If this pattern is indeed driven by space use intensity, there are many possible explanations— for instance, perhaps these species, in an attempt to avoid cannabis farms, end up concentrated in smaller areas. The results for deer are at least partially consistent with other studies that indicate they generally have a neutral occupancy response to human presence and footprint, but have an increased intensity of use response . Another potential emerging pattern is the possible behavioral flexibility of some mesopredator/omnivore species, lending limited support to our alternative hypothesis that omnivores would display greater variation in space use responses. While less consistent across all omnivores than the pattern with herbivores and ground birds above, gray fox, striped skunk, and raccoons all displayed different potential ability to use the space on and nearby cannabis farms. Fox occupancy probability decreased with distance to cannabis, implying a potential attraction to cannabis farms. Raccoon and striped skunk detection probability decreased with distance to cannabis, implying that they may have a higher space use intensity near to cannabis farms. This is consistent with other studies that demonstrate that these species are often behaviorally flexible and able to coexist in human-dominated spaces . This association with mesopredator use of human spaces is also often explained via mesopredator release, when larger predators avoid an area of disturbance and thereby open a niche for smaller predators . What is interesting is that in this case, however, our alternative hypothesis that carnivores would avoid farms was not supported, and predators largely did not respond to cannabis. Bear and coyote occupancy and detection did not respond to cannabis, 4×8 botanicare tray and although puma did not have enough detections to include in the single species models, one was photographed in the middle of one of our study farms.
Bobcat detection probability did increase with distance from cannabis farm but did not have a meaningful occupancy response. In fact, all four of these large predators were photographed at least once in the middle of a cannabis farm . Also interesting is that there was not a clear pattern of response for small mammal species that might be prey for the mesopredators. Unlike our alternative hypothesis that predicted a general attraction for all small mammals to cannabis farms, tree squirrels and ground squirrels had opposing responses. Tree squirrel occupancy increased with detection from cannabis farms, indicating avoidance, while ground squirrel occupancy decreased. For ground squirrels, our models suggest that while they are frequently found near cannabis farms, their space use intensity may be lower closer to farms. Again, there may be multiple reasons for this, but one possibility is that cannabis farms are being developed on ideal ground squirrel habitat, and while the squirrels have not yet relocated away from the farms, they are not as active on these sites due to the disturbance associated with the farms. Alternatively, cannabis farms may be creating new habitat for ground squirrels by clearing vegetation and irrigating the land, and the lower detection may simply reflect lower population densities as fewer individuals have discovered the new sites. It would be interesting to see whether these patterns change over time.This study has many limitations that are important to acknowledge. First, cannabis production comes in many forms in different locations, and this study does not represent all of them. This study is most applicable for small-scale and mixed light outdoor cannabis cultivation occurring on private lands in legacy production regions of the rural Western US. It is very likely that larger farms would have a greater impact on wildlife than those included in this study, or that farms developed in areas with existing agriculture might have less, or different kinds of effects.
Because cannabis production is often unique from other forms of agriculture, these types of observational studies are valuable and merit repeating in different contexts. Next, we recognize we are applying occupancy modeling for a purpose that it was not directly designed for, and in doing so, we are violating multiple assumptions of the model. The use of occupancy modeling to assess space use relationships is increasingly common in wildlife studies , and we have done our best to account for the violation of assumptions in our modeling approach. Ultimately, we have confidence in our results. For example, we included domestic dogs because their space use patterns are already well understood on the landscape. That the models reflect our understanding of reality on the ground for this domestic species gives us confidence in the results for the unknown wild species. One major limitation of our approach to interpreting detection as a combination of detectability and space use intensity is that the two are not entirely separable. We have included covariates that we believe address one aspect more than the other, but there could be unaccounted for detectability variables that confound our interpretation of space use intensity. More caution should therefore be taken when interpreting the detection results compared to the occupancy results. Future studies might be able to help disentangle some of these effects by examining temporal activity patterns of wildlife in addition to space use intensity. Finally, these data are all observational, and therefore cannot address specific mechanisms by which cannabis may affect local wildlife. Future studies isolating potential mechanisms of deterrence and attraction would help elucidate some of the species-specific behaviors documented in this study . Understanding the pathways by which wildlife respond to disturbance is critical for mitigating the impacts of anthropogenic change . It is well understood that wildlife respond to human disturbance in complex ways, which can have individual, population, and community effects .
To piece apart these complex interactions, it can be useful to isolate particular sources of disturbance and their effects on wildlife. Two sources of disturbance that have been identified as major anthropogenic drivers of wildlife behavioral change are light and noise pollution. Artificial light at night is an increasing global phenomenon, with the coverage of outdoor areas illuminated by artificial light increasing by 2.2% per year . This global increase in light can have far ranging consequences across taxa, including by causing animal disorientation, and by disrupting behavior or interactions . Noise pollution has been less studied than light pollution, however, the effects of noise on wildlife are also global, and may have individual, population, and community level impacts including disrupted reproductive signaling or prey vigilance, and added cumulative stress . Controlled experiments provide a powerful tool for exploring causal relationships between disturbance sources, such as light and sound, and wildlife responses . Experiments on noise and light effects are typically focused on individual species or taxa, but field experiments in particular offer an opportunity to study interactive effects of noise and light pollution . However, this approach is largely under-utilized, due to the logistical challenges of implementing such studies . Here, I describe an experimental approach to studying the separate and interactive effects of point source noise and light pollution on multi-taxa wildlife communities. Specifically, my approach applies a comprehensive experimental design to understand the effects of noise and light pollution commonly associated with cannabis farming. Recreational cannabis production in the western United States has been increasing rapidly following state-level legalization . Influenced by its illicit history, outdoor cannabis is often grown in remote and bio-diverse regions with minimal other non-timber agriculture . In these legacy systems, the proximity of cannabis to wilderness areas may lead to unusual disturbance patterns associated with cannabis cultivation where relatively small point source disturbances are surrounded by a matrix of more intact vegetation . Outdoor and mixed light cannabis farming presents a particular concern for environmental impacts because of their use of bright lights and loud equipment such as generators and fans . Observational research indicates that cannabis production is likely to affect wildlife space use . However, current research has not distinguished between sources of disturbance on cannabis farms, which is critical for designing appropriate interventions, including policy, to mitigate the effect of these disturbances. In this study, I designed and implemented an experiment to investigate the individual and combined effects of light and noise from cannabis farms on local wildlife. I was particularly interested in the impact of new developing farms in rural areas. To approach this question, I designed a series of experimental field trials that mimic light and sound disturbance from outdoor, greenhouse, flood table for greenhouse and mixed light cannabis production, and a monitoring array to measure resulting wildlife responses. The preliminary results of this effort to design and trial a comprehensive study of anthropogenic noise and light effects on wildlife are promising. Results to date suggest that this experimental design may be sufficiently rigorous, with enough sampling to quantify relationships and thresholds for different taxonomic groups in their response to experimental light and noise treatments that mimic conditions on cannabis farms. While more data needs to be collected, sorted, and analyzed, the study design detailed here may be sufficient for this study’s objectives and useful for other researchers interested in community responses to disturbance. Preliminary visualizations indicate that there will likely be species- and taxa- specific responses to each disturbance treatment. These results provide an early indication that I may be able to capture fairly fine-scale responses of at least medium-large mammals and flying insects. Current results mainly provide insights on response to light treatments, since there were fewer sound and combined light/sound trials in the first season of data collection. Considering I have not yet implemented more complex modeling to account for seasonal variations or other covariates, it is surprising that there is already an indication of mammalian avoidance and flying insect attraction to light treatments, providing limited support for hypothesized relationships.
Future analysis of these data will involve more complex Generalized Linear Mixed Model approaches, as has been used in other studies on light and noise effects on wildlife . This will allow me to account for seasonal variation or other covariates, examine potential habituation effects over time, and incorporate decibel and light intensity measurements at each site. Its just after 9 p.m. on a cold night in Shreverport Louisiana. A homeless African American man, Fate Winslow, approaches a man on the street and asks him what he is looking for. The man however, is no ordinary individual, the man that Fate approaches is an undercover cop. The cop tells him he wants two bags and promises him a $5 commission. Being homeless and in need of a meal for the night, Fate takes the officers money and returns with two bags of marijuana, after which he is ushered into the backseat of a patrol car. Three months later, Winslow is found guilty of selling a schedule 1 narcotic and is sentenced to life in a hard prison camp without the possibility of parole. Winston’s fate to die behind bars for a miniscule amount of pot is hard to believe, but it is not unique. While it would be comforting to think Fate’s was the only of its kind, unfortunately, this is not the case. As of August 2013, there are approximately 3,278 people serving life sentences without the possibility of parole for non –violent offenses according to the American Civil Liberties Union 2013 report. And, 79% of those individuals are sentenced for non-violent drug offenses . This reality is ever more shocking when considering that 23 states have legalized the medical use of marijuana, and 3 states and the District of Columbia, have legalized cannabis for recreational purposes for individuals over the age of 21. What do we make of this perplexing contradictory view of marijuana as medicine on one hand, and a criminal substance so abhorrent that we need to lock up users and sellers for the rest of their lives on the other?Some revere cannabis as the vehicle to spiritual enlightenment and consciousness , while others consider it to be a direct revelation from God . Many advocates claim marijuana has various health benefits all the way from the treatment of asthma, multiple sclerosis, nausea and glaucoma . Still, others condemned it as the road to perdition . How are we to understand these perplexing, polarizing and seemingly contradictory opinions of a plant that has no acute dangerous effects and which has caused no known overdoses ? People have reported feeling more relaxed and peaceful and that their thoughts were more profound and deeper .