Crosswise migration by Yellow Warblers,Nearctic‐Neotropical passerine migrants

Yellow Warblers (Setophaga petechia) are abundant breeding birds in North America, but their migratory and non‐breeding biology remain poorly understood. Studies where genetic and isotopic techniques were used identified parallel migration systems and longitudinal segregation among eastern‐ and western‐breeding populations of Yellow Warblers in North America, but these techniques have low spatial resolution. During the 2015 breeding season, we tagged male Yellow Warblers breeding in Maine (N = 10) and Wisconsin (N = 10) with light‐level geolocators to elucidate fine‐scale migratory connectivity within the eastern haplotype of this species and determine fall migration timing, routes, and wintering locations. We recovered seven of 20 geolocators (35%), including four in Maine and three in Wisconsin. The mean duration of fall migration was 49 d with departure from breeding areas in late August and early September and arrival in wintering areas in mid‐October. Most individuals crossed the Gulf of Mexico to Central America before completing the final eastward leg of their migration to northern South America. Yellow Warblers breeding in Maine wintered in north‐central Colombia, west of those breeding in Wisconsin that wintered in Venezuela and the border region between Brazil, Colombia, and Venezuela. Our results provide an example of crosswise migration, where the more easterly breeding population wintered farther west than the more westerly breeding population (and vice versa), a seldom‐documented phenomenon in birds. Our results confirm earlier work demonstrating that the eastern haplotype of northern Yellow Warblers winters in northern South America, and provide novel information about migratory strategies, timing, and wintering locations of birds from two different populations.     

Stable‐hydrogen isotope turnover in red blood cells of two migratory thrushes: application to studies of connectivity and carry‐over effects

ABSTRACT Understanding turnover rates of stable isotopes in metabolically active tissues is critical for making spatial connections for migratory birds because samples provide information about pre‐migratory location only until the tissue turns over to reflect local values. We calculated stable‐hydrogen isotope (δ²H) turnover rate in the red blood cells of two long‐distance migratory songbirds, Bicknell's Thrushes (Catharus bicknelli) and Swainson's Thrushes (Catharus ustulatus), using samples collected at a breeding site in New Brunswick, Canada. Blood from both species captured early in the breeding site was more positive in δ²H than blood sampled later in the summer, but did not match blood values for wintering Bicknell's Thrushes. An asymptotic exponential model was used to estimate turnover of red blood cell δ²H and yielded a half‐life estimate of 21 days and 14 days for Bicknell's and Swainson's thrushes, respectively. Red blood cells of both species approached the local breeding site value one month after the first individuals were detected at the site. For Bicknell's Thrushes, estimated δ²H in blood at arrival (?72‰) was closer to blood collected at wintering sites (mean ?61‰) than to expected breeding site δ²H (?120‰). Discrimination values calculated for red blood cells collected at the breeding site for both species were greater than expected based on studies using keratin. Turnover during migration currently limits the use of blood sampled early in the breeding season for connectivity/carry‐over effect studies. However, direct tracking technology such as geolocators can provide information about migration duration, timing, and stopovers that can be used to improve isotopic turnover equations for metabolically active tissues.     

Use of Museum Specimens to Refine Historical Pronghorn Subspecies Boundaries

Endangered Sonoran (Antilocapra americana sonoriensis) and Peninsular (A. a. peninsularis) pronghorn persist largely because of captive breeding and reintroduction efforts. Recovery team managers want to re-establish pronghorn in their native range, but there is currently uncertainty regarding the subspecies status of extinct pronghorn populations that historically inhabited southern California, USA, and northern Baja California, Mexico. To address this uncertainty, we genotyped museum specimens and conducted phylogenetic and population genetic analyses of historical data in the context of 3 contemporary pronghorn populations. The historical northern Baja California pronghorn share the most ancestry with contemporary Peninsular pronghorn, whereas pronghorn in southern California share more ancestry with contemporary American (A. a. americana) pronghorn. For reintroductions into northern Baja California, the Peninsular subspecies is more appropriate based on museum genetic data. For reintroductions into Southern California, ecological and genetic factors are both important, as the subspecies most genetically related to historical populations (American) may not be well-adapted to the hot, low-elevation deserts of the reintroduction area. © 2019 The Wildlife Society.     

The invasive bullfrog <Emphasis Type="Italic">Lithobates catesbeianus</Emphasis> in oases of Baja California Sur,Mexico: potential effects in a fragile ecosystem

The American bullfrog (Lithobates catesbeianus), considered as one of the world’s worst invasive species because of its negative effects on native fauna, has been introduced into over 40 countries in four continents. The invasion status in Mexico is poorly known. The first known record for this species in the Peninsula of Baja California, northwestern Mexico is an individual collected 35 years ago. A great portion of the peninsula is an arid desert where the sources of freshwater are the spring-fed oasis and mountain arroyos that support rare and endemic species closely associated with wetland conditions. Humans, who have introduced alien species, inhabit many of those oases. The aim of this work was to document the presence of the exotic bullfrog in 40 oases and mountain arroyos in Baja California Sur state during 2006–2009. Bullfrogs were found in 25% of the oases sampled; 15% have confirmed records of breeding populations and five oases are new location records. Our results show a considerable increase (50%) in the number of oasis invaded by bullfrogs in only 8 years. The animal populations of rare or endemic species associated with oases would be threatened by the arrival of bullfrogs. Actions for their control and eradication are urgently needed.     

Dichotomous strategies? The migration of Whimbrels breeding in the eastern Canadian sub‐Arctic

The conservation of migratory birds requires internationally coordinated efforts that, in turn, demand an understanding of population dynamics and connectivity throughout a species' range. Whimbrels (Numenius phaeopus) are a widespread long‐distance migratory shorebird with two disparate North American breeding populations. Monitoring efforts suggest that at least one of these populations is declining, but the level of migratory connectivity linking the two populations to specific non‐breeding sites or identifiable conservation threats remains unclear. We deployed light‐level geolocators in 2012 to track the migration of Whimbrels breeding near Churchill, Manitoba, Canada. In 2013, we recovered 11 of these geolocators, yielding complete migration tracks for nine individuals. During southbound migration, six of the nine Whimbrels stopped at two staging sites on the mid‐Atlantic seaboard of the United States for an average of 22 days, whereas three individuals made nonstop flights of ~8000 km from Churchill to South America. All individuals subsequently spent the entire non‐breeding season along the northern coasts of Brazil and Suriname. On their way north, all birds stopped at the same two staging sites used during southbound migration. Individuals staged at these sites for an average of 34 days, significantly longer than during southbound migration, and all departed within a 5‐day period to undertake nonstop flights ranging from 2600 to 3100 km to the breeding grounds. These extended spring stopovers suggest that female Whimbrels likely employ a mixed breeding strategy, drawing on both endogenous and exogenous reserves to produce their eggs. Our results also demonstrate that this breeding population exhibits a high degree of connectivity among breeding, staging, and wintering sites. As with other long‐distance migratory shorebirds, conservation efforts for this population of Whimbrels must therefore focus on a small, but widely spaced, suite of sites that support a large proportion of the population.     

The effects of geolocators on return rates,condition, and breeding success in Common Sandpipers Actitis hypoleucos

ABSTRACT

Capsule: Fitting geolocators to Common Sandpipers Actitis hypoleucos did not affect their return rates, return dates, body condition or reproductive success, but did cause leg injuries in some individuals.

Aims: To investigate the effect of fitting geolocators to Common Sandpipers on their return rates and timing, the condition in which they return and their subsequent breeding success.

Methods: We fitted geolocators to colour-ringed Common Sandpipers and monitored them throughout the breeding seasons prior to migration and following return from their wintering grounds. We then compared return rate, return date, change in body condition, hatching success, and fledging success between birds with and without the tags. We also fitted a number of smaller geolocators to wintering individuals in Africa and compared their return rates with a control group.

Results: We found no significant differences between birds with and without geolocators in any of the variables measured. However, several individuals fitted with the larger tags were found to have incurred leg injuries.

Conclusion: Our study highlights the need for complete transparency when reporting the effects of geolocators and shows the importance of continuous monitoring of individuals when carrying out tracking studies.     

Investigating connectivity and seasonal differences in wind assistance in the migration of Common Sandpipers

Many migratory bird species have undergone recent population declines, but there is considerable variation in trends between species and between populations employing different migratory routes. Understanding species-specific migratory behaviours is therefore of critical importance for their conservation. The Common Sandpiper Actitis hypoleucos is an Afro-Palaearctic migratory bird species whose European populations are in decline. We fitted geolocators to individuals breeding in England or wintering in Senegal to determine their migration routes and breeding or non-breeding locations. We used these geolocator data in combination with previously published data from Scottish breeding birds to determine the distributions and migratory connectivity of breeding (English and Scottish) and wintering (Senegalese) populations of the Common Sandpiper, and used simulated random migrations to investigate wind assistance during autumn and spring migration. We revealed that the Common Sandpipers tagged in England spent the winter in West Africa, and that at least some birds wintering in Senegal bred in Scandinavia; this provides insights into the links between European breeding populations and their wintering grounds. Furthermore, birds tagged in England, Scotland and Senegal overlapped considerably in their migration routes and wintering locations, meaning that local breeding populations could be buffered against habitat change, but susceptible to large-scale environmental changes. These findings also suggest that contrasting population trends in England and Scotland are unlikely to be the result of population-specific migration routes and wintering regions. Finally, we found that birds used wind to facilitate their migration in autumn, but less so in spring, when the wind costs associated with their migrations were higher than expected at random. This was despite the wind costs of simulated migrations being significantly lower in spring than in autumn. Indeed, theory suggests that individuals are under greater time pressures in spring than in autumn because of the time constraints associated with reproduction.     

Faster migration in autumn than in spring: seasonal migration patterns and non‐breeding distribution of Icelandic whimbrels Numenius phaeopus islandicus

Migration is fundamental in the life of many birds and entails significant energetic and time investments. Given the importance of arrival time in the breeding area and the relatively short period available to reproduce (particularly at high latitudes), it is expected that birds reduce spring migration duration to a greater extent than autumn migration, assuming that pressure to arrive into the wintering area might be relaxed. This has previously been shown for several avian groups, but recent evidence from four tracked Icelandic whimbrels Numenius phaeopus islandicus, a long distance migratory wader, suggests that this subspecies tends to migrate faster in autumn than in spring. Here, we 1) investigate differences in seasonal migration duration, migration speed and ground speed of whimbrels using 56 migrations from 19 individuals tracked with geolocators and 2) map the migration routes, wintering and stopover areas for this population. Tracking methods only provide temporal information on the migration period between departure and arrival. However, migration starts with the fuelling that takes place ahead of departure. Here we estimate the period of first fuelling using published fuel deposition rates and thus explore migration speed using tracking data. We found that migration duration was shorter in autumn than in spring. Migration speed was higher in autumn, with all individuals undertaking a direct flight to the wintering areas, while in spring most made a stopover. Wind patterns could drive whimbrels to stop in spring, but be more favourable during autumn migration and allow a direct flight. Additionally, the stopover might allow the appraisal of weather conditions closer to the breeding areas and/or improve body condition in order to arrive at the breeding sites with reserves.     

Long‐distance movements and evidence of post‐breeding elevational movements by Cassin’s Vireos

Bird migration is often framed as a straightforward journey between one breeding site and one wintering site, but recent research has shown that the reality is often more complex. Many species of birds undertake short‐distance movements separate from long‐distance migration. Such movements appear to be common in species that breed in western North America, where mountainous terrain creates a mosaic of habitats and climatic conditions. However, individual‐based tracking studies have disproportionately focused elsewhere, leaving gaps in our understanding of the year‐round movements of western species. I used tracking data from light‐level geolocators and citizen science data from eBird to study the movements of Cassin’s Vireos (Vireo cassinii) breeding in the Sierra Nevada mountains of California, USA. During three breeding seasons (2013–2015), my observations suggested that Cassin’s Vireos vacate their breeding territories during the post‐breeding period in July and August. In April and May 2016, I tagged 22 Cassin’s Vireos with light‐level geolocators and, in April and May 2017, recaptured four that had retained their geolocators. Geolocator data showed that these four birds remained in the same geographic region as their breeding territories (likely the same mountain range) during the post‐breeding period in July and August 2016, ruling out the possibility of long‐distance movements during this time. Analysis of eBird citizen science data suggested that Cassin’s Vireos undertake short‐distance molt‐migration to higher elevations in the Sierra Nevada Mountains during the post‐breeding period. Geolocator data revealed that long‐distance fall migration took place in September and spring migration in April or May, and the four birds spent the winter in different parts of the Mexican winter range of Cassin’s Vireos. These results add to the body of literature on the complex movements of migratory songbirds breeding in the mountains of western North America, an understanding that will be important for effective conservation in the future.     

Linking the wintering and breeding grounds of warblers along the Pacific Flyway

Long‐distance migration is a behavior that is exhibited by many animal groups. The evolution of novel migration routes can play an important role in range expansions, ecological interactions, and speciation. New migration routes may evolve in response to selection in favor of reducing distance between breeding and wintering areas, or avoiding navigational barriers. Many migratory changes are likely to evolve gradually and are therefore difficult to study. Here, we attempt to connect breeding and wintering populations of myrtle warblers (Setophaga coronata coronata) to better understand the possible evolution of distinct migration routes within this species. Myrtle warblers, unlike most other warblers with breeding ranges primarily in eastern North America, have two disjunct overwintering concentrations—one in the southeastern USA and one along the Pacific Coast—and presumably distinct routes to‐and‐from these locations. We studied both myrtle and Audubon's warblers (S. c. auduboni) captured during their spring migration along the Pacific Coast, south of the narrow region where these two taxa hybridize. Using stable hydrogen isotopes and biometric data, we show that those myrtle warblers wintering along the southern Pacific Coast of North America are likely to breed at high latitudes in Alaska and the Yukon rather than in Alberta or further east. Our interpretation is that the evolution of this wintering range and migration route along the Pacific Coast may have facilitated the breeding expansion of myrtle warblers into northwestern North America. Moreover, these data suggest that there may be a migratory divide within genetically similar populations of myrtle warblers.     

Scottish-breeding Greenshanks Tringa nebularia do not migrate far

ABSTRACT

Capsule: Scottish-breeding Greenshanks Tringa nebularia migrate largely to Ireland.

Aims: To describe the migration timings and determine the non-breeding areas (staging and wintering areas) of Scottish-breeding Greenshanks.

Methods: Breeding adult Greenshanks were marked with geolocators and/or unique permutations of colour-rings in Sutherland, northern Scotland. Sightings of the colour-ringed birds and data from geolocators on recaptured birds provided information on the migrations and locations of the non-breeding areas.

Results: Scottish-breeding Greenshanks spent the winter mainly in Ireland, with the range also including Wales, southern England and western France. Departure from the breeding grounds, as determined by the geolocators, took place in June and July; the median date for the last day in the breeding area was 16 July. Arrival on the breeding grounds took place in March and April; the median date for the first day back in the breeding area was 7 April. Some birds fed at an estuary close to their territories prior to breeding. There was fidelity to wintering areas, both within and between years. Short-term staging took place during both the southward and northward migrations for some birds, and one bird used the same staging area in different autumns. Members of one pair had separate wintering areas.

Conclusions: Scottish-breeding Greenshanks have a short migration, largely to the coasts of Ireland. The migrations involved short-term staging for some birds.     

Invasive migration of a mainland rodent to santa catalina island and its effect on the endemic species <Emphasis Type="Italic">Peromyscus slevini</Emphasis>

Santa Catalina Island has an endemic mouse, Peromyscus slevini, which is the only native rodent species on the island. However, specimens of P. fraterculus have been recorded on the island. P. fraterculus is the most common species of Peromyscus off Santa Catalina Island in the Baja California peninsula. The records show the absence of P. slevini in the 1990s and an increasing number of P. fraterculus during the 2000s. P. slevini has recently been collected in 2007. The current situation in Santa Catalina Island shows a strong expansion of P. fraterculus and the restriction of P. slevini to the canyons. This study confirms for the first time the recent invasion of a peninsular native species in one island on the Gulf of California. Peromyscus fraterculus is a better desert adapted species in contrast to P. slevini. Under those conditions, in the near future, P. slevini could be extinct.     

Experimental fruit removal does not affect territory structure of wintering Hermit Thrushes

ABSTRACT.   Food is generally considered to be the primary resource structuring winter territories in migrant songbirds, but there is little experimental evidence to support this. In southeastern Louisiana, ripe fruits, consumed opportunistically in the absence of preferred arthropod resources, are a primary food resource for wintering Hermit Thrushes ( Catharus guttatus ). To test the possible role of food in controlling space use during the winter, we reduced fruit availability in the territories of wintering Hermit Thrushes and compared responses of these thrushes to those in control territories where fruit availability was not altered. We found that thrushes did not adjust either territory size or location in response to midwinter reduction of fruit availability. One possible explanation for this lack of response is that sufficient food, including arthropods, was available in thrush territories even after removal of fruit. Another possibility is that the removal of fruit did reduce food levels below the level needed to meet energetic needs, but social constraints on territory structure, dictated by fall settlement spacing and maintained by agonistic interactions, prevented birds from adjusting territories to match food supply later in the season.     

Genetic diversity and population structure of North America’s rarest heron, the reddish egret (Egretta rufescens)

The global distribution of the reddish egret is characterized by disjunct colonies occurring from the Pacific side of Northwest Mexico to the Caribbean. We examined distantly isolated colonies of reddish egret to determine global population genetic structure. We used seven polymorphic microsatellites to accomplish five goals: (1) to assess range wide population differentiation among reddish egret (Egretta rufescens) populations, (2) identify extent of gene flow, (3) determine any historical occurrence of bottlenecks, (4) assess genetic differentiation between color morphs, (5) clarify subspecies status of E. r. dickeyi, a completely dark morph population located in and around the Baja California peninsula, Mexico. Genetic differentiation was dramatic (global Fst = 0.161) throughout the reddish egrets range extending from Baja California, Mexico to Great Inagua, Bahamas. Differentiation occurred among three distinct regions (Fst = 0.238) but not among colonies/islands within regions suggesting regional philopatry. Genetic diversity (alleles per locus, and heterozygosity) in Baja California Sur, Mexico and Great Inagua, Bahamas populations is lower than in the Texas/Mexico population due to minimal dispersal between regions and smaller population sizes. Dark and white color morphs when present within the same region showed no differentiation. Patterns of recent population bottlenecks are not evident in each of the three regional populations. With evidence of limited gene flow in addition to low genetic diversity and prospects of habitat loss we recommend that reddish egrets be managed as three distinct or evolutionary significant units.     

Latitudinal variation in population structure of wintering Pacific Black Brant

ABSTRACT.   Latitudinal variation in population structure during the winter has been reported in many migratory birds, but has been documented in few species of waterfowl. Variation in environmental and social conditions at wintering sites can potentially influence the population dynamics of differential migrants. We examined latitudinal variation in sex and age classes of wintering Pacific Black Brant ( Branta bernicla nigricans ). Brant are distributed along a wide latitudinal gradient from Alaska to Mexico during the winter. Accordingly, migration distances for brant using different wintering locations are highly variable and winter settlement patterns are likely associated with a spatially variable food resource. We used resightings of brant banded in southwestern Alaska to examine sex and age ratios of birds wintering at Boundary Bay in British Columbia, and at San Quintin Bay, Ojo de Liebre Lagoon, and San Ignacio Lagoon in Baja California from 1998 to 2000. Sex ratios were similar among wintering locations for adults and were consistent with the mating strategy of geese. The distribution of juveniles varied among wintering areas, with greater proportions of juveniles observed at northern (San Quintin Bay and Ojo de Liebre Lagoon) than at southern (San Ignacio Lagoon) locations in Baja California. We suggest that age-related variation in the winter distribution of Pacific Black Brant is mediated by variation in productivity among individuals at different wintering locations and by social interactions among wintering family groups.     

Migration routes and timing of Mountain Plovers revealed by geolocators

Understanding the migratory movements and habitats used during the annual cycle of migrants is essential to developing comprehensive conservation strategies. Mountain Plovers (Charadrius montanus) are short‐distance migrants listed as a species of conservation concern in many states across their range, however, little is known about their migratory ecology. We used data from geolocators to describe the first direct estimates of migratory routes and migration schedules for Mountain Plovers breeding in Phillips County, Montana. We attached geolocators to 36 Mountain Plovers in 2010–2012 and recovered five (13.9%; three males and two females). Four of five Mountain Plovers in our study overwintered in Texas, and one overwintered in Arizona. Migration routes were relatively linear, with the exception of one plover that moved south and then west to reach its winter range in Arizona. Two plovers left breeding areas in mid‐July and the other three left in late September. All plovers used stopover sites near either eastern Colorado or southwest Kansas. Plovers that departed earlier used stopover sites for ~100 d, whereas those that left later used them for ~35 d. All plovers in our study arrived in wintering areas by early November and departed by late March. Our results suggest that eastern Colorado and southwest Kansas are important stopover areas during migration, and highlight the need to better understand how these locations support non‐breeding plovers.     

Migration of the Little Ringed Plover Charadrius dubius breeding in South Sweden tracked by geolocators

Capsule Little Ringed Plovers breeding in South Sweden migrate towards the southeast in the autumn, via the Middle East, to winter in Saharan and sub-Saharan locations or in India, while the spring migration is more directly towards the north.

Aims To study the migration routes and wintering area of Little Ringed Plovers (Charadrius dubius) breeding in South Sweden, and to investigate the migration strategy and speed for this little studied shorebird.

Methods We use light-level geolocators to track the year-round movements of Little Ringed Plovers breeding in South Sweden.

Results Autumn migration proceeded towards the southeast, in three birds via lengthy stopovers in the Middle East, followed by movements towards the west and southwest to final winter destinations in Africa, while one male made a long stopover in northwestern Iran before migrating to India. The birds wintering in Africa probably stayed at freshwater locations in the Sahara or just south or north of the Sahara. Spring migration was more directly back to the breeding area. Overall migration speeds were similar during autumn and spring migration at about 189 and 209?km/day, respectively. The migration was carried out mainly as many short flights between stopovers. In particular, autumn migration was longer than the direct distance between breeding and wintering sites.

Conclusions This study shows that the geolocator method can successfully be used with relatively small (40?g) shorebirds. We found that a local population of Little Ringed Plover may have widely differing wintering sites (low connectivity), from sub-Saharan Africa to the Indian subcontinent. The migration strategy of the Little Ringed Plover, with multiple short flights, deviates from that of many other long-distance migrating shorebirds that, instead, make one or a few long flights.     

Disentangling Migratory Routes and Wintering Grounds of Iberian Near-Threatened European Rollers Coracias garrulus

Long-distance migrants are suffering drastic declines in the last decades. Causes beneath this problem are complex due to the wide spatial and temporal scale involved. We aim to reveal migratory routes, stopover areas, wintering grounds, and migratory strategies for the most southwestern populations of the near-threatened European Roller Coracias garrulus in order to identify conservation key areas for the non-breeding stage of this species. To this end, we used tracking data from seven satellite transmitters fitted to birds breeding in different populations throughout the Iberian Peninsula and four geolocators fitted to individuals in a southeastern Iberian population. Precise satellite data were used to describe daily activity patterns and speed in relation to the main regions crossed during the migration. Individuals from the most southwestern Iberian populations made a detour towards the Atlantic African coast whereas those from northeastern populations followed a straight north-to-south route. We identified important stopover areas in the Sahel belt, mainly in the surroundings of the Lake Chad, and wintering grounds on southwestern Africa farther west than previously reported for the species. Concerning the migratory strategy, satellite data revealed: 1) a mainly nocturnal flying activity, 2) that migration speed depended on the type of crossed habitat, with higher average speed while crossing the desert; and 3) that the migration was slower and lasted longer in autumn than in spring. The studied populations showed weak migratory connectivity, suggesting the confluence of birds from a wide range of breeding grounds in a restricted wintering area. Therefore, we suggest to target on defining precisely key areas for this species and identifying specific threats in them in order to develop an appropriate global conservation programme for the European Roller.     

Inter‐annual site fidelity and breeding origins of Gray‐cheeked Thrushes in white sand forests of the Peruvian Amazon

White sand terra firme forests are unusual ecosystems scattered across Amazonia, covering just 3% of the basin. These forests differ from surrounding forests in their scleromorphic vegetation, low nutrient content, and propensity to harbor endemics. We report the capture of 62 Gray‐cheeked Thrushes (Catharus minimus) during a study of the understory avifauna of Amazonian white sand forests near Iquitos, Peru, conducted from 20 June to 8 December 2010–2012. We captured and banded Gray‐cheeked Thrushes in white sand (N = 57) and adjacent weathered clay (N = 5) terra firme forests. Sampling for three consecutive days at 19 different sites each year, the inter‐annual site fidelity rate of Gray‐cheeked Thrushes was 4.8% (N = 3). One bird banded in 2010 was recaptured in 2012. Of the 62 birds, 19.3% (N = 12) were recaptured on subsequent days. All recaptures were in white sand forests. The 19.3% recapture rate of Gray‐cheeked Thrushes from sites re‐sampled no more than 2 d in a given year suggests the presence of settled and perhaps territorial birds. Using rectrices from 12 Gray‐cheeked Thrushes, stable‐hydrogen isotope analyses (δ²H) suggest that the geographic breeding or natal origin of all sampled birds was likely northwestern North America. Our results suggest that Gray‐cheeked Thrushes exhibit site fidelity and may concentrate in white sand forests—an uncommon and scattered ecosystem type in western Amazonia. However, annual tracking of individual Gray‐cheeked Thrushes is needed to fully assess regional patterns of settlement and movement, and the connectivity between breeding and wintering areas.