Tern Island Albatrosses - 1999

National Science Foundation

Satellite telemetry was used to identify the foraging distributions of two congeneric species of albatrosses that nest in the tropics/subtropics. Breeding black-footed albatross (Phoebastria nigripes) and Laysan albatross (Phoebastria immutabilis) nesting in Tern Island (Northwest Hawaiian Islands) and tracked during the 1998 breeding season (January - June) performed foraging trips to continental shelves off North America. Black-footed albatross made long trips to the west coast of North America (British Columbia to California). Laysan albatross traveled primarily to the north of the Hawaiian Islands, and reached the waters of the Aleutian Islands and the Gulf of Alaska. These albatross species mixed short and long trips during the chick-rearing period (February - June), but engaged in short foraging trips during the brooding period (within 18 days after chick hatched, January - February).



In 1999, the breeding success of both albatross species was depressed, with a large-scale failure for the Laysan albatross. Out of nine black-footed albatross tracked, two chicks died during this study. Out of sixteen Laysan albatross tracked, the eggs of seven birds did not hatch and eight chicks died during the tracking study. Due to this massive breeding failure, the satellite tracked birds abandoned their colony and dispersed widely across the North Pacific Ocean. Thus, the 1998 (central-place foraging) and 1999 (dispersal from colonies) tracking data should be considered separately.

The 1999 data provided information on albatross movements during a year of depressed reproductive success, when many birds abandoned the colony. An understanding on the interplay between the distribution and the reproductive success of North Pacific albatrosses has important implications for assessing how oceanographic variability influences their population dynamics.



We thank C. Alexander, L. Carsten, P. Fernández, F. Juola, P. Sievert, A. Viggiano and S. Wang for assistance in the field, and the U.S. Fish and Wildlife Service for logistical support. This research was funded by National Science Foundation grant DEB 9629539 to D. Anderson.

These albatross were tracked using PTT-100 Argos transmitters (Microwave Telemetry, Columbia, MD) operating at a 90-second repetition rate and programmed to operate on a 8:24 h ON:OFF duty cycle. Transmitter bench-tests before deployment revealed that the Argos location quality classes (lcs) had the following median position errors, expressed in kilometers: lc B (8.46), lc A (3.29), lc 0 (4.80), lc 1 (1.96), lc 2 (0.49), and lc 3 (0.26).



The low-quality class B locations were discarded because they mis-represented the telemetry tracks. Thus, this dataset includes 4635 high-quality locations (lc classes A or better) with median positional errors <4 km.

Overview

Attributes described below represent those in the original dataset provided by the provider.
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Attributes in dataset

Attribute (table column)	Description
record_number	definition not provided
bird_number	definition not provided
species	Species name recorded
day	Day
month	Month
year	Year
hours_gmt	Hours in GMT
minutes_gmt	Minutes in GMT
seconds_gmt	Seconds in GMT
argos_quality	Quality of Argos data
latitude	Latitude in decimal degrees
longitude	Longitude in decimal degrees
geom	Geometry field added by OBIS-SEAMAP
oid	Unique ID number (generated by OBIS-SEAMAP)