Seeing Wildlife – How Trail Cameras Can Help Your Conservation Efforts

KIM BANNISTER (AGBET Trustee and member of the Oruawharo Medlands Ecovision Group)

Have you discovered the joy of the trail camera? There’s never been a better time to dive in and really see what visitors you have in your back yard, be that small or large. Trail cameras are remarkably cheap fixed cameras which take still or moving images when triggered by detected movement. They use infrared lighting to capture monochrome images at night. The images are usually recorded on a memory card, resulting in the need to take the card out of the camera and transfer the images to a computer or phone. This sounds tedious but it’s often intriguing and even thrilling! Some camera types use WiFi or mobile connections to make some of this easier.

Conservation work in Aotearoa is heavily dependent on the use of trail cameras to monitor wildlife. This article draws on the author’s experience and aims to give some guidance about how and where they can be used, and to outline some of the remarkable technical innovations being trialled in Aotearoa, including the use of AI to process images captured with a thermal imaging camera.

Basic trail cameras using disposable batteries and memory card storage can be bought very cheaply from online stores such as Amazon. There is some luck involved since it’s hard to predict from online reviews how well the camera will perform, for example on detecting movement or resisting the elements. However, the investment is small. Local retailers offer a range of models, including those from well regarded brands such as Browning, at a higher price point. Wifi enabled cameras allow you to preview and download images from your camera using a phone app, which may be more convenient but takes much longer than direct transfer from a card. Cameras with a mobile connection can notify you when the camera is triggered, just like a security camera. If you’re in the market for a camera with a mobile network connection, you’re best to buy from a local provider to ensure compatibility with NZ mobile networks. Battery consumption concerns many of us - most of the manufacturers advise against using rechargeable 1.2V batteries, although it is possible to buy 1.5V rechargeable lithium batteries which seem to work well (although they are expensive). Some cameras have inbuilt rechargeable batteries, or can be powered by a solar panel. International websites(1) can provide a wealth of information and reviews of different cameras.

Cameras use either SD or microSD memory cards. My experience with the latter is that they are more difficult to handle in or out of a camera in the field, and annoyingly easy to drop or lose in the mud or long grass. The cards are cheap these days, so it’s worthwhile having twice as many as the number of cameras. This means you can swap in a new card when taking one out of the camera. Although images can be viewed on the tiny camera screen, it’s really only practicable to take the memory card(s) back to base and load the images onto a computer. You might find hundreds of images and/or videos to review, most triggered by something you’re not interested in. But as you flick through the pictures, just like panning for gold, you are eventually likely to find something of interest, whether it is friend or foe. Good housekeeping of your image library is needed to keep the pictures you want and discard the duds. The Miramar Peninsula predator control project reports that they reviewed 290,000 images collected from hundreds of cameras during 2021! The Perth River project team in South Westland has analysed over 2.5 million images from 142 trail cameras over 3 years. They have found that incidental images of bird species have enabled them to track bird numbers over the course of the project. Obviously this has involved an enormous amount of time maintaining cameras and collecting cards from very remote locations, not to mention the time on the computer analysing the images and cataloguing the data. Use of AI and thermal cameras is now vastly simplifying their work (see later section)(2).

Where might a trail camera be useful? A camera or two near a trap or bait station will enhance your understanding of your quarry enormously. You may well be surprised and annoyed to find your target animal visiting but ignoring the trap filled with your most delicious and irresistible bait. Possibly even dancing gleefully on the top of your trap! Or, you might find a video of a pāteke family with 6 chicks in tow, far from the nearest waterway. Ten months later, presumably the same family shows up again at the same spot - grown up, but missing a few siblings. Our monitoring of the pig trap (an essential part of the exercise) has captured some stunning images of visiting kahu, scooping up bits of rabbit. Perhaps (like me) you’ll be horrified to see how many cats (including the neighbours’) wander by. Pigs, pigs, and more pigs! Proof of the ineffectiveness of a five wire fence to contain a pig!

Your cameras can be strapped to a tree or a stake, or attached to an adjustable mount which can be screwed to a stake or screwed into a tree. Try to keep the camera as close as possible to the likely path of your quarry - although your camera may claim to detect movement 30m away, you are far more likely to get good results (especially for small animals) if you are much closer than that, for example 5m or even less, and close to ground level. More than one camera at an important location is useful, because passive infrared (PIR) motion sensors are imperfect and cameras do not always trigger, or trigger too late - so an additional camera monitoring from a different angle will often increase your chance of capturing the vital data. You will soon learn the factors likely to cause false triggers, for example moving vegetation or sunlight patterns. These can be minimised by camera positioning - for example by pointing south to avoid sunlight on the sensor, and by removing moving vegetation near the camera. The PIR motion sensors detect changes in infrared radiation, hopefully caused by a warm-blooded animal. Obviously, reptiles are not going to show up! Presumably this explains why my resident chevron skinks have not yet been seen on camera.

Readers will be familiar with the Tū Mai Taonga project on Aotea/Great Barrier Island, which aims to protect and restore native species and ecosystems through feral cat removal and intensified rat control, initially in the Aotea Conservation Park and Te Paparahi northern area. Trail cameras form an important part of this project, and 100 cameras have been deployed so far in some very remote parts of the island. The project team is working through the logistic issues associated with retrieving and processing SD cards, and minimising false triggers by adjusting camera settings and avoiding vegetation movement. Operations Manager, Chris Giblin, tells me that the team has found that rechargeable 1.2V batteries don’t perform well and need to be swapped out much more frequently than disposable batteries. A good solution to this conundrum is yet to be found! The cameras are recording visits by cats, rats, birds, pigs…all data is recorded in their sophisticated purpose-built geographic information system (GIS) for future analysis.

The landscape scale projects such as TMT, Miramar Peninsula and Perth River Valley examples show how larger scale projects can quickly gobble up enormous amounts of operator time maintaining cameras and reviewing trail camera images. The Cacophony Project (with support from PredatorFree2050) has been developing technology using thermal imaging cameras which produce videos based on IR detection. Although these images are lower resolution than those from a conventional camera, they are more specific for warm-blooded animals. This makes it easier for AI algorithms to accurately identify particular animal species to vastly simplify identification and counting of target animals. Remote large-scale projects such as the Predator Free South Westland project are already leveraging this technology, using AI interpretation of thermal camera images to produce reports from unattended remote sites which are uploaded to base at intervals. Cacophony offer a thermal imaging camera system for sale at a price which is becoming more affordable, although it will be of less interest to individuals like you and me than it will be to organisations using large scale predator control techniques(3).

The next chapter in the AI/thermal camera story is the development of automated kill traps which only activate when a target species is clearly identified, and not when some other smart character (such as a kea) is snooping around. This also enables a more open trap design, increasing the chance of a shy creature venturing in. Although this approach is spookily similar to talk of military weapons using AI to autonomously target humans, it offers a real path forward in the Predator Free 2050 vision. Whether this approach will be helpful for the future of predator control on Aotea (in the absence of possums and mustelids) remains to be seen. However, in the meantime there’s no reason why you shouldn’t get yourself some conventional trailcams to better your understanding of what is happening in the natural world around you. Have fun!

References

1. https://www.trailcampro.com

2. Native Birds Continue to Recover in the Perth River Valley — Zero Invasive Predators (ZIP) https://zip.org.nz/updates/2022/3/native-birds-continue-to-recover-in-the-perth-river-valley

3. Pre-order the DOC AI Cam: low cost low power thermal camera with machi – 2040