlantic Europe should be regarded as a problem with potential negative cons equences for the conservation of migrant bird species associated with this habitat.

Do BlackcapsSylvia atricapillaStopping Over at a Locality from Southern Iberia Refuel for Crossing the Sahara?

Summary. Do blackcaps Sylvia atricapilla stopping over at a locality from Southern Iberia refuel for crossing the Sahara? Migrants that cross large inhospitable areas must accumulate large loads of fuel to reach their destinations successfully. The stopover strategies of European long-distance migrants are relatively well studied for species that overwinter in tropical Africa, but less so for those that overwinter mainly around the Mediterranean and of which only a fraction reach tropical Africa. Our aim here was to analyse whether blackcaps Sylvia atricapilla stopping over in southern Iberia gain sufficient fuel in this region to be able to reach tropical Africa. Blackcaps were mistnetted during the autumn migration period of 2005 at a locality in Northern Iberia (Loza) and another in Southern Iberia (Donna). Blackcaps at Donana had lower fuel loads and a slower fuel deposition rate than at Loza, and the estimated flight ranges from both sites were insufficient to reach tropical Africa. The stopover dura...

Comparison of autumn and spring migration strategies of Neotropical migratory landbirds in northeast Belize

Migration represents one of the most vulnerable stages of a migrant's life cycle, but the strategies and stopover sites used by Neotropical migrants in Central America are not well known. We carried out constant effort mist netting and conducted censuses along transects during one autumn (2007) and one spring (2008) migration in northeast Belize. We recorded more landbird migrant species in autumn (63) than in spring (54), and spring abundance was >25% lower for 88% of transient species. These differences in presence and abundance indicate that routes and stopover strategies vary between seasons and species. In autumn, fuel loads, calculated as any increase in mass above lean body mass (LBM), were generally small (mean = 5.9% LBM and 10.1% LBM for wintering and transient species, respectively) and fuel deposition rates and minimum stopover durations suggest that some individuals replenished energy reserves in our study area. Variation in autumn fuel loads meant that some individuals had reserves sufficient for flights >1000 km. Fuel loads were larger in spring for 16 of 17 species, and the mean spring fuel load for transient species (32.5% LBM) was sufficient for a flight from northeast Belize to North America without refueling. The similarity in spring passage times between northeast Belize and the Gulf Coast of the United States also suggests that energy reserves were not replenished in northeast Belize prior to crossing the Gulf of Mexico. We hypothesize that sufficient energy reserves are accumulated during spring stopovers in northern South America or elsewhere in Mesoamerica to allow migrants to fly directly to North America without refueling.

Long-distance travellers stopover for longer: a case study with spoonbills staying in North Iberia

Long-distance migration is widespread among birds, connecting breeding and wintering areas through a set of stopover localities where individuals refuel and/or rest. The extent of the stopover is critical in determining the migratory strategy of a bird. Here, we examined the relationship between minimum length of stay of PVC-ringed birds in a major stopover site and the remaining flight distance to the overwintering area in the Eurasian spoonbill (Platalea l. leucorodia) during four consecutive autumn migrations. We also analysed the potential effect of timing (arrival date), as well as the role of experience in explaining stopover duration of spoonbills. Overall, birds wintering in Africa, and facing long-distance travel from the stopover site (ca. 3,000 km) stay for longer (2.7 ± 0.4 days) than Iberian winterers (1.5 ± 0.2 days) that perform a much shorter migration (ca. 800 km). These differences were consistent between years. Stopover duration was not significantly affected by the age of the bird. However, there was a significant reduction as migration advanced. Our results suggest that spoonbills develop different stopover strategies depending on the expected distance to the wintering grounds. Adults, especially long-distance migratory ones, could reduce the potential negative effects of density-dependence processes by avoiding stopover at the end of the migration period. These findings are of significant relevance for understanding differences in migratory behaviour within single populations, especially for declining waterbirds, as well as stress the relevance of preserving stopover localities for the conservation of intraspecific diversity in migratory species.

Ringing and the study of mechanisms of migration

The ringing of birds has unveiled many mysteries of avian migration, notably routes and destinations, but has also contributed to the elucidation of migration mechanisms. The understanding of orientation and navigation mechanisms, stopover and fuelling strategies, and of migration strategies has gained much from the analyses of recoveries from ringed birds, and ringing and recapture approaches still make a major contribution to our understanding of migration. Detailed single‐site studies could reveal internal and environmental factors governing stopover strategies, especially with sophisticated field experiments, but comparative multi‐site approaches would be of considerable value to unravel migration strategies and carry‐over effects between non‐breeding and breeding periods. This is particularly important in view of the fact that long‐distance migratory species are the ones with the most serious population declines.

Long-Haul Shipment Optimization for Less-Than-Truckload Carriers

Less-than-truckload (LTL) carriers supply freight transportation services for small parcel shipments. These companies consolidate multiple shipments in vehicles to guarantee the efficiency of the system. A method for LTL carriers is presented to solve the long-haul routing design problem with capacitated distribution centers and time-constrained shipments. The method uses direct, hub-and-spoke, and stopover strategies to allocate shipments in the set of routes. The resolution method is based on a tabu search algorithm. The search process in the solution domain is performed dynamically with four possible perturbations. The results obtained in a set of test problems demonstrate that the restart parameters play a significant role in the efficiency of the algorithm. Implementation of this computational technique in the long-haul operations network of the largest carrier in Spain reduced transportation costs by 6%.

Spring migration dynamics and sex-specific patterns in stopover strategy in the Wood Sandpiper Tringa glareola

Due to being a virtually monomorphic wader species, migration dynamics and sex-related migration patterns in the Wood Sandpiper (Tringa glareola) have rarely been investigated. We captured spring migrants at an important stopover site in northeastern Austria. Birds were individually color-marked, and sex was determined by an analysis of DNA from tail feather material. Among temporary residents (birds seen again after day of capture), males migrated on average 3 days earlier than females. However, since sexes did not differ in fat score, the length of stay and the proportion of transients (birds not seen again after day of capture) and temporary residents, we suggest that males and females adopt similar migration strategies in the spring. The large number of transients captured as well as shorter stopover durations in later temporary residents indicate that Wood Sandpipers minimize time at this stage of their northbound migration. Temporary residents earlier in the season exhibited lower fat stores than later ones. Nevertheless, since the fat stores of transients and temporary residents were similar even after the progress of the season had been accounted for, we assume that Wood Sandpipers may afford to exhibit individual flexibility in migration strategy and the use of stopover sites, especially early in the season. This variability may be a necessary adaptation to cope with possible varying environmental conditions at dynamic and unpredictable inland stopover sites. After having reached North Mediterranean regions, mean body mass of spring migrants gradually increases during successive stopovers, indicating that Wood Sandpipers follow a ‘hopping’ migration strategy. This emphasizes the high conservation value of even small artificial mudflat pools as important stepping stones in order to maintain a continuous network of wetland habitats for this continental migrant.

Climate changes and post-nuptial migration strategy by two reedbed passerines

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 35:147-157 (2007) - DOI: https://doi.org/10.3354/cr00721 Climate changes and post-nuptial migration strategy by two reedbed passerines Guillaume Péron1,2, Pierre-Yves Henry1,3, Pascal Provost4, Olivier Dehorter1, Romain Julliard1,* 1UMR 5173 MNHN-CNRS-UPMC, Centre de Recherche sur la Biologie des Populations d’Oiseaux, CP51, 55 rue Buffon, 75005 Paris, France 2UMR 5175, Centre d’Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique, 1919 route de Mende, 34293 Montpellier Cedex 5, France 3UMR 7179 MNHN-CNRS, Département Ecologie et Gestion de la Biodiversité, Muséum National d’Histoire Naturelle, 1 avenue du Petit Château, 91800 Brunoy, France 4Maison de l’Estuaire, Observatoire Avifaune de la ZPS Estuaire et Marais de la Basse Seine, Réserve Naturelle Nationale de l’Estuaire de la Seine, 20 rue Jean Caurret, 76600 Le Havre, France *Corresponding author. Email: julliard@mnhn.fr ABSTRACT: Phenology of biological systems is the expression of selective pressures forcing organisms to match their energy requirements to seasonal variations in resource availability. For long-distance migrant organisms, migration strategy is shaped by the availability and quality of stopovers during a precise time period. Ongoing climate changes alter the usual spatial and temporal distribution of resources, and, as a result, migrant species return earlier to their breeding grounds. Less is known on the evolution and determinants of timing of departure to wintering grounds, i.e. post-breeding migration. We analysed timing of post-nuptial migration and stopover strategy with capture–mark–recapture (CMR) data in 2 reedbed insectivorous passerines: the sedge warbler Acrocephalus schoenobaenus, specialised on a thermo-dependant prey, and the generalist reed warbler A. scirpaceus. Spring temperatures increased through years (0.16 ± 0.047°C yr–1), and studied species migrated earlier in recent years (–0.73 ± 0.086 d yr–1). Autumnal migration phenology was negatively related to spring (March) temperature (–2.54 ± 0.19 d °C–1), whereas it was not related to autumnal temperatures. We suggest that this results from a major time shift (i.e. advance) in biomass production caused by global warming. Stopover duration (estimated by CMR analysis) was positively related to body mass gain, with a trend for a stronger effect in the specialised species. However, neither stopover duration nor body mass gain were related to spring temperature, suggesting that the advance in migration timing efficiently adapted bird phenology to temporal variations in resources. KEY WORDS: Climate change · Stopover duration · Optimal migration · Acrocephalus scirpaceus · Acrocephalus schoenobaenus · Capture–Mark–Recapture Full text in pdf format PreviousNextCite this article as: Péron G, Henry P, Provost P, Dehorter O, Julliard R (2007) Climate changes and post-nuptial migration strategy by two reedbed passerines. Clim Res 35:147-157. https://doi.org/10.3354/cr00721 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 35, No. 1-2. Online publication date: December 31, 2007 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2007 Inter-Research.