Aspects Of Migratory Behavior Research Articles

Adcyap1 polymorphism covaries with breeding latitude in a Nearctic migratory songbird, the Wilson's warbler (Cardellina pusilla)

Understanding the genetic background of complex behavioral traits, showing multigenic control and extensive environmental effects, is a challenging task. Among such traits, migration is known to show a large additive genetic component. Yet, the identification of specific genes or gene regions explaining phenotypic variance in migratory behavior has received less attention. Migration ultimately depends on seasonal cycles, and polymorphism at phenological candidate genes may underlie variation in timing of migration or other aspects of migratory behavior. In this study of a Nearctic–Neotropical migratory songbird, the Wilson's warbler (Cardellina pusilla), we investigated the association between polymorphism at two phenological candidate genes, Clock and Adcyap1, and two aspects of the migratory phenotype, timing of spring migration through a stopover site and inferred latitude of the breeding destination. The breeding destination of migrating individuals was identified using feather deuterium ratio (δ 2H), which reliably reflects breeding latitude throughout the species' western breeding range. Ninety‐eight percent of the individuals were homozygous at Clock, and the rare heterozygotes did not deviate from homozygous migration phenology. Adcyap1 was highly polymorphic, and allele size was not significantly associated with migration date. However, Adcyap1 allele size significantly positively predicted the inferred breeding latitude of males but not of females. Moreover, we found a strong positive association between inferred breeding latitude and Adcyap1 allele size in long‐distance migrating birds from the northern sector of the breeding range (western Canada), while this was not the case in short‐distance migrating birds from the southern sector of the breeding range (coastal California). Our findings support previous evidence for a role of Adcyap1 in shaping the avian migratory phenotype, while highlighting that patterns of phenological candidate gene–phenotype associations may be complex, significantly varying between geographically distinct populations and even between the sexes.

Variation in songbird migratory behavior offers clues about adaptability to environmental change

For seasonally migrating birds, aspects of migratory behavior, such as the use of temperate versus tropical wintering areas, may influence their ability to respond to environmental change. Here, we infer potential flexibility in songbird migration from variation in two alternative stopover behaviors. Hierarchical Bayesian mark-recapture modeling was used to quantify stopover decisions over 19 years for four temperate and four tropical migratory species at a stopover site in southern Canada. Short-distance temperate migrants exhibited higher variability in behavior and greater responses to local weather than longer-distance tropical migrants, as measured by transience (the proportion of birds stopping <24 h, i.e. seeking brief sanctuary or subsequently relocating) and departure (re-initiation of migration by birds that stopped over for >24 h). In contrast to many previous works on climate-migration associations, annual variation in stopover behavior did not show strong links to broad-scale climatic fluctuations for either temperate or tropical migrants, nor was there any indication of directional changes in stopover behavior over the past two decades. In addition to suggesting that migratory songbirds-particularly tropical-wintering species-may face increasing threats with future climatic variability, our study highlights the potential importance of flexibility in en-route behavior for resilience to environmental change.

Intertidal migration and habitat use by subadult Dungeness crab Cancer magister in a NE Pacific estuary

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 308:183-195 (2006) - doi:10.3354/meps308183 Intertidal migration and habitat use by subadult Dungeness crab Cancer magister in a NE Pacific estuary Kirstin K. Holsman*, P. Sean McDonald, David A. Armstrong School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, Washington 98195, USA *Email: kkari@u.washington.edu ABSTRACT: Tidal migrations are inherent in the life histories of numerous demersal predators, and both the indirect and direct effects of these forays are important to the structure and function of littoral communities. In coastal estuaries of the Northeastern Pacific, Dungeness crabs Cancer magister are abundant and compose a significant portion of estuarine biomass. The nursery role of complex littoral habitats for young-of-the-year (0+) C. magister is well documented, yet the ecology of subsequent age classes within coastal estuarine systems, and within littoral areas in particular, remains unclear. The goal of our study was to elucidate habitat use and migratory patterns of subadult C. magister (40 to 130 mm carapace width; 1+ and >1+ yr classes) in littoral eelgrass Zostera marina, oyster Crassostrea gigas, and unstructured littoral habitats (ULH). We employed 3 sampling techniques (trapping, acoustic telemetry, and underwater video) designed to examine various aspects of migratory behavior within Willapa Bay, Washington, a representative coastal estuary. Baited trap surveys revealed that relative catches of subadult C. magister are 30 to 50% higher on ULH than eelgrass or oyster beds, and are negatively correlated with catches of another large cancrid crab, C. productus. Ultrasonic telemetry observations suggest that subadult C. magister making nighttime foraging incursions prefer ULH to other littoral habitats, and underwater video observations show that migrations are influenced by tidal rhythms since movements are correlated with the direction and velocity of current flow in adjacent channels. Our results dramatically alter the perception of C. magister as a predominantly sublittoral predator, and underscore the significance of littoral habitats as important foraging areas. KEY WORDS: Cancer magister · Dungeness crab · Habitat · Preference · Intertidal · Foraging · Estuaries · Sublittoral Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 308. Online publication date: February 16, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.

Seasonal changes in the migratory behaviour of the toad Bufo bufo: direction and magnitude of movements.

The migratory behaviour of the toad Bufo bufo was studied from February 1985 to April 1986 in the submontane region of Bavaria, West Germany. Toads were fitted with a mechanical tracking device to record individual paths of migration. Three aspects of migratory behaviour were quantified: orientation in relation to the breeding site, straightness of path, and locomotory activity. The annual activity period began with migration from the hibernation sites to the breeding pond in April. The paths went straight towards the breeding pond independent of the distance (70-420 m). During the period of oviposition the preference for the breeding site direction vanished and toads moved away from the breeding pond, but in less straight paths than before. In summer migratory activity decreased considerably and was restricted to small areas, the home ranges, at distances of 55-1600 m from the natal breeding pond. The straightness of path was rather low, because toads often returned to their starting points. During rainy nights toads occasionally left their home ranges for extensive excursions. In autumn most toads again migrated towards the breeding pond, but paths were significantly less straight and direct than in spring. However, toads stopped before reaching the breeding pond and hibernated in holes or under the leaf layer. The mortality rate of tracked toads was about 45%. The relative influence of 17 environmental variables on locomotory activity was evaluated by principal component analysis and stepwise multiple regression. Temperature at night and rainfall variables accounted for significant amounts of variance, whereas temperature by day, air humidity, and atmospheric pressure showed no correlation. Activity decreased if temperature approached 0° C or after long periods without rainfall. Within a certain range of tolerance, however, the locomotory activity of the toads was widely independent of environmental factors, indicating that endogeneous factors are more important sources of variation in the migratory behaviour of these toads than commonly assumed.

A Technique for Enumerating Kokanee Salmon (Oncorhynchus nerka) Fry Migrating through Streams, with an Appendix for Processing Catch Data by IBM 360 Fortran IV Computer Programs

A technique for enumerating kokanee salmon (Oncorhynchus nerka) fry migrating downstream was developed in Meadow Creek (a tributary to the Duncan River and Kootenay Lake, B.C.) and was used to obtain an estimate of 10.06 million kokanee fry in 1968. The hyperbolic relation between the nightly mean catch per net per minute (C) and nightly probable error (E) as the percent of the nightly total was expressed by log E = −0.5703 − 0.4568 log C; E was largest at the beginning and end, and smallest at the peak of fry migration. E was also calculated as the percent of the seasonal total, and in 1968 was ± 5.8%. Of this total, ±0.7% was accumulated during April, when 6.4% of the migration occurred; ±3.9% was accumulated in May, when 82.2% of the migration occurred; and the final ±1.2% was accumulated in June, when 11.2% of the migration occurred. The variability m abundance of try and spacing of groups of fry are considered to be the most important factors controlling the magnitude of error.Some aspects of migratory behaviour of kokanee fry in Meadow Creek were revealed and their effects on estimates of abundance are discussed.A series of IBM 360 Fortran IV computer programs for processing catch data are also given in an appendix.