Drone Surveys Are More Accurate Than Boat-Based Surveys of Bottlenose Dolphins (Tursiops truncatus)
Abstract
:1. Introduction
2. Materials and Methods
2.1. Group Counts
2.2. Behavioural Surveys
2.3. Data Analysis
3. Results
3.1. Group Counts
3.2. Behavioural Surveys
3.3. Additional Behavioural Events Recorded by the Drone
4. Discussion
4.1. Group Counts
4.2. Behavioural Observations
4.3. Additional Behavioural Events Detected from Drones
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Appendix A
Behavioural State | Boat-Based Frequency | Drone-Based Frequency | Difference (%) | p-Value |
---|---|---|---|---|
Resting | 0.56 | 0.48 | −15.1 | 0.024 |
Travelling | 0.25 | 0.38 | 55.2 | <0.001 |
Foraging | 0.07 | 0.03 | −58.3 | 0.014 |
Socialising | 0.01 | 0.02 | 166.7 | 0.129 |
Milling | 0.12 | 0.09 | −22.0 | 0.266 |
Dispersion | Boat-Based Frequency | Drone-Based Frequency | Difference (%) | p-Value |
---|---|---|---|---|
Tight | 0.29 | 0.20 | −30.1 | 0.007 |
Moderate | 0.36 | 0.26 | −27.0 | 0.006 |
Loose | 0.22 | 0.30 | 35.4 | 0.017 |
Sub-group | 0.13 | 0.23 | 80.4 | <0.001 |
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Behavioural State | Definition |
---|---|
Socialising | Dolphins observed chasing, copulating, and/or engaged in any other physical contact with another dolphin, such as rubbing and touching (excluding mother-calf pairs). Aerial behavioural events, such as horizontal and vertical jumps, may occur. |
Milling | Dolphins exhibited non-directional movements, with frequent changes in bearing that prevented dolphins from making headway in any specific direction. Most of the time appears to be ‘transition’ behaviour between behavioural states. |
Foraging | Dolphins involved in any effort to pursue, capture, and/or consume prey. Diving for long periods of time, showing repeated unsynchronised dives in different directions in a determined location, exhibiting behaviour such as fluke out dives. |
Resting | Dolphins observed in a tight group, engaged moving slowly and in a constant direction. Surfacing is generally more predictable, often more synchronous than observed in other behavioural states. |
Travelling | Dolphins engaged in persistent, directional movement, making noticeable headway along a specific compass bearing. Group space varies and individuals swim with short and relatively constant dive intervals. |
Group Dispersion | Definition |
---|---|
Tight | Less than one body length between individuals. |
Moderate | One to five body lengths between individuals. |
Loose | More than five body lengths between individuals. |
Sub-group | Dolphins are divided in two or more groups but act as part of a single pod. |
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Fettermann, T.; Fiori, L.; Gillman, L.; Stockin, K.A.; Bollard, B. Drone Surveys Are More Accurate Than Boat-Based Surveys of Bottlenose Dolphins (Tursiops truncatus). Drones 2022, 6, 82. https://doi.org/10.3390/drones6040082
Fettermann T, Fiori L, Gillman L, Stockin KA, Bollard B. Drone Surveys Are More Accurate Than Boat-Based Surveys of Bottlenose Dolphins (Tursiops truncatus). Drones. 2022; 6(4):82. https://doi.org/10.3390/drones6040082
Chicago/Turabian StyleFettermann, Ticiana, Lorenzo Fiori, Len Gillman, Karen A. Stockin, and Barbara Bollard. 2022. "Drone Surveys Are More Accurate Than Boat-Based Surveys of Bottlenose Dolphins (Tursiops truncatus)" Drones 6, no. 4: 82. https://doi.org/10.3390/drones6040082