Bird Migration Research Research Articles

Bird migration research today: some achievements and new challenges

This review deals with the topics of bird migration research that have seen significant progress in the recent years. In these fields, earlier views have been significantly re-considered. They include the manifestation of migration, i.e. length of migratory flights, their speed, duration of stopovers, flight altitude, which taken together form the spatio-temporal realization of migration. New data on this array of research questions make it possible to ask new questions about physiological adaptations that make such flights possible, and factors that govern these processes. Significant progress is also evident in the study of long-distance orientation and navigation of migrating birds. However, it mainly concerns the mechanisms of magnetoreception and use of magnetic cues for orientation. Besides, students of bird migration could not ignore the ‘-omics’ revolution, which, like the studies of the manifestation of migration, was mainly caused by technological advances, mainly by the advent of next generation sequencing techniques. The new data obtained by these methods raised the hope to sort out the genetic basis of endogenous control of bird migration. However, the gap between the expectations and the actual results remains. To close this gap, new research into the molecular and cellular mechanisms that underlie migratory behavior is necessary. The results available now mainly refer to the processes that are relatively well understood, mainly the mechanisms of energy turnover and stress response.

Animal Migration Patterns Extraction Based on Atrous-Gated CNN Deep Learning Model

Weather radar data can capture large-scale bird migration information, helping solve a series of migratory ecological problems. However, extracting and identifying bird information from weather radar data remains one of the challenges of radar aeroecology. In recent years, deep learning was applied to the field of radar data processing and proved to be an effective strategy. This paper describes a deep learning method for extracting biological target echoes from weather radar images. This model uses a two-stream CNN (Atrous-Gated CNN) architecture to generate fine-scale predictions by combining the key modules such as squeeze-and-excitation (SE), and atrous spatial pyramid pooling (ASPP). The SE block can enhance the attention on the feature map, while ASPP block can expand the receptive field, helping the network understand the global shape information. The experiments show that in the typical historical data of China next generation weather radar (CINRAD), the precision of the network in identifying biological targets reaches up to 99.6%. Our network can cope with complex weather conditions, realizing long-term and automated monitoring of weather radar data to extract biological target information and provide feasible technical support for bird migration research.

鸟类迁徙研究进展

鸟类迁徙研究进展

Satellite Forensics: Analysing Sparse Beacon Data to Reveal the Fate of DTUsat-2

The CubeSat DTUsat-2 was designed and built by students and faculty at the Technical University of Denmark and launched to low earth orbit on June 2014. Its mission was to aid ornithologists in bird migration research. Shortly after launch and orbit injection, it became apparent that all was not nominal. To understand the problem and find the causes, a forensic investigation was initiated. The investigation used recorded Morse-encoded beacons emitted by the satellite as a starting point. This paper presents the real-life data from DTUsat-2 on orbit and the methodologies used to visualize the key element in the investigation, namely, the correlation between orbit position and the beacon counter. Based on the data presented, an explanation for the observed behaviour of DTUsat-2 is given.

The power-speed relationship is U-shaped in two free-flying hawkmoths (Manducasexta).

A flying animal can minimize its energy consumption by choosing an optimal flight speed depending on the task at hand. Choice of flight speed can be predicted by modelling the aerodynamic power required for flight, and this tool has previously been used extensively in bird migration research. For insects, however, it is uncertain whether any of the commonly used power models are useful, as insects often operate in a very different flow regime from vertebrates. To investigate this, we measured aerodynamic power in the wake of two Manduca sexta flying freely in a wind tunnel at 1-3.8 ms-1, using tomographic particle image velocimetry (tomo-PIV). The expended power was similar in magnitude to that predicted by two classic models. However, the most ubiquitously used model, originally intended for vertebrates, failed to predict the sharp increase in power at higher speeds, leading to an overestimate of predicted flight speed during longer flights. In addition to measuring aerodynamic power, the tomo-PIV system yielded a highly detailed visualization of the wake, which proved to be significantly more intricate than could be inferred from previous smoke trail- and two-dimensional-PIV studies.

Wind tunnel as a tool in bird migration research

Wind tunnels, in which birds fly against an artificially generated air flow, have since long been used to evaluate aerodynamic properties of steady bird flight. A new generation of wind tunnels has also allowed the many processes associated with migratory flights to be studied in captivity. We review how wind tunnel studies of aerodynamics and migratory performance together have helped advancing our understanding of bird migration. Current migration theory is based on the power‐speed relationship of flight as well as flight range equations, both of which can be evaluated using birds flying in wind tunnels. In addition, and depending on wind tunnel properties, performance during gliding and climbing flight, and effects of air pressure, humidity and turbulence on bird flight has been measured. Long‐distance migrant species have been flown repeatedly for up to 16 h non‐stop, allowing detailed studies of the energy expenditure, fuel composition, protein turnover, water balance, immunocompetence and stress associated with sustained migratory flights. In addition, wind tunnels allow the fuelling periods between migratory flights to be studied from new angles. We end our review by suggesting several important topics for future wind tunnel studies, ranging from on of the key questions remaining, the efficiency at which chemical power in converted to mechanical power, to new useful avenues, such as improving and calibrating the techniques used for tracking of individual birds in the wild.

Which direction home?

The article discusses bird migration research by Kira Delmore and colleagues in the October 2014 issue of the journal "Ecology Letters" that found hybrids of Swainson's thrushes, whose parents came from different populations, flew intermediate migratory routes compared with their parents.

Optimal bird migration revisited

Using optimality perspectives is now regarded as an essential way of analysing and understanding adaptations and behavioural strategies in bird migration. Optimization analyses in bird migration research have diversified greatly during the two recent decades with respect to methods used as well as to topics addressed. Methods range from simple analytical and geometric models to more complex modeling by stochastic dynamic programming, annual routine models and multiobjective optimization. Also, game theory and simulation by selection algorithms have been used. A wide range of aspects of bird migration have been analyzed including flight, fuel deposition, predation risk, stopover site use, transition to breeding, routes and detours, daily timing, fly-and-forage migration, wind selectivity and wind drift, phenotypic flexibility, arrival time and annual molt and migration schedules. Optimization analyses have proven to be particularly important for defining problems and specifying questions and predictions about the consequences of minimization of energy, time and predation risk in bird migration. Optimization analyses will probably also be important in the future, when predictions about bird migration strategies can be tested by much new data obtained by modern tracking techniques and when the importance of new trade-offs, associated with, e.g., digestive physiology, metabolism, immunocompetence and disease, need to be assessed in bird migration research.

Optical Matrix Device: Technical Aspects of a New Tool for the Detection and Recording of Small Nocturnal Aerial Targets

The detection of flying targets in the night sky has provided interest for bird migration research over many years with methods largely dependent on moon watching or the use of radar and infrared camera. These methods lack the versatility of the system described in this paper which detects and automatically records aerial targets in the night sky of a size greater than 5 cm and at a distance of 100 to 1000 metres from the observer. The principle design features are first, an optical device for receiving images of targets on two high-sensitivity CCD matrices when illuminated by white light from searchlight beams and secondly, instantaneous parallactic electronic computation enabling the distance from device to target to be accurately measured, and sequential images of each target to be recorded to computer. The device has been tested on targets during the main seasonal nocturnal migration of birds and provides accurate image details of important target flight parameters including: altitude, linear size (wing span and body length), direction of flight (ground track), orientation of the body axis – heading, ground speed, wing-beat frequency, number of wing-beats in each series of beats, duration of the pause between each series of wing-beats, and type of flight trajectory. There are also the potential practical applications for aviation bird-strike at night as well as the remote monitoring of insects, bats and other targets of natural and artificial origin.

Automatic identification of bird targets with radar via patterns produced by wing flapping.

Bird identification with radar is important for bird migration research, environmental impact assessments (e.g. wind farms), aircraft security and radar meteorology. In a study on bird migration, radar signals from birds, insects and ground clutter were recorded. Signals from birds show a typical pattern due to wing flapping. The data were labelled by experts into the four classes BIRD, INSECT, CLUTTER and UFO (unidentifiable signals). We present a classification algorithm aimed at automatic recognition of bird targets. Variables related to signal intensity and wing flapping pattern were extracted (via continuous wavelet transform). We used support vector classifiers to build predictive models. We estimated classification performance via cross validation on four datasets. When data from the same dataset were used for training and testing the classifier, the classification performance was extremely to moderately high. When data from one dataset were used for training and the three remaining datasets were used as test sets, the performance was lower but still extremely to moderately high. This shows that the method generalizes well across different locations or times. Our method provides a substantial gain of time when birds must be identified in large collections of radar signals and it represents the first substantial step in developing a real time bird identification radar system. We provide some guidelines and ideas for future research.

The Problem of Estimating Wind Drift in Migrating Birds

Whether migrating birds compensate for wind drift or not is a fundamental question in bird migration research. The procedures to demonstrate and quantitatively estimate wind drift or compensation are fraught with difficulties and pitfalls. In this paper, we evaluate four methods that have been used in several studies over the past decades. We evaluate the methods by analysing a model migratory movement with a realistic scatter in flight directions, for the ideal cases of full drift and complete compensation. Results obtained with the different methods are then compared with the “true behaviour” of the model movement, illustrating that spurious patterns of drift and compensation arise in some cases. We also illustrate and evaluate the different methods of estimating drift for a real case, based on tracking radar measurements of bird migration in relation to winds. Calculating the linear regression of mean geographic track (resulting flight direction) and heading directions (directions of the birds' body axis) of a migratory movement under different wind conditions in relation to the angle α (the angle between mean track and heading) always provides robust and reliable results. Comparing mean flight directions between occasions with winds from the left and right of the mean flight direction of the whole migratory movement also always provides expected and correct measures of drift. In contrast, regressions of individual flight directions in relation to α (the angle between track and heading for the specific individuals or flocks) are liable to produce biased and spurious results, overestimating compensation/overcompensation if following winds dominate in the analysis and overestimating drift/overdrift if opposed winds are dominating. Comparing mean directions for cases with winds from the left and right in relation to individual flight directions also gives biased and spurious results unless there is full variation in wind directions or an equal distribution of crosswinds from left and right. The results of the methodological evaluation and the analysis of the real case indicate that some earlier analyses of wind drift may have to be re-evaluated.

Migration route of White‐tailed Sea Eagles Haliaeetus albicillain northeastern Asia

IbisVolume 140, Issue 4 p. 684-686 Migration route of White-tailed Sea Eagles Haliaeetus albicillain northeastern Asia Mutsuyski Ueta, Mutsuyski Ueta Research CenteK Wild Bird Society of Japan, 2–35-2 Minamidaira, Hino. Tokyo 191, JapanSearch for more papers by this authorFumio Sato, Fumio Sato Bird Migration Research Center, Yamashina Institutef'or Ornithology, Tsutsumine, Abiko, Chiba 270-11, JapanSearch for more papers by this authorEvgeni G. G. Lobkov, Evgeni G. G. Lobkov Kronntzky State Biosphere Reserve, 68401 0 Elizovo Kamchatka Region, RussiaSearch for more papers by this authorNagashisa Mita, Nagashisa Mita Radio Transmissions Technology Laboratory, Nippon Telegraph and Telephone Corporation, Take 1–2356. Yokosuka 238-03. Japan *Kumamoto University, Department of‘ Electrical and Computer Engineering, 2–39-1 Kurokami, Kurnamoto 860, JapanSearch for more papers by this author Mutsuyski Ueta, Mutsuyski Ueta Research CenteK Wild Bird Society of Japan, 2–35-2 Minamidaira, Hino. Tokyo 191, JapanSearch for more papers by this authorFumio Sato, Fumio Sato Bird Migration Research Center, Yamashina Institutef'or Ornithology, Tsutsumine, Abiko, Chiba 270-11, JapanSearch for more papers by this authorEvgeni G. G. Lobkov, Evgeni G. G. Lobkov Kronntzky State Biosphere Reserve, 68401 0 Elizovo Kamchatka Region, RussiaSearch for more papers by this authorNagashisa Mita, Nagashisa Mita Radio Transmissions Technology Laboratory, Nippon Telegraph and Telephone Corporation, Take 1–2356. Yokosuka 238-03. Japan *Kumamoto University, Department of‘ Electrical and Computer Engineering, 2–39-1 Kurokami, Kurnamoto 860, JapanSearch for more papers by this author First published: 28 June 2008 https://doi.org/10.1111/j.1474-919X.1998.tb04715.xCitations: 25 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume140, Issue4October 1998Pages 684-686 RelatedInformation

Recent Advances in Bird Migration Research Bird Migration. Physiology and Ecophysiology E. Gwinner

Recent Advances in Bird Migration Research Bird Migration. Physiology and Ecophysiology E. Gwinner

Research on Bird Migration

THE German Government has issued an announcement referring to the work of the German bird migration research stations in Heligoland and at Rossitten where rings are attached every year to the feet of more than 160,000 migratory birds. The rings are inscribed with identification numbers and with the address of one or other of the stations “Vogelwarte Helgoland” or “Vogelwarte Rossitten” respectively. The stations are anxious to receive reports of the finding of these birds in any part of the world with the view of gaining further information as to bird migration and other phenomena of bird life. They will gratefully acknowledge all such reports, and are prepared to furnish in reply information not only as regards the bird in question, but also as regards their work generally. Reports will be sufficiently addressed if directed to Vogelwarte Helgoland, Germany, or Vogelwarte Rossitten, Germany.