Taking animal tracking to new depths: synthesizing horizontal-vertical movement relationships for four marine predators
In animal ecology, a question of key interest for aquatic species is how changesin movement behavior are related in the horizontal and vertical dimensions when individualsforage. Alternative theoretical models and inconsistent empirical findings mean that thisquestion remains unresolved. Here we tes...
| Published in: | Ecology |
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| Main Authors: | , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Ecological Soc Amer
2015
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| Subjects: | |
| Online Access: | https://doi.org/10.1890/14-0469.1 http://www.ncbi.nlm.nih.gov/pubmed/26240863 http://ecite.utas.edu.au/106517 |
| Summary: | In animal ecology, a question of key interest for aquatic species is how changesin movement behavior are related in the horizontal and vertical dimensions when individualsforage. Alternative theoretical models and inconsistent empirical findings mean that thisquestion remains unresolved. Here we tested expectations by incorporating the verticaldimension (dive information) when predicting switching between movement states (residentor directed) within a state-space model. We integrated telemetry-based tracking and divingdata available for four seal species (southern elephant, Weddell, antarctic fur, and crabeater)in East Antarctica. Where possible, we included dive variables derived from the relationshipsbetween (1) dive duration and depth (as a measure of effort), and (2) dive duration and thepostdive surface interval (as a physiological measure of cost). Our results varied within andacross species, but there was a general tendency for the probability of switching into residentstate to be positively associated with shorter dive durations (for a given depth) and longerpostdive surface intervals (for a given dive duration). Our results add to a growing body ofliterature suggesting that simplistic interpretations of optimal foraging theory based only onhorizontal movements do not directly translate into the vertical dimension in dynamic marineenvironments. Analyses that incorporate at least two dimensions can test more sophisticatedmodels of foraging behavior. |
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