Sex-specific and individual preferences for hunting strategies in white sharks
Towner, A.V.; Leos-Barajas, V.; Langrock, R.; Schick, R.S.; Smale, M.J.; Kaschke, T.; Jewell, O.J.W; Papastamatiou, Y.P. (2016). Sex-specific and individual preferences for hunting strategies in white sharks. Funct. Ecol. 30(8): 1397–1407. https://dx.doi.org/10.1111/1365-2435.12613Additional data: In: Functional Ecology. Blackwell Publishers: Oxford. ISSN 0269-8463; e-ISSN 1365-2435, more |   |
| Author keywords | acoustic telemetry; foraging mode; fine-scale movement; hidden Markov Model; predator–prey |
| Authors | | Top | - Towner, A.V.
- Leos-Barajas, V.
- Langrock, R.
- Schick, R.S.
| - Smale, M.J.
- Kaschke, T.
- Jewell, O.J.W, more
- Papastamatiou, Y.P.
| |
| Abstract | 1. Fine-scale predator movements may be driven by many factors including sex, habitat anddistribution of resources. There may also be individual preferences for certain movementstrategies within a population which can be hard to quantify.2. Within top predators, movements are also going to be directly related to the mode of hunting,for example sit-and-wait or actively searching for prey. Although there is mounting evidencethat different hunting modes can cause opposing trophic cascades, there has been littlefocus on the modes used by top predators, especially those in the marine environment.3. Adult white sharks (Carcharhodon carcharias) are well known to forage on marine mammalprey, particularly pinnipeds. Sharks primarily ambush pinnipeds on the surface, but there hasbeen less focus on the strategies they use to encounter prey.4. We applied mixed hidden Markov models to acoustic tracking data of white sharks in acoastal aggregation area in order to quantify changing movement states (area-restricted searching(ARS) vs. patrolling) and the factors that influenced them. Individuals were re-tracked overmultiple days throughout a month to see whether state-switching dynamics varied or if individualspreferred certain movement strategies.5. Sharks were more likely to use ARS movements in the morning and during periods of chummingby ecotourism operators. Furthermore, the proportion of time individuals spent in the two differentstates and the state-switching frequency, differed between the sexes and between individuals.6. Predation attempts/success on pinnipeds were observed for sharks in both ARS and patrollingmovement states and within all random effects groupings. Therefore, white sharks can use both a ‘sitand-wait’ (ARS) and ‘active searching’ (patrolling) movements to ambush pinniped prey on the surface.7. White sharks demonstrate individual preferences for fine-scale movement patterns, whichmay be related to their use of different hunting modes. Marine top predators are generallyassumed to use only one type of hunting mode, but we show that there may be a mix withinpopulations. As such, individual variability should be considered when modelling behaviouraleffects of predators on prey species. |
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