Arizona’s diverse climate patterns and geologic features contribute to the unique ecological regions and species assemblages found throughout the state. These landscapes include a host of environments, ranging from alpine tundra conditions found on the San Francisco Peaks where elevation exceeds 12,000 feet and precipitation averages up to 40 inches per year, to the Sonoran Desert where average rainfall can be as little as three inches a year and the lowest elevations are just above sea level. Between these extremes exist some of the most diverse habitats in North America which are home to an equally-diverse number of wildlife species.
Many of Arizona’s biodiversity hotspots are inherently vulnerable due to their scarcity or limited extent or both. When additional stressors are placed on vulnerable species and natural communities from anthropogenic sources, the result can be devastating and long lasting. Throughout Arizona’s history and even pre-history, humans have impacted the landscape. Human settlements have caused land conversion, and growing human populations continue to result in loss of wildlife habitat. While mining, agriculture, and timber harvest have been important industries in Arizona since the 1880s, even with modernized practices, these industries continue to present unique challenges to wildlife and the greater environment. More recent and growing industries, such as renewable energy, tourism, outdoor recreation, along with the depletion of groundwater and expansion of transportation and service corridors to meet the needs of our growing population, have exponentially increased stressors to Arizona’s wildlife and their habitats.
Land use changes and modifications to natural disturbance regimes, such as natural fire regimes, are contributing to habitat loss, modification, and fragmentation, resulting in population declines of several native species. These changes are also leading to the introduction and expansion of non-native species that displace native species. In addition, we are just beginning to understand how our actions are contributing to climate variability, and how climate change will influence Arizona’s wildlife, which may intensify existing threats or create new and unexpected challenges.
While these challenges seem daunting, the good news is that there are actions that can be implemented to reduce and, in some cases, eliminate some threats, helping individual species to better cope with remaining challenges. In many cases, reduction of selected threats can increase the resiliency of ecological systems and wildlife communities to other threats.
The threats discussed in this chapter do not represent an exhaustive list of all challenges facing wildlife and their habitats in Arizona. However, these threats are currently having, or are likely to have, the most significant negative effects on fish and wildlife populations in the state. In Chapter 7: Habitat Profiles, these threats are linked to recommended conservation actions for each habitat type. By linking threats with recommended conservation actions, the AWCS provides an actionable plan to guide conservation efforts on the landscape. Specific habitat profiles and their associated threats and conservation actions are particularly valuable for managers, planners, and landowners who are responsible for on-the-ground implementation and local-level management decisions.
Threats are natural processes or human activities that may cause destruction, degradation, and/or impairment of biodiversity and/or habitats.
Conservation actions are activities that can be implemented to reach conservation goals and counteract adverse effects from threats.
One goal of the AWCS is to provide the information needed to easily incorporate environmental responsibility into decision-making processes, thereby facilitating progress while simultaneously conserving our wildlife and preserving the integrity of our landscapes. Regardless of our background, experience, or position, we are all stewards of the land and its resources, and it is up to each of us to protect and care for it. Greater awareness of the effects our actions have on our environment may be the single most important driver of positive change. Incorporating the values of wildlife and natural communities into decision-making processes can be accomplished proactively, complementing economic productivity and ensuring recreational access where needed.
Many of the threats described in this chapter coincide geographically and act in a cumulative or synergistic manner making it difficult, and perhaps impossible, to separate individual causal factors that influence habitats or species. Multiple factors are closely linked in cause-and-effect relationships across spatial and temporal scales. Adverse effects from multiple threats can have cumulative effects that are much more significant than the additive effects alone, with one or more threats predisposing species to additional stressors (Paine et al. 1998). For example, reduced fire frequency from a century of fire suppression, coupled with prolonged dry periods, is partly responsible for conditions that have allowed for major insect outbreaks in recent years (Peet 1988). Affected stands with high tree mortality quickly accumulate dead standing and downed woody fuels, greatly increasing the risk of catastrophic, stand-replacing wildfire. Meanwhile historical grazing practices add an additional layer of complexity by reducing fine fuels and altering structure and composition of forest and woodland communities which further alter the natural fire regime. These highly-disturbed systems are now at greater risk of invasion from non-native species, especially when faced with a changing climate. Species that typically occupy these areas are then forced, if possible, to either adapt or move to more suitable habitat. When suitable habitat conditions disappear, or shift faster than populations can adjust, the likelihood of species extirpation or extinction increases (Malcolm et al. 2006). Given the synergistic effects of multiple factors, it is difficult to predict the overall impact these factors will have on Arizona landscapes, habitats, and wildlife.
For the AWCS, we have adopted a standardized lexicon for threats and conservation actions. Using this standardized approach follows recommendations outlined in “Best Practices for State Wildlife Action Plans” by the Association for Fish and Wildlife Agencies (AFWA 2012). The use of universal terminology for conservation efforts will help facilitate cooperation and collaboration, especially between entities that share resources across state lines and other jurisdictions. Per AFWA’s recommendation, AZGFD adopted the standard lexicon outlined in Salafsky et al. (2008) and adapted this classification of threats and conservation actions for the AWCS. Specific changes included altering the numbering system slightly and removing some categories that have little or no relevance in Arizona.
The establishment of standardized language to describe all threats and conservation efforts is not an easy task, especially in a state as large and diverse as Arizona. The eleven broad categories of threats discussed below represent the most significant challenges to Arizona’s wildlife and habitats today. Sub-categories described in each section have been modified from Salafsky et al (2008) to better reflect those threats unique to Arizona. (Note: Threats are alphabetized and do not indicate priority or ranking in any form.)
Eleven categories of threats