Differences In Migratory Behaviour Research Articles

Supplemental feeding alters migration of a temperate ungulate.

Conservation of migration requires information on behavior and environmental determinants. The spatial distribution of forage resources, which migration exploits, often are altered and may have subtle, unintended consequences. Supplemental feeding is a common management practice, particularly for ungulates in North America and Europe, and carryover effects on behavior of this anthropogenic manipulation of forage are expected in theory, but have received limited empirical evaluation, particularly regarding effects on migration. We used global positioning system (GPS) data to evaluate the influence of winter feeding on migration behavior of 219 adult female elk (Cervus elaphus) from 18 fed ranges and 4 unfed ranges in western Wyoming. Principal component analysis revealed that the migratory behavior of fed and unfed elk differed in distance migrated, and the timing of arrival to, duration on, and departure from summer range. Fed elk migrated 19.2 km less, spent 11 more days on stopover sites, arrived to summer range 5 days later, resided on summer range 26 fewer days, and departed in the autumn 10 days earlier than unfed elk. Time-to-event models indicated that differences in migratory behavior between fed and unfed elk were caused by altered sensitivity to the environmental drivers of migration. In spring, unfed elk migrated following plant green-up closely, whereas fed elk departed the feedground but lingered on transitional range, thereby delaying their arrival to summer range. In autumn, fed elk were more responsive to low temperatures and precipitation events, causing earlier departure from summer range than unfed elk. Overall, supplemental feeding disconnected migration by fed elk from spring green-up and decreased time spent on summer range, thereby reducing access to quality forage. Our findings suggest that ungulate migration can be substantially altered by changes to the spatial distribution of resources, including those of anthropogenic origin, and that management practices applied in one season may have unintended behavioral consequences in subsequent seasons.

Does reduced feeding prior to release improve the marine migration of hatchery brown trout Salmo trutta smolts?

The aim of this study was to test the hypothesis that hatchery brown trout Salmo trutta smolts, with 50% reduced or no feeding over the last 5 months before release, were more likely to migrate to the sea than individuals with standard feeding ratios. The juvenile fish were divided into three groups 176 days before release: (A) with no feeding, (B) with 50% and (C) with 100% feeding. To study their seaward migration, 40 fish from each feeding group were tagged with acoustic transmitters and tracked by automatic listening stations in the River Nidelva, Trondheim, Norway, its estuary and in the nearest marine environment. At the time of release, mean condition factor was significantly lower in group A and the fish from groups A and B had higher levels of Na+, K+-ATPase. Significantly more fish from group A migrated to the sea, but the rate of downstream progression from release to the estuary did not differ between the three groups. In conclusion, the S. trutta smolts with no access to food in the last 176 day before release were more likely to migrate to the sea. Fish from all three feeding groups, however, appeared to smoltify and had the same rate of downstream progression to the estuary. This indicates that differences in migratory behaviour between individuals from the three feeding groups begin from the time when the fish reach saline waters. It is suggested that feeding in hatcheries has to be greatly reduced (by 50% or more) over several months to have a pronounced effect on the migratory behaviour in S. trutta.

Gender, Gender Ideology, and Couples’ Migration Decisions

Couples generally move to accommodate men’s, rather than women’s, career opportunities. Using Swedish panel data including 1,039 married or cohabiting individuals, this study examines the importance of traditional gender ideology and behavior in explaining this pattern. Two dimensions of gender and migration are examined: (a) the willingness to move for a partner’s career and (b) the likelihood of couple migration for one’s own work or educational opportunities. Findings show that women are more willing to move for their partner’s career. Childless women are more likely to move with their partners to pursue their own work or education than childless men, whereas mothers are less likely to report this than fathers. Gender ideology and division of household responsibilities do not explain the gender differences in migration behavior. They are more important for individuals’ willingness to move for their partners, with particularly pronounced gender differences among nonegalitarian respondents.

Individual differences in migratory behavior shape population genetic structure and microhabitat choice in sympatric blackcaps (Sylvia atricapilla)

In migratory birds, traits such as orientation and distance are known to have a strong genetic background, and they often exhibit considerable within-population variation. How this variation relates to evolutionary responses to ongoing selection is unknown because the underlying mechanisms that translate environmental changes into population genetic changes are unclear. We show that within-population genetic structure in southern German blackcaps (Sylvia atricapilla) is related to individual differences in migratory behavior. Our 3-year study revealed a positive correlation between individual migratory origins, denoted via isotope (δ2H) values, and genetic distances. Genetic diversity and admixture differed not only across a recently established migratory polymorphism with NW- and SW-migrating birds but also across δ2H clusters within the same migratory route. Our results suggest assortment based on individual migratory origins which would facilitate evolutionary responses. We scrutinized arrival times and microhabitat choice as potential mechanisms mediating between individual variation in migratory behavior and assortment. We found significant support that microhabitat choice, rather than timing of arrival, is associated with individual variation in migratory origins. Moreover, examining genetic diversity across the migratory divide, we found migrants following the NW route to be genetically more distinct from each other compared with migrants following the traditional SW route. Our study suggests that migratory behavior shapes population genetic structure in blackcaps not only across the migratory divide but also on an individual level independent of the divide. Thus, within-population variation in migratory behavior might play an important role in translating environmental change into genetic change.

Geographic variation in migration chronology and winter distribution of midcontinent greater white-fronted geese

We evaluated spatial and temporal differences in migratory behavior among different breeding groups of midcontinent greater white-fronted geese (Anser albifrons) using band-recovery data and observations of neck collared geese during migration and winter. Birds from different breeding areas were initially delineated by geographic distance into 6 banding reference areas (BRAs): 1) interior Alaska, 2) North Slope of Alaska, 3) western Northwest Territories (NWT), 4) western Nunavut, 5) central Nunavut, and 6) eastern Nunavut. The banding groups also differed by breeding habitat, with geese from interior Alaska nesting in the boreal forest (taiga), and all other groups breeding in tundra habitats. Geese from interior Alaska migrated earlier during autumn, and were more likely to winter farther south (in Mexico) than geese from other breeding areas. Geese banded in central and eastern Nunavut (Queen Maud Gulf and Inglis River) wintered farther east (in Louisiana) than geese from other breeding areas. Small-scale (within-state) geographic segregation of wintering flocks was evidenced by the recent (post-1990) nearly exclusive use of a new wintering area in north central Texas by geese from interior Alaska. Segregation among BRAs was also apparent in Mexico, where taiga geese were found predominantly in the central Highlands (states of Zacatecas and Durango), whereas tundra geese mostly used states along the Gulf Coast (primarily Tamaulipas). Interior Alaska birds initiated spring migration earlier than geese from other areas, and were more likely than others to stop in the Rainwater Basin of Nebraska, a region where cholera outbreaks periodically kill thousands of geese. Geese from interior Alaska were the first to arrive at spring staging areas in prairie Canada where BRAs exhibited spatial delineation (a longitudinal cline) in relation to breeding areas. Our results show significant geographic and temporal variation among taiga and tundra breeding cohorts during autumn, winter, and spring. Temporal and spatial differences in migratory behavior may allow management practices that accommodate potential demographic differences between taiga and tundra populations. © 2013 The Wildlife Society.

The trans‐equatorial loop migration system of Eleonora’s falcon: differences in migration patterns between age classes, regions and seasons

Internal factors such as experience (e.g. age) and motivation for breeding, and external ones such as environmental conditions (e.g. meteorology and landscape characteristics) can promote differences in migratory behaviour and routes among seasons, regions and populations. Using satellite telemetry we investigated whether such differences occur and which factors promote them among migrating Eleonora’s falcons breeding in the Mediterranean area (Spain and Croatia) and wintering in Madagascar. We found that during autumn migration no age differences occur when crossing the Sahara desert, but in the remaining African regions, juveniles were more prone than adults to fly at a slower and more tortuous rate, as well as exhibiting longer stop‐overs, particularly in the Sahel region. Such differences might be promoted by a lower foraging and pre‐migratory fattening efficiency in juveniles. During spring, routes were significantly more eastern than during autumn, resulting in a loop migration occurring in all studied populations. This could be accounted by seasonal variation in the distribution of trophic resources. Our results show that Eleonora’s falcons integrate spatially seasonal changing resources on a continental scale throughout their annual cycle, changing their movement patterns in response to internal (age) and external (habitat) factors. This loop migration pattern may prove to be widespread among other Palearctic trans‐continental migratory bird species.

Variation in candidate genes CLOCK and ADCYAP1 does not consistently predict differences in migratory behavior in the songbird genus Junco

Recent studies exploring the molecular genetic basis for migratory variation in animals have identified polymorphisms in two genes ( CLOCK and ADCYAP1) that are linked to circadian rhythms and correlate with migratory propensity and phenology among individuals and populations. Results from these initial studies are mixed, however, and additional data are needed to assess the generality and diversity of the molecular mechanisms that regulate the biology of migration. We sequenced CLOCK and ADCYAP1 in 15 populations across the two species of the avian genus Junco, a North American lineage in which multiple recently diverged subspecies and populations range from sedentary to long-distance migrants. We found no consistent associations between allele length and migratory status across the genus for either CLOCK or ADCYAP1. However, within two subspecies groups, populations that migrate longer distances have longer CLOCK alleles on average. Additionally, there was a positive relationship between ADCYAP1 allele length and migratory restlessness (zugunruhe) among individuals within one of two captive populations studied—a result similar to those reported previously within captive blackcaps ( Sylvia atricapilla). We conclude that, while both ADCYAP1 and CLOCK may correlate with migratory propensity within or among certain populations or species, previously identified relationships between migratory behavior and sequence variants cannot be easily generalized across taxa.

Molecular Evidence for Gender Differences in the Migratory Behaviour of a Small Seabird

Molecular sexing revealed an unexpectedly strong female bias in the sex ratio of pre-breeding European Storm Petrels (Hydrobates pelagicus), attracted to playback of conspecific calls during their northwards migration past SW Europe. This bias was consistent across seven years, ranging from 80.8% to 89.7% female (mean annual sex ratio ± SD = 85.5% female ±4.1%). The sex ratio did not differ significantly from unity (i.e., 50% female) among (i) Storm Petrel chicks at a breeding colony in NW France, (ii) adults found dead on beaches in Southern Portugal, (iii) breeding birds attending nest burrows in the UK, captured by hand, and (iv) adults captured near a breeding colony in the UK using copies of the same sound recordings as used in Southern Europe, indicating that females are not inherently more strongly attracted to playback calls than males. A morphological discriminant function analysis failed to provide a good separation of the sexes, showing the importance of molecular sexing for this species. We found no sex difference in the seasonal or nocturnal timing of migration past Southern Europe, but there was a significant tendency for birds to be caught in sex-specific aggregations. The preponderance of females captured in Southern Europe suggests that the sexes may differ in migration route or in their colony-prospecting behaviour during migration, at sites far away from their natal colonies. Such differences in migration behaviour between males and females are poorly understood but have implications for the vulnerability of seabirds to pollution and environmental change at sea during the non-breeding season.

Different Means to the Same End: Long-Distance Migrant Seabirds from Two Colonies Differ in Behaviour, Despite Common Wintering Grounds

Although seabirds that are trans-equatorial migrants show apparently broad overlap among populations in the non-breeding season, such large-scale pattern may conceal subtle but nevertheless key differences in migratory behaviour. These specializations could reflect adaptation to different environments during the breeding season, carry-over effects from the breeding to the nonbreeding period, or asymmetries in competitive ability of birds of different origin. We compared the migratory and wintering behaviour of Cory's shearwaters Calonectris diomedea nesting in Berlengas and in the Selvagens, two colonies in contrasting oceanographic environments, separated by ca. 1200 km. Although no differences were found in winter distribution, there was a marked divergence in timing, route and the use of staging areas during the postbreeding (autumn) migration. Birds from Berlengas typically travelled to oceanic waters in the North Atlantic for an extended stopover, whereas those from Selvagens rarely did so. In the South Atlantic, birds from Selvagens spent more time in flight, perhaps because they had higher energy and nutrient requirements for feather replacement compared to birds from Berlengas, which moult more flight feathers during breeding. Stable isotope analyses of feathers suggested that this variation in activity patterns was unrelated to trophic ecology. Differences in migration routes and stopovers may expose populations to distinct threats, and should be taken into consideration when defining units for conservation purposes and developing appropriate management strategies.

Contaminant Migration in the Vicinity of a Grease Lubricated Bearing Seal Contact

Lubricating grease is commonly used for lubricating “sealed and greased for life” rolling element bearings. This grease also provides an additional sealing function to protect the bearing against ingress of contaminants. In this work the sealing function of lubricating grease in the vicinity of the seal lip contact has been studied experimentally by measuring the migration of spherical fluorescent contaminant particles in the vicinity of the contact, as a function of shaft speed and lubricant type. The experimental results reveal that in some greases contaminant particles migrate towards the sealing contact where the shear rate reaches its highest value. However, for other greases, Newtonian base oils, and elastic fluids, this is not necessarily the case and contaminant particles consistently migrate away from the sealing contact. Various physical phenomena have been investigated to explain the difference in migration behavior. It is concluded that migration towards the sealing contact is driven by the viscosity gradient and migration away from the sealing contact is related to the Weissenberg number. The sealing function of grease in the vicinity of the sealing contact is due to the migration of contaminant particles. The migration reduces the probability of particles to reach the sealing and bearing contacts.

1017 POSTER Over Expression of ALDH1 as Stem Cell Marker, Is Associated With Mutated BRCA1 in Breast Carcinomas

Material and Methods: We detected CSCs from an esophagus ascites with the stemgent alkaline phosphatase staining kit II and characterised CD133+ cells by separating Linand CD133+ cells with the miltenyi diamond separating kit. These cells have been cultured with the esophagus CSC medium from cellsystem and analysed by determined surface marker (CD133, CD166) with FACS, quantitative gene expression of stem cell transcription factors (Oct3/4, Sox2, Nanog, cMyc) and their behaviour of migration under TGFb stimulation. Results: After separation of LinCD133+ from an esophagus ascites we cultured the cells under specific condition for CSCs. We could show that the number of CD133+ cells increase over a period of 21 days from 1% up to 7.8%. Furthermore we could demonstrate that 4% of CD133+ also positive for CD166. The gene expression of stem cell markers in CD133+ cells compared to CD133cells showed an up regulation of different markers e.g. Oct3/4, Nanog. We also obtained differences in migration behaviour. Conclusion: We not only demonstrated that cells with stemness characteristics exist in ascites, but also isolated and characterized them. These cells exhibit markers like CD133 and CD166 which describe for CSCs. Only in CD133+ cells is an up regulation of specific stem cell transcription factors. These results indicate that CD133+ cells from ascites feature a stem cell potential and maybe play an important role in metastases. This hypothesis is supported by the observance that the CD133+ cells showed different migration behaviour compared to CD133cells. The presented data not only demonstrated the importance of understanding CSCs but also to develop a clinical treatment.

Genetic variation and seasonal migratory connectivity in Wilson’s warblers (Wilsonia pusilla): species-level differences in nuclear DNA between western and eastern populations

There is growing interest in understanding patterns of seasonal migratory connectivity between breeding and wintering sites, both because differences in migratory behaviour can be associated with population differentiation and because knowledge of migratory connectivity is essential for understanding the ecology, evolution and conservation of migratory species. We present the first broad survey of geographic variation in the nuclear genome of breeding and wintering Wilson's warblers (Wilsonia pusilla), which have previously served as a research system for the study of whether genetic markers and isotopes can reveal patterns of migratory connectivity. Using 153 samples surveyed at up to 257 variable amplified fragment length polymorphism markers, we show that Wilson's warblers consist of highly distinct western and eastern breeding groups, with all winter samples grouping with the western breeding group. Within the west, there is weak geographic differentiation, at a level insufficient for use in the assignment of wintering samples to specific areas. The distinctiveness of western and eastern genetic groups, with no known intermediates, strongly suggests that these two groups are cryptic species. Analysis of mitochondrial cytochrome b sequence variation shows that the estimated coalescence time between western and eastern clades is approximately 2.3 Ma, a surprisingly old time of divergence that is more typical of distinct species than of subspecies. Given their morphological similarity but strong genetic differences, western and eastern Wilson's warblers present a likely case of association between divergence in migratory behaviour and the process of speciation.

The Mobility of Immigrants and Natives: Evidence from Internal Migration Following Job Displacement

Boman A. The mobility of immigrants and natives: evidence from internal migration following job displacement, Regional Studies. In times of change in the labour market, differences in migratory behaviour between groups affect the labour market outcome of these groups. One important group in society is that of immigrants, for which human capital migration theory presents two potentially conflicting hypotheses. One is based on immigrants having less location-specific human capital, increasing their probability of migration. The other is based on ethnicity: immigrants living in ethnic enclaves have higher costs of leaving the enclave, reducing their probability of migration. This paper disentangles and finds support for both hypotheses using high-quality data on a wide range of variables for essentially all individuals involuntarily displaced due to closures or substantial cutbacks of Swedish workplaces in 1987 and 1988. Boman A. La mobilité des immigrés et de la population autochtone: des preuves provenant de la migration interne suite au déplacement des emplois, Regional Studies. Au moment de la transformation du marché du travail, les différences du comportement migratoire des groupes touchent les possibilités d'emploi de ces derniers. Les immigrés constituent un groupe important de la société pour lequel la théorie de la migration du capital humain présente deux hypothèses qui risquent d'être en contradiction. L'un repose sur le principe suivant: les immigrés ont moins de capital humain qui dépend de la localisation, ce qui augmente la probabilité de la migration. L'autre repose sur la notion d'ethnicité: les frais de déplacement sont plus élevés pour les immigrés qui habitent des enclaves ethniques, ce qui réduit la probabilité de la migration. Cet article cherche à dévoiler et soutenir les deux hypothèses à partir des données très sûres relatives à une gamme de variables très large pour, avant tout, tous les individus qui ont été déplacés involontairement à cause des fermetures ou d'importantes réductions des lieux de travail en 1987 et en 1988. Mobilité géographique Migration interne Enclaves ethniques Immigrés Déplacement des emplois Boman A. Mobilität von Immigranten und Einheimischen: Belege aus der internen Migration nach einem Arbeitsplatzverlust, Regional Studies. In einer Zeit der Veränderungen auf dem Arbeitsmarkt wirken sich Unterschiede hinsichtlich des Migrationsverhaltens verschiedener Gruppen auf den Erfolg dieser Gruppen auf dem Arbeitsmarkt aus. Eine wichtige Gruppe in der Gesellschaft ist die der Immigranten, für die in der Theorie der Humankapital-Migration zwei potenziell widersprüchliche Hypothesen aufgestellt werden. Die eine stützt sich darauf, dass Immigranten über weniger standortspezifisches Humankapital verfügen, was ihre Wahrscheinlichkeit einer Migration erhöht. Der zweite stützt sich auf die Ethnizität: Für in ethnischen Enklaven lebende Immigranten ist ein Verlassen der Enklave mit höheren Kosten verbunden, was ihre Wahrscheinlichkeit einer Migration verringert. In diesem Beitrag werden diese beiden Hypothesen entwirrt, und es werden Belege zur Unterstützung beider Hypothesen gefunden. Hierfür werden hochwertige Daten über ein breites Spektrum von Variablen für praktisch alle Personen genutzt, die aufgrund von Schließungen oder erheblichen Verkleinerungen von schwedischen Arbeitsplätzen in den Jahren 1987 und 1988 auf unfreiwillige Weise ihren Arbeitsplatz verloren. Geografische Mobilität Interne Migration Ethnische Enklaven Immigranten Arbeitsplatzverlust Boman A. La movilidad de inmigrantes y autóctonos: evidencia de la migración interna tras el desplazamiento laboral, Regional Studies. En tiempos de cambio en el mercado laboral, las diferencias en el comportamiento migratorio entre grupos afecta a los resultados de estos grupos en el mercado laboral. Un grupo importante en la sociedad es la de inmigrantes para los que la teoría de migración de capital humano presenta dos hipótesis potencialmente conflictivas. Una se basa en que los inmigrantes tienen menos capital humano inherente a la localización lo que aumenta su probabilidad de emigrar. La otra se basa en la etnia: los inmigrantes que viven en enclaves étnicos tienen costes más altos a la hora de abandonar el enclave lo que reduce su probabilidad de migración. En este artículo simplificamos y encontramos argumentos para ambas hipótesis usando datos de alta calidad sobre toda una serie de variables para básicamente todos las personas desplazadas involuntariamente debido a cierres o recortes substanciales de los puestos de trabajo en Suecia entre 1987 y 1988. Movilidad geográfica Migración interna Enclaves étnicos Inmigrantes Desplazamiento laboral

Mitochondrial Evidence for Panmixia despite Perceived Barriers to Gene Flow in a Widely Distributed Waterbird

We examined the mitochondrial genetic structure of American white pelicans (Pelecanus erythrorhynchos) to: 1) verify or refute whether American white pelicans are panmictic and 2) understand if any lack of genetic structure is the result of contemporary processes or historical phenomena. Sequence analysis of mitochondrial DNA control region haplotypes of 367 individuals from 19 colonies located across their North American range revealed a lack of population genetic or phylogeographic structure. This lack of structure was unexpected because: 1) Major geographic barriers such as the North American Continental Divide are thought to limit dispersal; 2) Differences in migratory behavior are expected to promote population differentiation; and 3) Many widespread North American migratory bird species show historic patterns of differentiation resulting from having inhabited multiple glacial refugia. Further, high haplotype diversity and many rare haplotypes are maintained across the species' distribution, despite frequent local extinctions and recolonizations that are expected to decrease diversity. Our findings suggest that American white pelicans have a high effective population size and low natal philopatry. We suggest that the rangewide panmixia we observed in American white pelicans is due to high historical and contemporary gene flow, enabled by high mobility and a lack of effective physical or behavioral barriers.

Temporally stable population-specific differences in run timing of one-sea-winter Atlantic salmon returning to a large river system.

The understanding of migration patterns can significantly contribute to conservation and management. The spawning migrations of Atlantic salmon (Salmo salar) cover thousands of kilometers from the feeding areas at sea to their natal rivers to reproduce. Migrating salmon are exposed to intensive harvest, but little is known of the population-specific differences in migration behavior. In this study, timing of return migration was investigated among one-sea-winter Atlantic salmon within a river system. By utilizing knowledge of the genetic population structure, population of origin was reliably identified for c. 1500 fish caught in mixed stock fisheries after adopting an approach to minimize the complications arising from potential nonsampled populations. Results demonstrated significant and temporally stable differences among populations as well as between sexes. Generally, female salmon from tributary populations entered fresh water first. Run timing was not however related to in-river migration distance. Rather, one-sea-winter salmon from larger populations and with a higher proportion of multi-sea-winter females arrived later in the season. These findings are a significant step toward a more thorough understanding of the salmon migration behavior and behavioral ecology, providing concrete tools for the management and conservation of the remaining indigenous Atlantic salmon stocks.

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.

A comparative study of migratory behaviour and body mass as determinants of moult duration in passerines

Birds moult to maintain plumage function through life, but the factors that determine moult duration are poorly understood. In temperate areas, variation in moult duration could be largely associated with between‐species differences in migratory behaviour (migrants have less time for moulting after breeding), and body mass (because the aerodynamic cost of rapid moult increases allometrically with body size). Moreover, if the energetic cost of transport favours a smaller body size in migratory species, then the effects of migratory behaviour and body mass on moult duration could be confounded. We conducted a comparative study of the duration of adult complete moult in 48 European passerine species, in relation to body mass and migratory behaviour (sedentary, short‐distance migrants and long‐distance migrants). Lighter and more migratory species moulted faster than heavier and more sedentary species, but migration was not associated with body mass. If accelerated moult compromises the success of migration, changes in the physiology or phenology of moult in migratory birds are better interpreted as adaptive responses to compensate for such costs.

An experimental assessment of buffer width: Implications for salamander migratory behavior

Upland buffer zones are the primary proposed management tool for vernal-pool-breeding amphibians; however, experimental validation of the utility of buffers is lacking. We used clear cutting to experimentally manipulate upland buffer widths at 11 vernal pools in east-central Maine. Each pool was randomly assigned to one of three possible treatments: >1000-m buffer, 100-m buffer, or 30-m buffer. We radiotracked 40 adult spotted salamanders at these pools and modeled their migratory behavior with mixed-effects regression. Mean maximum distance salamanders moved from their breeding pool was 106.0 ± 15.4 m (range = 1.6–427.6 m). Salamanders were able to enter and cross clear cuts. We observed differences in migratory behavior between the 100-m buffer and reference treatments and between forest and clear-cut habitat; however, weather conditions and a salamander’s distance from the vernal pool strongly mediated the impact of buffer treatment on migration behavior. Our findings indicate that clear cuts are semi-permeable to adult spotted salamanders, but that degree of permeability and the effects of buffer treatment largely depend on weather conditions.

Differential Migration by Sex in the Great Bustard: Possible Consequences of an Extreme Sexual Size Dimorphism

AbstractWe explored migration patterns in Great bustards (Otis tarda), a species that shows strong sexual selection and the most extreme sexual size dimorphism among birds. The aim was to explain differential migration, examining whether Great bustards fulfil the main predictions of bird migration theory hypotheses and sexual segregation theory hypotheses. We radio‐tracked the seasonal movements of 65 males and 68 females in central Spain. We found four main sexual differences. First, the proportion of migratory males was higher than that of migratory females (86% vs. 51%). Second, males abandoned the leks immediately after the mating season (late May to early Jun.), whereas females remained there for another 3–7 mo. Third, 54% of the migratory males used two different post‐breeding areas, the first located northwards at 82 km from the breeding sites in summer, and the second southwards at 50 km in autumn–winter. Migratory females used only one area in autumn–winter which coincided geographically with that of males. And fourth, males returned to the breeding areas earlier (between Sep. and Mar.) than females (between Jan. and Apr.). These results show that the Great bustard is a differential migrant by sex in central Spain and support the weather sensitivity hypothesis (males were less tolerant to summer heat) and the specialization hypothesis (exclusive maternal care of the brood by females). Sexual differences in migratory behaviour are probably ultimately determined by the strong sexual selection in this species.

Movements by Adult Coho Salmon in the Lower Elwha River, Washington

Abstract The Elwha and Glines Canyon dams caused a dramatic decline in the numbers of all species of native Pacific salmonids (Oncorhynchus spp.) in the Elwha River. During the fall of 2005 and 2006, we radiotagged 49 adult coho salmon (O. kisutch) and tracked their movements between the Elwha River mouth and Elwha Dam (7.3 rkms). Half of all tagged fish were never relocated, likely due to emigration from the river. The remainder tended to migrate quickly and directly to one or two areas saturated with large woody debris and gravel, known to be high quality spawning habitat, and remain there. However, 7 of the 13 tagged fish in 2005 made multiple upstream and downstream movements prior to spawning. No tagged fish in either year migrated farther upstream than a rock weir approximately 4.9 km from the river mouth and 2.4 km downstream from the Elwha Dam, possibly indicating a migration barrier for coho salmon. We did not detect qualitative differences in migration behavior between hatchery and unknown-origi...