| 1. |
- Bäckman, Johan, et al.
(författare)
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Activity and migratory flights of individual free-flying songbirds throughout the annual cycle : Method and first case study
- 2017
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 48:2, s. 309-319
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Tidskriftsartikel (refereegranskat)abstract
- We describe a method and device (< 1.2 g) for recording, processing and storing data about activity and location of individuals of free-living songbirds throughout the annual cycle. Activity level was determined every five minutes from five 100 ms samples of accelerometer data with 5 s between the sampling events. Activity levels were stored on an hourly basis throughout the annual cycle, allowing periods of resting/sleep, continuous flight and intermediate activity (foraging, breeding) to be distinguished. Measurements from a light sensor were stored from preprogrammed key stationary periods during the year to provide control information about geographic location. Successful results, including annual actogram, were obtained for a red-backed shrike Lanius collurio carrying out its annual loop migration between northern Europe and southern Africa. The shrike completed its annual migration by performing > 66 (max. 73) nocturnal migratory flights (29 flights in autumn and > 37, max. 44, in spring) adding up to a total of > 434 (max. 495) flight hours. Migratory flights lasted on average 6.6 h with maximum 15.9 h. These flights were aggregated into eight travel episodes (periods of 4-11 nights when flights took place on the majority of nights). Daytime resting levels were much higher during the winter period compared to breeding and final part of spring migration. Daytime resting showed peaks during days between successive nocturnal flights across Sahara, continental Africa and the Arabian Peninsula, indicating that the bird was mostly sleeping between these long migratory flights. Annual activity and flight data for free-living songbirds will open up many new research possibilities. Main topics that can be addressed are e.g. migratory flight performance (total flight investment, numbers and characteristics of flights), timing of stationary periods, activity patterns (resting/sleep, activity level) in different phases of the annual cycle and variability in the annual activity patterns between and within individuals.
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| 2. |
- Bäckman, Johan, et al.
(författare)
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Actogram analysis of free-flying migratory birds : new perspectives based on acceleration logging
- 2017
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Ingår i: Journal of Comparative Physiology A. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 203:6-7, s. 543-564
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Tidskriftsartikel (refereegranskat)abstract
- The use of accelerometers has become an important part of biologging techniques for large-sized birds with accelerometer data providing information about flight mode, wing-beat pattern, behaviour and energy expenditure. Such data show that birds using much energy-saving soaring/gliding flight like frigatebirds and swifts can stay airborne without landing for several months. Successful accelerometer studies have recently been conducted also for free-flying small songbirds during their entire annual cycle. Here we review the principles and possibilities for accelerometer studies in bird migration. We use the first annual actograms (for red-backed shrike Lanius collurio) to explore new analyses and insights that become possible with accelerometer data. Actogram data allow precise estimates of numbers of flights, flight durations as well as departure/landing times during the annual cycle. Annual and diurnal rhythms of migratory flights, as well as prolonged nocturnal flights across desert barriers are illustrated. The shifting balance between flight, rest and different intensities of activity throughout the year as revealed by actogram data can be used to analyse exertion levels during different phases of the life cycle. Accelerometer recording of the annual activity patterns of individual birds will open up a new dimension in bird migration research.
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| 3. |
- Nilsson, Maria, et al.
(författare)
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Self-Disorders in Asperger Syndrome Compared to Schizotypal Disorder : A Clinical Study
- 2020
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Ingår i: Schizophrenia Bulletin. - : Oxford University Press (OUP). - 1745-1701 .- 0586-7614. ; 46:1, s. 121-129
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: There are historical and theoretical indications of a difference in subjective experience between autism spectrum disorder (ASD) and the schizophrenia spectrum. However, this difference has not been empirically explored. Therefore, to explore potential differences in subjective experience between the 2 spectra, we examined the presence/absence of self-disorders in Asperger syndrome/autism spectrum disorder (As/ASD) compared to schizotypal disorder (Sd). Self-disorders represent changes in basic self-awareness which have been found to accumulate within the schizophrenia spectrum. METHODS: All participants were recruited from clinical units and interviewed with a focus on the exploration of presence/absence of self-disorders, with the Examination of Anomalous Self-Experience (EASE) scale, and a general assessment of present psychopathology, with Schedules for Clinical Assessment in Neuropsychiatry (SCAN). RESULTS: A total of 51 participants (As/ASD, n = 22; Sd, n = 29) were included in the statistical analyses. When controlling for age, gender, years of education, mental problems before the age of 16, and special needs school attendance, there was a clear difference in presence/absence of self-disorders between the 2 groups, with significantly higher levels in the Sd group. Further, there was an overlap in SCAN-rated symptoms between the 2 groups. CONCLUSION: Our results indicate a significant difference between As/ASD and Sd at the level of the basic self, which, in turn, indicates that an exploration of anomalous self-experience is a valuable supplement in the clinical differentiation between As/ASD and Sd.
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| 4. |
- Pedersen, Lykke, et al.
(författare)
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Sex-specific difference in migration schedule as a precursor of protandry in a long-distance migratory bird
- 2019
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Ingår i: Science of Nature. - : Springer Science and Business Media LLC. - 0028-1042 .- 1432-1904. ; 106:7-8
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Tidskriftsartikel (refereegranskat)abstract
- Protandry, the earlier arrival of males at the breeding grounds relative to females, is common in migratory birds. However, due to difficulties in following individual birds on migration, we still lack knowledge about the spatiotemporal origin of protandry during the annual cycle, impeding our understanding of the proximate drivers of this phenomenon. Here, we use full annual cycle tracking data of red-backed shrikes Lanius collurio to investigate the occurrence of sex-related differences in migratory pattern, which could be viewed as precursors (proximate causes) to protandry. We find protandry with males arriving an estimated 8.3 days (SE = 4.1) earlier at the breeding area than females. Furthermore, we find that, averaged across all departure and arrival events throughout the annual cycle, males migrate an estimated 5.3 days earlier than females during spring compared to 0.01 days in autumn. Event-wise estimates suggest that a divergence between male and female migratory schedules is initiated at departure from the main non-breeding area, thousands of kilometres from-, and several months prior to arrival at the breeding area. Duration of migration, flight speed during migration and spatial locations of stationary sites were similar between sexes. Our results reveal that protandry might arise from sex-differential migratory schedules emerging at the departure from the main non-breeding area in southern Africa and retained throughout spring migration, supporting the view that sex-differential selection pressure operates during spring migration rather than autumn migration.
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| 5. |
- Sjöberg, Sissel, et al.
(författare)
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Barometer logging reveals new dimensions of individual songbird migration
- 2018
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857. ; 49:9
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in tracking technology are based on the use of miniature sensors for recording new aspects of individual migratory behaviour. In this study, we have used activity data loggers with barometric and temperature sensors to record the flight altitudes as well as ground elevations during stationary periods of migratory songbirds. We tracked one individual of red-backed shrike and one great reed warbler along their autumn migration from Europe to Africa. Both individuals performed their migration stepwise in travel segments and climbed most metres during the passage across the Mediterranean Sea and the Sahara Desert and least metres during the first flight segment in Europe. The great reed warbler reached its highest flight altitude of 3950 m a.s.l. during the travel segment from Europe to west Africa, while the red-backed shrike reached 3650 m a.s.l as maximum flight altitude during its travel segment from Sahel to southern Africa. Both individuals used both lowlands and highlands for resting periods along their migrations. Furthermore, temperature decreased with increasing altitude during migratory flights for both individuals, highlighting the potential to determine flight duration from temperature measurements. Finally, we discuss how barometric data could be used to investigate birds’ responses to changes in air pressure as a cue for departures on migratory flights. This new technique, i.e. using a miniature data logger with barometric pressure sensor to estimate flight altitudes and ground elevations, will open up new avenues for research and importantly advance our understanding on how small birds behave during migratory flights.
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| 6. |
- Thorup, Kasper, et al.
(författare)
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Response of an Afro-Palearctic bird migrant to glaciation cycles
- 2021
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 118:52
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Tidskriftsartikel (refereegranskat)abstract
- Migration allows animals to exploit spatially separated and seasonally available resources at a continental to global scale. However, responding to global climatic changes might prove challenging, especially for long-distance intercontinental migrants. During glacial periods, when conditions became too harsh for breeding in the north, avian migrants have been hypothesized to retract their distribution to reside within small refugial areas. Here, we present data showing that an Afro-Palearctic migrant continued seasonal migration, largely within Africa, during previous glacial-interglacial cycles with no obvious impact on population size. Using individual migratory track data to hindcast monthly bioclimatic habitat availability maps through the last 120,000 y, we show altered seasonal use of suitable areas through time. Independently derived effective population sizes indicate a growing population through the last 40,000 y. We conclude that the migratory lifestyle enabled adaptation to shifting climate conditions. This indicates that populations of resource-tracking, longdistance migratory species could expand successfully during warming periods in the past, which could also be the case under future climate scenarios.
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