Circadian and circannual programmes in avian migration

1996 ◽  
Vol 199 (1) ◽  
pp. 39-48 ◽  
Author(s):  
E Gwinner
Keyword(s):  
Migratory Birds ◽  
Circadian System ◽  
Autumn Migration ◽  
Temporal Orientation ◽  
First Year ◽  
Biological Clocks ◽  
Nocturnal Activity ◽  
Migratory Activity ◽  
Migrating Birds ◽  
Relevant Factors

In migratory birds, endogenous daily (circadian) and annual (circannual) rhythms serve as biological clocks that provide the major basis for their temporal orientation. Circannual rhythms are responsible for the initiation of migration both in autumn and spring. This function of timing migrations is particularly important for birds that spend the winter close to the equator where the environment is too constant or irregular to provide accurate timing cues. In addition, circannual rhythms produce programmes that determine both the temporal and the spatial course of migration. In Sylvia warblers, the time programmes controlling autumn migration are organized in a species- or population-specific manner. It has been proposed that, in first-year migrants, the time programme for autumn migration plays a major role in determining migratory distance, thus providing the vector component in a mechanism of vector navigation. It is not yet clear, however, whether this programme does indeed determine migratory distance or whether it only provides the temporal framework within which other factors determine how far a bird flies. Evidence against the first alternative comes from findings indicating that migratory activity can be drastically modified by a constellation of rather specific, but highly relevant, factors and that the resulting changes in migratory activity are not compensated by subsequent increases or decreases of migratory activity. In normally day-active but nocturnally migrating birds, circannual signals cause alterations in the circadian system leading to the development of nocturnal activity. Although the nature of these signals is unknown, there is evidence that changes in the diurnal pattern of melatonin secretion by the pineal gland are associated with, and possibly causally involved in, the waxing and waning of nocturnal activity. These changes in the melatonin pattern presumably also affect general synchronization properties of the circadian system to Zeitgebers in such a way that circadian rhythms adjust faster to new conditions after long transmeridian flights.

scholarly journals Circadian flight schedules in night-migrating birds caught on migration

2008 ◽  
Vol 4 (6) ◽  
pp. 619-622 ◽  
Author(s):  
Timothy Coppack ◽  
Simon F Becker ◽  
Philipp J.J Becker
Keyword(s):  
Migratory Birds ◽  
Activity Patterns ◽  
Stopover Site ◽  
Migratory Activity ◽  
Flight Schedules ◽  
Northern European ◽  
Temporal Cues ◽  
Key Factor ◽  
Migrating Birds ◽  
Songbird Migration

Many species of migratory birds migrate in a series of solitary nocturnal flights. Between flights, they stop to rest and refuel for the next segment of their journey. The mechanism controlling this behaviour has long remained elusive. Here, we show that wild-caught migratory redstarts ( Phoenicurus phoenicurus ) are consistent in their flight scheduling. An advanced videographic system enabled us to determine the precise timing of flight activity in redstarts caught at a northern European stopover site during their return trip from Africa. Birds were held captive for three days in the absence of photoperiodic cues (constant dim light) and under permanent food availability. Despite the absence of external temporal cues, birds showed clear bimodal activity patterns: intense nocturnal activity alternating with diurnal foraging and resting periods. The onset of their migratory activity coincided with the time of local sunset and was individually consistent on consecutive nights. The data demonstrate that night-migrating birds are driven by autonomous circadian clocks entrained by sunset cues. This timekeeping system is probably the key factor in the overall control of nocturnal songbird migration.

scholarly journals Protogyny in Autumn Migration: Do Male Birds ”Play Chicken”?

The Auk ◽  
2005 ◽  
Vol 122 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Alexander M. Mills
Keyword(s):  
Migratory Birds ◽  
Indirect Selection ◽  
Male Competition ◽  
Autumn Migration ◽  
Direct Selection ◽  
Differential Migration ◽  
The North ◽  
Parsimonious Explanation ◽  
Ground Conditions ◽  
Wintering Ground

AbstractProtandry, the earlier arrival of males than of females on breeding areas, occurs in many taxa, including many migratory birds. Numerous hypotheses have been generated to explain protandry. Using bird-banding records, I show that protogyny, the earlier migration of females, frequently occurs in the autumn, though it is less universal and less dramatic than spring protandry. In one species, it occurs in both hatch-year and adult birds. When (1) spring and autumn, (2) departures and arrivals, and (3) breeding and wintering ground conditions are considered, hypotheses generated only to explain spring protandry can be more thoroughly evaluated. Using that approach, the most parsimonious explanation of differential migration between the sexes explains earlier male arrival in spring and later male departure in autumn through either (1) indirect selection operating on intrasexual male competition for territories or (2) direct selection operating on intersexual relations requiring males to be present on breeding territories when females are present. In autumn-protogynous species, males may ”play chicken,” balancing the benefits of remaining longer than females and protecting territories for subsequent years against the costs of remaining in the north under deteriorating conditions and delaying the acquisition of a good winter territory.Protogynie et migration automnale: Est-ce que les mâles ”jouent les dégonflés”?

scholarly journals Teacher to Researcher: Reflections on a New Action Research Program for University EFL Teachers

2018 ◽  
Vol 20 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Anne Burns ◽  
Anne Westmacott
Keyword(s):  
Action Research ◽  
Foreign Language ◽  
Research Programme ◽  
Language Teachers ◽  
First Year ◽  
Foreign Language Teachers ◽  
Research Publication ◽  
Efl Teachers ◽  
The University ◽  
Relevant Factors

One of the current challenges facing many universities is how to support teachers in becoming researchers. This article discusses the experiences at a small private Chilean university of a new action research programme that was developed as a vehicle for helping teachers to become involved in research and write a research publication for peer-reviewed journals. We present findings from research into similar programmes about relevant factors for their success, describe the programme developed at the university with five English as a Foreign Language teachers in 2016, and discuss some reflections on this first year of the programme.

scholarly journals Factors influencing fall departure phenology in migratory birds that bred in northeastern North America

The Auk ◽  
2019 ◽  
Author(s):  
Émile Brisson-Curadeau ◽  
Kyle H Elliott ◽  
Pascal Côté
Keyword(s):  
North America ◽  
Short Distance ◽  
Migratory Birds ◽  
Breeding Habitat ◽  
Temperature Changes ◽  
Migration Timing ◽  
Warm Weather ◽  
Breeding Grounds ◽  
Timing Of Migration ◽  
Migrating Birds

Abstract The phenology of migrating birds is shifting with climate change. For instance, short-distance migrants wintering in temperate regions tend to delay their migration in fall during spells of warmer temperature. However, some species do not show strong shifts, and the factors determining which species will react to temperature changes by delaying their migration are poorly known. In addition, it is not known whether a slower migration or a postponed departure creates the observed delays in fall migration because most studies occur far south of the boreal breeding areas making it difficult to separate those 2 mechanisms. We used 22 yr of data at a northern observatory in eastern North America, at the southern edge of the boreal forest, to examine how 21 short-distance migrants responded to changing temperatures. We investigated if those species responding to temperature share life-history features (i.e. diet, size, total migration distance, breeding habitat, timing of migration). The period of migration in each species was, by far, the most important factor predicting the response of a species to temperature. Eight of the 13 species migrating in October changed their migration onset with temperature (usually by delaying migration by 1–2 days/°C), while the migration timing of none of the 8 species migrating in September was dependent on temperature. Furthermore, the absence of a greater migration delay by birds breeding farther from the study site (i.e. Arctic-breeding birds) suggests the mechanism is a postponed departure rather than a slower migration. We conclude that temperature variations in late fall influence the conditions on the breeding grounds, so that birds still present at that time benefit more from postponing their departure in warm weather.

scholarly journals Detoured flight direction responses along the southwest coast of Lake Erie by night-migrating birds

The Auk ◽  
2019 ◽  
Vol 136 (3) ◽  
Author(s):  
David V Gesicki ◽  
Erica L Cech ◽  
Verner P Bingman
Keyword(s):  
Lake Erie ◽  
Migratory Birds ◽  
Western Basin ◽  
Good Opportunity ◽  
Infrared Observations ◽  
The North ◽  
Flight Direction ◽  
Breeding Grounds ◽  
Topographical Feature ◽  
Migrating Birds

Abstract Migratory birds encounter the Great Lakes while moving through eastern North America toward breeding grounds to the North, which offers a good opportunity to study variation in migratory behavior as birds face a potentially influencing topographical feature. Using passive infrared technology, we documented the direction of relatively low-flying, nocturnal, mostly passerine migration in spring along the southern coast of Lake Erie’s western basin. We examined the extent to which spring migrants flew across Lake Erie as a continuation of the inland, northeasterly broad front migratory direction, as determined by weather radar and infrared observations, or displayed a tendency to deviate to more closely follow the direction of the coastline. We found that an estimated 62% of all low-flying migrants deviated their flight directions toward the coast of Lake Erie at 2 coastal sites, Cedar Point and Ottawa, which were characterized by northwest–southeast oriented coastlines. Migrants at a third coastal location, Maumee Bay, which has a more east–west oriented coastline, did not display similarly deviated flight directions. We found that even when winds were energetically favorable for a lake crossing, many migrants still routinely displayed deviated flight directions that approached paralleling the coastline. Further, the mean flight direction at one site, Ottawa, shifted more in the direction of the coastline as the night progressed, suggesting that time of night could influence the shift to a more coastal flight direction. The data indicate that the western basin of Lake Erie acts as a salient topographical feature influencing the flight directions of nocturnal migrants. The data further suggest that birds are making active decisions while in flight, based on current environmental and physiological conditions, about whether to continue to cross Lake Erie or take a coastal detour.

Functioning of the rat circadian system is modified by light applied in critical postnatal days

2001 ◽  
Vol 280 (4) ◽  
pp. R1023-R1030 ◽  
Author(s):  
M. M. Canal-Corretger ◽  
J. Vilaplana ◽  
T. Cambras ◽  
A. Díez-Noguera
Keyword(s):  
Light Pulse ◽  
Critical Period ◽  
Decisive Role ◽  
Circadian System ◽  
Constant Darkness ◽  
Biological Clocks ◽  
Critical Window ◽  
Lighting Conditions ◽  
Lactation Stage ◽  
Circadian Organization

Lighting conditions influence biological clocks. The present experiment was designed to test the presence of a critical window of days during the lactation stage of the rat in which light has a decisive role on the development of the circadian system. Rats were exposed to 4, 8, or 12 days of constant light (LL) during the first days of life. Their circadian rhythm was later studied under LL and constant darkness. The response to a light pulse was also examined. Results show that the greater the number of LL days during lactation, the stronger the rhythm under LL and the smaller the phase shift due to the light pulse. These responses are enhanced when rats are exposed to LL days around postnatal day 12. A mathematical model was built to explain the responses of the circadian system with respect to the timing of LL during lactation, and we deduced that between postnatal days 10 to 20there is a critical period of sensitivity to light; consequently, exposure to LL during this time modifies the circadian organization of the motor activity.

scholarly journals How hazardous is the Sahara Desert crossing for migratory birds? Indications from satellite tracking of raptors

2009 ◽  
Vol 6 (3) ◽  
pp. 297-300 ◽  
Author(s):  
Roine Strandberg ◽  
Raymond H. G. Klaassen ◽  
Mikael Hake ◽  
Thomas Alerstam
Keyword(s):  
Migratory Birds ◽  
Satellite Telemetry ◽  
Satellite Tracking ◽  
Sahara Desert ◽  
Annual Cycles ◽  
Marsh Harrier ◽  
Circus Aeruginosus ◽  
Course Changes ◽  
Carry Over ◽  
Migrating Birds

We investigated the risk associated with crossing the Sahara Desert for migrating birds by evaluating more than 90 journeys across this desert by four species of raptors (osprey Pandion haliaetus , honey buzzard Pernis apivorus , marsh harrier Circus aeruginosus and Eurasian hobby Falco subbuteo ) recorded by satellite telemetry. Forty per cent of the crossings included events of aberrant behaviours, such as abrupt course changes, slow travel speeds, interruptions, aborted crossings followed by retreats from the desert and failed crossings due to death, indicating difficulties for the migrants. The mortality during the Sahara crossing was 31 per cent per crossing attempt for juveniles (first autumn migration), compared with only 2 per cent for adults (autumn and spring combined). Mortality associated with the Sahara passage made up a substantial fraction (up to about half for juveniles) of the total annual mortality, demonstrating that this passage has a profound influence on survival and fitness of migrants. Aberrant behaviours resulted in late arrival at the breeding grounds and an increased probability of breeding failure (carry-over effects). This study also demonstrates that satellite tracking can be a powerful method to reveal when and where birds are exposed to enhanced risk and mortality during their annual cycles.

scholarly journals Seasonal changes in the altitudinal distribution of nocturnally migrating birds during autumn migration

2015 ◽  
Vol 2 (12) ◽  
pp. 150347 ◽  
Author(s):  
Frank A. La Sorte ◽  
Wesley M. Hochachka ◽  
Andrew Farnsworth ◽  
Daniel Sheldon ◽  
Benjamin M. Van Doren ◽  
...  
Keyword(s):  
Migratory Birds ◽  
Global Climate ◽  
Polar Front ◽  
Migratory Bird ◽  
Atmospheric Conditions ◽  
Altitudinal Distribution ◽  
Long Distance ◽  
Bird Populations ◽  
Intermediate Distance ◽  
Migrating Birds

Wind plays a significant role in the flight altitudes selected by nocturnally migrating birds. At mid-latitudes in the Northern Hemisphere, atmospheric conditions are dictated by the polar-front jet stream, whose amplitude increases in the autumn. One consequence for migratory birds is that the region’s prevailing westerly winds become progressively stronger at higher migration altitudes. We expect this seasonality in wind speed to result in migrants occupying progressively lower flight altitudes, which we test using density estimates of nocturnal migrants at 100 m altitudinal intervals from 12 weather surveillance radar stations located in the northeastern USA. Contrary to our expectations, median migration altitudes deviated little across the season, and the variance was lower during the middle of the season and higher during the beginning and especially the end of the season. Early-season migrants included small- to intermediate-sized long-distance migrants in the orders Charadriiformes and Passeriformes, and late-season migrants included large-bodied and intermediate-distance migrants in the order Anseriformes. Therefore, seasonality in the composition of migratory species, and related variation in migration strategies and behaviours, resulted in a convex–concave bounded distribution of migration altitudes. Our results provide a basis for assessing the implications for migratory bird populations of changes in mid-latitude atmospheric conditions probably occurring under global climate change.

scholarly journals Where in the air? Aerial habitat use of nocturnally migrating birds

2016 ◽  
Vol 12 (11) ◽  
pp. 20160591 ◽  
Author(s):  
Kyle G. Horton ◽  
Benjamin M. Van Doren ◽  
Phillip M. Stepanian ◽  
Andrew Farnsworth ◽  
Jeffrey F. Kelly
Keyword(s):  
Habitat Selection ◽  
Large Scale ◽  
Migratory Birds ◽  
Lower Atmosphere ◽  
Migration Activity ◽  
Maximum Wind ◽  
Eastern Usa ◽  
Migrant Birds ◽  
Spatio Temporal ◽  
Migrating Birds

The lower atmosphere (i.e. aerosphere) is critical habitat for migrant birds. This habitat is vast and little is known about the spatio-temporal patterns of distribution and abundance of migrants in it. Increased human encroachment into the aerosphere makes understanding where and when migratory birds use this airspace a key to reducing human–wildlife conflicts. We use weather surveillance radar to describe large-scale height distributions of nocturnally migrating birds and interpret these distributions as aggregate habitat selection behaviours of individual birds. As such, we detail wind cues that influence selection of flight heights. Using six radars in the eastern USA during the spring (2013–2015) and autumn (2013 and 2014), we found migrants tended to adjust their heights according to favourable wind profit. We found that migrants' flight altitudes correlated most closely with the altitude of maximum wind profit; however, absolute differences in flight heights and height of maximum wind profit were large. Migrants tended to fly slightly higher at inland sites compared with coastal sites during spring, but not during autumn. Migration activity was greater at coastal sites during autumn, but not during spring. This characterization of bird migration represents a critical advance in our understanding of migrant distributions in flight and a new window into habitat selection behaviours.

scholarly journals MOTIVATION BEHIND INTERNATIONAL UNDERGRADUATE STUDENTS CHOOSING ENGINEERING

2019 ◽  
Author(s):  
Juan Abelló ◽  
Alys Avalos-Rivera ◽  
Gabriel Potvin ◽  
Saloome Motavas ◽  
Vladan Prodanovic ◽  
...  
Keyword(s):  
Undergraduate Students ◽  
Family Influence ◽  
First Year ◽  
Motivating Factors ◽  
Expectancy Value ◽  
University Of British Columbia ◽  
Utility Cost ◽  
The University ◽  
Program Data ◽  
Relevant Factors

This paper reports on a pilot study that investigated what motivated a group of first-year international students in the Vantage College program at the University of British Columbia (UBC) to pursue a degree in engineering. The study also sought to examine whether students report changes in their motivation as a result of completing their first year in our program. Data were collected through an open-ended survey provided to our cohort of 69 students, from which we received 66 responses. The results were analyzed qualitatively based on an expectancy value theoretical framework (focused on interest, utility, cost, and attainment.) The findings showed strong agreement with interest and utility as motivating factors, little agreement with attainment and cost as relevant factors, and the presence of additional motivators not present in our initial framework. The strongest among the latter group was family influence, with ability also appearing, yet to a lower degree. Our results suggest that interest and utility are the strongest motivators (over one third of students), with family influence (about one quarter) and ability (about one eight) being less important. We found few instances of cost (about one tenth) and no significant instances of attainment; this may be because engineering identity is developed as a student progresses through the undergraduate program.

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