Four major foodborne illness outbreaks in 3 years have led to stricter requirements for leafy greens growers that may satisfy corporate buyers and reassure the public, but also highlight a serious need for more food safety research.

California ground squirrels (Otospermophilus spp.) cause more economic damage to California rangelands than any other rodent (Baldwin et al. 2022). Burrow systems can undermine stock pond dams, ranch roads, and even hillslopes. However, forage loss is generally the primary concern. When asked, ranchers offer detailed qualitative descriptions of the damage ground squirrels cause and how it impacts the economic viability of their operations. Damage by ground squirrels can be particularly concerning because ranching operations are often on the margins of profitability. Unfortunately, few studies have quantified economic losses from ground squirrels. Additionally, ranchers commonly lease grazing land from public agencies. In many cases, agency employees have a limited understanding of ranching operations and generally do not allow for control of ground squirrels. Quantitative data on ground squirrel impacts to rangelands and ranching operations may help land management agencies better understand the challenges faced by their lessees and justify targeted management actions in the future. Therefore, we tested the amount of standing crop removed by ground squirrels across 16 sites on the Central Coast and interior central California 2019 and 2020. Sampling was conducted during a 4 to 6-week period in May and early-June. This timeframe coincided with the period after juvenile squirrels emerged from natal dens, which allowed us to quantify the collective impact that the entire ground squirrel population had on the landscape. We included four different ground squirrel density categories per site: minimal (0-1 squirrel), low (2-6 squirrels), medium (7-15 squirrels), and high (more than 15 squirrels). To quantify ground squirrels, we counted individuals in 0.4-ha plots using binoculars from an observation point outside the plots. We conducted five ground squirrel counts, repeated twice a day over three days for a total of 30 counts per plot, and used the highest number observed in analyses. We estimated standing crop (biomass of herbaceous vegetation) using the comparative yield method. We also evaluated precipitation and livestock grazing intensity in relation to forage production. We found that each ground squirrel reduced standing crop by 27.2 kg per ha. Precipitation also influenced forage production: each cm of precipitation yielded 16.6 kg per ha of additional available forage. In our model, identified effects of livestock grazing intensity; interaction between livestock grazing intensity and ground squirrel abundance; and interaction between precipitation and ground squirrel abundance on residual standing crop were not statistically significant. Although grazing intensity does influence vegetation biomass, we did not identify a significant relationship between the two, likely because we were limited to collecting grazing intensity data at the scale of the field, not at the scale of our survey plots. Despite their economic impacts, ground squirrels are critically important to California rangeland ecosystems. Ground squirrel burrows are documented to provide habitat for native wildlife including burrowing owls (Athene cunicularia) and California tiger salamanders (Ambystoma californiense). Ground squirrel colonies are also known to be associated with increased native bird species richness, diversity, and abundance (Lenihan 2007). Because of these potential benefits to supporting native wildlife, active ground squirrel management should only be conducted on rangelands when ground squirrel damage exceeds levels considered tolerable by ranch managers. The level of damage considered intolerable will likely vary among managers of different sites. Results from this study could help ranchers and other land managers identify when such a threshold is exceeded

Adoption of electronic identification ear tags (EID) and DNA testing by commercial range sheep producers in the Western United States has been low, despite the availability of these technologies for over a decade. Jointly, these technologies offer an approach to provide individual animal performance data to improve flock health, genetic and reproductive management. This project involved a collaboration with five California sheep producers representing a broad geographic range, varying levels of pre-project EID adoption, and diverse operational practices. Tissue samples were collected from, and ear EIDs were placed in, a total of 2,936 rams and their potential lambs. We partnered with a commercial packing company, Superior Farms, to genotype the animals. Superior Farms used a targeted genotyping panel to assign parentage, and link individual animal identification (ID) to camera-graded carcass measurements. This enabled the collection of individual progeny carcass data and provided insight into sire performance, providing for the within-flock identification of prolific sires that were producing lambs with significantly more saleable meat as compared to their flock mates. Overall, almost 91% of lambs were successfully matched to their sire, and prolificacy ranging from 0-135 lambs per ram. There was as much as an $80 difference in the average edible product from camera-graded carcasses derived from lamb groups sired by different rams. A partial budget analysis modeling investment in an EID system coupled with an autodrafter and scale to collect individual weights and improve labor efficiency during processing, and a sheep flip chute to improve worker safety during foot trimmings, yielded a greater than 7:1 return on investment over a five-year time frame. Ideally, the data collection enabled by EIDs and DNA testing would feed into data-driven genetic evaluation programs to enable selection for more productive and profitable animals, and allow the US sheep industry to accelerate the rate of genetic improvement.