Showing papers by "Roger A. Baldwin published in 2018"
TL;DR: Overall, there does not appear to be a substantially greater risk of crop loss or contamination of foodborne pathogens in crops bordered by hedgerows in the Sacramento Valley, although potential damage could vary by the stage and type of crop and wildlife species present.
21 citations
TL;DR: While grassland restoration may promote persistence of native plant communities, restoration may not be beneficial to higher trophic levels, and in fact may reduce habitat value for some native predators in grasslands invaded by Mediterranean plant species.
Abstract: 1.In California's Central Valley, most native grasslands have been destroyed or degraded due to invasion, farming, and development. Grassland restoration is often assumed to provide improved wildlife habitat, ostensibly increasing the abundance and diversity of at least some native wildlife species relative to unrestored, invaded annual grasslands.
2.We compared rodent, snake and raptor activity and species richness at paired unrestored and restored grasslands across four blocked locations in the Central Valley using trapping and observational surveys in up to four seasons per guild from 2014–2015. Restored treatments were planted with native perennial grasses 13–24 years prior to study initiation but were partially re-invaded by Mediterranean annual grasses and forbs. Unrestored treatments contained similar non-native plant species assemblages as restored treatments, but did not contain any native grass.
3.Rodent, snake and raptor activity was generally higher in unrestored relative to restored treatments. For rodents, the non-native Mus musculus (house mouse) showed the greatest disparity in abundance, while greater raptors and snakes likely responded to greater rodent abundance.
4.Within treatments, species-specific rodent responses were related to structure of physical vegetation. In particular, Peromyscus maniculatus (native deer mouse) was associated with more bare ground and shorter vegetation, while the house mouse was associated with less bare ground and taller vegetation, regardless of treatment type. Substantial changes in rodent species composition were observed over short periods of time (< 3 months) after unplanned manipulation of vegetation structure via livestock grazing, with patterns reflecting the species-specific response to physical vegetation structure.
5.Synthesis and applications. Our results reveal that while grassland restoration may promote persistence of native plant communities, restoration may not be beneficial to higher trophic levels, and in fact may reduce habitat value for some native predators in grasslands invaded by Mediterranean plant species. Changes in vegetation structure can strongly impact wildlife species composition, suggesting a more nuanced approach is required for the restoration of desired wildlife communities. Thus, species-specific goals should be carefully considered to ensure improved alignment of restoration methods with expected restoration outcomes.
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8 citations
TL;DR: Following laboratory and field-enclosure trials, the use of a mechanical mixer was determined to be the more practical option given that it is quicker and requires less effort for mixing large quantities of bait, it minimized worker exposure to phosphine, and because it yielded mean concentrations that were closer to target values.
4 citations
TL;DR: A mesocosm-based study in central California, USA, to test the efficacy of anthraquinone and vegetation management for reducing girdling damage caused by California voles and appears to have substantial utility for minimizing vole girdle damage.
Abstract: Vole (Cricetidae) girdling of tree trunks is a common form of damage experienced by tree and vine growers throughout much of the Northern Hemisphere. Management programs that effectively incorporate chemical repellents and vegetation management would be of substantial assistance to growers that experience such damage. Anthraquinone has proven effective as a repellent against voles in lab trials, yet controlled field tests of combined anthraquinone and vegetation management programs are lacking. Therefore, we established a mesocosm-based study in central California, USA, to test the efficacy of anthraquinone and vegetation management for reducing girdling damage caused by California voles Microtus californicus to Clementine citrus trees Citrus clementine under semi-field conditions. We observed a 90–100% reduction in girdling damage for trees following a single application of anthraquinone during two trials in summer and spring, respectively. Removal of vegetation around the base of trees further reduced damage during the summer sampling period, with no girdling observed on anthraquinone-treated trees that were surrounded by bare soil. We did not observe this same relationship during spring, and we observed no relationship between vegetation management in the absence of anthraquinone treatments in either seasonal trial, suggesting that vegetation management had a lesser impact on vole girdling than anthraquinone applications. We observed no decrease in efficacy of anthraquinone across the duration of both sampling periods (5–6 weeks), indicating substantial longevity for anthraquinone. Anthraquinone appears to have substantial utility for minimizing vole girdling damage. Field testing is warranted for additional mammalian species to determine potential uses for other taxa.
4 citations
01 Jan 2018
TL;DR: This publication helps producers evaluate livestock lethal and non-lethal protection tools that may fit their site-specific needs.
Abstract: Author(s): Macon, Dan; Baldwin, Roger; Lile, David; Stackhouse, Jeff; Rivers, Carissa Koopmann; Saitone, Tina; Schohr, Tracy; Snell, Laura; Harper, John; Ingram, Roger; Rodrigues, Kim; Macaulay, Luke; Roche, Leslie | Abstract: Conflicts between livestock and predators are perhaps inevitable, especially on extensively managed rangelands This publication helps producers evaluate livestock lethal and non-lethal protection tools that may fit their site-specific needs.
4 citations
01 Jan 2018
TL;DR: Baldwin et al. as discussed by the authors evaluated the effectiveness of prebaiting with zinc phosphide-coated cabbage in managing ground squirrels in Siskiyou, Modoc, and Lassen Counties.
Abstract: Author(s): Baldwin, Roger A.; Halbritter, Heather; Meinerz, Ryan; Snell, Laura K.; Abbo, Benjamin G.; Goldade, David A. A.; Orloff, Steve B. | Abstract: Belding’s ground squirrels (Urocitellus beldingi) cause extensive damage in alfalfa and other hay crops throughout substantial portions of the Intermountain West. Recent management efforts have largely focused on shooting, burrow fumigation, and occasionally grain baits. However, these tools are often either too costly to implement or ineffective. In 2015, the California Department of Pesticide Regulation approved a Special Local Needs permit to use zinc phosphide-coated cabbage for managing Belding’s ground squirrels in Siskiyou, Modoc, and Lassen Counties. This baiting strategy could provide a cost effective and efficacious management approach, although efficacy data were lacking. Therefore, we established a study to assess the importance of spatial variability of location sites, prebaiting, and ground squirrel density on efficacy of zinc phosphide-coated cabbage for Belding’s ground squirrel management across impacted hay-growing regions in northeastern CA. We also assessed potential differences in bait mixing strategies (in a tub via hand mixing vs. the use of a commercial-style cement mixer) on targeted zinc phosphide concentrations, as well as the degradation rate of zinc phosphide and moisture content of cabbage under environmental conditions. We did not detect a significant difference between hand and mechanical mixing. However, mechanical mixing was closer to the target level (mean = 101% vs. 115% for mechanical and hand mixing, respectively), was more precise, and allowed for the mixing of larger batches. As such, mechanical mixing was the strategy we used for field application. Furthermore, both moisture content (0.29% loss per hour) and zinc phosphide concentration (31% loss in 48 hours) steadily declined during a three-day observation period, indicating a fairly minimal window of exposure for nontarget species. See Baldwin et al. (2018) for additional details on lab testing of mixing methods and residual zinc phosphide levels associated with cabbage bait. During field trials, we found that prebaiting increased overall efficacy by approximately 18%, with efficacy 23% greater in the western (eastern Siskiyou and western Modoc Counties) vs. eastern portions (south-central Modoc County) of the study area. The tested bait was also substantially more efficacious when initial ground squirrel populations were larger, presumably due to a greater need for forage at high densities. Ground squirrel activity was relatively consistent throughout the day, although peaks were noted from 09:00 to 11:00 and from 13:00 to 15:00. Consumption of cabbage bait diminished throughout the day after initial application. Consumption was again high the following morning, but again diminished throughout the remainder of the day. Ideal times for bait application were likely before 09:00 and again before 13:00, although ground squirrels continued to feed on bait throughout the day. Zinc phosphide-coated cabbage bait appears to be an effective management option when prebaiting is used in Siskiyou County and in western portions of Modoc County. Additional research is needed to determine methods to increase efficacy in central and eastern Modoc County. See Baldwin et al. (2019) for additional details on this study.
1 citations
01 Jan 2018
TL;DR: The removal of vegetation around the base of trees completely eliminated girdling damage for anthraquinone-treated trees during summer, although vegetation did not significantly impact damage for untreated trees duringSummer, nor for either anthraquone- treated or untreated Trees during spring.
Abstract: Author(s): Baldwin, Roger A.; Meinerz, Ryan; Witmer, Gary W.; Werner, Scott J. | Abstract: California voles cause extensive damage to tree crops through girdling of young stems. Recent laboratory trials have indicated substantial repellency (up to 84%) of anthraquinone (a post-ingestive repellent) to voles on treated grain. Given these lab results, we established a field study to test the efficacy of anthraquinone applications to tree stems to reduce girdling damage from voles. We also assessed the impact of vegetation around the base of trees to determine the impact of cover on girdling activity. In Fresno County, CA, during summer 2016 and spring 2017, we established twenty 3.35 × 2.44-m bins (hereafter mesocosms) where we evenly spaced eight 1-yr-old clementine orange trees. Cover crops including various grasses and forbs were planted on randomly-selected halves of each mesocosm. All trees were treated with anthraquinone in half of the mesocosms; trees were left untreated in the remaining half. We captured 40 voles and released two individuals into each mesocosm and tracked girdling damage once weekly for five weeks during summer and six weeks during spring. We observed a significant reduction in girdling damage on anthraquinone-treated trees. The removal of vegetation around the base of trees completely eliminated girdling damage for anthraquinone-treated trees during summer, although vegetation did not significantly impact damage for untreated trees during summer, nor for either anthraquinone-treated or untreated trees during spring. We did not observe an increase in damage over time in anthraquinone-treated mesocosms, indicating that anthraquinone maintained its repellency during the duration of this study. Anthraquinone appears to be highly repellent to voles, and it is worthy of field study in other mammalian species as well.
01 Jan 2018
TL;DR: Meinerz et al. as discussed by the authors evaluated the effectiveness of two different CO2 injection devices for managing ground squirrels and pocket gophers: the Pressurized Exhaust Rodent Controller (PERC) and Cheetah rodent control machine.
Abstract: Author(s): Meinerz, Ryan; Kavermann, Matthew; Orloff, Steve B.; Baldwin, Roger A. | Abstract: Pocket gophers and ground squirrels cause extensive damage to many crops. Pressurized exhaust injection devices are increasingly used for managing these rodents, although no data were available to support their use. Therefore, we established a study to: 1) determine the efficacy of pressurized exhaust machines for pocket gopher and ground squirrel management, 2) compare these results to other burrow fumigant options, and 3) compare their cost effectiveness. Specifically, we tested two different pressurized exhaust machines for both ground squirrels and pocket gophers: Pressurized Exhaust Rodent Controller (PERC), and 2) Cheetah rodent control machine. For California ground squirrels, efficacy for the PERC machine was greater in moist soils (mean = 100%) than in drier soils (mean = 66%). Initial treatments using the PERC machine were more expensive than other burrow fumigation options, given the large cost of the machine. However, costs quickly dropped below that of gas cartridges (~44 days), and eventually dropped below that of aluminum phosphide if used extensively (~830 days). Efficacy for the Cheetah rodent control machine was far less encouraging for California ground squirrels, with results showing increased squirrel numbers at treatment sites (mean = +115%) post-treatment. For pocket gophers, aluminum phosphide (mean = 86%) and trapping (mean = 81%) proved to be more effective than PERC applications (mean = 56%) in heavy organic soils. We observed somewhat greater PERC efficacy in mineral soils (mean = 68%), suggesting potential variability in efficacy across soil types. At this point, the use of the PERC machine appears to be a viable option for inclusion into Integrated Pest Management programs for burrowing rodents where alternative options are limited; the Cheetah rodent control machine showed no utility for ground squirrel management in our study. More extensive testing of pressurized exhaust devices in differing soil types and under variable moisture levels is needed to determine their utility across a broader spectrum of treatment situations.
01 Jan 2018
TL;DR: Macon et al. as discussed by the authors conducted a longitudinal survey of rangeland cattle, sheep and goat producers in northern California to quantify the direct and indirect impacts from gray wolves, which are increasing in numbers in the state, and other large carnivores on rangelands livestock production.
Abstract: Author(s): Macon, Dan; Lile, David; Stackhouse, Jeff; Rivers, Carissa Koopmann; Schohr, Tracy; Snell, Laura; Harper, John; Ingram, Roger; Rodrigues, Kim; Baldwin, Roger A.; Saitone, Tina; Macaulay, Luke; Roche, Leslie | Abstract: While the direct economic impacts of gray wolves and other predators on rangeland livestock production are relatively easy to measure, indirect impacts (e.g., reduced livestock productivity and increased expense) may be more economically significant. We initiated a long-term (10 year), longitudinal survey of rangeland cattle, sheep and goat producers in northern California to quantify the direct and indirect impacts from gray wolves, which are increasing in numbers in the state, and other large carnivores on rangeland livestock production. During winter/spring 2017, we hosted seven producer-researcher workshops across northern California, featuring livestock-predator conflict experts. At these workshops, we collected the first round of survey data from 90 livestock operations. Our initial survey results document the adoption rates, efficacy and cost of a variety of commonly used livestock protection tools on rangeland livestock operations at a variety of scales.