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Juvenile Osprey Navigation during Trans-Oceanic Migration.

Horton TW, Bierregaard RO, Zawar-Reza P, Holdaway RN, Sagar P - PLoS ONE (2014)

Bottom Line: Although some species of bird, fish, insect, mammal, and reptile are capable of drift compensation, our understanding of the spatial reference frame, and associated coordinate space, in which these navigational behaviors occur remains limited.These results are best explained by extreme navigational precision in an exogenous spatio-temporal reference frame, such as positional orientation relative to Earth's magnetic field and pacing relative to an exogenous mechanism of keeping time.Through integration of movement and meteorological data, we propose a new theoretical framework, chord and clock navigation, capable of explaining the precise spatial orientation and temporal pacing performed by juvenile ospreys during their long-distance migrations over open ocean.

View Article: PubMed Central - PubMed

Affiliation: Department of Geological Science, University of Canterbury, Christchurch, New Zealand.

ABSTRACT
To compensate for drift, an animal migrating through air or sea must be able to navigate. Although some species of bird, fish, insect, mammal, and reptile are capable of drift compensation, our understanding of the spatial reference frame, and associated coordinate space, in which these navigational behaviors occur remains limited. Using high resolution satellite-monitored GPS track data, we show that juvenile ospreys (Pandion haliaetus) are capable of non-stop constant course movements over open ocean spanning distances in excess of 1500 km despite the perturbing effects of winds and the lack of obvious landmarks. These results are best explained by extreme navigational precision in an exogenous spatio-temporal reference frame, such as positional orientation relative to Earth's magnetic field and pacing relative to an exogenous mechanism of keeping time. Given the age (<1 year-old) of these birds and knowledge of their hatching site locations, we were able to transform Enhanced Magnetic Model coordinate locations such that the origin of the magnetic coordinate space corresponded with each bird's nest. Our analyses show that trans-oceanic juvenile osprey movements are consistent with bicoordinate positional orientation in transformed magnetic coordinate or geographic space. Through integration of movement and meteorological data, we propose a new theoretical framework, chord and clock navigation, capable of explaining the precise spatial orientation and temporal pacing performed by juvenile ospreys during their long-distance migrations over open ocean.

No MeSH data available.


Related in: MedlinePlus

Relationship between osprey airspeed and tailwind velocity.Symbols correspond with one-hourly osprey GPS-enabled PTT tag locations. Linear least-squares regression equation is represented as the solid black line.
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pone-0114557-g005: Relationship between osprey airspeed and tailwind velocity.Symbols correspond with one-hourly osprey GPS-enabled PTT tag locations. Linear least-squares regression equation is represented as the solid black line.

Mentions: We were surprised to find a highly significant negative linear covariation between active forward movement velocity and tailwind velocity (p<<0.05; ANOVA, F = 189.08; dfreg = 1; dferr = 242; α = 0.05; Figure 5). This finding demonstrates that birds experiencing stronger tailwinds maintained lower active forward movement velocities, as would be expected given the energetic demands of non-stop long-distance migration. However, our results also show that birds experiencing headwinds (i.e. negative tailwinds) maintained the highest active forward movement velocities, often in excess of 50 km/h (Figure 5), rather than allowing their forward movement velocities to decrease. Such adjustments to forward movement velocity in response to variable winds is consistent with optimal bird migration theory, whereby the maintenance of flight speed minimizes either the overall energetic cost or flight duration of a bird's migration [42], [43]. However, the orientational and navigational requirements of migratory flight optimization are not insignificant. In order to optimize its movement behavior by increasing/decreasing flight speed in response to changing winds, a bird must first be able to determine that its forward movement velocity has changed: a process that requires not only a mechanism of positional orientation but also a mechanism for determining the passage of time.


Juvenile Osprey Navigation during Trans-Oceanic Migration.

Horton TW, Bierregaard RO, Zawar-Reza P, Holdaway RN, Sagar P - PLoS ONE (2014)

Relationship between osprey airspeed and tailwind velocity.Symbols correspond with one-hourly osprey GPS-enabled PTT tag locations. Linear least-squares regression equation is represented as the solid black line.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4262435&req=5

pone-0114557-g005: Relationship between osprey airspeed and tailwind velocity.Symbols correspond with one-hourly osprey GPS-enabled PTT tag locations. Linear least-squares regression equation is represented as the solid black line.
Mentions: We were surprised to find a highly significant negative linear covariation between active forward movement velocity and tailwind velocity (p<<0.05; ANOVA, F = 189.08; dfreg = 1; dferr = 242; α = 0.05; Figure 5). This finding demonstrates that birds experiencing stronger tailwinds maintained lower active forward movement velocities, as would be expected given the energetic demands of non-stop long-distance migration. However, our results also show that birds experiencing headwinds (i.e. negative tailwinds) maintained the highest active forward movement velocities, often in excess of 50 km/h (Figure 5), rather than allowing their forward movement velocities to decrease. Such adjustments to forward movement velocity in response to variable winds is consistent with optimal bird migration theory, whereby the maintenance of flight speed minimizes either the overall energetic cost or flight duration of a bird's migration [42], [43]. However, the orientational and navigational requirements of migratory flight optimization are not insignificant. In order to optimize its movement behavior by increasing/decreasing flight speed in response to changing winds, a bird must first be able to determine that its forward movement velocity has changed: a process that requires not only a mechanism of positional orientation but also a mechanism for determining the passage of time.

Bottom Line: Although some species of bird, fish, insect, mammal, and reptile are capable of drift compensation, our understanding of the spatial reference frame, and associated coordinate space, in which these navigational behaviors occur remains limited.These results are best explained by extreme navigational precision in an exogenous spatio-temporal reference frame, such as positional orientation relative to Earth's magnetic field and pacing relative to an exogenous mechanism of keeping time.Through integration of movement and meteorological data, we propose a new theoretical framework, chord and clock navigation, capable of explaining the precise spatial orientation and temporal pacing performed by juvenile ospreys during their long-distance migrations over open ocean.

View Article: PubMed Central - PubMed

Affiliation: Department of Geological Science, University of Canterbury, Christchurch, New Zealand.

ABSTRACT
To compensate for drift, an animal migrating through air or sea must be able to navigate. Although some species of bird, fish, insect, mammal, and reptile are capable of drift compensation, our understanding of the spatial reference frame, and associated coordinate space, in which these navigational behaviors occur remains limited. Using high resolution satellite-monitored GPS track data, we show that juvenile ospreys (Pandion haliaetus) are capable of non-stop constant course movements over open ocean spanning distances in excess of 1500 km despite the perturbing effects of winds and the lack of obvious landmarks. These results are best explained by extreme navigational precision in an exogenous spatio-temporal reference frame, such as positional orientation relative to Earth's magnetic field and pacing relative to an exogenous mechanism of keeping time. Given the age (<1 year-old) of these birds and knowledge of their hatching site locations, we were able to transform Enhanced Magnetic Model coordinate locations such that the origin of the magnetic coordinate space corresponded with each bird's nest. Our analyses show that trans-oceanic juvenile osprey movements are consistent with bicoordinate positional orientation in transformed magnetic coordinate or geographic space. Through integration of movement and meteorological data, we propose a new theoretical framework, chord and clock navigation, capable of explaining the precise spatial orientation and temporal pacing performed by juvenile ospreys during their long-distance migrations over open ocean.

No MeSH data available.


Related in: MedlinePlus