Head direction cells in a migratory bird prefer north

Animals exhibit remarkable navigation abilities as if they have an internal compass. Head direction (HD) cells encoding the animal’s heading azimuth are found in the brain of several animal species; the HD cell signals are dependent on the vestibular nuclei, where magnetic responsive cells are present in birds. However, it is difficult to determine whether HD cell signals drive the compass orientation in animals, as they do not necessarily rely on the magnetic compass under all circumstances. Recording of HD cell activities from the medial pallium of shearwater chicks (Calonectris leucomelas) just before their first migration, during which they strongly rely on compass orientation, revealed that shearwater HD cells prefer a north orientation. The preference remained stable regardless of geolocations and environmental cues, suggesting the existence of a magnetic compass regulated by internally generated HD signals. Our findings provide insight into the integration of the direction and magnetoreception senses.

Click here to read the full article.

Editors remarks

This paper is interesting as it talks about the latest research on head direction cells.  Personally I am not persuaded that birds have a magnetic sensor in their beaks, but this is an interesting paper anyway.

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How young animals learn to migrate

While advances in biologging have revealed many spectacular animal migrations, it remains poorly understood how young animals learn to migrate.

Even in social species, it is unclear how migratory skills are transmitted from one generation to another and what implications this may have.

Here we show that in Caspian terns Hydroprogne caspia family groups, genetic and foster male parents carry the main responsibility for migrating with young. During migration, young birds stayed close to an adult at all times, with the bond dissipating on the wintering grounds.

Solo-migrating adults migrated faster than did adults accompanying young. Four young that lost contact with their parent at an early stage of migration all died. During their first solo migration, subadult terns remained faithful to routes they took with their parents as young.

Our results provide evidence for cultural inheritance of migration knowledge in a long-distance bird migrant and show that sex-biased (allo)parental care en route shapes migration through social learning. 

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Olfactory landmarks and path integration converge to form a cognitive spatial map

This paper on olfactory landmarks is interesting as it covers the idea that the distinctive smell of a place can help navigation by creating a new landmark for helping an animal navigate.

The recognition of a spatial landmark by its sensory features poses a problem for neural circuits. Fischler-Ruiz, et al. show how this problem is solved when mice use odour cues to navigate in the dark. In the hippocampus, path integration imposes spatial meaning on odour cues, thereby creating new landmarks.

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Adaptation and Evolution of Bird Migration

In this paper you find a rather fascinating overview of the migration of Birds.

Malik, Y. S., Arun Prince Milton, A., Ghatak, S. & Ghosh, S. 2021 Adaptation and Evolution of Bird Migration. In Role of Birds in Transmitting Zoonotic Pathogens, pp. 3-14. Singapore Springer Singapore. Malik 2021

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‘Frostbit Boy’ rescued among dolphins after 12 hours at sea

Ruairí McSorley who had gone swimming has been rescued after getting into difficulty while swimming off the coast of Co Kerry. He was discovered surrounded by a pod of dolphins four kilometres from the shore of Castlegregory Beach. Read the full story.

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Modelling collective navigation via non-local communication

A recent paper called “Modelling collective navigation via non-local communication”
has been published by S. T. Johnston(1) and K. J. Painter(2).

They tell us that a group of individuals produce better navigational results than
individuals which is why flocks of birds are more efficient than a solo migrant. The
RAF confirms this where they have found that a more than one navigator does
a better job.

Collective migration occurs throughout the animal kingdom, and demands both the
interpretation of navigational cues and the perception of other individuals within the
group. Navigational cues orient individuals towards a destination, while it has been
demonstrated that communication between individuals enhances navigation through
a reduction in orientation error.

We develop a mathematical model of collective navigation that synthesises navigational cues and perception of other individuals. Crucially, this approach incorporates uncertainty inherent to cue interpretation and perception in the decision making process, which can arise due to noisy environments.

We demonstrate that collective navigation is more efficient than individual navigation, provided a threshold number of other individuals are perceptible. This benefit is even more pronounced in low navigation information environments. In navigation ‘blindspots’, where no information is available, navigation is enhanced through a relay that connects individuals in information- poor regions to individuals in information-rich regions. As an expository case study, we apply our framework to minke whale migration in the northeast Atlantic Ocean, and quantify the decrease in navigation ability due to anthropogenic noise pollution.

1 Systems Biology Laboratory, School of Mathematics and Statistics, and Department of Biomedical Engineering, University of Melbourne, Parkville, Victoria 3010, Australia
2 Dipartimento Interateneo di Scienze, Progetto e Politiche del Territorio (DIST) Politecnico di Torino, Viale Pier Andrea Mattioli, Torino 39 10125, Italy

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New Study Fuels Debate About Source of Birds’ Magnetic Sense

animal avian beak bird
Photo by Pixabay on Pexels.com

This link gives you a very good overview of the latest arguments about whether Cryptochromes,  which are sensitive to magnetic fields and exist in the eyes of birds, help with their navigation.  All the great and good involved in this field are quoted.  I personally do not think that the quantum effects in a Cryptochrome can exist in the “noisy” high temperature environment of the eye of a bird.

Richard Nissen
editor

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