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- Title
Simulating the distribution of southern Buller's albatross using an individual-based population model.
- Authors
Broekhuizen, N.; Stahl, J. C.; Sagar, P. M.
- Abstract
Summary 1. A spatially explicit, individual-based population model (IBPM) for southern Buller's albatross Thalassarche bulleri bulleri was developed to simulate the species’ at-sea distribution and interactions with fishing fleets. 2. Satellite tracking data for birds from colonies on Snares Islands and Solander Island (south of South Island, New Zealand) suggest that the feeding grounds utilized by a bird, and the duration of its foraging trips, are dependent upon colony, sex, pairing status and developmental stage of egg/chick. These dependencies were incorporated into the IBPM. 3. Simulated distributions were compared with independent shipboard observations by using the IBPM to make replicated ‘virtual counts’ corresponding to each shipboard count. Each shipboard count was assigned a score reflecting the likelihood that a count of this magnitude would have arisen if the true populations behave as described by the IBPM. 4. Randomization tests indicated that, for the months in which we had adequate telemetry data (March–July), predicted and observed distributions were very similar at scales down to 1 degree2 . There was some evidence that bird densities around the south-west corner of New Zealand's South Island were underpredicted in July, and at the scale of individual shipboard counts the ship data showed greater fine-scale aggregation than the virtual data. 5. Comparison of observed and simulated distributions early in the breeding season (January and February, for which we had no telemetry data) suggested that the foraging behaviour of birds prior to egg laying differs from that exhibited by either breeding or pre-breeding birds later in the season. 6. Synthesis and applications . In combination with reported by-catch rates, our IBPM may enable us to derive fishing gear-specific per -capita capture rates for Buller's albatross. Our results also emphasize that it may be necessary to represent responses of individual...
- Subjects
ALBATROSSES; BIRD populations
- Publication
Journal of Applied Ecology, 2003, Vol 40, Issue 4, p678
- ISSN
0021-8901
- Publication type
Article
- DOI
10.1046/j.1365-2664.2003.00834.x