GLOBEC (GLOBal Ocean ECosystems Dynamics) NEP (Northeast Pacific) Northern California Current Bird Data from R/V New Horizon cruises NH0005 and 0007.

As a part of the GLOBEC-Northeast Pacific project, we investigated variation in the abundance of marine birds in the context of biological and physical habitat conditions in the northern portion of the California Current System (CCS) during cruises during the upwelling season 2000. Continuous surveys of seabirds were conducted simultaneously in June (onset of upwelling) and August (mature phase of upwelling).

Seabird surveys were conducted continuously during daylight, using a 300-m-wide transect strip. Within that strip, birds were counted that occurred within the 90 degree quadrant off the ship's bow that offered the best observation conditions.

Observed counts of seabirds recorded as flying in a steady direction were adjusted for the effect of flight speed and direction relative to that of the ship (Spear et al., 1992; Spear and Ainley, 1997b). The effect of such flux is the most serious bias encountered during seabird surveys at sea (Spear et al., 2005). Known as random directional movement (as opposed to nonrandom directional movement, which occurs when birds are attracted or repelled from the survey vessel), this problem usually results in density overestimation because most species fly faster than survey vessels; densities of birds that fly slower or at a similar speed as the survey vessel (e.g., storm-petrels), or are flying in the same direction, are usually underestimated (Spear et al., 1992)

(extracted from: David G. Ainley, Larry B. Spear, Cynthia T. Tynan, John A. Barth, Stephen D. Pierce, R. Glenn Ford and Timothy J. Cowles, 2005. Physical and biological variables affecting seabird distributions during the upwelling season of the northern California Current. Deep Sea Research Part II: Topical Studies in Oceanography, Volume 52, Issues 1-2, January 2005, Pages 123-143)

For more information, see http://cis.whoi.edu/science/bcodmo/dataset.cfm?id=10053&flag=view or http://globec.whoi.edu/jg/info/globec/nep/ccs/birds%7Bdir=globec.whoi.edu/jg/dir/globec/nep/ccs/,data=globec.whoi.edu/jg/serv/globec/nep/ccs/birds.html0%7D

Contact: Cynthia T. Tynan, ctynan@whoi.edu, Woods Hole Oceanographic Institution David G. Ainley, dainley@penguinscience.com, H.T. Harvey & Associates