Lucas K. Hall

Water Developments and Canids in Two North American Deserts: A Test of the Indirect Effect of Water Hypothesis

Anthropogenic modifications to landscapes intended to benefit wildlife may negatively influence wildlife communities. Anthropogenic provisioning of free water (water developments) to enhance abundance and distribution of wildlife is a common management practice in arid regions where water is limiting. Despite the long-term and widespread use of water developments, little is known about how they influence native species. Water developments may negatively influence arid-adapted species (e.g., kit fox, Vulpes macrotis) by enabling water-dependent competitors (e.g., coyote, Canis latrans) to expand distribution in arid landscapes (i.e., indirect effect of water hypothesis). We tested the two predictions of the indirect effect of water hypothesis (i.e., coyotes will visit areas with free water more frequently and kit foxes will spatially and temporally avoid coyotes) and evaluated relative use of free water by canids in the Great Basin and Mojave Deserts from 2010 to 2012. We established scent stations in areas with (wet) and without (dry) free water and monitored visitation by canids to these sites and visitation to water sources using infrared-triggered cameras. There was no difference in the proportions of visits to scent stations in wet or dry areas by coyotes or kit foxes at either study area. We did not detect spatial (no negative correlation between visits to scent stations) or temporal (no difference between times when stations were visited) segregation between coyotes and kit foxes. Visitation to water sources was not different for coyotes between study areas, but kit foxes visited water sources more in Mojave than Great Basin. Our results did not support the indirect effect of water hypothesis in the Great Basin or Mojave Deserts for these two canids.

Vigilance of kit foxes at water sources: A test of competing hypotheses for a solitary carnivore subject to predation

Animals that are potential prey do not respond equally to direct and indirect cues related to risk of predation. Based on differential responses to cues, three hypotheses have been proposed to explain spatial variation in vigilance behavior. The predator-vigilance hypothesis proposes that prey increase vigilance where there is evidence of predators. The visibility-vigilance hypothesis suggests that prey increase vigilance where visibility is obstructed. Alternatively, the refuge-vigilance hypothesis proposes that prey may perceive areas with low visibility (greater cover) as refuges and decrease vigilance. We evaluated support for these hypotheses using the kit fox (Vulpes macrotis), a solitary carnivore subject to intraguild predation, as a model. From 2010 to 2012, we used infrared-triggered cameras to record video of kit fox behavior at water sources in Utah, USA. The refuge-vigilance hypothesis explained more variation in vigilance behavior of kit foxes than the other two hypotheses (AICc model weight=0.37). Kit foxes were less vigilant at water sources with low overhead cover (refuge) obstructing visibility. Based on our results, the predator-vigilance and visibility-vigilance hypotheses may not be applicable to all species of prey. Solitary prey, unlike gregarious prey, may use areas with concealing cover to maximize resource acquisition and minimize vigilance.

Relationship between cheatgrass coverage and the relative abundance of snakes on Antelope Island, Utah

ABSTRACT. Cheatgrass (Bromus tectorum) is an invasive annual known to negatively impact many shrub-dependent organisms; however, relatively little research has examined how it affects snake communities. Bromus tectorum is abundant at Antelope Island State Park, Davis County, Utah, and could be a possible threat to snake populations. Study sites representing different B. tectorum coverage percentages were established to measure relative abundance of snakes. Snakes were captured from June to September 2005 primarily by using funnel traps attached to drift-fence arrays. Linear regression revealed a negative relationship between B. tectontm coverage (%) and the relative abundance of the Great Basin gopher snake (Pituophis catenifer deserticola) and the western racer (Coluber mormon). These results (1) suggest that B. tectorum invasions result in reduced snake abundance in shrubsteppe habitat on Antelope Island and (2) add to our understanding of the relationships between B. tectorum and native fauna.

EFFECT OF CHEATGRASS ON ABUNDANCE OF THE NORTH AMERICAN DEERMOUSE (PEROMYSCUS MANICULATUS)

Abstract This study addressed the effects that cheatgrass (Bromus tectorum) had on populations of the North American deermouse (Peromyscus maniculatus) at Antelope Island State Park, Davis County, Utah. Linear regression revealed a significant negative relationship between cover of cheatgrass and relative abundance of North American deermice. These results concur with conclusions of others suggesting that cheatgrass negatively impacts abundance of rodents. Resumen Este estudio consideró los efectos que Bromus tectorum impone a las poblaciones de Peromyscus maniculatus en el Parque Estatal Antelope Island, condado de Davis, Utah. Regresión lineal indicó una relación negativa significativa entre la cobertura de B. tectorum y la abundancia relativa de P. maniculatus. Estos resultados coinciden con las conclusiones de otros que sugieren que B. tectorum afecta negativamente la abundancia de roedores.

Comparative Study of Trapping Methods for Ground-Nesting Shorebirds

Abstract. Several methods exist to capture ground-nesting birds, yet questions remain concerning their effectiveness, cost and safety. An experiment was conducted comparing traps commonly used to capture ground-nesting shorebirds. Data were collected on Snowy Plovers (Charadrius nivosus) nesting at Great Salt Lake, Utah during the 2009 breeding season. The three most common traps used to capture nesting Snowy Plovers (spring trap, walk-in funnel trap, leg-hold noose mats) were compared in the time required to use the trap (e.g. time to install at nest), capture success and construction costs. These results indicated that the funnel trap had the lowest total time at the nest (P < 0.01) and per trapping attempt, highest capture rate, fewest failed set up attempts, low disturbance to the nest site and was the least expensive to build. Based on these findings, the funnel trap should allow avian researchers to maximize their time, resources and efforts when trapping ground-nesting shorebirds.

The influence of periodic increases of human activity on crepuscular and nocturnal mammals: Testing the weekend effect

Human recreation can negatively affect wildlife, particularly on weekends when human activity is highest (i.e., the weekend effect). Much of what we understand about the weekend effect is based on research conducted on diurnal species, which have greater temporal overlap with humans. Because nocturnal species generally avoid times when humans are active, they are likely less affected by anthropogenic activity on weekends. Our objective was to test the weekend effect in relation to the degree of nocturnality of mammals in a recreational area. We predicted that as nocturnality increased, the effect of human activity would decrease. To address our objective, we placed 50 remote cameras along the Diamond Fork River in Utah from January to June 2015. We found that three out of the four focal species supported our predictions. Mule deer (crepuscular) reduced activity throughout our entire study area during weekends and avoided campgrounds. Beavers and mountain lions (both nocturnal) did not negatively respond to increased human activity. Raccoons (nocturnal) reduced activity during weekends, but only within campground areas. Our findings indicate that as the temporal overlap increases between wildlife and humans, so does the influence that humans have on wildlife.