Landscape Characteristics Predict Locations for Potential Human–Wildlife Interactions With Timber Rattlesnakes in Minnesota, USA

While management measures cannot eliminate human–wildlife conflicts, they have the potential to minimize the damage done to both parties, especially if areas where the nature of the potential interaction can be predicted before an encounter occurs. The timber rattlesnake (Crotalus horridus) represents a wildlife species associated with public misconceptions that may foster unwarranted fears and retribution. This species is native to the eastern and southern regions of the United States, including a small population remnant in the southeastern region of Minnesota. To gain a better understanding of the environmental predictors relevant to human–snake encounters in Minnesota (that require action such as relocation), we studied point locations of human–snake interactions requiring human intervention in Winona County in southeastern Minnesota over a 13-year period between 2006 and 2019. We used the points to create a model to predict areas of increased potential for human–snake interactions. Our analysis identified areas with high potential for such contact between humans and rattlesnakes. This research highlighted environmental factors favorable to timber rattlesnake encounters with humans and may serve as a guide for management efforts to mitigate human–snake conflicts

Simulations Reveal the Power and Peril of Artificial Breeding Sites for Monitoring and Managing Animals

Despite common use, the efficacy of artificial breeding sites (e.g., nest boxes, bat houses, artificial burrows) as tools for monitoring and managing animals depends on the demography of target populations and availability of natural sites. Yet, the conditions enabling artificial breeding sites to be useful or informative have yet to be articulated. We use a stochastic simulation model to determine situations where artificial breeding sites are either useful or disadvantageous for monitoring and managing animals. Artificial breeding sites are a convenient tool for monitoring animals and therefore occupancy of artificial breeding sites is often used as an index of population levels. However, systematic changes in availability of sites that are not monitored might induce trends in occupancy of monitored sites, a situation rarely considered by monitoring programs. We therefore examine how systematic changes in unmonitored sites could bias inference from trends in the occupancy of monitored sites. Our model also allows us to examine effects on population levels if artificial breeding sites either increase or decrease population vital rates (survival and fecundity). We demonstrate that trends in occupancy of monitored sites are misleading if the number of unmonitored sites changes over time. Further, breeding site fidelity can cause an initial lag in occupancy of newly installed sites that could be misinterpreted as an increasing population, even when the population has been continuously declining. Importantly, provisioning of artificial breeding sites only benefits populations if breeding sites are limiting or if artificial sites increase vital rates. There are many situations where installation of artificial breeding sites, and their use in monitoring, can have unintended consequences. Managers should therefore not assume that provision of artificial breeding sites will necessarily benefit populations. Further, trends in occupancy of artificial breeding sites should be interpreted in light of potential changes in the availability of unmonitored sites and the potential of lags in occupancy owing to site fidelity

Using Motion-Activated Trail Cameras to Study Diet and Productivity of Cliff-Nesting Golden Eagles

Studies of cliff-nesting raptors can be challenging because direct observations of nest contents are difficult. Our goals were to develop a protocol for installing motion-activated trail cameras at Golden Eagle (Aquila chrysaetos) nests to record diet information and productivity, and to estimate prey detection probability using different diet study methods. In 2014 and 2015, we installed cameras at 12 Golden Eagle nests with 18–42-d-old nestlings. Following installation, we monitored adult behavior using direct observation and post-installation image review. At two nests, adult eagles did not return to nests or exhibited behaviors suggesting avoidance of the cameras, but returned to the nests after cameras were removed. We visited the 10 remaining nests every 4 d to collect prey remains and pellets to generate prey-specific detection estimates for both images, and prey remains and pellets. Compared to inspection of prey remains and pellets, cameras recorded twice the number of prey (622 vs. 316), were more likely to detect the smallest and largest prey, and cost half as much. Cameras recorded productivity, fledging dates, and in one case, a nestling death. Trail cameras may be a reliable and cost-effective option to address clearly defined research goals and obtain required information about eagle behavior and nest contents. However, cameras should be used judiciously because installation creates a persistent manipulation at the nest. Camera appearance should be minimized, and post-installation monitoring that allows for timely responses to nest-avoidance behavior by adult eagles is important to prevent adverse effects on nesting success

SEARCH: Spatially Explicit Animal Response to Composition of Habitat.

Complex decisions dramatically affect animal dispersal and space use. Dispersing individuals respond to a combination of fine-scale environmental stimuli and internal attributes. Individual-based modeling offers a valuable approach for the investigation of such interactions because it combines the heterogeneity of animal behaviors with spatial detail. Most individual-based models (IBMs), however, vastly oversimplify animal behavior and such behavioral minimalism diminishes the value of these models. We present program SEARCH (Spatially Explicit Animal Response to Composition of Habitat), a spatially explicit, individual-based, population model of animal dispersal through realistic landscapes. SEARCH uses values in Geographic Information System (GIS) maps to apply rules that animals follow during dispersal, thus allowing virtual animals to respond to fine-scale features of the landscape and maintain a detailed memory of areas sensed during movement. SEARCH also incorporates temporally dynamic landscapes so that the environment to which virtual animals respond can change during the course of a simulation. Animals in SEARCH are behaviorally dynamic and able to respond to stimuli based upon their individual experiences. Therefore, SEARCH is able to model behavioral traits of dispersing animals at fine scales and with many dynamic aspects. Such added complexity allows investigation of unique ecological questions. To illustrate SEARCH\u27s capabilities, we simulated case studies using three mammals. We examined the impact of seasonally variable food resources on the weight distribution of dispersing raccoons (Procyon lotor), the effect of temporally dynamic mortality pressure in combination with various levels of behavioral responsiveness in eastern chipmunks (Tamias striatus), and the impact of behavioral plasticity and home range selection on disperser mortality and weight change in virtual American martens (Martes americana). These simulations highlight the relevance of SEARCH for a variety of applications and illustrate benefits it can provide for conservation planning

Commentary: Research Recommendations for Understanding the Decline of American Kestrels (\u3cem\u3eFalco sparverius\u3c/em\u3e) Across Much of North America

Across much of North America, populations of American Kestrels (Falco sparverius) have been in decline for decades (Farmer et al. 2008, Farmer and Smith 2009, Smallwood et al. 2009a, Paprocki et al. 2014, Sauer et al. 2014). Hypothesized causes of kestrel declines include predation by Cooper\u27s Hawks (Accipiter cooperii; Farmer et al. 2008), pathogens (e.g., Nemeth et al. 2006), habitat loss (Sullivan and Wood 2005, Farmer et al. 2008, Bolgiano et al. 2015), pesticides (Smallwood et al. 2009a, Rattner et al. 2015), and climate change (Steenhof and Peterson 2009b), yet no hypothesized factor has been supported empirically (Farmer et al. 2006, Smallwood et al. 2009a). Despite the effort spent evaluating threats, the lack of a “smoking-gun” to explain the decline of this charismatic species has led many professional and citizen scientists to call for action on several unlikely, and unsupported, threats. Here, we evaluate and build on hypothesized causes of declines considered by other authors (e.g., Sullivan and Wood 2005, Farmer et al. 2008, Smallwood et al. 2009a) to synthesize conclusions and articulate research needs

Does Personality Affect the Probability That Piute Ground Squrriels (\u3cem\u3eUrocitellus Mollis\u3c/em\u3e) Will Be Shot by Recreational Hunters?

Recreational shooting of Piute ground squirrels (Urocitellus mollis) in southern Idaho is an activity growing in popularity. One factor that may influence shooting success is the personality of individuals within a population. We hypothesized that bold individual ground squirrels would be more/less likely to be targeted by a hunter and would be more/less disturbed by gun fire. To test these hypotheses, we simulated recreational shooting to identify which personalities are more susceptible hunters and more responsive to gun fire. We preformed simulations in March of 2015 on a population of Piute ground squirrels with known personalities. Bold and shy individuals were coded by dying the fur of squirrels in a way distinguishable by observers during simulations which took place at three sites with varying vegetative cover. We recorded the frequency of detection of each personality type through a hunting scope. In addition, we observed the behavioral response (e.g. flee, vigilance, alarm call) of ground squirrels to a recording of a .22 caliber fire. We also identified whether raptors were attracted to the simulated shooting area for scavenging in response to the sound of the gun fire. We calculated whether the detection and behavioral responses of squirrel personalities in shooting simulations was disproportionate to that of the marked population. This information can lead to a greater understanding of the role of behavioral factors in the survival of Piute ground squirrels and provide insight into how recreational shooting could influence the personality landscape of a dominant prey species

Habitat Features Predict the Distribution of Recreational Shooters in the Morley Nelson Snake River Birds of Prey National Conservation Area

The Morley Nelson Snake River Birds of Prey National Conservation Area (NCA) is a popular destination of many Treasure Valley residents. There, recreationists participate in various pastimes such as target shooting, recreational shooting/hunting, and wildlife viewing. However, these activities have the potential to interfere with one another. Recreational shooting of Piute ground squirrels (Urocitellus mollis) could affect prey availability and scavenging opportunities for associated raptor species, most notably local golden eagle (Aquila chrysaetos) populations. To assess possible interactions among shooters, prey and raptors, the spatial density and habitat preference of human shooters must be determined. We hypothesized that higher shooter density would be correlated with proximity to high-use roads and habitat with high visibility. To test this hypothesis, the spatial density and habitat preference of human shooters was determined. First, three routes of approximately 16 km each were established throughout the northwest section of the NCA through “hunter hotspots” of various habitat types. Routes were driven on weekends, starting in the morning, from February 28 to March 21, 2015. Data was collected opportunistically on all shooters observed including group size, demographics, location, and the habitat characteristics (e.g. proximity to roads and visibility) of shooting sites. These data were used to determine which habitat features best predicted shooting locations. This study may directly inform future research on golden eagle scavenging ecology, competition between hunters and eagles, and the potential for lead entry into the ecosystem through use of lead ammunition

Secondary magnetic inclusions in detrital zircons from the Jack Hills, Western Australia, and implications for the origin of the geodynamo

The time of origin of Earth’s dynamo is unknown. Detrital zircon crystals containing ferromagnetic inclusions from the Jack Hills of Western Australia have the potential to contain the oldest records of the geodynamo. It has recently been argued that magnetization in these zircons indicates that an active dynamo existed as far back as 4.2 Ga. However, the ages of ferromagnetic inclusions in the zircons are unknown. Here we present the first detailed characterization of the mineralogy and spatial distribution of ferromagnetic minerals in Jack Hills detrital zircons. We demonstrate that ferromagnetic minerals in most Jack Hills zircons are commonly located in cracks and on the zircons’ exteriors. Hematite is observed to dominate the magnetization of many zircons, while other zircons also contain significant quantities of magnetite and goethite. This indicates that the magnetization of most zircons is likely to be dominantly carried by secondary minerals that could be hundreds of millions to billions of years younger than the zircons’ crystallization ages. We conclude that the existence of the geodynamo prior to 3.5 Ga has yet to be established

Secondary magnetic inclusions in detrital zircons from the Jack Hills, Western Australia, and implications for the origin of the geodynamo

The time of origin of Earth’s dynamo is unknown. Detrital zircon crystals containing ferromagnetic inclusions from the Jack Hills of Western Australia have the potential to contain the oldest records of the geodynamo. It has recently been argued that magnetization in these zircons indicates that an active dynamo existed as far back as 4.2 Ga. However, the ages of ferromagnetic inclusions in the zircons are unknown. Here we present the first detailed characterization of the mineralogy and spatial distribution of ferromagnetic minerals in Jack Hills detrital zircons. We demonstrate that ferromagnetic minerals in most Jack Hills zircons are commonly located in cracks and on the zircons’ exteriors. Hematite is observed to dominate the magnetization of many zircons, while other zircons also contain significant quantities of magnetite and goethite. This indicates that the magnetization of most zircons is likely to be dominantly carried by secondary minerals that could be hundreds of millions to billions of years younger than the zircons’ crystallization ages. We conclude that the existence of the geodynamo prior to 3.5 Ga has yet to be establishe