FLAME University, Pune, Maharashtra, India
Initially developed as an instrument for wildlife photography, camera traps were subsequently used in hunting and have now transformed into a conservation tool (Kucera & Barrett, 2010). Camera traps allow us to observe activities taking place in the wild with minimal intrusion and have many current and potential applications in sea turtle research and conservation.
Any camera that is not triggered by a human (instantly or at a pre-set time) is a camera trap, although some studies that use the term include pre-programmed cameras. In the past, camera trap studies have primarily focused on terrestrial mammals, exploring behavioural patterns as well as their presence in certain habitats. Such methods allowed researchers to collect relatively unbiased data for long periods of time. With technological advances, increased availability, and reduced prices, the popularity of camera traps as a research tool grew and they were adopted to study a variety of species.
For camera trap studies to be viable, it is necessary for researchers to know the exact area in which the target animal is expected, to ensure that it will trigger the camera trap. As terrestrial phases of the sea turtle life cycle are confined to predictable regions of nesting beaches and areas immediately adjacent to known nest locations, camera trapping is a viable method to study turtle biology and threats during nesting, egg incubation and hatchling emergence; camera traps could also be used during in-water observational and monitoring projects. This paper demonstrates the current and potential application of camera traps in sea turtle research and conservation using examples from studies of freshwater and marine species of turtles, then reviews the technical aspects of deploying camera traps in terrestrial and marine environments.
APPLICATIONS OF CAMERA TRAPS ON NESTING BEACHES
Monitoring nesting sea turtles
There are no reports of triggered camera traps being deployed to monitor nesting beaches at this time. However, time-lapse beach photography projects using pre-programmed cameras with trap capabilities have been employed using two approaches. One is to position cameras at sites where much or all of the beach is visible, for example on a headland or sand cliff overlooking a cove, and to program the camera to take photos every morning and record fresh new tracks made by nesting turtles (S. Whiting, pers.comm). Another approach is to use the camera to take pictures at intervals to record how many days turtle tracks remain visible on the beach. When used for such a purpose, however, care is needed to ensure that representative beach microhabitats are monitored to account for the impact of different environmental conditions on track longevity. At select beaches at Diego Garcia and Nelson Islands in the British Indian Ocean Territory, time lapse photography is being used to inform beach monitoring frequency and improve estimates of nesting activities in the study locations (Esteban & Mortimer, 2018; Wood et al., 2019). Similar approaches could be used at other sites, depending on physical characteristics of the nesting beach and surrounds.
Identifying predators of nesting sea turtles, eggs and hatchlings
Camera traps can be used to complement findings from other methods of identifying predators, such as trackboards (Buzuleciu et al., 2016), scat analysis (Dawson et al., 2016) and physical observation (Doody et al., 2009; Erb & Wyneken, 2019; Unger & Santana, 2019). However, the potential for cameras to introduce bias and affect rates of predation by attracting or deterring some predator species from their normal behaviour (e.g., Richardson et al., 2009) should also be taken into consideration.
Animal predation on nesting turtles is rare, and throughout countries in the Indian Ocean and Southeast Asia it may be limited to isolated incidents involving saltwater crocodiles (Whiting & Whiting, 2011) and hyenas (Olendo et al., 2016). In the event that predation on nesting sea turtles by these or other species does increase, camera traps could give insight into predator behaviour. For example, Guilder et al. (2015) and Escobar-Lasso et al. (2016) determined the importance of sea turtles as a dietary item to jaguars (Panthera onca) in Costa Rica, as well as jaguar feeding and scavenging behaviour, using camera traps.
While predation on nesting sea turtles might be rare, depredation of nests is an ongoing concern in the same region (Ekanayake et al., 2002, 2010; Islam et al., 2002a,b; Shanker & Choudhury, 2006; Ficetola, 2008; Tripathy & Raiasekhar, 2009; Thi et al., 2011; Whiting & Whiting, 2011; Salleh et al., 2012; Ellepola et al., 2014; Mancini et al., 2015; Nasher & Al Jumaily, 2015; Olendo et al., 2016; Phillott et al., 2018a; Williams et al., 2019). To mitigate this threat, eggs are often relocated to a fenced area commonly known as a hatchery (Salleh et al., 2012; Abd. Mutalib & Fadzly, 2015; Phillott, 2018; Phillott & Kale, 2018, Phillott et al., 2018a,b; Howard et al., 2019). However, best practices in the collection, transport and incubation of eggs and handling of hatchlings have to be followed to reduce risks to embryo survival and hatchling fitness (reviewed by Phillott & Shanker, 2018), and require economic and human resources that might not be available to local conservationists. An alternative to reducing predation of eggs and hatchlings by relocating them to a hatchery is protecting nests in situ.
As the appropriate method for protecting sea turtle eggs in their original location on the nesting beach can depend on the species of predator (reviewed by Phillott (2020) in this issue of IOTN), tools to identify animals depredating nests are also required. Predators can potentially be identified from their tracks and patterns of digging into a nest (e.g., Gandu et al., 2013; Korein et al., 2019) but these signs might actually be created by scavenging behaviour or secondary predation after earlier predators have opened the nest (e.g., Barton & Roth, 2008).
Camera traps have proved effective in helping researchers identify species that pose a threat to sea turtle eggs. The use of camera traps to monitor artificial nests was first popular amongst ornithological studies and has been adopted to understand sea turtle predators. Maier et al. (2002) studied the depredation of artificial freshwater turtle nests using subterranean triggers to activate the shutter of a 35mm film camera. The triggers were installed within the nest chamber, connected by a trigger wire to a camera facing the entrance to the nest. It effectively captured images of predators such as racoons (Procyon lotor), striped skunks (Mephitis mephitis), gray foxes (Urocyon cinereoargenteus), and fishers (Martes pennanti). Motion-triggered camera traps have also been used in such studies; for example, artificial nests of alligator snapping (Macrochelys temminckii) turtles near the primary nesting area were monitored to identify and quantify the relative contribution to nest depredation by raccoons (Procyon lotor), armadillos (Dasypus novemcinctus), opossums (Didelphis virginiana), bobcats (Lynx rufus) and otters (Lontra canadensis) (Holcomb & Carr, 2013).
Camera traps have also been used to identify predators of hatchlings. Erb & Wyneken (2019) investigated the nest-to-surf mortality of loggerhead (Caretta caretta) sea turtle hatchlings by combining techniques of camera trapping, direct observation and hatchling track maps. The camera traps were placed behind nests and programmed to take an image every 5 to 10 seconds using the time lapse mode, recording predation events by ghost crabs (Ocypode quadrata), night herons (Nyctanassa violacea) and gray foxes. Bieber-Ham (2010) used camera traps to identify raccoons and opossums as predators and monitor their feeding on painted, plaster-cast turtles (Chrysemys picta) hatchling replicas. Giuliano et al. (2014) used camera traps to film and photograph nocturnal depredation on flatback (Natator depressus) sea turtle hatchlings by nankeen night herons (Nycticorax caledonicus) and black-necked storks (Ephippiorhynchus asiaticus), the first steps in assessing the impact of avifauna predation on turtle population dynamics.
Determining the behavioural patterns of predators
The behavioural patterns of predators, including foraging times and cues used to find nests, can also be studied using camera traps. Anyone planning this type of study might find the review of camera trapping for conservation behaviour research by Caravaggi et al. (2017) helpful to read.
The characteristics of loggerhead sea turtle nest visitations by lace monitors (Varanus varius) and yellow-spotted monitors (V. panoptes) were studied using camera traps (Lei & Booth, 2017a,b; Madden Hof et al., 2020). By capturing motion-triggered still images and metadata (time and date), the number and frequency of visits in different time frames within a day (Lei & Booth, 2017a) and temperature at with depredation occurred by each species were recorded (Madden Hof et al., 2020). Images also revealed that nest predation significantly increased after hatchlings emerged from the nest, suggesting visual and olfactory cues guided goannas to the nests (Lei & Booth, 2017b). Similarly, Buzuleciu et al. (2016) found that skunks and raccoons may rely on olfactory cues to locate diamondback terrapin eggs soon after oviposition then visual and/or tactile cues once the scent of freshly excavated soil had dissipated. Understanding when eggs are most vulnerable to predation and by which species can guide management decisions, such as the timing of nest protection strategies.
As flag markers may be used to indicate the position of sea turtle nests on the nesting beach, Tuberville & Burke (1994) investigated the potential attractive or repulsive effect of flags on predators of freshwater turtle eggs. A combination of camera traps, track boards and baited stations, to reduce the probability of bias, found that flagging neither attracts or repels nest predators, confirming that it can safely be used as a method of marking and identifying individual nests.
Assessing nest protection strategies
Methods of protecting nests from predators can be assessed using camera traps. Geller (2012) created fenced and unfenced areas at Ouachita map turtle (Graptemys ouachitensis) nesting sites which were baited and monitored using camera traps. The study found a lower predation rate of fenced nests in comparison to unfenced nests, and the camera traps revealed predator behaviour. The fencing comprised one strand of electrified wire and two strands of unelectrified wire, and racoons were observed testing the fences deliberately before receiving shocks. This indicates the potential for conditioning raccoons to avoid the nesting areas.
Eskew (2012) employed camera traps to test the efficiency of coyote (Canis latrans) trapping efforts in decreasing predation of loggerhead sea turtle eggs. Traps were deployed to monitor nests before and after rounds of coyote trapping and found a reduction in coyote depredation of nests. The researchers chose to use camera traps over physical observations of nests in order to avoid the potential disturbance caused by a human presence; the use of a camera trap also allows uninterrupted data collection while being less labour intensive.
Camera traps were also used to test the efficacy of different raccoon excluder devices on simulated diamondback terrapin nests (Buzuleciu et al., 2015), allowing researchers to understand why some cage features were more successful than others without the potential interference that may be associated with direct observations.
Surveillance for illegal take of eggs
Recently, camera traps have also emerged as a covert and relatively inexpensive surveillance tool, monitoring remote regions to detect the illegal take of sea turtle eggs without the need for regular patrols by rangers (Wearn & Glover-Kapfer, 2017). Camera traps on nesting beaches can identify those involved in the illegal take of eggs and collect evidence against them. The use of networked camera traps would also allow preventive measures to be taken when illegal take is detected. As camera traps used for this purpose are at a high risk of theft, equipment must be as covert as possible as well as located at a height that captures identifiable features of responsible persons (Wearn & Glover-Kapfer, 2017).
In-water studies of sea turtles
Due to the failure of sensors underwater, remote exploration of the aquatic realm using camera traps has been limited (Wearn & Glover-Kapfer, 2017). Instead, studies have used submerged underwater cameras to record continuous videos and hence gain an insight into the activities of marine organisms. The use of Baited Remote Underwater Video (BRUV) systems has allowed researchers to study marine species diversity (Osgood et al., 2019) and behaviour (Bond et al., 2012) by recording the organisms which were attracted to the bait. Favaro et al. (2012) developed a modified version of this, known as the TrapCam, which was also effective in obtaining in situ observations of marine animals at depths up to 100m and could be modified to understand sea turtle interactions with deep-water fishing gear.
Recent innovations in camera trap systems have, however, proved promising in capturing remotely triggered images of underwater phenomena. An underwater stereo camera such as the TrigCam can be programmed with an algorithm to record images whenever a predefined change in pixels is detected. The technology allows researchers to tailor their study to target wildlife of a specific size (Williams et al., 2014), and may be useful in studies of the in-water behaviour of animals such as sea turtles.
TECHNICAL ASPECTS OF CAMERA TRAPS
Camera and trigger features
When choosing a camera trap, care must be taken to ensure the features of the trap model are compatible with the specific nature of the study. Newey et al. (2015) provides a user’s perspective on the deployment, operation and data management when using more affordable ‘recreational’ models in comparison to expensive ‘professional’ models which could help novices in camera trap usage in their decision about which model to purchase. Features of the camera and trap trigger as described below should also be considered.
As the quality of data captured is dependent on the effectiveness of the trigger system, the trade-off between availability, affordability, and suitability of camera traps with desired features must be considered. The target animal for the study will also help determine whether a camera trap should employ an indirect or a direct trigger system.
An indirect trigger system- which senses the presence of the animal in the vicinity of the camera trap via movement or heat signatures- is ideal when the target animal is large and endothermic, like feral pigs or dogs. Of these, a passive infrared (PIR) trigger is the most suitable considering the large body mass and heat signal of many predators, and most commercially available camera traps have PIR triggers as the market is driven primarily by its demand for deer scouting and hunting. These trigger systems are also more concealable and less startling (Wearn & Glover-Kapfer, 2017). An emerging technology for underwater camera traps also employs an indirect trigger system. It employs a software algorithm to trigger recording when an animal appears by detecting a change in pixels. The algorithm may be tailored to capture animals of a particular size and, hence, reduce the possibility of unwanted shots (Williams et al., 2014).
Smaller mammals and reptiles may not have a heat signal strong enough to trigger a PIR (Eskew 2012; Hobbs & Brehme, 2017) and might require the use of direct triggers. These include mechanical triggers which can be installed within the nest chamber such that the camera trap is triggered only when directly pushed or pulled by the animal during depredation or when the nest is otherwise disturbed. Options include tilt switches (as in Maier et al., 2002), trip wires, pull wires, pressure plates, and active IR (AIR) triggers (Tuberville & Burke, 1994). The most modern direct trigger, AIR sensors require the animal to move through a predictable path such that it disturbs an IR beam between a transmitter and receiver. However, in addition to being less commercially available, these are also more visible and intrusive and many studies have found PIR camera traps to be effective, even in the cases of reptiles like monitor lizards (Beukeboom, 2015; Lei & Booth, 2017a,b; Madden Hof et al., 2020) and small mammals like rats (Gronwald et al., 2019). Many camera traps have the option of increasing PIR sensitivity, which would increase the likelihood of capturing ectotherms (Wearn & Glover-Kapfer, 2017).
In addition to motion-triggered image capture, the time lapse feature of camera traps can also be used to record potential predators in the nest environment at regular intervals (Geller, 2012; Beukeboom, 2015; Erb & Wyneken, 2019). This setting would ensure that images will be taken even if the trigger does not detect the presence of a predator; however, it produces a huge volume of images for analysis.
It is also important to consider the detection zone and field of view of the camera. These are integral to the study as the detection zone is the range within which movement must occur to trigger the camera and the field of view of the camera is the area that will fall within the frame of the image. If the study is investigating nest predation, a detection zone that is narrower than the field of view would be appropriate as it would prevent accidental triggers and empty shots, ensuring all the shots taken include the target i.e. the predator at the nest (Trolliet et al., 2014). However, if the study intends to include nesting behaviour or hatchling predation, a wide detection zone would be important as the target activity may occur beyond the immediate nest. The trigger speed of the camera and the relay time (delay between each shot) should also be factored in when choosing a camera trap. A fast trigger speed can compensate for a narrow detection zone (Rovero et al., 2013).
The camera must also have a battery capacity sufficient for it to be deployed for potentially extended periods of time. This is dependent on the number and type of batteries used as well as the energy efficiency of the camera. Based on the battery life as well as the capacity of the memory card, the camera trap may have to be regularly visited and items replaced. In cases of remote camera trapping locations, networked camera traps may be deployed which can send almost real-time data to the researcher. Though these are expensive, they also allow the data to be regularly backed up such that in case of any damage or theft, the data is not lost (Wearn & Glover-Kapfer, 2017).
Cameras deployed at night on nesting beaches should have the feature of IR flash. While white flashes can produce coloured images as opposed to the monochrome images from IR flashes, the former may deter predators and introduce bias while IR flashes are invisible to most animals. A visible white flash could also attract human attention to the camera trap and increase the risk of theft (Wearn & Glover-Kapfer, 2017), or temporarily misorient hatchlings. In specific cases where the red glow of IR frightens predators, such as coyotes (Eskew, 2012), no-glow (black) IR cameras can be deployed which emit a wavelength that is almost undetectable (Wearn & Glover-Kapfer, 2017).
If images are only to be used for detection and identification of predators, lower quality images would suffice but if the collected images may be used for campaigns or conservation awareness programs then higher resolution images will be required. In cases where individual predators need to be identified, a higher resolution may be necessary to discern unique features. Additionally, if the study requires insights into behavioral aspects, the video feature available in many camera traps would be helpful (Giuliano et al., 2014; Gronwald et al., 2019).
Camera mount and position
Camera traps in a beach environment may be mounted on a tripod, wooden stakes, metal t-posts (Urbanek & Sutton, 2019) or PVC pipes (Eskew, 2012). The mount structure must be sturdy enough to carry the weight of the camera trap and ensure it does not move. If there is a nearby tree or pole, these could be ideal mounts. One of the biggest challenges when using camera traps is reducing the possibility of theft. To prevent theft, the camera traps can be placed within commercially available housing cases that can only be opened with a special key. These housings also protect the cameras from damage by animals. Most anti-theft cases are intended to be attached to trees or poles that cannot be removed. However, these are often difficult to find in the sea turtle nesting environment. Deploying the camera traps only at night may reduce the risk of theft (Shipman, 2019); however, this schedule provides limited data and requires regular installment and removal.
Camera traps are designed to be robust and weatherproof, however most of them are not built for a beach environment. It may be necessary to regularly clean the camera traps of sand. To prevent damage due to humidity, desiccation packs can be placed in the camera trap or within its casing (King, 2016). The casing should have seals that prevent entry of rain, dust, sand and insects etc.
Depending on the target predator, the camera trap must be installed at an appropriate height to ensure that the animal will fall within the detection range as well as the field of view of the camera. They can be tilted slightly downwards to avoid triggers due to sunrise and sunset. Additionally, unless required, the camera trap detection range should not include the ocean as this may lead to waves and tidal movements acting as triggers (King, 2016). This is important to make sure the memory card is not exhausted due to repetitive empty shots.
Camera trapping surveys often produce large amounts of data (still images or video) that are cumbersome to analyse. Using a PIR that senses movement can result in a high proportion of images that are empty shots due to detection of non-animal movement (false triggers) such as the movement of foliage. Many studies sort the images manually; however, emerging camera trap data analysis software that weigh pixel variations against the background to filter out images void of animals can be used to streamline the process of analysis (see Hobbs & Brehme, 2017; Wearn & Glover-Kapfer, 2017).
ETHICAL CONSIDERATIONS WHEN USING CAMERA TRAPS
In environments where there is a high degree of human activity, projects must consider the privacy of local residents. Steps should be taken to avoid non-consensual monitoring and surveillance. For example, local communities should be informed about the purpose, general location, and operation of cameras before traps are installed. Projects can also implement community-based conservation, compensating locals for regularly checking the camera traps, retrieving memory cards, and replacing batteries. Additionally, there must be a plan to respectfully delete any accidental images of people.
Abd. Mutalib, A.H. & N. Fadzly. 2015. Assessing hatchery management as a conservation tool for sea turtles: A case study in Setiu, Terengganu. Ocean and Coastal Management 113: 47-53.
Barton, B.T. & J.D. Roth. 2008. Implications of intraguild protection for sea turtle nest protection. Biological Conservation 141: 2139-2145.
Beukeboom, R. 2015. Threats to the early life stages of the Mary River turtle (Elusor macrurus) from Queensland, Australia. Master’s thesis. Utrecht University, Utrecht, Netherlands.
Bieber-Ham, L.M. 2010. Population and nesting ecology of painted turtles (Chrysemys picta) in Pennsylvania. Honours thesis. Dickinson College, Carlisle, United States.
Bond, M.E., E.A. Babcock, E.K. Pikitch, D.L. Abercrombie, N.F. Lamb & D.D. Chapman. 2012. Reef sharks exhibit site-fidelity and higher relative abundance in marine reserves on the Mesoamerican Barrier Reef. PLoS ONE 7: e32983. DOI: 10.1371/journal.pone.0032983.
Buzuleciu, S.A., M.E. Spencer & S.L. Parker. 2015. Predator exclusion cage for turtle nests: A novel design. Chelonian Conservation and Biology 14: 196-201.
Buzuleciu, S.A., D.P. Crane & S.L. Parker. 2016. Scent of disinterred soil as an olfactory cue used by raccoons to locate nests of diamond-backed terrapins. Herpetological Conservation and Biology 11: 539-551.
Caravaggi, A., P.B. Banks, A.C. Burton, C.M.V. Finlay, P.M. Haswell, M.W. Hayward, M.J. Rowcliffe, et al. 2017. A review of camera trapping for conservation behaviour research. Remote Sensing in Ecology and Conservation 3: 109-122.
Dawson, S.J., H.M. Crawford, R.M. Huston, P.J. Adams & P.A. Fleming. 2016. How to catch red foxes red handed: Identifying predation of freshwater turtles and nests. Wildlife Research 43: 615-622.
Doody, J.S., M. Pauza, B. Stewart & C. Camacho. 2009. Nesting behavior of the pig-nosed turtle, Carettochelys insculpta, in Australia. Chelonian Conservation and Biology 8: 185-191.
Ekanayake, E.M.L., K.B. Ranawana T. Kapurusinghe, M.G.C. Premakumara & M.M. Saman. 2002. Marine turtle conservation in Rekawa turtle rookery in southern Sri Lanka. Ceylon Journal of Science (Biological Science) 30: 79-88.
Ekanayake, E.M.L., R.S. Rajakaruna, T. Kapurusinghe, M.M. Saman, D.S. Rathnakumara, P. Samaraweera & K.B. Ranawana. 2010. Nesting behaviour of the green turtle at Kosgoda rookery, Sri Lanka. Ceylon Journal of Science (Biological Science) 39: 109-120.
Ellepola, G., S. Harischandra & M.G.G. Dhanushka. 2014. In situ turtle nest protection program in Panama-Okanda coastal stretch in the east coast of Sri Lanka: A successful conservation activity with community participation. Journal of the Department of Wildlife Conservation 2014-2: 163-170.
Erb, V. & J. Wyneken. 2019. Nest-to-surf mortality of loggerhead sea turtle (Caretta caretta) hatchlings on Florida’s east coast. Frontiers in Marine Science 6: 1-10.
Escobar-Lasso, S., M. Gil-Fernández, H. Herrera, L.G. Fonseca, E. Carrillo-Jiménez, J. Sáenz & G. Wong. 2016. Scavenging on sea turtle carcasses by multiple jaguars in Northwestern Costa Rica. Therya 7: 231-239.
Eskew, T. 2012. Best management practices for reducing coyote depredation on loggerhead sea turtles in South Carolina. Master’s thesis. Clemson University, Clemson, United States.
Esteban, N. & J.A. Mortimer. 2018. Sea turtle conservation research Diego Garcia, BIOT. 21 November – 11 December 2018. Expedition Report to the Foreign and Commonwealth Office. https://biot.gov.io/wp-content/uploads/2018_Nov_BIOT_turtle_expedition_report.pdf. Accessed on May 01, 2020.
Favaro, B., C. Lichota, I.M. Côté & S.D. Duff. 2012. TrapCam: An inexpensive camera system for studying deep-water animals: Inexpensive tool for deep-water observations. Methods in Ecology and Evolution 3: 39-46.
Ficetola, G.F. 2008. Impacts of human activities and predators on the nest success of the hawksbill turtle, Eretmochelys imbricata, in the Arabian Gulf. Chelonian Conservation and Biology 7: 255-257.
Gandu, M.D., M. López-Mendiaharsu, D.W. Goldberg, G.G. Lopez & F. Tognin. 2013. Predation of sea turtle nests by armadillos in the northern coast of Bahia, Brazil. Marine Turtle Newsletter 139: 12-13.
Geller, G. 2012. Reducing predation of freshwater turtle nests with a simple electric fence. Herpetological Review 43: 398-403.
Giuliano, C., M. Guinea, D. Wright & A. Raith. 2014. Nocturnal avian predation of flatback sea turtle hatchlings, Natator depressus, on Bare Sand Island, NT. In: Proceedings of the Second Australian and Second Western Australian Marine Turtle Symposia Perth 25-27 August 2014 (comps. Whiting, S.D. & A. Tucker). Science Division, Department of Parks and Wildlife: Perth, Western Australia. Pp 27-29.
Gronwald, M., Q. Genet & M. Touron. 2019. Predation on green sea turtle, Chelonia mydas, hatchlings by invasive rats. Pacific Conservation Biology 25: 423-424.
Guilder, J., B. Barca, S. Arroyo-Arce, R. Gramajo & R. Salom-Pérez. 2015. Jaguars (Panthera onca) increase kill utilization rates and share prey in response to seasonal fluctuations in nesting green turtle (Chelonia mydas mydas) abundance in Tortuguero National Park, Costa Rica. Mammalian Biology 80: 65-72.
Hobbs, M.T. & C.S. Brehme. 2017. An improved camera trap for amphibians, reptiles, small mammals, and large invertebrates. PLoS ONE 12: e0185026. DOI: 10.1371/journal.pone.0185026.
Holcomb, S.R. & J.L. Carr. 2013. Mammalian depredation of artificial alligator snapping turtle (Macrochelys temminckii) nests in north Louisiana. Southeastern Naturalist 12: 478-491.
Howard, R., K. Myint, P. Maw, P. Zaw & M. Tiwari. 2019. Improving marine turtle conservation in Myanmar. Oryx 53: 409.
Islam, M.Z. 2002a. Marine turtle nesting at St. Martin’s Island, Bangladesh. Marine Turtle Newsletter 96: 19-21.
Islam, M.Z. 2002b. Threats to sea turtles in St Martin’s Island, Bangladesh. Kachhapa 6: 8-12.
King, J. 2016. Flatbacks and foxes: Using cameras to capture sea turtle nest predation. Honours thesis. Murdoch University, Murdoch, Australia.
Korein, E., A. Caballol, P. Lovell, L. Exley, C.P. Marin, J, Carillo, G. Bond, et al. 2019. Using bamboo nest covers to prevent predation on sea turtle eggs. Marine Turtle Newsletter 156: 33-37.
Kucera, T.E. & R.H. Barrett. 2010. A history of camera trapping. In: Camera Traps in Animal Ecology (eds. O’Connell, A.F., J.D. Nichols & K.U. Karanth). Pp. 9-26. Springer: Tokyo, Japan.
Lei, J. & D.T. Booth. 2017a. Who are the important predators of sea turtle nests at Wreck Rock beach? PeerJ – the Journal of Life and Environmental Sciences 5: e3515. DOI: 10.7717/peerj.3515.
Lei, J. & D.T. Booth. 2017b. How do goannas find sea turtle nests? Austral Ecology 43: 309-315.
Madden Hof, C.A., G. Shuster, N. McLachlan, B. McLachlan, S. Giudice, C. Limpus & T. Eguchi. 2020. Protecting nests of the critically endangered South Pacific loggerhead turtle Caretta caretta from goanna Varanus spp. predation. Oryx 54: 323-331.
Maier, T.J., M.N. Marchand, R.M. Degraaf & J.A. Litvaitis. 2002. A subterranean camera trigger for identifying predators excavating turtle nests. Herpetological Review 22: 284-287.
Mancini, A., I. Elsadek I. & M.A.N. El-Alwany. 2015. Marine turtles of the Red Sea. In: The Red Sea (eds. Rasul, N.M.A. & I.C.F. Stewart). Pp. 551-565. Springer-Verlag: Berlin, Germany.
Nasher, A.K. & M. Al Jumaily. 2015. Steps to building long term sea turtle conservation program in Yemen. Wildlife Middle East 7: 1-2.
Newey, S., P. Davidson, S. Nazir, G. Fairhurst, F. Verdicchio, R.J. Irvine & R. van der Wal. 2015. Limitations of recreational camera traps for wildlife management and conservation research: A practitioner’s perspective. Ambio 44 (Suppl. 4): S624-S635.
Olendo, M., C.N. Munga, G.M. Okemwa, H. Ong’anda, L. Mulupi, L. Mwasi & H. Mohamed. 2016. Current status of sea turtle protection in Lamu Seascape, Kenya: Trends in nesting, nest predation and stranding levels. Western Indian Ocean Journal of Marine Science 15: 1-13.
Osgood, G.J., M.E. McCord, & J.K. Baum. 2019. Using baited remote underwater videos (BRUVs) to characterize chondrichthyan communities in a global biodiversity hotspot. PLoS ONE 14: e0225859. DOI: 10.1371/journal.pone.0225859.
Phillott, A.D. 2018. A review of sea turtle hatcheries in Bangladesh. Indian Ocean Turtle Newsletter 27: 29-30.
Phillott, A.D. 2020. Protection of in situ turtle nests from depredation. Indian Ocean Turtle Newsletter 32: 31-40
Phillott, A.D. & N. Kale. 2018. The use of sea turtle hatcheries as an ex situ conservation strategy in India. Indian Ocean Turtle Newsletter 27: 18-29.
Phillott, A.D. & K. Shanker. 2018. Best practices in sea turtle hatchery management for South Asia. Indian Ocean Turtle Newsletter 27: 31-34.
Phillott, A.D., F. Firdous & U. Shahid. 2018a. Sea turtle hatchery practices and hatchling production in Karachi, Pakistan, from 1979-1997. Indian Ocean Turtle Newsletter 27: 2-8.
Phillott, A.D., S. Hewapathiranage & R. Rajakaruna. 2018b. Unregulated sea turtle hatcheries and management practices an ongoing concern in Sri Lanka. Indian Ocean Turtle Newsletter 27: 8-17.
Richardson, T.W., T. Gardali & S.H. Jenkins. 2009. Review and meta-analysis of camera effects on avian nest success. Journal of Wildlife Management 73: 287-293.
Rovero, F., F. Zimmermann, D. Berzi, & P. Meek. 2013. Which camera trap type and how many do I need? A review of camera features and study designs for a range of wildlife research applications. Hystrix, the Italian Journal of Mammalogy 24: 148-156.
Salleh, S.M., M. Yobe & S.A.M. Sah. 2012. The distribution and conservation status of green Turtles (Chelonia mydas) and olive ridley turtles (Lepidochelys olivacea) on Pulau Pinang beaches (Malaysia), 1995-2009. Tropical Life Sciences Research 23: 63-76.
Shanker, K. & B.C. Choudhury. 2006. Marine Turtles of the Indian Subcontinent. Universities Press: Hyderabad. India.
Shipman, A.M. 2019. Investigation of nest predation as a cause of turtle population declines on the Sequoyah National Wildlife Refuge, Oklahoma. Masters thesis. Rochester Institute of Technology, Rochester, USA.
Thi, K., H.H. Kyi, M.M. Kyaw & T.S. Myint. 2011. Comparative study on hatching rate and incubation period of sea turtles from Kadongalay Island and Thameehla Island in Ayeyrawady region and Oyster Island in Rakhine State. Universities Research Journal 4: 11-23.
Tripathy, B. & P.S. Raiasekhar. 2009. Natural and anthropogenic threats to olive ridley sea turtles (Lepidochelys olivacea) at the Rushikulya rookery of Orissa coast, India. Indian Journal of Marine Sciences 38: 439-443.
Trolliet, F., M.-C. Huynen, C. Vermeulen & A. Hambuckers. 2014. Use of camera traps for wildlife studies. A review. Biotechnology, Agronomy, Society and Environment 18: 446-454.
Tuberville, T.D. & V.J. Burke. 1994. Do flag markers attract turtle nest predators? Journal of Herpetology 28: 514-516.
Unger, S.D. & A. Santana. 2019. Turtles and trail cameras: Non-invasive monitoring using artificial platforms. Basic and Applied Herpetology 33: 93-100.
Urbanek, R.E., & H. Sutton. 2019. Mesocarnivore presence and behavior on a barrier island during sea turtle nesting season. Ocean & Coastal Management 178: Article 104850. DOI: 10.1016/j.ocecoaman.2019.104850.
Wearn, O.R. & P. Glover-Kapfer. 2017. Camera-trapping for conservation: A guide to best-practices. Technical report to WWF-UK. https://www.wwf.org.uk/sites/default/files/2019-04/CameraTraps-WWF-guidelines.pdf. Accessed on May 01, 2020.
Whiting, S.D. & A.U. Whiting. 2011. Predation by the saltwater crocodile (Crocodylus porosus) on sea turtle adults, eggs, and hatchlings. Chelonian Conservation and Biology 10: 198-205.
Williams, J.L., S.J. Pierce, M. Hamann & M.M.P.B. Fuentes. 2019. Using expert opinion to identify and determine the relative impact of threats to sea turtles in Mozambique. Aquatic Conservation: Marine and Freshwater Ecosystems 29: 1936-1948.
Williams, K., A. De Robertis, Z. Berkowitz, C. Rooper, & R. Towler. 2014. An underwater stereo-camera trap. Methods in Oceanography 11: 1-12.
Wood, H., N. Esteban, J.-O. Laloe & M. Nicoll. 2019. Seabird and Sea Turtle Ecology in BIOT: June – July 2019 Research Expedition Report. https://biot.gov.io/science/2019-science-expeditions/7-june-seabirds-and-turtles-exped/. Accessed on May 01, 2020.
OTHER USEFUL RESOURCES