Motion‐activated cameras (“camera traps”) are increasingly used in ecological and management studies for remotely observing wildlife and are amongst the most powerful tools for wildlife research. However, studies involving camera traps result in millions of images that need to be analysed, typically by visually observing each image, in order to extract data that can be used in ecological analyses. We trained machine learning models using convolutional neural networks with the ResNet‐18 architecture and 3,367,383 images to automatically classify wildlife species from camera trap images obtained from five states across the United States. We tested our model on an independent subset of images not seen during training from the United States and on an out‐of‐sample (or “out‐of‐distribution” in the machine learning literature) dataset of ungulate images from Canada. We also tested the ability of our model to distinguish empty images from those with animals in another out‐of‐sample dataset from Tanzania, containing a faunal community that was novel to the model. The trained model classified approximately 2,000 images per minute on a laptop computer with 16 gigabytes of RAM. The trained model achieved 98% accuracy at identifying species in the United States, the highest accuracy of such a model to date. Out‐of‐sample validation from Canada achieved 82% accuracy and correctly identified 94% of images containing an animal in the dataset from Tanzania. We provide an r package (Machine Learning for Wildlife Image Classification) that allows the users to (a) use the trained model presented here and (b) train their own model using classified images of wildlife from their studies. The use of machine learning to rapidly and accurately classify wildlife in camera trap images can facilitate non‐invasive sampling designs in ecological studies by reducing the burden of manually analysing images. Our r package makes these methods accessible to ecologists.

Summary1. The eruption of invasive wild pigs (IWPs) Sus scrofa throughout the world exemplifies the need to understand the influences of exotic and nonnative species expansions. In particular, the continental USA is precariously threatened by a rapid expansion of IWPs, and a better understanding of the rate and process of spread can inform strategies that will limit the expansion. 2. We developed a spatially and temporally dynamic model to examine three decades of IWP expansion, and predict the spread of IWPs throughout the continental USA, relative to where IWPs previously inhabited. We used the model to predict where IWPs are likely to invade next. 3. The average rate of northward expansion increased from 6Á5 to 12Á6 km per year, suggesting most counties in the continental USA could be inhabited within the next 3-5 decades. The spread of IWPs was primarily associated with expansion into areas with similar environmental characteristics as their previous range, with the exception of spreading into colder regions. We identified that climate change may assist spread into northern regions by generating milder winters with less snow. Otherwise, the spread of IWPs was not dependent on agriculture, precipitation or biodiversity at the county level. The model correctly predicted 86% of counties that were invaded during 2012, and those predictions indicate that large portions of the USA are in immediate danger of invasion. 4. Synthesis and applications. Anti-invasion efforts should focus along the boundaries of current occupied range to stop natural expansion, and anti-invasion policies should focus on stopping anthropogenic transport and release of invasive wild pigs. Our results demonstrate the utility of a spatio-temporal examination to inform strategies for limiting the spread of invasive wild pigs.

All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. from Canada. We also tested the ability of our model to distinguish empty images from those 56 with animals in another out-of-sample dataset from Tanzania, containing a faunal community 57 that was novel to the model. (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/346809 doi: bioRxiv preprint first posted online Jun. 13, 2018; 3 4. The use of machine learning to rapidly and accurately classify wildlife in camera trap images 66 can facilitate non-invasive sampling designs in ecological studies by reducing the burden of 67 manually analyzing images. We present an R package making these methods accessible to 68 ecologists. We discuss the implications of this technology for ecology and considerations that 69 should be addressed in future implementations of these methods. 70

Populations of invasive wild pigs (Sus scrofa) are increasing in many regions of the world, in particular the United States and Australia. Invasive wild pigs cause extensive damage to ecological resources and agriculture. Development and registration of a safe and humane toxic bait offers a practical and cost‐effective tool to control invasive species. Currently, no toxicants are approved for use on invasive wild pigs in the United States and those approved in Australia are under scrutiny because of concerns regarding humaneness and effects on nontarget species. We tested a newly formulated bait containing the micro‐encapsulated active ingredient, sodium nitrite (HOGGONE®; Animal Control Technologies Australia P/L, Victoria, Australia), that is considered humane and safer for nontarget species because it does not bioaccumulate. We examined palatability, lethality, and stability of the bait (i.e., fresh compared to 8‐month‐old bait) on groups of captive invasive wild pigs. We found HOGGONE® was a preferred food item, averaging 475 g of toxic bait consumed per animal during the first night offered. Consumption of HOGGONE® resulted in 95% mortality (53 of 56) in the treatment groups across 2 treatment nights. Most mortalities (98%) occurred during the first night the toxic bait was offered. Camera evidence suggested that deaths occurred within 3 hr post‐offering. The toxic bait was stable and effective up to 8 months post manufacture. Our results support current applications to register HOGGONE® for reducing damage from invasive wild pigs in the United States and Australia. Further research is required to evaluate HOGGONE® on free‐ranging invasive wild pigs using bait stations that exclude nontarget species. © 2017 The Wildlife Society.

Invasive feral swine (Sus scrofa) cause extensive damage to agricultural and wildlife resources throughout the United States. Development of sodium nitrite as a new, orally delivered toxicant is underway to provide an additional tool to curtail growth and expansion of feral swine populations. A micro-encapsulation coating around sodium nitrite is used to minimize detection by feral swine and maximize stability for the reactive molecule. To maximize uptake of this toxicant by feral swine, development a bait matrix is needed to 1) protect the micro-encapsulation coating so that sodium nitrite remains undetectable to feral swine, 2) achieve a high degree of acceptance by feral swine, and 3) be minimally appealing to non-target species. With these purposes, a field evaluation at 88 sites in south-central Texas was conducted using remote cameras to evaluate preferences by feral swine for several oil-based bait matrices including uncolored peanut paste, black-colored peanut paste, and peanut-based slurry mixed onto whole-kernel corn. These placebo baits were compared to a reference food, whole-kernel corn, known to be readily taken by feral swine (i.e., control). The amount of bait consumed by feral swine was also estimated using remote cameras and grid boards at 5 additional sites. On initial exposure, feral swine showed reduced visitations to the uncolored peanut paste and peanut slurry treatments. This reduced visitation subsided by the end of the treatment period, suggesting that feral swine needed time to accept these bait types. The black-colored peanut paste was visited equally to the control throughout the study, and enough of this matrix was consumed to deliver lethal doses of micro-encapsulated sodium nitrite to most feral swine during 1–2 feeding events. None of the treatment matrices reduced visitations by nontarget species, but feral swine dominated visitations for all matrices. It was concluded that black-colored peanut paste achieved satisfactory preference and consumption by feral swine, and no discernable preference by non-target species, compared to the other treatments.

These results demonstrate the potential for toxic bait to be an effective tool for reducing populations of wild pigs with minimal risks to non-target species, if optimized delivery procedures are followed. © 2018 Society of Chemical Industry.

Populations of invasive wild pigs (Sus scrofa; hereafter, wild pigs) are expanding, requiring costeffective tools for control, and disease prevention, such as toxic or vaccine baits. Specifically, development of a novel and humane toxicant is underway for control of wild pigs in the United States and Australia. A speciesspecific bait station for delivering the toxic bait must be used to protect nontarget animals. Further, a bait station must be designed to maximize feeding by wild pigs by accommodating their group-feeding behaviors. We sought to develop a bait station that delivered bait to the maximum proportion of wild pigs and excluded the most ubiquitous nontarget species, specifically white-tailed deer (Odocoileus virginianus) and raccoons (Procyon lotor). We used direct observations and cameras during 2015 to evaluate wild pig feeding behavior and nontarget access for various sizes, arrangements, and construction materials of prototype bait stations in pen and field settings in Texas, USA. We found that a bait station constructed of 2 back-to-back troughs, 1.1 m in length, without a divider was sufficient for feeding the largest proportion of wild pigs in pens. Using this design of bait station at 30 field sites, we found that wild pigs fed more frequently from plastic than metal bait stations, although both bait stations reduced feeding by wild pigs compared with control sites. From near-video imagery at 3 field sites, we identified that 80% of wild pigs (33 of 41), 0% of white-tailed deer (0 of 7), and 17% of raccoons (1 of 6) accessed the bait stations on the final night of testing following a 2-week acclimation and training period. Future steps toward development of a wild pig-specific bait station include adding resistance to the lids of bait stations to completely exclude raccoons and identify baiting strategies that most efficiently acclimate wild pigs to using bait stations. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Native to the eastern United States, American bullfrogs have been introduced throughout the western U.S. and to several other countries and islands around the world. Bullfrogs are well adapted for many of the permanent water sources that occur within the U.S., and once introduced, they typically become dominant. Because of their large size and voracious appetite, bullfrogs outcompete and prey upon many indigenous species. They are hypothesized to be cause significant negative impacts, which may contribute to the endangerment and extinction of some sensitive species. There are few, if any, effective and efficient control methods to manage invasive bullfrogs. Current methods such as hand or net capture, shooting, and gigging can be labor intensive and often fail to reduce bullfrog numbers. Draining wetland habitats and broadcasting toxicants have severe negative effects on non-target species. New management options, such as locally-sprayed toxicants and multiple-capture traps, could be useful for reducing populations of invasive bullfrogs. However, researchers should make certain that non-target species are not affected by these management techniques.