QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online December 3, 2004
Journal of Experimental Biology 207, 4679-4695 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01331

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lovvorn, J. R. Articles by Liggins, G. A. Search for Related Content PubMed PubMed Citation Articles by Lovvorn, J. R. Articles by Liggins, G. A. Social Bookmarking                         What's this?

Stroke patterns and regulation of swim speed and energy cost in free-ranging Brünnich's guillemots

James R. Lovvorn^1,*, Yutaka Watanuki², Akiko Kato³, Yasuhiko Naito³ and Geoffrey A. Liggins^4,

¹ Department of Zoology, University of Wyoming, Laramie, WY 82071, USA
² Graduate School of Fisheries Sciences, Hokkaido University, Minato-cho 3-1-1, Hakodate 041-8611, Japan
³ National Institute of Polar Research, 9-10 Kaga 1-chome, Itabashi-ku, Tokyo 173-8515, Japan
⁴ Department of Mechanical Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada

View larger version (18K): [in a new window]   Fig. 1. Fitted curves for (A) drag D (in Newtons) vs speed U (m s–1), and (B) drag coefficient CD vs Reynolds number Re, measured on frozen birds in a tow tank for a common guillemot (COGU) mounted on a sting (from Lovvorn et al., 1999), and for the same COGU and a Brünnich's guillemot (BRGU) towed with a harness and drogue system (from Lovvorn et al., 2001). Vertical lines indicate the range of speeds and Re observed in free-ranging BRGU during descent and ascent (Figs 2 and 3). The equation for the BRGU towed with the harness and drogue is D=1.08+2.55U2–1.38U3+0.276U4.

View larger version (31K): [in a new window]   Fig. 2. Changes in depth over time (A,D), and of vertical speed vs depth during descent (B,E) and ascent (C,F), as measured with time-depth recorders (TDRs) during three dives each by two Brünnich's guillemots (A–C; BRGU 82 and D–F; BRGU 87) near Svalbard, Norway. Curves are based on recordings at 1 s intervals.

View larger version (28K): [in a new window]   Fig. 3. Changes in (A) estimated buoyancy vs depth and (B) depth vs time, and (C–H) body angle (from horizontal), vertical speed, actual swim speed and stroke rate vs depth, for a Brünnich's guillemot (BRGU 13) during descent to 113 m (C–E) and during ascent (F–H). Values are averages over 3 s intervals of recordings at 1 Hz. The depth of neutral buoyancy was estimated as 71 m.

View larger version (22K): [in a new window]   Fig. 4. Changes in acceleration parallel to the body fuselage (surge) throughout single swimming strokes by a Brünnich's guillemot (BRGU 13) during descent (A–C) and horizontal swimming at the bottom of a dive (D). Curves for depths >2 m during descent and at the bottom represent pooled groups of strokes with similar curves (numbers of pooled strokes in parentheses). Plots are of deviations from the mean acceleration during an entire stroke (including upstroke and downstroke), based on regression equations fitted to accelerometer recordings at 0.03125 s intervals (32 Hz). The first peak is for the upstroke, and the second for the downstroke. The first two entire strokes encompass a change in body angle from horizontal to vertical, perhaps confounding surge measurements.

View larger version (22K): [in a new window]   Fig. 5. Changes in acceleration parallel to the body fuselage (surge) throughout single swimming strokes by a Brünnich's guillemot (BRGU 13) during ascent. Plots are of deviations from the mean acceleration during an entire stroke (including upstroke and downstroke), based on regression equations fitted to accelerometer recordings at 0.03125 s intervals (32 Hz). Some curves represent pooled groups of strokes with similar curves (numbers of pooled strokes in parentheses). Periods of gliding separated almost all strokes, and only clearly recognizable strokes with acceleration peaks >1 m s–2 were included. Other conventions are as in Fig. 4.

View larger version (12K): [in a new window]   Fig. 6. Fraction of mean speed during a stroke vs fraction of stroke period (duration) corresponding to the five basic types of acceleration curve during descent and at the bottom in Fig. 4. At the bottom, curves were very similar when calculated for mean speeds of 1.76 and 2.18 m s–1, and were subsequently pooled (see text). Equations for curves are in Table 1.

View larger version (13K): [in a new window]   Fig. 7. Fraction of mean speed during a stroke vs fraction of stroke period (duration) corresponding to the four basic types of acceleration curve during ascent in Fig. 5. Equations for curves are in Table 1. Unlike curves for descent in Fig. 6, these curves did not have consistent periods and did not occur over particular depth ranges.

View larger version (28K): [in a new window]   Fig. 8. Modeled changes in mechanical work stroke–1 (A–D) and cumulative work (cum.; E–H) against drag (A,E), buoyancy (B,F), inertia (surge acceleration; C,G) and all three combined (D,H) during descent, based on dive parameters for a Brünnich's guillemot (BRGU 13; Figs 3 and 6; Table 1) and drag of a frozen Brünnich's guillemot (Fig. 1A). Solid circles are for a dive in which all strokes follow Curve 3 in Fig. 6, and open circles are for a dive in which all strokes follow Curve 4 in Fig. 6; triangles are for a dive in which the bird moves at steady speed with no oscillatory (accelerational) stroking. The total cumulative costs of descent for the three conditions are annotated in the bottom right panel. For work stroke–1, very high values during the first (7.2 J) and second (5.2 J) strokes are not shown.

View larger version (16K): [in a new window]   Fig. 9. Modeled changes in mechanical work stroke–1 against drag, buoyancy, inertia (surge acceleration) and all three combined during ascent and horizontal swimming at the bottom (109 m), based on dive parameters for a Brünnich's guillemot (BRGU 13; Figs 3, 6 and 7; Table 1) and drag of a frozen Brünnich's guillemot (Fig. 1A). The depth of neutral buoyancy was estimated as 71 m (Fig. 3A). Values at the bottom were based on an estimated mean speed of 1.76 m s–1.

View larger version (13K): [in a new window]   Fig. 10. Depth and duration of glides during a single ascent by a Brünnich's guillemot (BRGU 13). All glides were separated by a single stroke, except the glide at 44 m, which was preceded by two very short strokes in succession.

View larger version (18K): [in a new window]   Fig. 11. Modeled changes in (A) total mechanical work stroke–1 and (B) cumulative total work, throughout descent by a Brünnich's guillemot with the respiratory volume at the water surface assumed in all other simulations in this paper (`standard', 0.153 l), and with respiratory volume at the surface increased and decreased by 60%. Total mechanical work for entire dives is annotated in the lower figure.

View larger version (15K): [in a new window]   Fig. 12. Modeled changes in mechanical work stroke–1 against drag, buoyancy, inertia (surge acceleration), and all three combined by a Brünnich's guillemot at a range of mean swim speeds during descent at depths of 10, 50 and 100 m. Vertical solid lines delimit the range of mean speeds observed in free-ranging Brünnich's guillemots (1.4–2 m s–1, Figs 2 and 3). Vertical dotted line indicates the maximum speed observed in common guillemots swimming horizontally in a tank (about 2.6 m s–1, Swennen and Duiven, 1991).

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter